Astrophysics
New submissions
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New submissions for Wed, 26 Feb 20
- [1] arXiv:2002.10460 [pdf, other]
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Title: The solar wind from a stellar perspective: how do low-resolution data impact the determination of wind properties?Authors: S. Boro Saikia, M. Jin, C.P. Johnstone, T. Lüftinger, M. Güdel, V. S. Airapetian, K. G. Kislyakova, C. P. FolsomComments: accepted for publication in A&ASubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Alfv\'en-wave-driven 3D magnetohydrodynamic (MHD) models, which are increasingly used to predict stellar wind properties, contain unconstrained parameters and rely on low-resolution stellar magnetograms. We explore the effects of the input Alfv\'en wave energy flux and the surface magnetogram on the wind properties predicted by the Alfv\'en Wave Solar Model (AWSoM). We lowered the resolution of two solar magnetograms during solar cycle maximum and minimum using spherical harmonic decomposition. The Alfv\'en wave energy was altered based on non-thermal velocities determined from a far ultraviolet (FUV) spectrum of the solar twin 18 Sco. Additionally, low-resolution magnetograms of three solar analogues were obtained using Zeeman Doppler imaging (ZDI). Finally, the simulated wind properties were compared to Advanced Composition Explorer (ACE) observations. AWSoM simulations using well constrained input parameters taken from solar observations can reproduce the observed solar wind mass and angular momentum loss rates. The resolution of the magnetogram has a small impact on the wind properties and only during cycle maximum. However, variation in Alfv\'en wave energy influences the wind properties irrespective of the solar cycle activity level. Furthermore, solar wind simulations carried out using the low-resolution magnetogram of the three stars instead of the solar magnetogram could lead to an order of a magnitude difference in the simulated wind properties. The choice in Alfv\'en energy has a stronger influence on the wind output compared to the magnetogram resolution. The influence could be even stronger for stars whose input boundary conditions are not as well constrained as those of the Sun. Unsurprisingly, replacing the solar magnetogram with a stellar magnetogram could lead to completely inaccurate solar wind properties, and should be avoided in solar and stellar wind simulations.
- [2] arXiv:2002.10462 [pdf, other]
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Title: Populations of double white dwarfs in Milky Way satellites and their detectability with LISAAuthors: V. Korol, S. Toonen, A. Klein, V. Belokurov, F. Vincenzo, R. Buscicchio, D. Gerosa, C. J. Moore, E. Roebber, E. M. Rossi, A. VecchioComments: 9 pages, 6 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Milky Way dwarf satellites are unique objects that encode the early structure formation and therefore represent a window into the high redshift Universe. So far, their study was conducted using electromagnetic waves only. The future Laser Interpreter Space Antenna (LISA) has the potential to reveal Milky Way satellites in gravitational waves emitted by double white dwarf (DWD) binaries. We investigate gravitational wave (GW) signals detectable by LISA as a possible tool for the identification and characterisation of the Milky Way satellites. We use the binary population synthesis technique to model the population of DWDs in dwarf satellites and we assess the impact on the number of LISA detections when making changes to the total stellar mass, distance, star formation history and metallicity of satellites. We calibrate predictions for the known Milky Way satellites on their observed properties. We find that DWDs emitting at frequencies $\gtrsim 3\,$mHz can be detected in Milky Way satellites at large galactocentric distances. The number of these high frequency DWDs per satellite primarily depends on its mass, distance, age and star formation history, and only mildly depends on the other assumptions regarding their evolution such as metallicity. We find that dwarf galaxies with $M_\star>10^6\,$M$_{\odot}$ can host detectable LISA sources with a number of detections that scales linearly with the satellite's mass. We forecast that out of the known satellites, Sagittarius, Fornax, Sculptor and the Magellanic Clouds can be detected with LISA. As an all-sky survey that does not suffer from contamination and dust extinction, LISA will provide observations of the Milky Way and dwarf satellites galaxies valuable for Galactic archaeology and near-field cosmology.
- [3] arXiv:2002.10463 [pdf, ps, other]
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Title: Betelgeuse Just Isn't That Cool: Effective Temperature Alone Cannot Explain the Recent Dimming of BetelgeuseComments: 13 pages, 4 figures; accepted for publication in ApJ LettersSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
We present optical spectrophotometry of the red supergiant Betelgeuse from 2020 February 15, during its recent unprecedented dimming episode. By comparing this spectrum to stellar atmosphere models for cool supergiants, as well as spectrophotometry of other Milky Way red supergiants, we conclude that Betelgeuse has a current effective temperature of 3600 +/- 25 K. While this is slightly cooler than previous measurements taken prior to Betelgeuse's recent lightcurve evolution, this drop in effective temperature is insufficient to explain Betelgeuse's recent optical dimming. We propose that episodic mass loss and an increase in the amount of large-grain circumstellar dust along our sightline to Betelgeuse is the most likely explanation for its recent photometric evolution.
- [4] arXiv:2002.10464 [pdf, other]
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Title: Dimensionality Reduction of SDSS Spectra with Variational AutoencodersComments: 22 pages, 16 figures, submitted to AJ; code available at this https URLSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)
High resolution galaxy spectra contain much information about galactic physics, but the high dimensionality of these spectra makes it difficult to fully utilize the information they contain. We apply variational autoencoders (VAEs), a non-linear dimensionality technique, to a sample of spectra from the Sloan Digital Sky Survey. In contrast to Principal Component Analysis (PCA), a widely used technique, VAEs can capture non-linear relationships between latent parameters and the data. We find that a VAE can reconstruct the SDSS spectra well with only six latent parameters, outperforming PCA with the same number of components. Different galaxy classes are naturally separated in this latent space, without class labels having been given to the VAE. The VAE latent space is interpretable because the VAE can be used to make synthetic spectra at any point in latent space. For example, making synthetic spectra along tracks in latent space yields sequences of realistic spectra that interpolate between two different types of galaxies. Using the latent space to find outliers may yield interesting spectra: in our small sample, we immediately find unusual data artifacts and stars misclassified as galaxies. In this exploratory work, we show that VAEs create compact, interpretable latent spaces that capture non-linear features of the data and that VAEs can enable the fast exploration of large astronomical data sets.
- [5] arXiv:2002.10465 [pdf, other]
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Title: Milky Way Satellites Shining Bright in Gravitational WavesAuthors: Elinore Roebber, Riccardo Buscicchio, Alberto Vecchio, Christopher J. Moore, Antoine Klein, Valeriya Korol, Silvia Toonen, Davide Gerosa, Janna Goldstein, Sebastian M. Gaebel, Tyrone E. WoodsComments: 7 pages, 2 figures, submittedSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
The population of Milky Way satellite galaxies is of great interest for cosmology, fundamental physics, and astrophysics. They represent the faint end of the galaxy luminosity function, are the most dark-matter dominated objects in the local Universe, and contain the oldest and most metal-poor stellar populations. Recent surveys have revealed around 60 satellites, but this could represent less than half of the total. Characterization of these systems remains a challenge due to their low luminosity. We consider the gravitational wave observatory LISA as a potential tool for studying these satellites through observations of their short-period double white dwarf populations. LISA will observe the entire sky without selection effects due to dust extinction, complementing optical surveys, and could potentially discover massive satellites hidden behind the disk of the galaxy.
- [6] arXiv:2002.10467 [pdf, other]
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Title: A new white dwarf companion to the $Δμ$ star GJ 3346Authors: M. Bonavita, C. Fontanive, S. Desidera, V. D'Orazi, A. Zurlo, K. Muzic, B. Biller, R. Gratton, D. Mesa, A. SozzettiComments: 10 pages, 7 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
We present the discovery of a white dwarf companion at 3.6" from GJ3346, a nearby ($\pi\sim$42 mas) K star observed with SPHERE@VLT as part of an open time survey for faint companions to objects with significant proper motion discrepancies ($\Delta\mu$) between Gaia DR1 and Tycho-2. Syrius-like systems like GJ3346AB, which include a main sequence star and a white dwarf, can be difficult to detect because of the intrinsic faintness of the latter. They have, however, been found to be common contaminants for direct imaging searches. White dwarfs have in fact similar brightness to sub-stellar companions in the infrared, while being much brighter in the visible bands like those used by Gaia. Combining our observations with Gaia DR2 and with several additional archival data sets, we were able to fully constrain the physical properties of GJ3346B, such as its effective temperature (11$\times$10$^3\pm$500 K) as well as the cooling age of the system (648$\pm$58 Myrs). This allowed us to better understand the system history and to partially explains the discrepancies previously noted in the age indicators for this objects. Although further investigation is still needed, it seems that GJ3346, which was previously classified as young, is in fact most likely to be older than 4 Gyrs. Finally, given that the mass (0.58$\pm$0.01$M_{\odot}$)} and separation (85 au) of GJ3346B are compatible with the observed $\Delta\mu$, this discovery represents a further confirmation of the potential of this kind of dynamical signatures as selection methods for direct imaging surveys targeting faint, sub-stellar companions.
- [7] arXiv:2002.10468 [pdf, other]
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Title: The Physical Nature of Starburst-Driven Galactic OutflowsComments: 29 pages, 21 figures. Submitted to ApJ. Comments welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present the fourth of the Cholla Galactic OutfLow Simulations suite (CGOLS). Using a physically-motivated prescription for clustered supernova feedback, we successfully drive a multiphase outflow from a disk galaxy. The high resolution ($< 5\,\mathrm{pc}$) across a relatively large domain ($20\,\mathrm{kpc}$) allows us to capture the hydrodynamic mixing and dynamical interactions between the hot and cool ($T \sim 10^4\,\mathrm{K}$) phases in the outflow, which in turn leads to direct evidence of a qualitatively new mechanism for cool gas acceleration in galactic winds. We show that mixing of momentum from the hot phase to the cool phase accelerates the cool gas to $800\,\mathrm{km}\,\mathrm{s}^{-1}$ on kpc scales, with properties inconsistent with the physical models of ram pressure acceleration or with bulk cooling from the hot phase. The mixing process also affects the hot phase, modifying its radial profiles of temperature, density, and velocity from the expectations of radial supersonic flow. This mechanism provides a physical explanation for the high velocity, blue shifted, low ionization absorption lines often observed in the spectra of starburst and high redshift galaxies.
- [8] arXiv:2002.10469 [pdf, other]
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Title: Hidden magnetic fields of young sunsComments: 25 pages, 26 figures; accepted for publication in A&ASubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Global magnetic fields of active solar-like stars are nowadays routinely detected with spectropolarimetric measurements and are mapped with Zeeman-Doppler imaging (ZDI). However, due to the cancellation of opposite field polarities, polarimetry captures only a tiny fraction of the magnetic flux and cannot assess the overall stellar surface magnetic field if it is dominated by a small-scale component. Analysis of Zeeman broadening in high-resolution intensity spectra can reveal these hidden complex magnetic fields. Historically, there were very few attempts to obtain such measurements for G dwarf stars due to the difficulty of disentangling Zeeman effect from other broadening mechanisms affecting spectral lines. Here we developed a new magnetic field diagnostic method based on relative Zeeman intensification of optical atomic lines with different magnetic sensitivity. Using this technique we obtained 78 field strength measurements for 15 Sun-like stars, including some of the best-studied young solar twins. We find that the average magnetic field strength $Bf$ drops from 1.3-2.0 kG in stars younger than about 120 Myr to 0.2-0.8 kG in older stars. The mean field strength shows a clear correlation with the Rossby number and with the coronal and chromospheric emission indicators. Our results suggest that magnetic regions have roughly the same local field strength $B\approx3.2$ kG in all stars, with the filling factor $f$ of these regions systematically increasing with stellar activity. Comparing our results with the spectropolarimetric analyses of global magnetic fields in the same stars, we find that ZDI recovers about 1% of the total magnetic field energy in the most active stars. This figure drops to just 0.01% for the least active targets.
- [9] arXiv:2002.10471 [pdf, other]
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Title: Small-scale structure traced by neutral hydrogen absorption in the direction of multiple-component radio continuum sourcesAuthors: Daniel R. Rybarczyk, Snezana Stanimirovic, Ellen G. Zweibel, Claire E. Murray, John M. Dickey, Brian Balber, Carl HeilesComments: 29 pages, 19 figures, 4 tables. Submitted to ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
We have studied the small scale distribution of atomic hydrogen (HI) using 21-cm absorption spectra against multiple-component background sources from the 21-SPONGE survey and the Millennium Arecibo Absorption Line Survey. We have found $>5\sigma$ optical depth variations at a level of $\sim0.03-0.5$ between 13 out of 14 adjacent sightlines separated by a few arcseconds to a few arcminutes, suggesting the presence of neutral structures on AU scales (we refer to all AU-scale structure as tiny scale atomic structure, TSAS). The optical depth variations are strongest in directions where the HI column density and the fraction of HI in the cold neutral medium (CNM) are highest, which tend to be at low Galactic latitudes. By measuring changes in the properties of Gaussian components fitted to the absorption spectra, we find that changes in both the peak optical depth and the linewidth of TSAS absorption features contribute to the observed optical depth variations, while changes in the central velocity do not appear to strongly impact the observed variations. Both thermal and turbulent motions contribute appreciably to the linewidths, but the turbulence does not appear strong enough to confine overpressured TSAS. In a majority of cases, the TSAS column densities are sufficiently high that these structures can radiatively cool fast enough to maintain thermal equilibrium with their surroundings, even if they are overpressured. We also find that a majority of TSAS is associated with the CNM. For TSAS in the direction of the Taurus molecular cloud and the local Leo cold cloud, we estimate densities over an order of magnitude higher than typical CNM densities.
- [10] arXiv:2002.10473 [pdf, other]
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Title: Multiple Images and Flux Ratio Anomaly of Fuzzy Gravitational LensesComments: 6 pages, 4 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
Extremely light bosonic wave dark matter ($\psi$DM) is an emerging dark matter candidate contesting the conventional cold dark matter paradigm and a model subject to intense scrutiny of late. This work for the first time reports testable salient features pertinent to gravitational lenses of $\psi$DM halos. $\psi$DM halos are distinctly filled with large-amplitude, small-scale density fluctuations with $\delta\rho/\rho_{\rm halo}\sim 1$ in form of density granules. This halo characteristically yields fuzzy gravitational lenses that can yield ubiquitous flux ratio anomalies of few tens percent levels often found in lensed quasar multiple images. These fuzzy lenses may also produce rare hexad images and octad images, formed when the sources are located in some well-defined zones of highly distorted caustics. We have found new critical features appearing in the highly de-magnified lens center when the halo has sufficiently high surface density near a very compact massive core.
- [11] arXiv:2002.10474 [pdf, other]
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Title: High redshift JWST predictions from IllustrisTNG: II. Galaxy line and continuum spectral indices and dust attenuation curvesAuthors: Xuejian Shen, Mark Vogelsberger, Dylan Nelson, Annalisa Pillepich, Sandro Tacchella, Federico Marinacci, Paul Torrey, Lars Hernquist, Volker SpringelComments: Submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present predictions for high redshift ($z=2-10$) galaxy populations based on the IllustrisTNG simulation suite and a full Monte Carlo dust radiative transfer post-processing. Specifically, we discuss the ${\rm H}_{\alpha}$ and ${\rm H}_{\beta}$ + $[\rm O \,III]$ luminosity functions up to $z=8$. The predicted ${\rm H}_{\beta}$ + $[\rm O \,III]$ luminosity functions are consistent with present observations at $z\lesssim 3$ with $\lesssim 0.1\,{\rm dex}$ differences in luminosities. However, the predicted ${\rm H}_{\alpha}$ luminosity function is $\sim 0.3\,{\rm dex}$ dimmer than the observed one at $z\simeq 2$. Furthermore, we explore continuum spectral indices, the Balmer break at $4000$\AA (D4000) and the UV continuum slope $\beta$. The median D4000 versus sSFR relation predicted at $z=2$ is in agreement with the local calibration despite a different distribution pattern of galaxies in this plane. In addition, we reproduce the observed $A_{\rm UV}$ versus $\beta$ relation and explore its dependence on galaxy stellar mass, providing an explanation for the observed complexity of this relation. We also find a deficiency in heavily attenuated, UV red galaxies in the simulations. Finally, we provide predictions for the dust attenuation curves of galaxies at $z=2-6$ and investigate their dependence on galaxy colors and stellar masses. The attenuation curves are steeper in galaxies at higher redshifts, with bluer colors, or with lower stellar masses. We attribute these predicted trends to dust geometry. Overall, our results are consistent with present observations of high redshift galaxies. Future JWST observations will further test these predictions.
- [12] arXiv:2002.10478 [pdf, ps, other]
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Title: A Neutron Star-White Dwarf Binary Model for Periodic Fast Radio BurstsComments: 6 pages, 2 figures, to be submittedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
We propose a neutron star-white dwarf (NS-WD) binary model with an elliptical orbit to explain the periodic activity of repeating fast radio bursts (FRBs). The WD fills its Roche lobe at the pericenter, and the mass transfer may occur from the WD to the NS around this point, resulting in multiple bursts. In this scenario, the activity period is identical to the orbital period of the binary. We show that such a model may work well for the period roughly from ten minutes to two days. In order to interpret the recently reported 16.35-day periodicity of FRB 180916.J0158+65, an extremely high eccentricity ($e > 0.95$) is required according to our model.
- [13] arXiv:2002.10483 [pdf, other]
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Title: Coupling parsec and gigaparsec scales: primordial non-Gaussianity with multi-tracer intensity mappingComments: 12 pages, 5 figures, submitted to MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
Primordial non-Gaussianity (PNG) is a key probe of the origins of primordial fluctuations in the early universe. It has been shown that multi-tracer measurements of large-scale structure can produce high-precision measurements of PNG. Future line intensity mapping surveys are well-suited to these measurements owing to their ability to rapidly survey large volumes and access the large scales at which PNG becomes important. In this paper, we explore for the first time how multi-tracer PNG measurements with intensity mapping surveys depend on the sub-galactic scale physics which drives line emission. We consider an example cross-correlation between CO maps, and find that the choice of astrophysical models has a substantial impact on $f_{\mathrm{NL}}$ measurements at sufficiently high signal-to-noise. This in effect creates a coupling between horizon-scale PNG measurements and the molecular cloud-scale interstellar medium. We discuss how these effects depend on noise level and survey design. We further find that the cross-correlation shot noise, an effect nearly unique to intensity mapping measurements, plays an important role in multi-tracer analyses and cannot be neglected.
- [14] arXiv:2002.10486 [pdf, ps, other]
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Title: Hot gas in galaxy halos traced by coronal broad Lyman alpha absorbersAuthors: Philipp RichterComments: 17 pages, 10 figures; accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
We explore the possibility to systematically study the extended, hot gaseous halos of low-redshift galaxies with Coronal Broad Ly alpha Absorbers (CBLAs). These are weak, thermally broadenend HI absorption lines arising from the tiny fraction of neutral hydrogen that resides in the collisionally ionized, million-degree halo gas in these galaxies. Using a semi-analytic approach, we model the spatial density and temperature distribution of hot coronal gas to predict strength, spectral shape, and cross section of CBLAs as a function of galaxy-halo mass and line-of-sight impact parameter. For virial halo masses in the range log (M/M_sun)=10.6-12.6, the characteristic logarithmic CBLA HI column densities and Doppler parameters are log N(HI)=12.4-13.4 and b(HI)=70-200 km/s, indicating that CBLAs represent weak, shallow spectral features that are difficult to detect. Yet, the expected number density of CBLAs per unit redshift in the above given mass range is dN/dz(CBLA)~3, implying that CBLAs have a substantial absorption cross-section. We compare the model predictions with a combined set of ultraviolet (UV) absorption-line spectra from HST/COS and HST/STIS that trace the halos of four low-redshift galaxies. We demonstrate that CBLAs already might have been detected in these spectra, but the complex multi-component structure and the limited signal-to-noise ratio (S/N) complicate the interpretation of these CBLA candidate systems. Our study suggests that CBLAs represent a very interesting absorber class that potentially will allow us to further explore the hot coronae of galaxies with UV spectral data.
- [15] arXiv:2002.10492 [pdf, other]
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Title: Circumbinary Planets -- The Next StepsAuthors: David V. MartinComments: Invited conference proceedings for Universe of Binaries, Binaries in the Universe in Telc, Czech Republic, September 2019Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
The Kepler mission opened the door to a small but bonafide sample of circumbinary planets. Some initial trends have been identified and used to challenge our theories of planet and binary formation. However, the Kepler sample is not only small but contains biases. I will present a circumbinary plan for the future. Specifically, I will cover the BEBOP radial velocity survey, the latest TESS transit mission and a new technique for digging out small circumbinary planets in archival Kepler photometry.
- [16] arXiv:2002.10500 [pdf, other]
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Title: Optical spectroscopy of type-2 LINERsComments: Proceedings for the IAU Symposium 356, "Nuclear activity in galaxies across cosmic time". Based on Hermosa-Mu\~noz et al. 2020, accepted for publication in A&A (arxiv:2001.02955)Subjects: Astrophysics of Galaxies (astro-ph.GA)
Low-Ionisation Nuclear Emission-line Regions (LINERs) are the least luminous and the most numerous among the local population of Active Galactic Nuclei (AGN). They can be classified as type-1 or type-2 if their optical spectra show or do not show, respectively, a broad component. It is associated with the presence of a Broad Line Region (BLR) in these systems. However, recent studies have proven that the classification of type-1 LINERs may be controversial, since space- and ground-based spectroscopy provide contradicting results on the presence of very broad components (Cazzoli et al. 2018). We have studied the nuclear spectra of 9 type-2 LINERs with intermediate spectral resolution HST/STIS data. We present the results on our analysis of the different spectral components, and discuss the eventual presence of BLR components in type-2 LINER galaxies, together with the possible presence of outflows, both in comparison with type-1 LINERs. We have found a BLR component in 7 out of the 9 analysed objects within the HST/STIS data.
- [17] arXiv:2002.10511 [pdf, other]
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Title: A Systematic Search for Galaxy Proto-Cluster Cores at $z\sim 2$Comments: 13 pages, 11 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
A proto-cluster core is the most massive dark matter halo (DMH) in a given proto-cluster. To reveal the galaxy formation in core regions, we search for proto-cluster cores at $z\sim 2$ in $\sim 1.5\, \mathrm{deg}^{2}$ of the COSMOS field. Using pairs of massive galaxies ($\log(M_{*}/M_{\odot})\geq11$) as tracers of cores, we find 75 candidate cores, among which 54\% are estimated to be real. A clustering analysis finds that these cores have an average DMH mass of $2.6_{-0.8}^{+0.9}\times 10^{13}\, M_{\odot}$, or $4.0_{-1.5}^{+1.8}\, \times 10^{13} M_{\odot}$ after contamination correction. The extended Press-Schechter model shows that their descendant mass at $z=0$ is consistent with Fornax-like or Virgo-like clusters. Moreover, using the IllustrisTNG simulation, we confirm that pairs of massive galaxies are good tracers of DMHs massive enough to be regarded as proto-cluster cores. We then derive the stellar mass function (SMF) and the quiescent fraction for member galaxies of the 75 candidate cores. We find that the core galaxies have a more top-heavy SMF than field galaxies at the same redshift, showing an excess at $\log(M_{*}/M_{\odot})\gtrsim 10.5$. The quiescent fraction, $0.17_{-0.04}^{+0.04}$ in the mass range $9.0\leq \log(M_{*}/M_{\odot})\leq 11.0$, is about three times higher than that of field counterparts, giving an environmental quenching efficiency of $0.13_{-0.04}^{+0.04}$. These results suggest that stellar mass assembly and quenching are accelerated as early as at $z\sim 2$ in proto-cluster cores.
- [18] arXiv:2002.10529 [pdf, other]
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Title: Scattered light noise characterisation at the Virgo interferometer with tvf-EMD adaptive algorithmAuthors: Alessandro Longo, Stefano Bianchi, Wolfango Plastino, Nicolas Arnaud, Antonino Chiummo, Irene Fiori, Bas Swinkels, Michal WasSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
A methodology of adaptive time series analysis, based on Empirical Mode Decomposition (EMD), and on its time varying version tvf-EMD has been applied to strain data from the gravitational wave interferometer (IFO) Virgo in order to characterise scattered light noise affecting the sensitivity of the IFO in the detection frequency band. Data taken both during hardware injections, when a part of the IFO is put in oscillation for detector characterisation purposes, and during periods of science mode, when the IFO is fully locked and data are used for the detection of gravitational waves, were analysed. The adaptive nature of the EMD and tvf-EMD algorithms allows them to deal with nonlinear non-stationary data and hence they are particularly suited to characterise scattered light noise which is an intrinsically nonlinear and non-stationary noise. Obtained results show that tvf-EMD algorithm allows to obtain more precise results compared to the EMD algorithm, yielding higher cross-correlation values with the auxiliary channels that are the culprits of scattered light noise.
- [19] arXiv:2002.10547 [pdf, other]
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Title: The Hills Mechanism and the Galactic Center S--starsComments: 17 pages, 15 figures + Appendix. Submitted to ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
Our Galactic Center contains young stars, including the few million year old clockwise disk of O and B stars between 0.05 pc to 0.5 pc from the Galactic Center, and the S--star cluster of early B--type stars at a galactocentric distance of ~0.01 pc. Recent observations suggest the S--stars are remnants of tidally disrupted binaries from the clockwise disk. In particular, Koposov et al. 2020 recently discovered a hypervelocity star that was ejected from the Galactic Center five million years ago with a velocity vector that is consistent with this disk. We perform a detailed study of this scenario. First, we quantify the plausible range of binary semi--major axes in the clockwise disk. We find that the dynamical evaporation of such binaries is dominated by other disk stars rather than more numerous old, isotropic stellar population. For the expected range of binary semi--major axes in the clockwise disk, binary tidal disruptions (also known as the Hills mechanism) can reproduce the observed S--star semi--major axis distribution. Reproducing the observed thermal eccentricity distribution of the S--stars requires an additional relaxation process. The flight time of the recently discovered hypervelocity star from the Galactic Center and the most recent constraints on the S--stars' ages both suggest this process has to be effective within ten million years. We consider three possibilities: (i) scalar resonant relaxation from the surrounding isotropic star cluster (ii) torques from the clockwise disk, and (iii) an intermediate mass black hole. We conclude that only the latter would be fast enough to reproduce the observed S--star eccentricity distribution. Finally, we show that the primary star from an unequal mass binary would be deposited at larger semi--major axes than the secondary, possibly explaining the dearth of O stars among the S--stars.
- [20] arXiv:2002.10556 [pdf, other]
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Title: The lithium-rotation connection in the newly discovered young stellar stream Psc-Eri (Meingast 1)Authors: J. Arancibia-Silva (1 and 2), J. Bouvier (3), A. Bayo (1 and 2), P.A.B. Galli (4), W. Brandner (5), H. Bouy (4), D. Barrado (6) ((1) Instituto de Física y Astronomía, Universidad de Valparaíso, Chile, (2) Núcleo Milenio Formación Planetaria - NPF, Universidad de Valparaíso, Chile, (3) IPAG, Univ. Grenoble Alpes, France, (4) Laboratoire d'Astrophysique de Bordeaux, Univ. Bordeaux, Pessac, France, (5) Max Planck Institute for Astronomy, Heidelberg, Germany, (6) Depto. Astrofísica, Centro de Astrobiología (INTA-CSIC), Villanueva de la Cañada, Spain)Comments: 5 pages, 2 figures, 1 table. Accepted to A&A lettersSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Context. As a fragile element, lithium is a sensitive probe of physical processes occurring in stellar interiors. Aims. We aim at investigating the relationship between lithium abundance and rotation rate in low-mass members of the newly discovered 125~Myr-old Psc-Eri stellar stream. Methods. We obtained high resolution optical spectra and measure the equivalent width of the 607.8 nm LiI line for 40 members of the Psc-Eri stream, whose rotational periods have been derived by arXiv:1905.10588. Results. We show that a tight correlation exists between lithium content and rotation rate among the late-G to early K-type stars of the Psc-Eri stream. Fast rotators are systematically Li-rich, while slow rotators are Li-depleted. This trend mimics the one previously reported for the similar age Pleiades cluster. Conclusions. The lithium-rotation connection thus seems to be universal over a restricted effective temperature range for low-mass stars at or close to the zero-age main sequence, and does not depend on environmental conditions.
- [21] arXiv:2002.10559 [pdf, other]
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Title: Do nuclear rings in barred galaxies form at the shear minimum of the rotation curve?Comments: 6 pages, 2 figures. Comments welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA)
It has been recently suggested that (i) nuclear rings in barred galaxies (including our own Milky Way) form at the radius where the shear parameter of the rotation curve reaches a minimum; (ii) the acoustic instability of Montenegro et al. is responsible for driving the turbulence and angular momentum transport in the central regions of barred galaxies. Here we test these suggestions by running simple hydrodynamical simulations in a scale-free logarithmic barred potential. Since the rotation curve of this potential is scale-free, the shear minimum theory predicts that no ring should form. We find that in contrast to this prediction, a ring does form in the simulation, with morphology consistent with that of nuclear rings in real barred galaxies. This proves that the presence of a shear-minimum is not a necessary condition for the formation of a ring. We also find that perturbations that are predicted to be acoustically unstable wind up and eventually propagate off to infinity, so that the system is actually stable. We conclude that (i) the shear-minimum theory is an unlikely mechanism for the formation of nuclear rings in barred galaxies; (ii) the acoustic instability is a spurious result and may not be able to drive turbulence in the interstellar medium, at least for the case without self-gravity. The question of the role of turbulent viscosity remains open.
- [22] arXiv:2002.10562 [pdf, ps, other]
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Title: The GAPS Programme at TNG XXI -- A GIARPS case-study of known young planetary candidates: confirmation of HD 285507 b and refutation of AD Leo bAuthors: I. Carleo, L. Malavolta, A. F. Lanza, M. Damasso, S. Desidera, F. Borsa, M. Mallonn, M. Pinamonti, R.Gratton, E. Alei, S. Benatti, L. Mancini, J. Maldonado, K. Biazzo, M. Esposito, G. Frustagli, E.González-Álvarez, G. Micela, G. Scandariato, A. Sozzetti, L. Affer, A. Bignamini, A. S. Bonomo, R. Claudi, R. Cosentino, E. Covino, A. F. M. Fiorenzano, P. Giacobbe, A. Harutyunyan, G. Leto, A. Maggio, E.Molinari, V. Nascimbeni, I. Pagano, M. Pedani, G. Piotto, E. Poretti, M. Rainer, S. Redfield, C. Baffa, A. Baruffolo, N. Buchschacher, V. Billotti, M. Cecconi, G. Falcini, D. Fantinel, L. Fini, A. Galli, A.Ghedina, F. Ghinassi, E. Giani, C. Gonzalez, M. Gonzalez, J. Guerra, M. Hernandez Diaz, N.Hernandez, M. Iuzzolino, M. Lodi, E. Oliva, L. Origlia, H. Perez Ventura, A. Puglisi, C. Riverol, et al. (7 additional authors not shown)Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
The existence of hot Jupiters is still not well understood. Two main channels are thought to be responsible for their current location: a smooth planet migration through the proto-planetary disk or the circularization of an initial high eccentric orbit by tidal dissipation leading to a strong decrease of the semimajor axis. Different formation scenarios result in different observable effects, such as orbital parameters (obliquity/eccentricity), or frequency of planets at different stellar ages. In the context of the GAPS Young-Objects project, we are carrying out a radial velocity survey with the aim to search and characterize young hot-Jupiter planets. Our purpose is to put constraints on evolutionary models and establish statistical properties, such as the frequency of these planets from a homogeneous sample. Since young stars are in general magnetically very active, we performed multi-band (visible and near-infrared) spectroscopy with simultaneous GIANO-B + HARPS-N (GIARPS) observing mode at TNG. This helps to deal with stellar activity and distinguish the nature of radial velocity variations: stellar activity will introduce a wavelength-dependent radial velocity amplitude, whereas a Keplerian signal is achromatic. As a pilot study, we present here the cases of two already claimed hot Jupiters orbiting young stars: HD285507 b and AD Leo b. Our analysis of simultaneous high-precision GIARPS spectroscopic data confirms the Keplerian nature of HD285507's radial velocities variation and refines the orbital parameters of the hot Jupiter, obtaining an eccentricity consistent with a circular orbit. On the other hand, our analysis does not confirm the signal previously attributed to a planet orbiting AD Leo. This demonstrates the power of the multi-band spectroscopic technique when observing active stars.
- [23] arXiv:2002.10575 [pdf, other]
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Title: Oscillation of high-energy neutrinos from choked jets in stellar and merger ejectaComments: 10 pagesSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present a comprehensive study on oscillation of high-energy neutrinos from two different environments: blue supergiant progenitors that may harbor low-power gamma-ray burst (GRB) jets and neutron star merger ejecta that would be associated with short gamma-ray bursts. We incorporate the radiation constraint that gives a necessary condition for nonthermal neutrino production, and account for the time evolution of the jet, which allows us to treat neutrino oscillation in matter more accurately. For massive star progenitors, neutrino injection inside the star can lead to nonadiabatic oscillation patterns in the 1 TeV - 10 TeV and is also visible in the flavor ratio. For neutron star merger ejecta, we find a similar behavior in the 100 GeV - 10 TeV region and the oscillation may result in a $\nu_e$ excess around 1 TeV. These features, which enable us to probe the progenitors of long and short GRBs, could be seen by future neutrino detectors with precise flavor ratio measurements. We also discuss potential contributions to the diffuse neutrino flux measured by IceCube, and find parameter sets allowing choked low-power GRB jets to account for the neutrino flux in the 10 TeV - 100 TeV range without violating the existing constraints.
- [24] arXiv:2002.10576 [pdf, ps, other]
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Title: The Rise of Active Galactic Nuclei in the GAlaxy Evolution and Assembly semi-analytic modelAuthors: Fabio Fontanot (1,2), Gabriella De Lucia (1), Michaela Hirschmann (3), Lizhi Xie (4), Pierluigi Monaco (5,1,2), Nicola Menci (6), Fabrizio Fiore (1), Chiara Feruglio (1,2), Stefano Cristiani (1,2), Francesco Shankar (7) ((1) INAF - Trieste Astronomical Observatory, Italy (2) IFPU - Institute for Fundamental Physics of the Universe, Trieste, Italy (3) DARK - Niels Bohr Institute, Copenhagen, Denmark (4) Tianjin Normal University, China (5) University of Trieste, Italy (6) INAF - Rome Astronomical Observatory, Italy (7) University of Southampton, UK)Comments: 16 pages, 12 figures, 1 table, MNRAS submittedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
We present a new implementation of the GAlaxy Evolution and Assembly (GAEA) semi-analytic model, that features an improved modelling of the process of cold gas accretion onto supermassive black hole (SMBHs), derived from both analytic arguments and high-resolution simulations. We consider different scenarios for the loss of angular momentum required for the available cold gas to be accreted onto the central SMBHs, and we compare different combinations of triggering mechanisms, including galaxy mergers and disk instabilities in star forming discs. We compare our predictions with the luminosity function (LF) observed for Active Galactic Nuclei (AGN) and we confirm that a non-instantaneous accretion timescale (either in the form of a low-angular momentum reservoir or as an assumed light curve evolution) is needed in order to reproduce the measured evolution of the AGN-LF and the so-called AGN-downsizing trend. Moreover, we also study the impact of AGN feedback, in the form of AGN-driven outflows, on the SF properties of model galaxies, using prescriptions derived both from empirical studies or from numerical experiments. We show that AGN-driven outflows are effective in suppressing the residual star formation rate in massive galaxies ($> 10^{11} {\rm M}_\odot$) without changing their overall assembly history. Finally, we study the Eddington ratio distribution as a function of SMBH mass, showing that only objects more massive than $10^8 {\rm M}_\odot$ are already in a self-regulated state as inferred from observations.
- [25] arXiv:2002.10584 [pdf, ps, other]
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Title: Cepheid distances based on Gaia and VMC@VISTA observationsComments: 8 pages, 3 figures, invited talk to appear on Astronomical Society of the Pacific Conference Series "RRLyrae/Cepheid2019: Frontiers of Classical Pulsators: Theory and Observations", Cloudcroft, NM, USA October 13-18, 2019Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
We present new accurate Period-Luminosity (PL) and Period-Wesenheit (PW) relations in the V,J,Ks bands based on a sample of more than 4500 Cepheids in the Large Magellanic Cloud (LMC) whose photometry was obtained in the context of the VISTA Magellanic Clouds (VMC) Survey. The excellent precision of these data allows us to study the geometry of the LMC and to establish a solid baseline for extra-galactic distance scale studies. To calibrate the zero points of these PL/PW relations, we adopted Gaia Data Release 2 parallaxes for more than 2000 Milky Way Cepheids. The implications for the measurement of $H_0$ are briefly discussed.
- [26] arXiv:2002.10587 [pdf, ps, other]
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Title: Asymmetrical nebula of the M33 variable GR290 (WR/LBV)Authors: Olga V. Maryeva, Gloria Koenigsberger, Sergey V. Karpov, Tatiana A. Lozinskaya, Oleg V. Egorov, Corinne Rossi, Massimo Calabresi, Roberto F. ViottiComments: 11 pages, 10 figures, accepted for publication in A&ASubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Context: GR290 (M33 V0532=Romano's star) is a luminous M33 object undergoing photometric variability typical for luminous blue variable (LBV) stars. It lies inside Wolf-Rayet region in the Hertzsprung-Russell diagram and possesses a WN8 type spectrum at the light minima. Analysis of Gran Telescopio Canarias (GTC) spectra obtained in 2016 led to the conclusion that it is surrounded by an unresolved HII region formed mostly of ejected material from the central star, and disclosed the presence of a second, more extended asymmetrical emission region. Aims: The aim of this paper is to further explore the structure of the nearby environment of GR290. Methods: Long-slit spectra of GR290 were obtained with three slit orientations in the visual and red spectral regions. The emission-line distribution for each slit was analyzed. Results: We confirm the presence of an asymmetric HII region that extends ~50 pc to the south; ~30pc to the north and southeast; ~20 pc to the east and northwest and ~10pc to the west. We also present the first spectrum to be acquired of a star belonging to the neighboring OB88 association, J013501.87+304157.3, which we classify as a B-type supergiant with a possible binary companion.
- [27] arXiv:2002.10588 [pdf, ps, other]
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Title: TESS Photometry of the Eclipsing $δ$ Scuti Star AI HydraeComments: 16 pages, including 5 figures and 5 tables, accepted for publication in PASJSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
AI Hya has been known as an eclipsing binary with a monoperiodic $\delta$ Sct pulsator. We present the results from its {\it TESS} photometry observed during Sector 7. Including our five minimum epochs, the eclipse timing diagram displays the apsidal motion with a rate of $\dot{\omega}$ = 0.075$\pm$0.031 deg year$^{-1}$, which corresponds to an apsidal period of U = 4800$\pm$2000 years. The binary star model represents that the smaller, less massive primary component is 427 K hotter than the pulsating secondary, and our distance of 612$\pm$36 pc is in good agreement with the $Gaia$ distance of 644$\pm$26 pc. We subtracted the binary effects from the observed {\it TESS} data and applied a multifrequency analysis to these residuals. The result reveals that AI Hya is multiperiodic in its pulsation. Of 14 signals detected, four ($f_1$, $f_2$, $f_3$, $f_6$) may be considered independent pulsation frequencies. The period ratios of $P_{\rm pul}/P_{\rm orb}$ = 0.012$-$0.021 and the pulsation constants of $Q$ = 0.30$-$0.52 days correspond to $\delta$ Sct pulsations in binaries. We found that the secondary component of AI Hya pulsates in both radial fundamental $F$ modes ($f_2$ and $f_3$) and non-radial $g_1$ modes with a low degree of $\ell$ = 2 ($f_1$ and $f_6$).
- [28] arXiv:2002.10595 [pdf, other]
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Title: Is there NaI in the atmosphere of HD 209458b? Effect of the centre-to-limb variation and Rossiter-McLaughlin effect in transmission spectroscopy studiesAuthors: N. Casasayas-Barris, E. Palle, F. Yan, G. Chen, R. Luque, M. Stangret, E. Nagel, M. Zechmeister, M. Oshagh, J. Sanz-Forcada, L. Nortmann, F. J. Alonso-Floriano, P. J. Amado, J. A. Caballero, S. Czesla, S. Khalafinejad, M. Lopez-Puertas, J. Lopez-Santiago, K. Molaverdikhani, D. Montes, A. Quirrenbach, A. Reiners, I. Ribas, A. Sanchez-Lopez, M. R. Zapatero OsorioComments: 19 pages, 19 figures, acceptedSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
HD 209458b was the first transiting planet discovered, and the first for which an atmosphere, in particular NaI, was detected. With time, it has become one of the most frequently studied planets, with a large diversity of atmospheric studies using low- and high-resolution spectroscopy. Here, we present transit spectroscopy observations of HD 209458b using the HARPS-N and CARMENES spectrographs. We fit the Rossiter-McLaughlin effect by combining radial velocity data from both instruments (nine transits in total), measuring a projected spin-orbit angle of $-1.6\pm0.3~{\rm deg}$. We also present the analysis of high-resolution transmission spectroscopy around the NaI region at $590~{\rm nm}$, using a total of five transit observations. In contrast to previous studies where atmospheric NaI absorption is detected, we find that for all of the nights, whether individually or combined, the transmission spectra can be explained by the combination of the centre-to-limb variation and the Rossiter-McLaughlin effect. This is also observed in the time-evolution maps and transmission light curves, but at lower signal-to-noise ratio. Other strong lines such as H$\alpha$, CaII IRT, the MgI triplet region, and KI D1 are analysed, and are also consistent with the modelled effects, without considering any contribution from the exoplanet atmosphere. Thus, the transmission spectrum reveals no detectableNaI absorption in HD 209458b. We discuss how previous pioneering studies of this benchmark object may have overlooked these effects. While for some star-planet systems these effects are small, for other planetary atmospheres the results reported in the literature may require revision.
- [29] arXiv:2002.10601 [pdf, other]
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Title: Comment on "Collision and radiative processes in emission of atmospheric carbon dioxide''Comments: 12 pages, 5 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph)
Recently, Smirnov published a paper [1] which dismisses the role of increasing concentrations of anthropogenic CO$_2$ on global warming of planet Earth. We show that these conclusions are the consequence of two flaws in Smirnov's theoretical model which neglect the effects of the increased concentrations of CO$_2$ on the absorption of Earth's blackbody radiation in the 12--15$\mu$m region. The influence of doubling the concentration of CO$_2$ in the atmosphere on the surface temperature is not $\Delta$T=0.02K, or even $\Delta$T=0.4K if only one of the two mistakes in Smirnov's analysis is corrected. The correct value lies within $\Delta$T=1.1-1.3K as outlined by other authors analysis using simplified, yet more theoretically consistent models.
- [30] arXiv:2002.10605 [pdf, ps, other]
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Title: Determining $H_0$ Model-Independently and Consistency TestsComments: 8 pages, 6 figures, 3 tablesSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We determine the Hubble constant $H_0$ precisely (2.3\% uncertainty) in a manner independent of cosmological model through Gaussian process regression, using strong lensing and supernova data. Strong gravitational lensing of a variable source can provide a time-delay distance $D_{\Delta t}$ and angular diameter distance to the lens $D_{\rm{d}}$. These absolute distances can anchor Type Ia supernovae, which give an excellent constraint on the shape of the distance-redshift relation. Updating our previous results to use the H0LiCOW program's milestone dataset consisting of six lenses, four of which have both $D_{\Delta t}$ and $D_{\rm{d}}$ measurements, we obtain $H_0=72.8_{-1.7}^{+1.6}\rm{\ km/s/Mpc}$ for a flat universe and $H_0=77.3_{-3.0}^{+2.2}\rm{\ km/s/Mpc}$ for a non-flat universe. We carry out several consistency checks on the data and find no statistically significant tensions, though a noticeable redshift dependence persists in a particular systematic manner that we investigate. Speculating on the possibility that this trend of derived Hubble constant with lens distance is physical, we show how this can arise through modified gravity light propagation, which would also impact the weak lensing $\sigma_8$ tension.
- [31] arXiv:2002.10630 [pdf, ps, other]
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Title: A Possible Origin of kHZ QPOs in Low-Mass X-ray BinariesComments: 20 pages, 6 figures; To be published in Publ. Aston. Soc. Japan, Vol. 72 (2020)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
A possible origin of kHz QPOs in low-mass X-ray binaries is proposed. Recent numerical MHD simulations of accretion disks with turbulent magnetic fields of MRI definitely show the presence of two-armed spiral structure in quasi-steady state of accretion disks. In such deformed disks, two-armed ($m=2$) c-mode ($n=1$) oscillations are excited by wave-wave resonant instability. Among these excited oscillations, the fundamental in the radial direction ($n_r=0$) will be the higher kHz QPO of a twin QPOs, and the first overtone ($n_r=1$) in the radial direction will be the lower kHz QPO of the twin. A possible cause of the twin high-frequency QPOs (HFQPOs) in BH X-ray binaries is also discussed.
- [32] arXiv:2002.10634 [pdf]
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Title: Ultramafic talc-carbonate unit -- The North Pole Dome and Dresser FormationAuthors: Adrian J. BrownComments: 8 pages, 4 Figures, chapter 10 of The North Pole Dome and Dresser Formation Field Guide by M. van KranendonkSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Geophysics (physics.geo-ph)
Here we describe the ultramafic talc-carbonate unit of the North Pole Dome. The North Pole Dome (NPD) is located in the centre of the East Pilbara Terrane (Van Kranendonk et al., 2007). The NPD is a structural dome of bedded, dominantly mafic volcanic rocks of the Warrawoona and Kelly Groups that dip gently away from the North Pole Monzogranite exposed in the core of the dome (Figure 1) (Van Kranendonk, 1999, 2000). Average dips vary from 30 to 60 degrees in the inner part of the dome to about 60 to 80 degrees in the outer part of the dome (Van Kranendonk, 2000). The North Pole Monzogranite is interpreted to represent a syn-volcanic laccolith to the Panorama Formation (Thorpe et al., 1992) and has been estimated to extend approximately 1.5km below the surface, based on gravity surveys (Blewett et al., 2004). Felsic volcanic formations are interbedded with the greenstones (Hickman, 1983), and these are capped by cherts that indicate hiatuses in volcanism (Barley, 1993; Van Kranendonk, 2006). An overall arc-related model for hydrothermal activity is favored by Barley (1993), whereas more recent studies have indicated a mantle-plume model for igneous and hydrothermal activity at the North Pole Dome (Van Kranendonk et al., 2002, 2007; Smithies et al., 2003; Van Kranendonk and Pirajno, 2004).
- [33] arXiv:2002.10644 [pdf, other]
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Title: The SPOTS Models: A Grid of Theoretical Stellar Evolution Tracks and Isochrones For Testing The Effects of Starspots on Structure and ColorsComments: 19 pages, 10 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
One-dimensional stellar evolution models have been successful at representing the structure and evolution of stars in diverse astrophysical contexts, but complications have been noted in the context of young, magnetically active stars, as well as close binary stars with significant tidal interactions. Numerous puzzles are associated with pre-main sequence and active main-sequence stars, relating to their radii, their colors, certain elemental abundances, and the coevality of young clusters, among others. A promising explanation for these puzzles is the distorting effects of magnetic activity and starspots on the structure of active stars. To assist the community in evaluating this hypothesis, we present the Stellar Parameters Of Tracks with Starspots (SPOTS) models, a grid of solar-metallicity stellar evolutionary tracks and isochrones which include a treatment of the structural effects of starspots. The models range from 0.1-1.3\msun and from spot-less to a surface covering fraction of 85\%, and are evolved from the pre-main sequence to the red giant branch (or 15~Gyr). We also produce two-temperature synthetic colors for our models using empirically-calibrated color tables. We describe the physical ingredients included in the SPOTS models and compare their predictions to other modern evolution codes. Finally, we apply these models to several open questions in the field of active stars, including the radii of young eclipsing binaries, the color scale of pre-main sequence stars, and the existence of sub-subgiants, demonstrating that our models can explain many peculiar features of active stars.
- [34] arXiv:2002.10661 [pdf, other]
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Title: Energy Optimization in Extrasolar Planetary Systems: The Transition from Peas-in-a-Pod to Runaway GrowthComments: 16 pages, 5 figures, accepted for publication in MNRASSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Motivated by the trends found in the observed sample of extrasolar planets, this paper determines tidal equilibrium states for forming planetary systems --- subject to conservation of angular momentum, constant total mass, and fixed orbital spacing. In the low-mass limit, valid for superearth-class planets with masses of order $m_{\rm p}\sim10M_\oplus$, previous work showed that energy optimization leads to nearly equal mass planets, with circular orbits confined to a plane. The present treatment generalizes previous results by including the self-gravity of the planetary bodies. For systems with sufficiently large total mass $m_{\scriptstyle T}$ in planets, the optimized energy state switches over from the case of nearly equal mass planets to a configuration where one planet contains most of the material. This transition occurs for a critical mass threshold of approximately $m_{\scriptstyle T} \ge m_{\scriptstyle C}\sim40M_\oplus$ (where the value depends on the semimajor axes of the planetary orbits, the stellar mass, and other system properties). These considerations of energy optimization apply over a wide range of mass scales, from binary stars to planetary systems to the collection of moons orbiting the giant planets in our solar system.
- [35] arXiv:2002.10666 [pdf, other]
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Title: NuRIA: Numerical Relativity Injection Analysis of spinning binary black hole signals in Advanced LIGO dataComments: 10 pages, 7 figures, LIGO DCC number P1900366Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc)
The advent of gravitational wave (GW) astronomy has provided us with observations of black holes more massive than those known from X-ray astronomy. However, the observation of an intermediate-mass black hole (IMBH) remains a big challenge. After their second observing run, the LIGO \& Virgo Scientific collaborations (LVC) placed upper limits on the coalescence rate density of non-precessing IMBH binaries (IMBHBs). In this article, we explore the sensitivity of two of the search pipelines used by the LVC to signals from 69 numerically simulated IMBHBs with generic spins, out of which 27 have a precessing orbital plane. In particular, we compare the matched-filter search PyCBC, and the coherent model-independent search technique cWB. We find that, in general, cWB is more sensitive to IMBHBs than PyCBC, with their difference depending on the masses and spins of the source. Consequently, we use cWB to place the first upper limits on the merger rate of generically spinning IMBH binaries using publicly available data from the first Advanced LIGO observing run.
- [36] arXiv:2002.10676 [pdf, other]
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Title: LATIS: The Ly$α$ Tomography IMACS SurveyAuthors: Andrew B. Newman, Gwen C. Rudie, Guillermo A. Blanc, Daniel D. Kelson, Sunny Rhoades, Tyson Hare, Victoria Pérez, Andrew J. Benson, Alan Dressler, Valentino Gonzalez, Juna A. Kollmeier, Nicholas P. Konidaris, John S. Mulchaey, Michael Rauch, Olivier Le Fèvre, Brian C. Lemaux, Olga Cucciati, Simon J. LillyComments: accepted to ApJ; Fig. 26 contains animated rendering of the IGM mapsSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
We introduce LATIS, the Ly$\alpha$ Tomography IMACS Survey, a spectroscopic survey at Magellan designed to map the z=2.2-2.8 intergalactic medium (IGM) in three dimensions by observing the Ly$\alpha$ forest in the spectra of galaxies and QSOs. Within an area of 1.7 deg${}^2$, we will observe approximately half of $\gtrsim L^*$ galaxies at z=2.2-3.2 for typically 12 hours, providing a dense network of sightlines piercing the IGM with an average transverse separation of 2.5 $h^{-1}$ comoving Mpc (1 physical Mpc). At these scales, the opacity of the IGM is expected to be closely related to the dark matter density, and LATIS will therefore map the density field in the $z \sim 2.5$ universe at $\sim$Mpc resolution over the largest volume to date. Ultimately LATIS will produce approximately 3800 spectra of z=2.2-3.2 galaxies that probe the IGM within a volume of $4 \times 10^6 h^{-3}$ Mpc${}^3$, large enough to contain a representative sample of structures from protoclusters to large voids. Observations are already complete over one-third of the survey area. In this paper, we describe the survey design and execution. We present the largest IGM tomographic maps at comparable resolution yet made. We show that the recovered matter overdensities are broadly consistent with cosmological expectations based on realistic mock surveys, that they correspond to galaxy overdensities, and that we can recover structures identified using other tracers. LATIS is conducted in Canada-France-Hawaii Telescope Legacy Survey fields, including COSMOS. Coupling the LATIS tomographic maps with the rich data sets collected in these fields will enable novel studies of environment-dependent galaxy evolution and the galaxy-IGM connection at cosmic noon.
- [37] arXiv:2002.10692 [pdf, other]
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Title: Globular Clusters of the Galaxy: Chemical Composition vs KinematicsComments: 23 pages, 3 figures, 1 tableJournal-ref: Astrophysical Bulletin,2019, Volume 74, Issue 4, p.403-423Subjects: Astrophysics of Galaxies (astro-ph.GA)
A comprehensive statistical analysis of the relationship between the chemical and spatially kinematic parameters of the globular clusters of the Galaxy has been performed. The data of the author's compilation catalog contain astrophysical parameters for 157 clusters and the relative abundances of {\alpha}-elements for 69 clusters. For 121 clusters, the data are supplemented by spatially kinematic parameters taken from the literature. The phenomenon of reddening of horizontal branches of low-metal accreted globular clusters is discussed. We consider the contradiction between the criteria for clusters to belong to the subsystems of the thick disk and the halo in terms of chemical and kinematic properties. It consists in the fact that, regardless of belonging to the galactic subsystems by kinematics, almost all metallic ([Fe/H] >-1.0) clusters are located close to the center and plane of the Galaxy, while among the less metallic of both subsystems there are many distant ones. Differences in the abundances of {\alpha}-elements in the stellar objects of the Galaxy and the surrounding low-mass dwarf satellite galaxies confirm the well-known conclusion that all globular clusters and field stars of the accreted halo are remnants of galaxies of higher mass than the current environment of the Galaxy. A possible exception is a distant low-metal cluster with low relative abundance of {\alpha}-elements Rup 106.
- [38] arXiv:2002.10717 [pdf, ps, other]
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Title: ASASSN-16oh: nova outburst with no-mass-ejection -- A new type of supersoft X-ray sources in old populationsComments: 21 pages, 10 figures, to appear in ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
ASASSN-16oh is a peculiar transient supersoft X-ray source without mass-ejection signature in the field of the Small Magellanic Cloud. Maccarone et al. (2019) concluded that ASASSN-16oh is the first dwarf nova with supersoft X-ray originated from an equatorial accretion belt on a white dwarf (WD). Hillman et al. (2019) proposed a thermonuclear runaway model that both the X-rays and $V$/$I$ photons are emitted from the hot WD. We calculated the same parameter models as Hillman et al.'s and found that they manipulated on/off the mass-accretion, and their best fit $V$ light curves are 6 mag fainter, and decay about 10 times slower, than that of ASASSN-16oh. We propose a nova model induced by high rate mass-accretion during a dwarf nova outburst, i.e., the X-rays originate from a surface of the hydrogen-burning WD whereas the $V/I$ photons from the irradiated disk. Our model explains the main observational properties of ASASSN-16oh. We also obtained thermonuclear runaway models with no-mass-ejection for a wide range of parameters of the WD mass and mass accretion rates including both natural and forced novae in low-metal environments of $Z=0.001$ and $Z=0.0001$. They are a new type of periodic supersoft X-ray sources with no-mass-ejection, and also a bright transient in $V$/$I$ bands if they have a large disk. We suggest that such objects are a candidate of type Ia supernova progenitors because its mass is increasing at a very high efficiency $(\sim 100 \%)$.
- [39] arXiv:2002.10728 [pdf, ps, other]
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Title: Separate silicate and carbonaceous solids formed from mixed atomic and molecular species diffusing in neon iceAuthors: Gaël Rouillé (1 and 2), Cornelia Jäger (1 and 2), Thomas Henning (1) ((1) Friedrich-Schiller-Universität Jena, (2) Max Planck Institute for Astronomy)Comments: 20 pages, 9 figures, accepted for publication in The Astrophysical JournalSubjects: Astrophysics of Galaxies (astro-ph.GA); Materials Science (cond-mat.mtrl-sci)
The formation and growth of refractory matter on pre-existing interstellar dust grain surfaces was studied experimentally by annealing neon-ice matrices in which potential precursors of silicate grains (Mg and Fe atoms, SiO and SiO$_2$ molecules) and of solid carbon (C$_n$ molecules, $n$ = 2-10) were initially isolated. Other molecules, mainly O$_3$, CO, CO$_2$, C$_3$O, and H$_2$O, were embedded at the same time in the matrices. The annealing procedure caused the cold dopants to diffuse and interact in the neon ice. Monitoring the procedure in situ with infrared spectroscopy revealed the disappearance of the silicon oxide and carbon molecules at temperatures lower than 13 K, and the rise of the Si-O stretching band of silicates. Ex situ electron microscopy confirmed the formation of silicate grains and showed that their structure was amorphous. It also showed that amorphous carbon matter was formed simultaneously next to the silicate grains, the two materials being chemically separated. The results of the experiments support the hypothesis that grains of complex silicates and of carbonaceous materials are re-formed in the cold ISM, as suggested by astronomical observations and evolution models of cosmic dust masses. Moreover, they show that the potential precursors of one material do not combine with those of the other at cryogenic temperatures, providing us with a clue as to the separation of silicates and carbon in interstellar grains.
- [40] arXiv:2002.10729 [pdf, other]
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Title: Inconsistency of Chemical Properties of Stellar Populations in the Thick Disk Subsystem of Our GalaxyComments: 15 pages, 4 figures,Subjects: Astrophysics of Galaxies (astro-ph.GA)
Using modern published data on velocities and spectroscopic definitions of chemical elements in stellar objects of the Galaxy, we investigated the relationship of chemical composition with the kinematics of different populations. The paper shows that the old stellar populations of the Galaxy, belonging (by the kinematic criterion) to the thick disk subsystem---globular clusters, field variables of the type RR Lyrae (lyrids), as well as close F--G dwarfs and field giants, have different chemical composition. In particular, the dwarfs and giants of the field are on average more metallic than the globular clusters and lyrids of the field. Moreover, the relative abundances of $\alpha$-elements in the range $\rm{[Fe/H]} > -1.0$ are the highest for globular clusters, and are the lowest for for field variables of the RR Lyrae type. Based on the analysis of the nature of the dependences of [$\alpha$/Fe] on [Fe/H] for these objects it was suggested that the thick disk subsystem in the Galaxy is composite and at least three components exist independently within it. The oldest one includes metal-rich globular clusters that formed from a single proto-galactic cloud shortly after the start of type Ia supernovae outbursts. Then the subsystem of field stars of a thick disk was formed as a result of ``heating'' of stars of already formed thin disk of the Galaxy by a rather massive dwarf satellite galaxy that fell on it. And finally, subsystems of field stars with the kinematics of not only a thick, but even a thin disk that fell on the Galaxy from this captured satellite galaxy.
- [41] arXiv:2002.10737 [pdf, other]
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Title: The HSC-SSP Transient Survey: Implications from Early Photometry and Rise Time of Normal Type Ia SupernovaeAuthors: Ji-an Jiang, Naoki Yasuda, Keiichi Maeda, Mamoru Doi, Toshikazu Shigeyama, Nozomu Tominaga, Masaomi Tanaka, Takashi J. Moriya, Ichiro Takahashi, Nao Suzuki, Tomoki Morokuma, Ken'ichi NomotoComments: 13 pages, 5 figures, accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
With a booming number of Type Ia supernovae (SNe Ia) discovered within a few days of their explosions, a fraction of SNe Ia that show luminosity excess in the early phase (early-excess SNe Ia) have been confirmed. In this article, we report early-phase observations of seven photometrically normal SNe Ia (six early detections and one deep non-detection limit) at the COSMOS field through a half-year transient survey as a part of the Hyper Suprime-Cam Subaru Strategic Program (HSC SSP). In particular, a blue light-curve excess was discovered for HSC17bmhk, a normal SN Ia with rise time longer than 18.8 days, during the first four days after the discovery. The blue early excess in optical wavelength can be explained not only by interactions with a non-degenerate companion or surrounding dense circumstellar matter but also radiation powered by radioactive decays of $^{56}$Ni at surface of the SN ejecta. Given the growing evidence of the early-excess discoveries in normal SNe Ia that have longer rise times than the average and a similarity in the nature of the blue excess to a luminous SN Ia subclass, we infer that early excess discovered in HSC17bmhk and other normal SNe Ia are most likely attributed to radioactive $^{56}$Ni decay at the surface of the SN ejecta. In order to successfully identify normal SNe Ia with early excess similar to that of HSC17bmhk, early UV photometries or high-cadence blue-band surveys are necessary.
- [42] arXiv:2002.10762 [pdf, other]
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Title: Fourth-order Coronagraph for High-Contrast Imaging of Exoplanets with Off-axis Segmented TelescopesComments: Resubmitted to AJ after revision from referee's reportSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
We propose a coronagraphic system with fourth-order null for off-axis segmented telescopes, which is sufficiently insensitive to the telescope pointing errors and finite angular diameter of the host star to enable high-contrast imaging of potentially habitable planets. The inner working angle of the coronagraphic system is close to $1\lambda/D$, and there is no outer limit. The proposed coronagraphic system is made up of a new focal plane mask and an optimized Lyot stop with the second-order null. The new focal plane mask is an extension of the band-limited masks with a phase modulation. We construct a coronagraphic system with fourth-order null by placing two of the new coronagraph systems in succession to be orthogonal to each other. The proposed system is limited to narrow-band usage. The characteristics of the proposed coronagraph system are derived analytically, which includes: (1)the leak of stellar lights due to finite stellar diameter and pointing jitter of a telescope, and (2)the peak throughput. We achieve the performance simulations of this coronagraphic system based on these analytical expressions, considering a monochromatic light of 0.75$\mathrm{\mu}$m and off-axis primary mirror with a diameter of 8.5m. Thanks to the wide working area of the mask, the result shows that terrestrial planets orbiting K and G-dwarfs can be detected under the condition that the telescope pointing jitter is less than $0.01\lambda/D\approx240$as. The proposed coronagraphic system is promising for detection of potentially habitable planets with future space off-axis hexagonally segmented telescopes.
- [43] arXiv:2002.10768 [pdf, ps, other]
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Title: A Type Ia supernova at the heart of superluminous transient SN 2006gyComments: Author version of paper published in Science on Jan 24 2020Journal-ref: Science, January 24 2020, Vol. 367, Issue 6476, pp. 415-418Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Superluminous supernovae radiate up to 100 times more energy than normal supernovae. The origin of this energy and the nature of their stellar progenitors are poorly understood. We identify neutral iron lines in the spectrum of one such transient, SN 2006gy, and show that they require a large mass of iron (>~0.3 Msun) expanding at 1500 km/s. We demonstrate that a model of a standard Type Ia supernova hitting a shell of circumstellar material produces a light curve and late-time iron-dominated spectrum that match SN 2006gy. In such a scenario, common envelope evolution of the progenitor system can synchronize envelope ejection and supernova explosion and may explain these bright transients.
- [44] arXiv:2002.10771 [pdf, other]
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Title: CMB bounds on primordial black holes including dark matter halo accretionComments: 13 pages, 7 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Even if massive ($10\,M_\odot \lesssim M \lesssim 10^4 M_\odot$) primordial black holes (PBHs) can only account for a small fraction of the dark matter (DM) in the universe, they may still be responsible for a sizable fraction of the coalescence events measured by LIGO/Virgo, and/or act as progenitors of the supermassive black holes (SMBHs) observed already at high redshift ($z\gtrsim 6$). In presence of a dominant, non-PBH DM component, the bounds set by CMB via an altered ionization history are modified. We revisit the cosmological accretion of a DM halo around PBHs via toy models and dedicated numerical simulations, deriving updated CMB bounds which also take into account the last Planck data release. We prove that these constraints dominate over other constraints available in the literature at masses $M\gtrsim 20-50\,M_\odot$ (depending on uncertainty in accretion physics), reaching the level $f_{\rm PBH}<3\times 10^{-9}$ around $M\sim 10^{4}\,M_\odot$. These tight bounds are nonetheless consistent with the hypothesis of a primordial origin of the SMBH massive seeds.
- [45] arXiv:2002.10795 [pdf, other]
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Title: The Local Universe from Calar Alto (LUCA)Comments: 14 pages, 25 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)
LUCA (Local Universe from Calar Alto) was conceived as a new generation science program for the Calar Alto Observatory. It proposed the construction of a large Integral Field Unit (IFU) spectrograph with six thousands optical fibers (IFU-6000) at the CAHA 3.5-m telescope to map our universe neighborhood in 3D with an unprecedented spatial resolution. Two galaxy samples were defined to map the local universe: (i) 102 galaxies in the Local Volume, out to 11 Mpc, and (ii) 218 galaxies in the Virgo cluster. A complementary project was developed to map the three largest galaxies in the local universe, M31, M33, and M101 with the Schmidt telescope. In this white paper we describe the LUCA Project science justification and survey strategy, as well as a technical description of the IFU-6000 instrument, its performance, and design.
- [46] arXiv:2002.10812 [pdf, ps, other]
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Title: Internal Kinematics of the Seyfert Galaxy Mkn 938Comments: 9 pages, 7 figures, to be published in Astrophysical Bulletin, v. 75Journal-ref: Astrophysical Bulletin, 2020, vol. 75, No.1Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
We present the results of a detailed study of the central part of the Seyfert galaxy Mkn 938. Observational data were obtained with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences using integral-field spectrograph MPFS and a scanning Fabry--Perot interferometer. Mkn 938 is interesting for being a result of a merger of two gas-rich galaxies, and we observe the final stage of this interaction accompanied with an extremely powerful burst of star formation and nuclear activity. Our analysis of the kinematics of gas and stars revealed the presence of gas outflow in the circumnuclear region Mkn 938 with velocities ranging from -370 to -480 km/s, and allowed us for the first time to map the high-velocity galactic wind in NaD absorption line on large spatial scale in this galaxy.
- [47] arXiv:2002.10823 [pdf, other]
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Title: Spatial distribution of exoplanet candidates based on Kepler and $Gaia$ dataComments: 17 pages, 5 figures, accepted in A&ASubjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
The spatial distribution of exoplanets in the Galaxy is important for our understanding of planet formation and evolution. We aim to determine the spatial gradients of exoplanet occurrence in the Solar neighbourhood and in the vicinity of open clusters. We combined Kepler and Gaia DR2 data for this purpose, splitting the volume sampled by the Kepler mission into certain spatial bins. We determined an uncorrected and bias-corrected exoplanet frequency and metallicity for each bin. There is a clear drop in the uncorrected exoplanet frequency with distance for F-type stars, a decline with increasing distance along the Galactic longitude l=90 deg, and a drop with height above the Galactic plane. We find that the metallicity behaviour cannot be the reason for the drop of the exoplanet frequency around F stars with increasing distance. We argue that the above-mentioned gradients of uncorrected exoplanet frequency result from a single bias of undetected smaller planets around fainter stars. When we correct for observational biases, most of these gradients in exoplanet frequency become statistically insignificant. Only a slight decline of the planet occurrence with distance for F stars remains significant at the 3 sigma level. Apart from that, the spatial distribution of exoplanets in the Kepler field of view is compatible with a homogeneous one. At the same time, we do not find a significant change in the exoplanet frequency with increasing distance from open clusters. As a byproduct, we identified six exoplanet host star candidates that are members of open clusters. Four of them are in the NGC 6811 (KIC 9655005, KIC 9533489, Kepler-66, Kepler-67) and two belong to NGC 6866 (KIC 8396288, KIC 8331612). Two out of the six had already been known to be cluster members.
- [48] arXiv:2002.10834 [pdf, other]
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Title: Validation of Selection Function, Sample Contamination and Mass Calibration in Galaxy Cluster SamplesAuthors: S. Grandis, M. Klein, J. J. Mohr, S. Bocquet, M. Paulus, the Dark Energy Survey Collaboration, the South Pole Telescope CollaborationComments: 28 pages, 23 figureSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We construct and validate the selection function of the MARD-Y3 sample. This sample was selected through optical follow-up of the 2nd ROSAT faint source catalog (2RXS) with Dark Energy Survey year 3 (DES-Y3) data. The selection function is modeled by combining an empirically constructed X-ray selection function with an incompleteness model for the optical follow-up. We validate the joint selection function by testing the consistency of the constraints on the X-ray flux--mass and richness--mass scaling relation parameters derived from different sources of mass information: (1) cross-calibration using SPT-SZ clusters, (2) calibration using number counts in X-ray, in optical and in both X-ray and optical while marginalizing over cosmological parameters, and (3) other published analyses. We find that the constraints on the scaling relation from the number counts and SPT-SZ cross-calibration agree, indicating that our modeling of the selection function is adequate. Furthermore, we apply a largely cosmology independent method to validate selection functions via the computation of the probability of finding each cluster in the SPT-SZ sample in the MARD-Y3 sample and vice-versa. This test reveals no clear evidence for MARD-Y3 contamination, SPT-SZ incompleteness or outlier fraction. Finally, we discuss the prospects of the techniques presented here to limit systematic selection effects in future cluster cosmological studies.
- [49] arXiv:2002.10840 [pdf, other]
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Title: MADX -- A simple technique for source detection and measurement using multi-band imaging from the Herschel-ATLAS surveyComments: 10 pages, 11 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)
We describe the method used to detect sources for the Herschel-ATLAS survey. The method is to filter the individual bands using a matched filter, based on the point-spread function (PSF) and confusion noise, and then form the inverse variance weighted sum of the individual bands, including weights determined by a chosen spectral energy distribution. Peaks in this combined image are used to estimate the source positions. The fluxes for each source are estimated from the filtered single-band images, interpolated to the exact sub-pixel position. We test the method by creating simulated maps in three bands with PSFs, pixel sizes and Gaussian instrumental noise that match the 250, 350 and 500 micron bands of Herschel-ATLAS. We use our method to detect sources and compare the measured positions and fluxes to the input sources. The multi-band approach allows reliable source detection a factor 1.2 to 3 lower in flux compared to single-band source detection, depending on the source colours. The false detection rate is reduced by a factor between 4 and 10, and the variance of the source position errors is reduced by about a factor 1.5. We also consider the effect of confusion noise and find that the appropriate matched filter gives a further improvement in completeness and noise over the standard PSF filter approach. Overall the two modifications give a factor of 1.5 to 3 improvement in the depth of the recovered catalogues compared to a single-band PSF filter approach.
- [50] arXiv:2002.10885 [pdf, other]
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Title: Thick accretion disk and Its super Eddington luminosity around spinning blackholesSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
According to the disk accretion model theory of Shakura and Sunyayev (1973), accretion disk surrounding the spinning astronomical compact objects (BH, NS) consists of fluid rings obeying the Keplerian motions. Therefore, as we approach the center of compact objects, angular momentum drops, but angular velocity and hence the dissipative heat and accretion rate grow. As a result, the shape of the accretion disk "puffs up" (gets thicker) near the surface of the spinning-compact objects. We, therefore, illustrate the geometry of this thick inner portion of the accretion disk in the context of Mukhopadhyyay's Pseudo Newtonian potential approximation for full General Theory of Relativity.
- [51] arXiv:2002.10895 [pdf, ps, other]
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Title: Power spectra of solar brightness variations at different inclinationsAuthors: N.-E. Nèmec (1), A. I. Shapiro (1), N. A. Krivova (1), S. K. Solanki (1,2), R. V. Tagirov (1,3), R. H. Cameron (1), S. Dreizler (4) ((1) Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany, (2) School of Space Research, Kyung Hee University, Yongin, Gyeonggi, Korea, (3) Astrophysics Group, Imperial College London, London, UK, (4) Institut für Astrophysik, Georg-August-Universität Göttingen, Göttingen, Germany)Comments: 11 pages, 9 figures plus 3 additional figures in the appendix, accepted for publication in Astronomy & AstrophysicsSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Magnetic features on the surfaces of cool stars cause variations of their brightness. Such variations have been extensively studied for the Sun. Recent planet-hunting space telescopes allowed measuring brightness variations in hundred thousands of other stars. The new data posed the question of how typical is the Sun as a variable star. Putting solar variability into the stellar context suffers, however, from the bias of solar observations being made from its near-equatorial plane, whereas stars are observed at all possible inclinations. We model solar brightness variations at timescales from days to years as they would be observed at different inclinations. In particular, we consider the effect of the inclination on the power spectrum of solar brightness variations. The variations are calculated in several passbands routinely used for stellar measurements. We employ the Surface Flux Transport Model (SFTM) to simulate the time-dependent spatial distribution of magnetic features on both near- and far-sides of the Sun. This distribution is then used to calculate solar brightness variations following the SATIRE (Spectral And Total Irradiance REconstruction) approach. We have quantified the effect of the inclination on solar brightness variability at timescales down to a day. Thus, our results allow making solar brightness records directly comparable to those obtained by the planet-hunting space telescopes. Furthermore, we decompose solar brightness variations into the components originating from the solar rotation and from the evolution of magnetic features.
- [52] arXiv:2002.10896 [pdf, ps, other]
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Title: Population of hot subdwarf stars studied with Gaia III. Catalogue of known hot subdwarf stars: Data Release 2Authors: S. GeierComments: 8 pages, A&A acceptedSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
In light of substantial new discoveries of hot subdwarfs by ongoing spectroscopic surveys and the availability of new all-sky data from ground-based photometric surveys and the Gaia mission Data Release 2, we compiled an updated catalogue of the known hot subdwarf stars. The catalogue contains 5874 unique sources including 528 previously unknown hot subdwarfs and provides multi-band photometry, astrometry from Gaia, and classifications based on spectroscopy and colours. This new catalogue provides atmospheric parameters of 2187 stars and radial velocities of 2790 stars from the literature. Using colour, absolute magnitude, and reduced proper motion criteria, we identified 268 previously misclassified objects, most of which are less luminous white dwarfs or more luminous blue horizontal branch and main-sequence stars.
- [53] arXiv:2002.10950 [pdf, other]
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Title: TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). Motivations and protocol version 1.0Authors: Thomas J. Fauchez, Martin Turbet, Eric T. Wolf, Ian Boutle, Michael J. Way, Anthony D. Del Genio, Nathan J. Mayne, Konstantinos Tsigaridis, Ravi K. Kopparapu, Jun Yang, Francois Forget, Avi Mandell, Shawn D. Domagal GoldmanComments: Accepted and published in Geoscientific Model Development (GMD)Journal-ref: Geosci. Model Dev., 13, 707-716, 2020Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Upcoming telescopes such as the James Webb Space Telescope (JWST), or the Extremely Large Telescope (ELTs), may soon be able to characterize, through transmission, emission or reflection spectroscopy, the atmospheres of rocky exoplanets orbiting nearby M dwarfs. One of the most promising candidates is the late M dwarf system TRAPPIST-1 which has seven known transiting planets for which Transit Timing Variation (TTV) measurements suggest that they are terrestrial in nature, with a possible enrichment in volatiles. Among these seven planets, TRAPPIST-1e seems to be the most promising candidate to have habitable surface conditions, receiving ~66 % of the Earth's incident radiation, and thus needing only modest greenhouse gas inventories to raise surface temperatures to allow surface liquid water to exist. TRAPPIST-1e is therefore one of the prime targets for JWST atmospheric characterization. In this context, the modeling of its potential atmosphere is an essential step prior to observation. Global Climate Models (GCMs) offer the most detailed way to simulate planetary atmospheres. However, intrinsic differences exist between GCMs which can lead to different climate prediction and thus observability of gas and/or cloud features in transmission and thermal emission spectra. Such differences should preferably be known prior to observations. In this paper we present a protocol to inter-compare planetary GCMs. Four testing cases are considered for TRAPPIST-1e but the methodology is applicable to other rocky exoplanets in the Habitable Zone. The four test cases included two land planets composed with a modern Earth and pure CO2 atmospheres, respectively, and two aqua planets with the same atmospheric compositions. Currently, there are four participating models (LMDG, ROCKE-3D, ExoCAM, UM), however this protocol is intended to let other teams participate as well.
- [54] arXiv:2002.10953 [pdf, other]
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Title: Predicting Coronal Mass Ejections Using SDO/HMI Vector Magnetic Data Products and Recurrent Neural NetworksComments: 12 pages, 2 figures. arXiv admin note: text overlap with arXiv:1905.07095Journal-ref: The Astrophysical Journal, Volume 890, Number 1, 2020Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Machine Learning (cs.LG)
We present two recurrent neural networks (RNNs), one based on gated recurrent units and the other based on long short-term memory, for predicting whether an active region (AR) that produces an M- or X-class flare will also produce a coronal mass ejection (CME). We model data samples in an AR as time series and use the RNNs to capture temporal information of the data samples. Each data sample has 18 physical parameters, or features, derived from photospheric vector magnetic field data taken by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). We survey M- and X-class flares that occurred from 2010 May to 2019 May using the Geostationary Operational Environmental Satellite's X-ray flare catalogs provided by the National Centers for Environmental Information (NCEI), and select those flares with identified ARs in the NCEI catalogs. In addition, we extract the associations of flares and CMEs from the Space Weather Database Of Notifications, Knowledge, Information (DONKI). We use the information gathered above to build the labels (positive versus negative) of the data samples at hand. Experimental results demonstrate the superiority of our RNNs over closely related machine learning methods in predicting the labels of the data samples. We also discuss an extension of our approach to predict a probabilistic estimate of how likely an M- or X-class flare will initiate a CME, with good performance results. To our knowledge this is the first time that RNNs have been used for CME prediction.
- [55] arXiv:2002.10961 [pdf, other]
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Title: GW170817 and GW190425 as Hybrid Stars of Dark and Nuclear MattersComments: 6 pages, 5 figures, 1 tableSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
We propose three scenarios for hybrid compact stars consisting of nuclear and dark matters to intepret the LIGO/Virgo events GW170817 and GW190425. The equation of state for the nuclear matter is extracted from holographic quantum chromodynamics, and the one for the dark matter is extracted from the massive boson with quartic self-coupling. We study the mass-radius and tidal Love number-mass relations for these hybrid compact stars, and find that they can well explain GW170817 and GW190425. Some of the hybrid stars can have compact neutron or mixed cores around 10km while possessing a thick dark matter shell, which can then explain the astrophysical observations of neutron stars with compact photon radius and mass higher than 2 solar masses. Reversely, we also infer the dark matter model from the parameter estimation of GW190425. Our scenarios of compact hybrid stars can be further tested by the coming LIGO/Virgo O3 events.
- [56] arXiv:2002.10967 [pdf]
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Title: Evidence of presolar SiC in the Allende Curious Marie calcium aluminum rich inclusionAuthors: O. Pravdivtseva (1), F. L. Tissot (2), N. Dauphas (3), S. Amari (1) ((1) Washington University in Saint Louis, USA, (2) California Institute of Technology, USA, (3) University of Chicago, USA)Comments: 4 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Calcium aluminum rich inclusions (CAIs) are one of the first solids to have condensed in the solar nebula, while presolar grains formed in various evolved stellar environments. It is generally accepted that CAIs formed close to the Sun at temperatures above 1500 K, where presolar grains could not survive, and were then transported to other regions of the nebula where the accretion of planetesimals took place. In this context, a commonly held view is that presolar grains are found solely in the fine-grained rims surrounding chondrules and in the low-temperature fine-grained matrix that binds the various meteoritic components together. Here we demonstrate, based on noble gas isotopic signatures, that presolar SiC have been incorporated into fine-grained CAIs in the Allende carbonaceous chondrite at the time of their formation, and have survived parent body processing. This finding provides new clues on the conditions in the nascent solar system at the condensation of first solids.
- [57] arXiv:2002.11009 [pdf, ps, other]
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Title: An X-ray activity cycle on the young solar-like star $ε\ \rm Eridani$Authors: M. Coffaro, B. Stelzer, S. Orlando, J. Hall, T.S. Metcalfe, U. Wolter, M. Mittag, J. Sanz-Forcada, P.C. Schneider, L. DucciComments: 21 pages, 27 figures, 2 tables. Accepted by Astronomy and Astrophysics. Abstract shortened for the arXiv listingSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
In 2015 we started the XMM-Newton monitoring of the young solar-like star Epsilon Eridani (440 Myr), one of the youngest solar-like stars with a known chromospheric CaII cycle. By analyzing the most recent Mount Wilson S-index CaII data of this star, we found that the chromospheric cycle lasts 2.92 +/- 0.02 yr, in agreement with past results. From the long-term X-ray lightcurve, we find clear and systematic X-ray variability of our target, consistent with the chromospheric CaII cycle. The average X-ray luminosity results to be 2 x 10^28 erg/s, with an amplitude that is only a factor 2 throughout the cycle. We apply a new method to describe the evolution of the coronal emission measure distribution of Epsilon Eridani in terms of solar magnetic structures: active regions, cores of active regions and flares covering the stellar surface at varying filling fractions. Combinations of these magnetic structures can describe the observed X-ray emission measure of Epsilon Eridani only if the solar flare emission measure distribution is restricted to events in the decay phase. The interpretation is that flares in the corona of Epsilon Eridani last longer than their solar counterparts. We ascribe this to the lower metallicity of Epsilon Eridani. Our analysis revealed also that the X-ray cycle of Epsilon Eridani is strongly dominated by cores of active regions. The coverage fraction of cores throughout the cycle changes by the same factor as the X-ray luminosity. The maxima of the cycle are characterized by a high percentage of covering fraction of the flares, consistent with the fact that flaring events are seen in the corresponding short-term X-ray lightcurves predominately at the cycle maxima. The high X-ray emission throughout the cycle of Epsilon Eridani is thus explained by the high percentage of magnetic structures on its surface.
- [58] arXiv:2002.11014 [pdf, other]
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Title: First discovery of an ultra-cool white dwarf benchmark in common proper motion with an M dwarfAuthors: M C Lam, N C Hambly, N Lodieu, S Blouin, E J Harvey, R J Smith, M C Galvez-Ortiz, Z H ZhangComments: 11 pages, 4 figures, 5 tables, accepted for publication in MNRASSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Ultra-cool white dwarfs are among the oldest stellar remnants in the Universe. Their efficient gravitational settling and low effective temperatures are responsible for the smooth spectra they exhibit. For that reason, it is not possible to derive their radial velocities or to find the chemistry of the progenitors. The best that can be done is to infer such properties from associated sources, which are coeval. The simplest form of such a system is a common proper motion pair where one star is an evolved degenerate and the other a main sequence star. In this work we present the discovery of the first of such a system, the M dwarf LHS 6328 and the ultra-cool white dwarf PSO J1801+625, from the Pan-STARRS 1 3{\pi} survey and the Gaia Data Release 2. Follow-up spectra were collected covering a usable wavelength range of 3750 to 24500 {\AA}. Their spectra show that the white dwarf has an effective temperature of 3550K and surface gravity of logg = 7.45{\pm}0.13 or logg = 7.49{\pm}0.13 for a CO or He core, respectively, when compared against synthetic spectra of ultra-cool white dwarf atmosphere models. The system has slightly sub-solar metallicity with -0.25<[Fe/H]<0.0, and a spatial velocity of (U, V, W) = (-114.26{\pm}0.24, 222.94{\pm}0.60, 10.25{\pm}0.34) km/s, the first radial velocity and metallicity measurements of an ultra-cool white dwarf. This makes it the first and only benchmark of its kind to date.
- [59] arXiv:2002.11031 [pdf, ps, other]
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Title: Central wavelengths and profile shapes of diffuse interstellar bands vs. physical parameters of intervening cloudsComments: 15 pages, 8 figuresJournal-ref: Acta Astronomica, 2019, vol. 69, issue 4, pp. 369-380Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
This paper tries to establish whether there are variations of the central wavelengths or the profile shapes of diffuse interstellar bands (DIBs) and whether these variations are caused by different physical parameters of translucent clouds.
For this purpose we used spectra of two stars seen through two different single clouds: HD34078 (AE Aur) \& HD73882 acquired using
two different instruments: the MIKE spectrograph, fed with the 6.5 m Magellan telescope at Las Campanas Observatory, and the UVES, fed with the 8 m Kueyen telescope at the Paranal observatory. The wavelength displacements of the DIBs at 6196, 6203, 6376, 6379 and 6614 \AA\ with respect to the well known interstellar atomic and molecular lines (K{\sc i} and CH) have been measured. The mentioned shift is seemingly absent in the DIBs at 4726, 4964, 4763, and 4780 \AA. In addition the considered profiles may show (in HD34078) extended red wings. The observed phenomena are likely related to physical parameters of intervening clouds (rotational temperatures of molecular species) and may help in the identification of the DIB carriers. - [60] arXiv:2002.11036 [pdf, other]
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Title: Planet gap opening across stellar massesComments: 15 pages, 14 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Annular structures in proto-planetary discs, such as gaps and rings, are now ubiquitously found by high-resolution ALMA observations. Under the hypothesis that they are opened by planets, in this paper we investigate how the minimum planet mass needed to open a gap varies across different stellar host masses and distances from the star. The dependence on the stellar host mass is particularly interesting because, at least in principle, gap opening around low mass stars should be possible for lower mass planets, giving us a look into the young, low mass planet population. Using dusty hydrodynamical simulations, we find however the opposite behaviour, as a result of the fact that discs around low mass stars are geometrically thicker: gap opening around low mass stars can require more massive planets. Depending on the theoretical isochrone employed to predict the relationship between stellar mass and luminosity, the gap opening planet mass could also be independent of stellar mass, but in no case we find that gap opening becomes easier around low mass stars. This would lead to the expectation of a {\it lower} incidence of such structures in lower mass stars, since exoplanet surveys show that low mass stars have a lower fraction of giant planets. More generally, our study enables future imaging observations as a function of stellar mass to be interpreted using information on the mass vs. luminosity relations of the observed samples.
- [61] arXiv:2002.11053 [pdf, other]
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Title: CO, Water, and Possible Methanol in Eta Carinae Approaching PeriastronAuthors: Patrick W. Morris, Steven B. Charnley, Michael Corcoran, Martin Cordiner, Augusto Damineli, Jose H. Groh, Theodore R. Gull, Laurent Loinard, Thomas Madura, Andrea Mehner, Anthony Moffat, Maureen Y. Palmer, Gioia Rau, Noel D. Richardson, Gerd WeigeltComments: Accepted by ApJ LettersSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
In circumstellar gas, the complex organic molecule methanol has been found almost exclusively around young stellar objects, and is thus regarded as a signpost of recent star formation. Here we report the first probable detection of methanol around an evolved high-mass star, in the complex circumstellar environment around the Luminous Blue Variable $\eta$ Carinae, while using ALMA to investigate molecular cloud conditions traced by CO (2-1) in an orbit phase of the massive binary preceding the 2020 periastron. Favoring methanol over a $^{13}$CS alternative, the emission originates from hot ($T_{\rm{gas}} \simeq$ 700 K) material, $\sim$2$''$ (0.02 pc) across, centered on the dust-obscured binary in contrast to the CO which traces inner layers of the extended massive equatorial torus, and is accompanied by prominent absorption in a cooler ($T_{\rm{gas}} \simeq$ 110 K) layer of gas. We also report detections of water in $Herschel$/HIFI observations at 557 GHz and 988 GHz. The methanol abundance is several to 50 times higher than observed towards several lower mass stars, while water abundances are similar to those observed in cool, dense molecular clouds. The very high methanol:water abundance ratio in the core of $\eta$ Carinae may suggest methanol formation processes similar to Fischer-Tropsch-type catalytic reactions on dust grains. These observations prove that complex molecule formation can occur in the chemically evolved environments around massive stars in the end stages of their evolution, given sufficient gas densities and shielding conditions as may occur in material around massive interacting companions and merger remnants.
- [62] arXiv:2002.11070 [pdf, other]
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Title: Uncertainties and biases in modelling 16 Cyg A and BAuthors: M. BazotComments: 13 pages, 7 figures, to appear in A & ASubjects: Solar and Stellar Astrophysics (astro-ph.SR)
In this study I assess how existing data for the solar analogues 16 Cyg A and B, in particular the asteroseismic measurements obtained from \emph{Kepler}, constrain theoretical stellar models. The goal is two-fold: first to use these stars as benchmarks to discuss which precisions can realistically be expected on the inferred stellar quantities; and second to determine how well 'non-standard' prescriptions, such as microscopic diffusion and overshoot, are constrained. I used a Bayesian statistical model to infer the values of the stellar parameters of 16 Cyg A and B. I sampled the posterior density of the stellar parameters via a Markov chain Monte Carlo (MCMC) algorithm, tested different physical prescription, and examined the impact of using different seismic diagnostics. General good agreement is found with several recent modelling studies on these stars, even though some discrepancies subsist regarding the precise estimates of the uncertainties on the parameters. An age of $6.88\pm0.12$ Gyr is estimated for the binary system. The inferred masses, $1.07\pm0.02$ M$_{\odot}$ for Cyg A and $1.05\pm0.02$ M$_{\odot}$ for Cyg B, are shown to be stable with respect to changes in the physical prescriptions considered for the modelling. For both stars, microscopic diffusion has a significant effect on the estimates of the initial metallicity. Overshoot is confined to very small regions below the convective zone. I show that a proper treatment of the seismic constraints is necessary to avoid biases in the estimate of the mass.
- [63] arXiv:2002.11074 [pdf, other]
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Title: Stellar mass measurements in Abell 133 with Magellan / IMACSSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present the analysis of deep optical imaging of the galaxy cluster Abell 133 with the IMACS instrument on Magellan. Our multi-band photometry enables stellar mass measurements in the cluster member galaxies down to a mass limit of $M_\star=3\times10^8\,M_\odot$ ($\approx 0.1$ of the Large Magellanic Cloud stellar mass). We observe a clear difference in the spatial distribution of large and dwarf galaxies within the cluster. Modeling these galaxies populations separately, we can confidently track the distribution of stellar mass locked in the galaxies to the cluster's virial radius. The extended envelope of the cluster's brightest galaxy can be tracked to $\sim 200$ kpc. The central galaxy contributes $\sim 1/3$ of the the total cluster stellar mass within the radius $r_{500c}$.
- [64] arXiv:2002.11083 [pdf, other]
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Title: Deformation of the gravitational wave spectrum by density perturbationsComments: 30 pages, 8 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
We study the effect of primordial scalar curvature perturbations on the propagation of gravitational waves over cosmic distances. We point out that such curvature perturbations deform the isotropic spectrum of any stochastic background of gravitational waves of primordial origin through the (integrated) Sachs-Wolfe effect. Computing the changes in the amplitude and frequency of the propagating gravitational wave induced at linear order by scalar curvature perturbations, we show that the resulting deformation of each frequency bin of the gravitational wave spectrum is described by a linearly biased Gaussian with the variance $\sigma^2 \simeq \int d\ln k \Delta_{\mathcal R}^2$, where $\Delta_{\mathcal R}^2(k)$ denotes the amplitude of the primordial curvature perturbations. The linear bias encodes the correlations between the changes induced in the frequency and amplitude of the gravitational waves. Taking into account the latest bounds on $\Delta_{\mathcal R}^2$ from primordial black hole and gravitational wave searches, we demonstrate that the resulting ${\mathcal O}(\sigma)$ deformation can be significant for extremely peaked gravitational wave spectra. We further provide an order of magnitude estimate for broad spectra, for which the net distortion is ${\mathcal O}(\sigma^2)$.
- [65] arXiv:2002.11091 [pdf, ps, other]
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Title: Precise determination of the inflationary epoch and constraints for reheatingAuthors: Gabriel GermanComments: 4 pages, no figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
We present a simple formula which allows to calculate the value of the inflaton field, denoted by $\phi$, at the scale $k$. From here all inflationary observables follow. We illustrate the procedure with Starobinsky model of inflation. This gives an spectral index $n_s=0.96534$ with running $\alpha=-6.1 \times 10^{-4}$, tensor-to-scalar ratio $r=0.0034$ within reach of future experiments and an inflationary energy scale of $7.8 \times 10^{15}GeV$. We also discuss the reheating epoch finding a constraint equation for the effective number of degrees of freedom $g_{re}$. This constraint translates into constraints for the reheating temperature at the end of the reheating era $T_{re}$ and for the number of e-folds during reheating and also during matter domination. For the Starobinsky model we find that $g_{re} \lesssim 83$ giving a bound $T_{re}\lesssim 80\,GeV$ with $40.2 > N_{re} > 31.2$ and $17.4 < N_{rd} < 26.4$ for the number of e-folds during reheating and during radiation domination, respectively.
- [66] arXiv:2002.11095 [pdf, other]
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Title: Carbon- and Oxygen-rich Asymptotic Giant Branch (AGB) stars in the Bulge Asymmetries and Dynamical Evolution (BAaDE) surveySubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Detections of SiO masers from the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey more tightly define the region where Oxygen-rich (O) Asymptotic Giant Branch (AGB) stars reside in multiple infrared (IR) color-color diagrams. Using MSX and 2MASS data along with radio spectra from the BAaDE survey we find that three main populations were observed in the BAaDE survey: O-rich AGB stars of which about $73\%$ host SiO masers, Carbon-rich (C) AGB stars which do not host these masers, and a small contaminating set of possible Young Stellar Objects (YSOs). The distinction between YSOs and AGB stars can be drawn using only MSX data, specifically the $[D]-[E]$ color, while the shorter wavelengths provided by 2MASS are necessary to divide potential C- and O-rich AGB stars. Divisions similar to these have been seen in multiple earlier IR-studies, but BAaDE currently provides a sample of $\sim$ 15000 sources which far exceeds previous studies in sample size, and therefore provides much more distinct divisions. With these IR distinctions in place, we discuss the sources which are exceptions in either their molecular detections or IR colors, as well as the distribution of the three populations in Galactic coordinates.
Cross-lists for Wed, 26 Feb 20
- [67] arXiv:2002.09548 (cross-list from nucl-th) [pdf, other]
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Title: Three-Nucleon Forces: Implementation and Applications to Atomic Nuclei and Dense MatterAuthors: Kai HebelerComments: 134 pages, 69 figures, 7 tablesSubjects: Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
Recent advances in nuclear structure theory have significantly enlarged the accessible part of the nuclear landscape via ab initio many-body calculations. These developments open new ways for microscopic studies of light, medium-mass and heavy nuclei as well as nuclear matter and represent an important step towards a systematic and comprehensive understanding of atomic nuclei across the nuclear chart. While remarkable agreement has been found between different many-body methods for a given nuclear Hamiltonian, the comparison with experiment and the understanding of theoretical uncertainties are still important open questions. The observed discrepancies to experiment indicate deficiencies in presently used nuclear interactions and operators. Chiral effective field theory (EFT) allows to systematically derive contributions to nucleon-nucleon (NN), three-nucleon (3N) and higher-body interactions including estimates of theoretical uncertainties. While the treatment of NN interactions in many-body calculations is well established, the calculation of 3N interactions and their incorporation in ab initio frameworks is still a frontier.
This work reviews in detail recent and current developments on the derivation and implementation of improved 3N interactions and provides a comprehensive introduction to fundamental methods for their practical calculation and representation. We further give an overview of novel and established methods that facilitate the inclusion and treatment of 3N interactions in ab initio nuclear structure frameworks and present a selection of the latest calculations of atomic nuclei as well as nuclear matter based on state-of-the-art nuclear NN and 3N interactions derived within chiral EFT. Finally, we discuss ongoing efforts, open questions and future directions. - [68] arXiv:2002.10481 (cross-list from hep-ph) [pdf, other]
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Title: Revisiting cosmic ray antinuclei fluxes with a new coalescence modeComments: 1+21 pages, 14 pdf figuresSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE)
Antideuteron and antihelium nuclei have been proposed as promising detection channels for dark matter because of the low astrophysical backgrounds expected. To estimate both potential exotic contributions and their backgrounds, one usually employs the coalescence model in momentum space. Here we use instead a newly developed coalescence model based on the Wigner function representations of the produced nuclei states. This approach includes both the process-dependent size of the formation region of antinuclei, and the momentum correlations of coalescing antinucleons in a semi-classical picture. The model contains a single universal parameter $\sigma$ that we tune to experimental data on antideuteron production in electron-positron, proton-proton and proton-nucleus collisions. The obtained value $\sigma\simeq 1$ fm agrees well with its physical interpretation as the size of the formation region of antinuclei in collisions of point-like particles. This model allows us therefore to calculate in a consistent frame-work the antideuteron and antihelium fluxes both from secondary production and from dark matter annihilations. We find that the antihelium-3 flux falls short by more than an order of magnitude of the detection sensitivity of the AMS-02 experiment, assuming standard cosmic ray propagation parameters, while the antideuteron flux can be comparable to the sensitivities of the AMS-02 and GAPS experiments.
- [69] arXiv:2002.10496 (cross-list from gr-qc) [pdf, other]
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Title: Black Hole Superradiance in f(R) GravitiesComments: 22 pages, 4 captioned figures, 2 tablesSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
We study the superradiance amplification factor (SAF) for a charged massive scalar wave scattering off small and slowly rotating Kerr-Newman black holes in f(R) gravity immersed in asymptotically flat and de-Sitter spacetimes. The f(R)-Kerr-Newman family solution induces an extra distinguishable effect on the contribution of the black hole's electric charge to the metric and that in turn affects the SAFs and their frequency ranges. While our analysis are general, but we present the numerical results for the Starobinsky and Hu-Sawicki f(R) models of gravity as our working examples. In the case of asymptotically flat spacetime, the SAFs predicted in Starobinsky f(R) model are not distinguishable from those of GR while for Hu-Sawicki model the SAFs can be weaker or stronger than those of GR within the frequency parameters space. In the case of asymptotically de-Sitter spacetime, superradiance scattering does not occur in Starobinsky model while in Hu-Sawicki model the results of SAFs and their frequency regimes are different from standard ones which can have important astronomical implications.
- [70] arXiv:2002.10831 (cross-list from gr-qc) [pdf, ps, other]
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Title: Solving the curvature and Hubble parameter inconsistencies through structure formation-induced curvatureComments: 16 pages, 1 figureSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Recently it has been noted by Di Valentino, Melchiorri and Silk (2019) that the enhanced lensing signal relative to that expected in the spatially flat $\Lambda$CDM model poses a possible crisis for the Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) class of models usually used to interpret cosmological data. The 'crisis' amounts to inconsistencies between cosmological datasets arising when the FLRW curvature parameter $\Omega_k$ is determined from the data rather than constrained to be zero a priori. Moreover, the already substantial discrepancy between the Hubble parameter as determined by Planck and local observations increases to the level of $5\sigma$. While such inconsistencies might arise from systematic effects of astrophysical origin affecting the Planck Cosmic Microwave Background (CMB) power spectra at small angular scales, it is an option that the inconsistencies are due to the failure of the FLRW assumption. In this paper we recall how the FLRW curvature ansatz is expected to be violated for generic relativistic spacetimes. We explain how the FLRW conservation equation for volume-averaged spatial curvature is modified through structure formation, and we illustrate in a simple framework how the curvature tension in a FLRW spacetime can be resolved - and is even expected to occur - from the point of view of general relativity. Requiring early-time convergence towards a Friedmannian model with a spatial curvature parameter $\Omega_{k0}$ equal to that preferred from the Planck power spectra resolves the Hubble tension within our dark energy-free model.
- [71] arXiv:2002.10884 (cross-list from nucl-th) [pdf, other]
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Title: Constraints on the symmetry energy and its associated parameters from nuclei to neutron starsComments: 10 pages, 11 figures, 2 tables, accepted by Phys.Rev.C. arXiv admin note: text overlap with arXiv:1911.05380Subjects: Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
The symmetry energy obtained with the effective Skyrme energy density functional is related to the values of isoscalar effective mass and isovector effective mass, which is also indirectly related to the incompressibility of symmetric nuclear matter. In this work, we analyze the values of symmetry energy and its related nuclear matter parameters in five-dimensional parameter space by describing the heavy ion collision data, such as isospin diffusion data at 35 MeV/u and 50 MeV/u, neutron skin of $^{208}$Pb, and tidal deformability and maximum mass of neutron star. We obtain the parameter sets which can describe the isospin diffusion, neutron skin, tidal deformability and maximum mass of neutron star, and give the incompressibility $K_0$=250.23$\pm$20.16 MeV, symmetry energy coefficient $S_0$=31.35$\pm$2.08 MeV, the slope of symmetry energy $L$=59.57$\pm$10.06 MeV, isoscalar effective mass $m_s^*/m$=0.75$\pm$0.05 and quantity related to effective mass splitting $f_I$=0.005$\pm$0.170. At two times normal density, the symmetry energy we obtained is in 35-55 MeV. To reduce the large uncertainties of $f_I$, more critical works in heavy ion collisions at different beam energies are needed.
- [72] arXiv:2002.10951 (cross-list from gr-qc) [pdf, ps, other]
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Title: A Fluctuation Dissipation Relation for Relativistic starsAuthors: Seema SatinComments: arXiv admin note: text overlap with arXiv:1711.06859Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
A fluctuation-dissipation relation for perturbed configuration of a relativistic star is obtained. The stochastic fluctuations of the classical stress tensor comprising the matter content ( a perfect fluid) of the relativistic star, act as the source in a classical Einstien-Langevin equation describing the system. We discuss the linear response of these fluctuations of the stress tensor and develop a fluctuation-dissipation relation from the first principles. Thus a system-bath separation in terms of spacetime metric and matter content is proposed, to study equilibrium and non equilibrium statistical properties for a relativistic star. This is not derived from or related to the scalar fields or quantum stress tensors and their fluctuations, as is usually the case for semiclassical stochastic gravity.
Replacements for Wed, 26 Feb 20
- [73] arXiv:1610.07783 (replaced) [pdf, ps, other]
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Title: GMRT observations of IC 711 -- The longest head-tail radio galaxy knownComments: 15 pages. 12 figures, 3 tables, accepted in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [74] arXiv:1807.00397 (replaced) [pdf, other]
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Title: Extended Cosmology in Palatini f(R)-theoriesComments: 24 pages, 14 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [75] arXiv:1812.08135 (replaced) [pdf, other]
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Title: Forecasting [C II] line-intensity mapping measurements between the end of reionization and the epoch of galaxy assemblyComments: 11 pages + appendix (16 total), 3 figures, 5 tables; accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [76] arXiv:1902.00300 (replaced) [pdf]
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Title: MASER: A Science Ready Toolbox for Low Frequency Radio AstronomyAuthors: Baptiste Cecconi, Alan Loh, Pierre Le Sidaner, Renaud Savalle, Xavier Bonnin, Quynh Nhu Nguyen, Sonny Lion, Albert Shih, Stéphane Aicardi, Philippe Zarka, Corentin Louis, Andrée Coffre, Laurent Lamy, Laurent Denis, Jean-Mathias Grießmeier, Jeremy Faden, Chris Piker, Nicolas André, Vincent Génot, Stéphane Erard, Joseph N Mafi, Todd A King, Jim Sky, Markus DemleitnerComments: Submitted to Data Science Journal special issue after PV2018 conferenceSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
- [77] arXiv:1904.04493 (replaced) [pdf, other]
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Title: Weyl Symmetry Inspired Inflation and Dark MatterComments: 18 pages, 1 figure; Accepted in Phys. Lett. BSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [78] arXiv:1906.02064 (replaced) [pdf, other]
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Title: Resolving starlight: a quantum perspectiveAuthors: Mankei TsangComments: 19 pages, 8 figures. v2: streamlined as per referees' suggestions. Accepted by Contemporary PhysicsSubjects: Quantum Physics (quant-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM); Optics (physics.optics)
- [79] arXiv:1907.04339 (replaced) [pdf, other]
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Title: VVV Survey Microlensing: Catalog of Best and Forsaken EventsAuthors: Maria Gabriela Navarro, Rodrigo Contreras Ramos, Dante Minniti, Joyce Pullen, Roberto Capuzzo-Dolcetta, Philip W. LucasComments: 51 pages, 26 figures, 4 tables. Accepted - The Astrophysical JournalSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
- [80] arXiv:1907.13582 (replaced) [pdf, other]
- [81] arXiv:1908.00543 (replaced) [pdf, other]
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Title: Deep learning dark matter map reconstructions from DES SV weak lensing dataComments: Accepted MNRAS, 7 pages, 5 figures, added interpretation of DeepMass improvementJournal-ref: Monthly Notices of the Royal Astronomical Society, Volume 492, Issue 4, March 2020, Pages 5023-5029Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [82] arXiv:1909.05567 (replaced) [pdf, other]
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Title: The rise and fall of an extraordinary Ca-rich transient -- The discovery of ATLAS19dqr/SN 2019bkcAuthors: S. J. Prentice, K. Maguire, A. Flörs, S. Taubenberger, C. Inserra, C. Frohmaier, T. W. Chen, J. P. Anderson, C. Ashall, P. Clark, M. Fraser, L. Galbany, A. Gal-Yam, M. Gromadzki, C. P. Gutiérrez, P. A. James, P. G. Jonker, E. Kankare, G. Leloudas, M. R. Magee, P. A. Mazzali, M. Nicholl, M. Pursiainen, K. Skillen, S. J. Smartt, K. W. Smith, C. Vogl, D. R. YoungComments: Accepted for publication in Astronomy & Astrophysics. Minor changes to section 4.3, some minor discussion added regarding opacities and line identificationSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [83] arXiv:1909.08420 (replaced) [pdf, other]
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Title: Transversely trapping surfaces: Dynamical versionComments: 34 pages, 10 figures, figures improved, minor corrections, published versionJournal-ref: Prog. Theor. Exp. Phys. (2020) 023E02Subjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics of Galaxies (astro-ph.GA)
- [84] arXiv:1909.11044 (replaced) [pdf, ps, other]
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Title: Gamma radiation from areal radius minima in a quasi-spherical Szekeres metricAuthors: Andrzej KrasińskiComments: 35 pages, 9 figures. Literature on GRBs updated, conclusions section extended, small editorial corrections. This text matches the published one. Length spuriously increased because of APPB page displayJournal-ref: Acta Phys. Polon. B51, 483 (2020)Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [85] arXiv:1911.01428 (replaced) [pdf, other]
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Title: Planet-disk interaction in disks with cooling: basic theoryComments: 22 pages, 8 figures, accepted for publication in ApJSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [86] arXiv:1911.02868 (replaced) [pdf, other]
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Title: Theoretical priors in scalar-tensor cosmologies: Thawing quintessenceAuthors: Carlos García-García, Emilio Bellini, Pedro G. Ferreira, Dina Traykova, Miguel ZumalacárreguiComments: V1: 13 pages, 11 figures, comments welcome; V2: 14 pages, 11 figures, minor clarifications added, accepted for publication in PRDSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [87] arXiv:1911.13088 (replaced) [pdf, other]
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Title: Calibration and 21-cm Power Spectrum Estimation in the Presence of Antenna Beam VariationsComments: 14 pages, 8 figures. Accepted for publication in MNRAS December 2019. Erratum submitted in February 2020Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [88] arXiv:1912.02264 (replaced) [pdf, other]
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Title: A New Likely Redback Millisecond Pulsar Binary with a Massive Neutron Star: 4FGL J2333.1--5527Authors: Samuel J. Swihart, Jay Strader, Ryan Urquhart, Jerome A. Orosz, Laura Shishkovsky, Laura Chomiuk, Ricardo Salinas, Elias Aydi, Kristen C. Dage, Adam M. KawashComments: Accepted to ApJ; 9 pages, 6 figures, 1 tableSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [89] arXiv:2001.00923 (replaced) [pdf, other]
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Title: A Joint Fermi-GBM and LIGO/Virgo Analysis of Compact Binary Mergers From the First and Second Gravitational-wave Observing RunsAuthors: The Fermi Gamma-ray Burst Monitor Team, the LIGO Scientific Collaboration, the Virgo Collaboration: R. Hamburg, C. Fletcher, E. Burns, A. Goldstein, E. Bissaldi, M. S. Briggs, W. H. Cleveland, M. M. Giles, C. M. Hui, D. Kocevski, S. Lesage, B. Mailyan, C. Malacaria, S. Poolakkil, R. Preece, O. J. Roberts, P. Veres, A. von Kienlin, C. A. Wilson-Hodge, J. Wood, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Aich, L. Aiello, A. Ain, P. Ajith, G. Allen, A. Allocca, P. A. Altin, A. Amato, S. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Ansoldi, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Arene, N. Arnaud, S. M. Aronson, S. Ascenzi, G. Ashton, et al. (1205 additional authors not shown)Comments: Accepted for publication in ApJ. 18 pages, 4 figures, 1 tableSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [90] arXiv:2001.04065 (replaced) [pdf, other]
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Title: Constraints on the Emission of Gamma Rays from M31 with HAWCAuthors: HAWC Collaboration: A. Albert, R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, K. P. Arunbabu, D. Avila Rojas, H. A. Ayala Solares, E. Belmont-Moreno, S. Y. BenZvi, C. Brisbois, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, S. Dichiara, B. L. Dingus, M. A. DuVernois, K. Engel, C. Espinoza, H. Fleischhack, N. Fraija, A. Galván-Gámez, D. García-Aguilar, J. A. García-González, F. Garfias, M. M. González, J. A. Goodman, J. P. Harding, S. Hernandez, B. Hona, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, D. Kieda, W. H. Lee, H. León Vargas, A. L. Longinotti, G. Luis-Raya, K. Malone, S. S. Marinelli, et al. (36 additional authors not shown)Comments: Accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [91] arXiv:2001.06904 (replaced) [pdf, other]
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Title: UV & U-band luminosity functions from CLAUDS and HSC-SSP -- I. Using four million galaxies to simultaneously constrain the very faint and bright regimes to $z \sim 3$Authors: Thibaud Moutard, Marcin Sawicki, Stéphane Arnouts, Anneya Golob, Jean Coupon, Olivier Ilbert, Xiaohu Yang, Stephen GwynComments: 18 pages, 11 figures (26 pages, 18 figures including the Appendix). Accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [92] arXiv:2001.07182 (replaced) [pdf, ps, other]
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Title: Could quasar lensing time delays hint to cored dark matter halos, instead of $H_0$ tension?Comments: 11 pages, 4 figures. v2: added comparison to stellar kinematics constraints. Results and conclusions unchangedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph)
- [93] arXiv:2002.02110 (replaced) [pdf, ps, other]
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Title: Resolving the Excess of Long GRBs at low redshift in the Swift EraComments: 15 pages, 18 figures, accepted for publication in mnras, fixing tables layout (v2)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [94] arXiv:2002.03033 (replaced) [pdf, ps, other]
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Title: On the orbital evolution of 2020 AV2, the first asteroid ever observed to go around the Sun inside the orbit of VenusComments: 5 pages, 5 figures, 2 tables. Revised to match the version published in Monthly Notices of the Royal Astronomical Society LettersSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [95] arXiv:2002.08297 (replaced) [pdf, other]
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Title: A Binary Comb Model for Periodic Fast Radio BurstsComments: 8 pages, 2 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
- [96] arXiv:2002.08377 (replaced) [pdf, other]
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Title: Time Dependent Radiation Hydrodynamics on a Moving MeshComments: 13 pages, 8 figures, accepted to MNRASSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)
- [97] arXiv:2002.09411 (replaced) [pdf, other]
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Title: Multi-scale simulations of particle acceleration in astrophysical systemsComments: 202 pages, 43 figures, to be published in the Living Reviews of Computational AstrophysicsSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [98] arXiv:2002.09955 (replaced) [pdf, other]
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Title: Observational constraints on dark matter decaying via gravity portalsSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [99] arXiv:2002.10409 (replaced) [pdf, other]
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Title: A Modified Spheromak Model Suitable for Coronal Mass Ejection SimulationsSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
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