Astrophysics
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New submissions for Tue, 17 Mar 20
- [1] arXiv:2003.06424 [pdf, other]
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Title: HST/STIS transmission spectrum of the ultra-hot Jupiter WASP-76 b confirms the presence of sodium in its atmosphereAuthors: C. von Essen, M. Mallonn, S. Hermansen, M. C. Nixon, N. Madhusudhan, H. Kjeldsen, G. TautvaišienėComments: 14 pages, 10 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
We present an atmospheric transmission spectrum of the ultra-hot Jupiter WASP-76 b by analyzing archival data obtained with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). The dataset spans three transits, two with a wavelength coverage between 2900 and 5700 Armstrong, and the third one between 5250 and 10300 Armstrong. From the one-dimensional, time dependent spectra we constructed white and chromatic light curves, the latter with typical integration band widths of ~200 Armstrong. We computed the wavelength dependent planet-to-star radii ratios taking into consideration WASP-76's companion. The resulting transmission spectrum of WASP-76 b is dominated by a spectral slope of increasing opacity towards shorter wavelengths of amplitude of about three scale heights under the assumption of planetary equilibrium temperature. If the slope is caused by Rayleigh scattering, we derive a lower limit to the temperature of ~870 K. Following-up on previous detection of atomic sodium derived from high resolution spectra, we re-analyzed HST data using narrower bands centered around sodium. From an atmospheric retrieval of this transmission spectrum, we report evidence of sodium at 2.9-sigma significance. In this case, the retrieved temperature at the top of the atmosphere (10-5 bar) is 2300 +412-392 K. We also find marginal evidence for titanium hydride. However, additional high resolution ground-based data are required to confirm this discovery.
- [2] arXiv:2003.06427 [pdf, other]
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Title: Measuring the Tidal Response of Structure Formation: Anisotropic Separate Universe Simulations using TreePMComments: 18 pages, 9 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present anisotropic ``separate universe'' simulations which modify the N-body code Gadget-4 in order to represent a large-scale tidal field through an anisotropic expansion factor. These simulations are used to measure the linear, quasi-linear and nonlinear response of the matter power spectrum to a spatially uniform trace-free tidal field up to wavenumber $k = 10 h \text{Mpc}^{-1}$. Together with the response to a large-scale overdensity measured in previous work, this completely describes the nonlinear matter bispectrum in the squeezed limit. We find that the response amplitude does not approach zero on small scales in physical coordinates, but rather a constant value, $R_K\approx 0.5$ for $k \geq 3 h\text{Mpc}^{-1}$ at $z=0$. This shows that even the inner regions of haloes are affected by the large-scale tidal field. We also measure directly the alignment of halo shapes with the tidal field, finding a clear signal which increases with halo mass.
- [3] arXiv:2003.06429 [pdf, other]
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Title: Absorption line abundances in the SMC-like galaxy UGC 5282: evidence for ISM dilution from inflows on kpc scalesAuthors: David V. Bowen, Todd M. Tripp, Edward B. Jenkins, Max Pettini, Doron Chelouche, Renyue Cen, Donald G. YorkComments: Accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present an HST Cosmic Origins Spectrograph (COS) spectrum of the QSO SDSS J095109.12+330745.8 ($z_{em} = 0.645$) whose sightline passes through the SMC-like dwarf galaxy UGC 5282 ($M_B = -16.0$, $cz = 1577$ km s$^{-1}$ ), 1.2 kpc in projection from the central HII region of the galaxy. Damped Ly$\alpha$ (DLA) absorption is detected at the redshift of UGC 5282 with $\log$[$N$(HI) cm$^{-2}\:$] = 20.89$^{+0.12}_{-0.21}\:\:$. Analysis of the accompanying SII, PII and OI metal lines yields a neutral gas metallicity $Z_{HI}$ of [S/H] $\simeq$ [P/H] $= -0.80\pm0.24$. The metallicity of ionized gas from the central HII region, $Z_{HII}\:$, measured from its emission lines is [O/H]$= -0.37\pm0.10$, a difference of $+0.43\pm 0.26$ from $Z_{HI}\:$. This difference $\delta$ is consistent with that seen towards HII regions in other star-forming galaxies and supports the idea that ionized gas near star forming regions show systematically higher metallicities than exist in the rest of a galaxy's neutral interstellar medium (ISM). The positive values of $\delta$ found in UGC 5282 (and the other star forming galaxies) is likely due to infalling low metallicity gas from the intergalactic medium which mixes with the galaxy's ISM on kpc scales. This model is also consistent with broad Ly$\alpha$ emission detected at the bottom of the DLA absorption, offset by $\sim 125$ km s$^{-1}$ from the absorption velocity. Models of galaxy evolution which attempt to replicate population characteristics, such as the mass-metallicity relation, may need to start with a galaxy metallicity represented by $Z_{HI}$ rather than that measured traditionally from $Z_{HII}\:$.
- [4] arXiv:2003.06432 [pdf, other]
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Title: On the short term modulation of cosmic rays by high-speed streams at the Pierre Auger surface array detectorsComments: 14 pages, 11 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Space Physics (physics.space-ph)
We present an analysis of the short-term modulation (one rotation of Bartels-27 days) of the galactic cosmic rays (GCR) by the solar wind, based on the cosmic ray rates observed by the Pierre Auger Observatory (PAO) on their surface detectors in scaler mode. The incidence of GCR with energies below $\sim$ 50 TeV, at the top of the atmosphere, produces more than 90\% of the secondary particles registered at ground level, i.e., they are subject to solar modulation. The modulation is consistent with at least two components: The first is the modulation of the amplitude of the cosmic rays diurnal variation, anti-correlated with the solar-wind speed. The second one occurs during the high-speed stream (HSS), the baseline of the cosmic rays diurnal variation train falls, following the time profile of the solar-wind speed inversely. Based on the radial gradient of the cosmic ray diffusion theory and under some other premises, such as the latitude dependence on diurnal variation and the inclusion of drift processes in the propagation of GCR, a semi-empirical description of the modulation is possible to do, and it hereafter is called as Toy-model. Although the Toy-model does not include fluctuations due to propagation in the atmosphere, it provides satisfactory results when compared with the PAO scaler mode data. We present details of these observations as well as the Toy-model validation.
- [5] arXiv:2003.06436 [pdf, ps, other]
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Title: Early neutron star evolution in high-mass X-ray binariesAuthors: Wynn C. G. Ho (Haverford), M. J. P. Wijngaarden (Southampton), Nils Andersson (Southampton), Thomas M. Tauris (Aarhus), F. Haberl (MPE)Comments: 7 pages, 4 figures; accepted for publication in MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
The application of standard accretion theory to observations of X-ray binaries provides valuable insights into neutron star properties, such as their spin period and magnetic field. However, most studies concentrate on relatively old systems, where the neutron star is in its late propeller, accretor, or nearly spin equilibrium phase. Here we use an analytic model from standard accretion theory to illustrate the evolution of high-mass X-ray binaries early in their life. We show that a young neutron star is unlikely to be an accretor because of the long duration of ejector and propeller phases. We apply the model to the recently discovered ~4000 yr old high-mass X-ray binary XMMU J051342.6-672412 and find that the system's neutron star, with a tentative spin period of 4.4 s, cannot be in the accretor phase and has a magnetic field B > (a few)x10^13 G, which is comparable to the magnetic field of many older high-mass X-ray binaries and is much higher than the spin equilibrium inferred value of (a few)x10^11 G. The observed X-ray luminosity could be the result of thermal emission from a young cooling magnetic neutron star or a small amount of accretion that can occur in the propeller phase.
- [6] arXiv:2003.06443 [pdf, other]
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Title: Star formation law in the EoR from [CII] and CIII] linesComments: 6 pages, 1 figure, Accepted for publication in MNRAS LettersSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present a novel method to simultaneously characterise the star formation law and the interstellar medium properties of galaxies in the Epoch of Reionization (EoR) through the combination of [CII] 158$\mu$m (and its known relation with star formation rate) and CIII]$\lambda$1909{\AA} emission line data. The method, based on a Markov Chain Monte Carlo algorithm, allows to determine the target galaxy average density, $n$, gas metallicity, $Z$, and burstiness parameter, $\kappa_s$, quantifying deviations from the Kennicutt-Schmidt relation. As an application, we consider COS-3018 (z=6.854), the only EoR Lyman Break Galaxy so far detected in both [CII] and CIII]. We show that COS-3018 is a moderate starburst ($\kappa_s \approx 3$), with $Z\approx 0.4\, Z_{\odot}$, and $n \approx 500\, {\rm cm^{-3}}$. Our method will be optimally applied to joint ALMA and JWST targets.
- [7] arXiv:2003.06449 [pdf, other]
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Title: Extreme Ultraviolet and Soft X-Ray Diffraction Efficiency of a Blazed Reflection Grating Fabricated by Thermally Activated Selective Topography EquilibrationComments: 19 pages, 16 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Future observatories utilizing reflection grating spectrometers for extreme ultraviolet (EUV) and soft X-ray (SXR) spectroscopy require high-fidelity gratings with both blazed groove facets and custom groove layouts that are often fanned or feature a slight curvature. While fabrication procedures centering on wet anisotropic etching in monocrystalline silicon produce highly efficient blazed gratings, the precision of a nonparallel groove layout is limited by the cubic structure of the silicon crystal. This motivates the pursuit of alternative techniques to grating manufacture, namely thermally activated selective topography equilibration (TASTE), which uses gray-scale electron-beam lithography to pattern multilevel structures in resist followed by an optimized polymer thermal reflow to smooth the 3D patterns into continuous surface relief profiles. Using TASTE, a mold for a reflection grating with a periodicity of 400 nm and grooves resembling an asymmetric sawtooth was patterned in 130 nm thick poly(methyl methacrylate) resist on a silicon substrate over a 50 mm by 7.5 mm area. This structure was coated with 15 nm of gold by electron-beam physical vapor deposition using titanium as an adhesion layer and then tested for EUV and SXR diffraction efficiency at beamline 6.3.2 of the Advanced Light Source synchrotron facility. Results demonstrate a quasi-blaze response characteristic of a 27 degree blaze angle with groove facets smooth to 1.5 nm rms. Absolute peak-order efficiency ranges from 75% to 25%, while total relative efficiency measures gap90% across the measured bandpass of 15.5 nm > lambda > 1.55 nm.
- [8] arXiv:2003.06453 [pdf, other]
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Title: Extended Red Emission: Observational constraints for modelsComments: 10 pages, 2 figures, preprint to be published in the Topical Collection on "Unexplained Spectral Phenomena in the Interstellar Medium" of Astrophysics and Space ScienceSubjects: Astrophysics of Galaxies (astro-ph.GA)
Extended Red Emission (ERE) is a widely observed optical emission process, present in a wide range of circumstellar and interstellar environments in the Milky Way galaxy as well as other galaxies. Definitive identifications of the ERE carriers and the ERE process are still a matter of debate. Numerous models have been proposed in recent decades, often developed without consideration of the growing body of observational constraints, which by now invalidate many of these models. This review focuses on the most well-established observational constraints which should help to delineate the way toward a generally accepted explanation of the ERE and an understanding of its place in the radiation physics of the interstellar medium.
- [9] arXiv:2003.06519 [pdf, other]
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Title: Hubble Space Telescope Search for Activity in High Perihelion ObjectsComments: 30 pages, 11 figures, 4 tables. Accepted by AJSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Solar system objects with perihelia beyond the orbit of Jupiter ($q >$ 5 AU) are too cold for water ice to generate an appreciable coma via sublimation. Despite this, numerous high perihelion objects (HPOs) including many comets and recently escaped Kuiper belt objects (``Centaurs'') are observed to be active out at least to the orbit of Saturn ($q \sim$ 10 AU). Peak equilibrium temperatures at 10 AU ($\sim$125 K), while far too low to sublimate water ice, are sufficient to sublimate super-volatiles such as CO and CO$_2$ ice. Temperatures at 10 AU are also high enough to trigger the rapid crystallization of exposed amorphous ice, thus constituting another possible driver of distant activity. While supervolatile ices can sublimate strongly (as $r_H^{-2}$) to at least Kuiper belt (30 AU) distances, crystallization is an exponential function of temperature that cannot be sustained much beyond $\sim$10 AU. The heliocentric dependence of the activity thus suggests an observational test. If activity in high perihelion objects is triggered by crystallization, then no examples of activity should be found with perihelia $q >>$ 10 AU. If, on the other hand, activity is due to free sublimation of exposed supervolatile ices, or another cause, then distant activity might be detected. We obtained sensitive, high resolution Hubble Space Telescope observations of HPOs to search for activity beyond the crystallization zone. No examples of activity were detected in 53 objects with $q >$ 15 AU, consistent with the crystallization trigger hypothesis. However, sensitivity limits are such that we cannot reject the alternative hypothesis that mass loss is driven by the sublimation of supervolatile ices. We also searched for binary companions in our sample, finding none and setting an empirical 3$\sigma$ limit to the binary fraction of $<8$\%.
- [10] arXiv:2003.06522 [pdf, other]
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Title: Planet-induced Vortices with Dust Coagulation in Protoplanetary DisksAuthors: Ya-Ping Li (1), Hui Li (1), Shengtai Li (1), Tilman Birnstiel (2,3), Joanna Drazkowska (2), Sebastian Stammler (2) ((1) LANL, (2) LMU, (3) Exzellenzcluster ORIGINS)Comments: Accepted for publication in ApJL, 10 pages, 5 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
In this work, we study how the dust coagulation/fragmentation will influence the evolution and observational appearances of vortices induced by a massive planet embedded in a low viscosity disk by performing global 2D high-resolution hydrodynamical simulations. Within the vortex, due to its higher gas surface density and steeper pressure gradients, dust coagulation, fragmentation and drift (to the vortex center) are all quite efficient, producing dust particles ranging from micron to $\sim 1.0\ {\rm cm}$, as well as overall high dust-to-gas ratio (above unity). In addition, the dust size distribution is quite non-uniform inside the vortex, with the mass weighted average dust size at the vortex center ($\sim 4.0$ mm) being a factor of $\sim10$ larger than other vortex regions. Both large ($\sim$ mm) and small (tens of micron) particles contribute strongly to affect the gas motion within the vortex. As such, we find that the inclusion of dust coagulation has a significant impact on the vortex lifetime and the typical vortex lifetime is about 1000 orbits. After the initial gaseous vortex is destroyed, the dust spreads into a ring with a few remaining smaller gaseous vortices with a high dust concentration and a large maximum size ($\sim$ mm). At late time, the synthetic dust continuum images for the coagulation case show as a ring inlaid with several hot spots at 1.33 mm band, while only distinct hot spots remain at 7.0 mm.
- [11] arXiv:2003.06528 [pdf, ps, other]
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Title: Cosmological signatures of torsion and how to distinguish torsion from the dark sectorComments: 12 pages, 6 figures, 1 table; free-licensed fortran code and plotting scripts to reproduce Figures 1-6 are included in the ArXiv packageSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
Torsion is a non-Riemannian geometrical extension of general relativity that allows including the spin of matter and the twisting of spacetime. Cosmological models with torsion have been considered in the literature to solve problems of either the very early (high redshift $z$) or the present-day Universe. This paper focuses on distinguishable observational signatures of torsion that could not be otherwise explained with a scalar field in pseudo-Riemannian geometry. We show that when torsion is present, the cosmic duality relation between the angular diameter distance, $D_{\mathrm A}$, and the luminosity distance, $D_{\mathrm L}$, is broken. We show how the deviation described by the parameter $\eta = D_{\mathrm L}/[ D_{\mathrm A}(1+z)^2] -1 $ is linked to torsion and how different forms of torsion lead to special-case parametrisations of $\eta$, including $\eta_0 z$, $\eta_0 z/(1+z)$, and $\eta_0 \ln (1+z)$. We also show that the effects of torsion could be visible in low-redshift data, inducing biases in supernovae-based $H_0$ measurements. We also show that torsion can impact the Clarkson-Bassett-Lu (CBL) function ${\cal C}(z) = 1 + H^2 (D D'' - D'^2) + H H' D D'$, where $D$ is the transverse comoving distance. If $D$ is inferred from the luminosity distance, then, in general non-zero torsion models, ${\cal C}(z) \ne 0$. For pseudo-Riemannian geometry, the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric has ${\cal C}(z) \equiv 0$; thus, measurement of the CBL function could provide another diagnostic of torsion.
- [12] arXiv:2003.06539 [pdf]
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Title: Measures of 62 Southern PairsComments: 24 pages, 6 Figures (Fig5 consists of 61 Rectilinear Plots and Fig6 consists of 5 orbital plots)Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
We report lucky imaging observations of 62 pairs at mid-southern declinations sourced from the WDS with separations larger than 4 arc seconds and magnitude less than 10. The measures comprise separations and PA calibrated against Alpha Centauri AB and drift scans, presented as weighted means of these two calibration methods, with formal internal uncertainties \delta\rho = 80 mas and \delta PA = 0.056(deg). We also compare our measures against 1) extrapolated historic measures, 2) GAIA DR2 data and 3) measures determined from HIPPARCOS and GAIA observations. Our best estimate of our bias against these 3 databases are \rho \approx 10 \pm 30 mas and PA \approx 0.04 \pm 0.08(deg). These formal uncertainties are consistent with the internal uncertainties of \delta\rho = 80 mas and \delta PA = 0.056(deg). We also report Rectilinear Elements for 61 pairs, Grade 5 Orbital Elements for 5 pairs and suggest 5 pairs as optical doubles (4 of which are new).
- [13] arXiv:2003.06577 [pdf, other]
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Title: Rotational Disruption of Nonspherical Cometary Dust Particles by Radiative TorquesAuthors: Joonas HerranenSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Rigorous statistical numerical analysis of the response of a nonspherical dust particle ensemble composed of aggregates of astronomical silicate is presented. It is found that the rotational disruption mechanism is not only likely to occur but to be a key element in explaining many separate observations of cometary dust. Namely, radiative torques are shown to spin-up and align cometary dust within the timescales of cometary activity. Additionally, the radiative torque alignment and disruption mechanisms within certain conditions are shown to be consistent with observations of rapid polarization of dust and spectral bluing of dust. The results indicate that radiative torques should be taken into account nearly universally when considering the evolution of cometary dust.
- [14] arXiv:2003.06586 [pdf, other]
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Title: Hunting for the host galaxy groups of binary black holes and the application in constraining Hubble constantComments: 16 pages, 26 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)
The discovery of gravitational-wave (GW) signals, produced by the coalescence of stellar-mass binary black holes (SBBHs), opens a new window to study the astrophysical origins and dynamical evolutions of compact binaries. In addition, these GW events can be treated as the standard sirens to constrain various cosmological parameters. Both issues require the host identification for these GW events, with help of the spatial resolution of GW detector networks. In this paper, we investigate the capabilities of various detector networks for identifying the SBBHs' host galaxy groups, rather than their host galaxies, which can overcome the influence of galaxies' proper motions in dark matter halos for measuring the cosmological parameters. In our analysis, the group catalog of SDSS DR7 with redshift $z\in(0.01,0.1)$ is considered as an example of the application. We find that for the second-generation (2G) detector network, the host galaxy groups of around $17\%$ $30-30\ M_{\odot}$ SBBHs can be identified. For the 3G detector network, this fraction becomes $\sim 99\%$. We also investigate the potential constraint on the Hubble constant $H_0$ by these GW events, if their redshift information is extracted from the candidates of host galaxy groups. We find that, by five-year observations, 2G detector network is expected to give a constraint of $\Delta H_0/H_0\sim (1\%,4\%)$, which can be more than two order smaller if considering the 3G detector network.
- [15] arXiv:2003.06587 [pdf, other]
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Title: Particle acceleration in astrophysical jetsComments: To appear in New Astronomy Reviews special volume '100 Years of Astrophysical Jets' (eds. Rob Fender and Ralph Wijers). 23 pages, 8 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Plasma Physics (physics.plasm-ph)
In this chapter, we review some features of particle acceleration in astrophysical jets. We begin by describing four observational results relating to the topic, with particular emphasis on jets in active galactic nuclei and parallels between different sources. We then discuss the ways in which particles can be accelerated to high energies in magnetised plasmas, focusing mainly on shock acceleration, second-order Fermi and magnetic reconnection; in the process, we attempt to shed some light on the basic conditions that must be met by any mechanism for the various observational constraints to be satisfied. We describe the limiting factors for the maximum particle energy and briefly discuss multimessenger signals from neutrinos and ultrahigh energy cosmic rays, before describing the journey of jet plasma from jet launch to cocoon with reference to the different acceleration mechanisms. We conclude with some general comments on the future outlook.
- [16] arXiv:2003.06595 [pdf, other]
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Title: The MALATANG Survey: Dense Gas and Star Formation from High Transition HCN and HCO+ maps of NGC253Authors: Xue-Jian Jiang, Thomas R. Greve, Yu Gao, Zhi-Yu Zhang, Qinghua Tan, Richard de Grijs, Luis C. Ho, Michal J. Michalowski, Malcolm J. Currie, Christine D. Wilson, Elias Brinks, Yiping Ao, Yinghe Zhao, Jinhua He, Nanase Harada, Chentao Yang, Qian Jiao, Aeree Chung, Bumhyun Lee, Matthew W. L. Smith, Daizhong Liu, Satoki Matsushita, Yong Shi, Masatoshi Imanishi, Mark G. Rawlings, Ming Zhu, David Eden, Timothy A. Davis, Xiaohu LiComments: accepted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
To study the high-transition dense-gas tracers and their relationships to the star formation of the inner $\sim$ 2 kpc circumnuclear region of NGC253, we present HCN $J=4-3$ and HCO$^+ J=4-3$ maps obtained with the James Clerk Maxwell Telescope (JCMT). With the spatially resolved data, we compute the concentration indices $r_{90}/r_{50}$ for the different tracers. HCN and HCO$^+$ 4-3 emission features tend to be centrally concentrated, which is in contrast to the shallower distribution of CO 1-0 and the stellar component. The dense-gas fraction ($f_\text{dense}$, traced by the velocity-integrated-intensity ratios of HCN/CO and HCO$^+$/CO) and the ratio $R_\text{31}$ (CO 3-2/1-0) decline towards larger galactocentric distances, but increase with higher SFR surface density. The radial variation and the large scatter of $f_\text{dense}$ and $R_\text{31}$ imply distinct physical conditions in different regions of the galactic disc. The relationships of $f_\text{dense}$ versus $\Sigma_\text{stellar}$, and SFE$_\text{dense}$ versus $\Sigma_\text{stellar}$ are explored. SFE$_\text{dense}$ increases with higher $\Sigma_\text{stellar}$ in this galaxy, which is inconsistent with previous work that used HCN 1-0 data. This implies that existing stellar components might have different effects on the high-$J$ HCN and HCO$^+$ than their low-$J$ emission. We also find that SFE$_\text{dense}$ seems to be decreasing with higher $f_\text{dense}$, which is consistent with previous works, and it suggests that the ability of the dense gas to form stars diminishes when the average density of the gas increases. This is expected in a scenario where only the regions with high-density contrast collapse and form stars.
- [17] arXiv:2003.06602 [pdf, other]
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Title: Geodesic Noise and Gravitational Wave Observations by Pulsar Timing ArraysComments: 4 pages, 2 figures, 1 tableSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
Signals from millisecond pulsars travel to us along geodesics that are affected by the space--time metric along the line-of-sight. The exact length and redshifting along the geodesics determine the Time-of-Arrival (ToA) of the pulses. The metric is determined by the distribution of dark matter, gas, and stars in the galaxy and, in the final stages of travel, by the distribution of solar system bodies. The inhomogeneous distribution of stellar masses can have a small but significant statistical effect on the ToAs through the perturbation of geodesics. This will result in additional noise in ToA observations that may affect Pulsar Timing Array (PTA) constraints on gravitational waves at very low frequencies. We employ a simple model for the stellar distribution in our galaxy to estimate the scale of both static and dynamic sources of what we term generically ``geodesic noise''. We find that geodesic noise is ${\cal O}(10)$ ns for typical lines-of-sight. This indicates that it is relevant for estimates of PTA sensitivity and may limit future efforts for detection of gravitational waves by PTAs.
- [18] arXiv:2003.06603 [pdf, other]
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Title: The pivot energy of Solar Energetic Particles Affecting the Martian surface radiation environmentAuthors: Jingnan Guo, Robert F. Wimmer-Schweingruber, Yuming Wang, Manuel Grande, Daniel Matthiae, Cary Zeitlin, Bent Ehresmann, Donald M. HasslerJournal-ref: J. Guo*, R. F. Wimmer-Schweingruber, Y. Wang, et al. (2019). The Pivot Energy of Solar Energetic Particles Affecting the Martian Surface Radiation Environment, The Astrophysical Journal Letters , 883, 1, L12Subjects: Earth and Planetary Astrophysics (astro-ph.EP); High Energy Astrophysical Phenomena (astro-ph.HE)
Space radiation is a major risk for humans, especially on long-duration missions to outer space, e.g., a manned mission to Mars. Galactic cosmic rays (GCR) contribute a predictable radiation background, the main risk is due to the highly variable and currently unpredictable flux of solar energetic particles (SEPs). Such sporadic SEP events may induce acute health effects and are thus considered a critical mission risk for future human exploration of Mars. Therefore, it is of utmost importance to study, model, and predict the surface radiation environment during such events. It is well known that the deep-space SEP differential energy spectrum at high energies is often given by a power law. We use a measurement-validated particle transport code to show that, for large SEP events with proton energy extending above ~ 500 MeV with a power-law distribution, it is sufficient to measure the SEP flux at a pivot energy of ~ 300 MeV above the Martian atmosphere to predict the dose rate on the Martian surface. In conjunction with a validation by in-situ measurements from the Martian surface, this remarkable simplification and elegant quantification could enable instant predictions of the radiation environment on the surface of Mars upon the onset of large SEP events.
- [19] arXiv:2003.06614 [pdf, other]
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Title: Combined search for neutrinos from dark matter self-annihilation in the Galactic Centre with ANTARES and IceCubeAuthors: ANTARES Collaboration: A. Albert, M. André, M. Anghinolfi, M. Ardid, J.-J. Aubert, J. Aublin, B. Baret, S. Basa, B. Belhorma, V. Bertin, S. Biagi, M. Bissinger, J. Boumaaza, M. Bouta, M.C. Bouwhuis, H. Brânzaş, R. Bruijn, J. Brunner, J. Busto, A. Capone, L. Caramete, J. Carr, S. Celli, M. Chabab, T. N. Chau, R. Cherkaoui El Moursli, T. Chiarusi, M. Circella, A. Coleiro, M. Colomer, R. Coniglione, P. Coyle, A. Creusot, A. F. Díaz, A. Deschamps, C. Distefano, I. Di Palma, A. Domi, C. Donzaud, D. Dornic, D. Drouhin, T. Eberl, N. El Khayati, A. Enzenhöfer, A. Ettahiri, P. Fermani, G. Ferrara, F. Filippini, L. Fusco, P. Gay, H. Glotin, R. Gozzini, R. Gracia Ruiz, K. Graf, C. Guidi, S. Hallmann, H. van Haren, A.J. Heijboer, Y. Hello, J.J. Hernández-Rey, J. Hößl, et al. (436 additional authors not shown)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present the results of the first combined dark matter search targeting the Galactic Centre using the ANTARES and IceCube neutrino telescopes. For dark matter particles with masses from 50 to 1000 GeV, the sensitivities on the self-annihilation cross section set by ANTARES and IceCube are comparable, making this mass range particularly interesting for a joint analysis. Dark matter self-annihilation through the $\tau^+\tau^-$, $\mu^+\mu^-$, $b\bar{b}$ and $W^+W^-$ channels is considered for both the Navarro-Frenk-White and Burkert halo profiles. In the combination of 2,101.6 days of ANTARES data and 1,007 days of IceCube data, no excess over the expected background is observed. Limits on the thermally-averaged dark matter annihilation cross section $\langle\sigma_A\upsilon\rangle$ are set. These limits present an improvement of up to a factor of two in the studied dark matter mass range with respect to the individual limits published by both collaborations. When considering dark matter particles with a mass of 200 GeV annihilating through the $\tau^+\tau^-$ channel, the value obtained for the limit is $7.44 \times 10^{-24} \text{cm}^{3}\text{s}^{-1}$ for the Navarro-Frenk-White halo profile. For the purpose of this joint analysis, the model parameters and the likelihood are unified, providing a benchmark for forthcoming dark matter searches performed by neutrino telescopes.
- [20] arXiv:2003.06662 [pdf]
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Title: Magnetar formation through a convective dynamo in protoneutron starsAuthors: Raphaël Raynaud (CEA Saclay), Jérôme Guilet (CEA Saclay), Hans-Thomas Janka (MPA Garching), Thomas Gastine (IPGP)Comments: 6 pages, 4 figuresJournal-ref: Science Advances, 2020, Vol. 6, no. 11, eaay2732Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
The release of spin-down energy by a magnetar is a promising scenario to power several classes of extreme explosive transients. However, it lacks a firm basis because magnetar formation still represents a theoretical challenge. Using the first three-dimensional simulations of a convective dynamo based on a protoneutron star interior model, we demonstrate that the required dipolar magnetic field can be consistently generated for sufficiently fast rotation rates. The dynamo instability saturates in the magnetostrophic regime with the magnetic energy exceeding the kinetic energy by a factor of up to 10. Our results are compatible with the observational constraints on galactic magnetar field strength and provide strong theoretical support for millisecond protomagnetar models of gamma-ray burst and superluminous supernova central engines.
- [21] arXiv:2003.06680 [pdf, other]
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Title: Europa's Hemispheric Color Dichotomy as a Constraint on Non-synchronous RotationSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Europa's surface reflectance exhibits a pronounced hemispheric dichotomy, which is hypothesized to form due to enhanced irradiation of the trailing hemisphere by energetic particles entrained in the jovian magnetosphere. We propose that this pattern can only persist if the timescale for discoloration is much shorter than that of Europa's rotation relative to the synchronous state. By decomposing the longitudinal ultraviolet and visible color variations from Voyager data into sine and cosine terms, we demonstrate that the contribution due to non-synchronous rotation is small. The results of this analysis suggest that there is essentially no non-synchronous rotation of Europa on geologic timescales, with the period of non-synchronous rotation $> 1$ Gyr. This same conclusion is reached with two models of discoloration: one representing an actively discoloring surface, and the other assuming that the present-day exogenic discoloration on the surface is in steady-state. This constraint depends on the age of the crater Pwyll, which is assumed to be $\sim 10^6$ yr; an older age would indicate a slower non-synchronous rotation period. This result magnifies the outstanding problem of generating sufficient stress to explain Europa's pervasive tectonic features.
- [22] arXiv:2003.06704 [pdf]
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Title: New CCD Photometric Investigation of High Amplitude Delta Scuti Star V2455 CygSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
New V-band CCD observations of variable star V2455 Cyg were performed during two nights in September 2017. According to all times of maximum light and new maxima, the O-C curve was analyzed. The period changes of V2455 Cyg were investigated and the rate of increasing period was obtained to be(1/p* dp/dt) = 1.99 *10^(-7) yr^(-1). Frequency analysis indicated that V2455 Cyg pulsates with the radial p-mode and the fundamental frequency is 10.61574 d^(-1). Physical parameters of V2455 Cyg at mean temperature, were determined (e.g, R = 2.52 R(sun) and M = 1.92 M(sun)). The position of this star in H-R diagram confirms that V2455 Cyg is a high amplitude Delta Scuti star.
- [23] arXiv:2003.06733 [pdf, other]
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Title: Kilonova Emission From Black Hole-Neutron Star Mergers. I. Viewing-Angle-Dependent LightcurvesAuthors: Jin-Ping Zhu, Yuan-Pei Yang, Liang-Duan Liu, Yan Huang, Bing Zhang, Zhuo Li, Yun-Wei Yu, He GaoComments: 41 pages, 16 figures, 3 tables, submitted to ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
In this paper, we present a numerical method to study the predicted lightcurves as a function of viewing angle. We extrapolate the fitting formulae for the mass and velocity of tidal dynamical ejecta across a wide range of mass ratio validated with 66 simulations and use them in the calculations of the kilonova lightcurves. The calculated peak luminosity of a BH-NS merger kilonova is typically about a few times $10^{41}\ {\rm erg\ s^{-1}}$, which is always $\lesssim4.5\times10^{41}\ {\rm erg\ s^{-1}}$. This corresponds to the AB absolute magnitudes fainter than $\sim -15\ {\rm mag}$ in optical and $\sim -16\ {\rm mag}$ in infrared. Since the projected photosphere area of the dynamical ejecta is much larger than that of the disk wind outflows, the dynamical ejecta usually contribute to the majority of the kilonova emission from BH-NS mergers. The fitted blackbody temperature and the shape of the observed multi-band lightcurves are insensitive to the line of sight. The peak time of the observed multi-band lightcurves, affected by the light propagation effect, is related to the relative motion direction between the dynamical ejecta and the observer. The observed luminosity varies with the projected photosphere area determined by the viewing angles. However, the predicted peak luminosity only varies by a factor of $\sim (2 - 3)$ (or by $\sim1\ {\rm mag}$) for different viewing angles. When the short-duration gamma-ray burst afterglow is taken into account, for an on-axis geometry, the kilonova emission is usually outshone by the afterglow emission and can be only observed in the redder bands, especially in the $K$-band at late times. Compared with GW170817/AT2017gfo, the BH-NS merger kilonovae are optically dim but possibly infrared bright. At the same epoch after the merger, the blackbody fitting temperature of the BH-NS merger kilonovae is lower than that of GW170817/AT2017gfo.
- [24] arXiv:2003.06753 [pdf, other]
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Title: Escape from the swamp with spectatorComments: 10 pages, 4 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
In the context of string theory, several conjectural conditions have been proposed for low energy effective field theories not to be in swampland, the UV-incomplete class. The recent ones represented by the de Sitter and trans-Planckian censorship conjectures in particular seem to conflict with the inflation paradigm of the early universe. We first point out that scenarios where inflation is repeated several times (multi-phase inflation) can be easily compatible with these conjectures. In other words, we relax the constraint on the single inflation for the large scale perturbations to only continue at least around 10 e-folds. In this context, we then investigate if a spectator field can be a source of the almost scale-invariant primordial perturbations on the large scale. As a consequence of such an isocurvature contribution, the resultant perturbations exhibit the non-vanishing non-Gaussianity in general. Also the perturbation amplitude on smaller scales can be completely different from that on the large scale due to the multiplicity of inflationary phases. These signatures will be a smoking gun of this scenario by the future observations.
- [25] arXiv:2003.06770 [pdf, other]
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Title: Intrinsic Color Indices of Early-Type Dwarf StarsAuthors: Dingshan Deng (1), Yang Sun (1), Mingjie Jian (2), Biwei Jiang (1), Haibo Yuan (1) ((1) Department of Astronomy, Beijing Normal University (2) Department of Astronomy, School of Science, The University of Tokyo)Comments: 20 pages, 11 figures, accepted for publication in The Astrophysical JournalSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Early-type stars are short lived and scarce in comparison with other types. Based on the recently released catalogs of early type stars from the largest LAMOST spectroscopic survey, the intrinsic colors of the stars with effective temperature up to 32,000\,K are determined for the bands from ultraviolet to infrared by using the blue-edge method. Analytic relations are derived for the intrinsic color index with the effective temperature for the \emph{WISE}, 2MASS, \emph{Gaia}, APASS, SDSS, Pan-STARRS1, and \emph{GALEX} bands. The results are generally consistent with previous works. In addition, the intrinsic colors of O-type dwarfs and OB supergiants are roughly estimated.
- [26] arXiv:2003.06799 [pdf, other]
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Title: Electrical and seismological structure of the martian mantle and the detectability of impact-generated anomaliesComments: 5 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
We derive synthetic electrical conductivity, seismic velocity, and density distributions from the results of martian mantle convection models affected by basin-forming meteorite impacts. The electrical conductivity features an intermediate minimum in the strongly depleted topmost mantle, sandwiched between higher conductivities in the lower crust and a smooth increase towards almost constant high values at depths greater than 400 km. The bulk sound speed increases mostly smoothly throughout the mantle, with only one marked change at the appearance of $\beta$-olivine near 1100 km depth. An assessment of the detectability of the subsurface traces of an impact suggests that its signature would be visible in both observables at least if efficient melt extraction from the shock-molten target occurs, but it will not always be particularly conspicuous even for large basins; observations with extensive spatial and temporal coverage would improve their detectability. Electromagnetic sounding may be a more promising method for investigating the properties of impact structures than seismology and, as far as the mantle is concerned, than gravity. It could also help constraining the water content of the mantle in general. By comparing electromagnetic sounding data of an impact structure with model predictions, it might also be possible to answer the open question of the efficiency of impact-generated melt extraction.
- [27] arXiv:2003.06824 [pdf, ps, other]
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Title: H-alpha Images of Ultra-Flat Edge-On Spiral GalaxiesComments: 19 pages, 2 tables, 8 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present the H$\alpha$ images of ultra-flat (UF) spiral galaxies seen practically edge-on. The galaxies have the angular diameter in the $B$ band $a> 1.9^{\prime}$ and the apparent axial ratio $(a/b) >10$. We found that their H$\alpha$ images look, on average, almost two times thinner than those in the red continuum. The star-formation rate in the studied objects, determined from the H$\alpha$ flux, is in good agreement with that calculated from the $FUV$ flux from the GALEX survey if we use the modified Verheijen and Sancisi formula taking into account the internal extinction in the UF galaxies. The logarithm of the specific star-formation rate in the UF galaxies shows a small scatter, $0.19$, with a smooth decrease from $-10.4$ for dwarf spirals to $-10.7$ for massive ones. The relative amount of the hydrogen mass in UF disks varies from about 50\% in dwarf disks to about 8\% in massive ones. Structural distortions are less common in the UF galaxies (about 16\%) than those in thick (less isolated) disks of edge-on spiral galaxies. On the cosmic time scale, 13.7 Gyr, large spiral disks are more efficient "engines" for gas processing into stars than dwarf spirals.
- [28] arXiv:2003.06842 [pdf, other]
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Title: An imaging line survey of OMC-1 to OMC-3Comments: 38 pages, 15 figures, 8 tables. Accepted by A&ASubjects: Astrophysics of Galaxies (astro-ph.GA)
Aims: Our aim is to identify the dominant molecular cooling lines and characteristic emission features in the 1.3 mm window of distinct regions in the northern part of the Orion A molecular cloud. By defining and analysing template regions, we also intend to help with the interpretation of observations from more distant sources which cannot be easily spatially resolved.
Methods: We analyse an imaging line survey covering the area of OMC-1 to OMC-3 from 200.2 to 281.8 GHz obtained with the PI230 receiver at the APEX telescope. Masks are used to define regions with distinct properties (e.g. column density or temperature ranges) from which we obtain averaged spectra. Lines of 29 molecular species (55 isotopologues) are fitted for each region to obtain the respective total intensity.
Results: We find that strong sources like Orion KL have a clear impact on the emission on larger scales. Although not spatially extended, their line emission contributes substantially to spectra averaged over large regions. Conversely, the emission signatures of dense, cold regions like OMC-2 and OMC-3 (e.g. enhanced N$_{2}$H$^{+}$ emission and low HCN/HNC ratio) seem to be difficult to pick up on larger scales, where they are eclipsed by signatures of stronger sources. In all regions, HCO$^{+}$ appears to contribute between 3% and 6% to the total intensity, the most stable value for all bright species. N$_{2}$H$^{+}$ shows the strongest correlation with column density, but not with typical high-density tracers like HCN, HCO$^{+}$, H$_{2}$CO, or HNC. Common line ratios associated with UV illumination, CN/HNC and CN/HCO$^{+}$, show ambiguous results on larger scales, suggesting that the identification of UV illuminated material may be more challenging. The HCN/HNC ratio may be related to temperature over varying scales. - [29] arXiv:2003.06870 [pdf]
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Title: HD 145263: Spectral Observations of Silica Debris Disk Formation via Extreme Space Weathering?Authors: C.M. Lisse, H.Y.A. Meng, M.L. Sitko, A. Morlok, B.C. Johnson, A.P. Jackson, R.J. Vervack Jr., C.H. Chen, S.J. Wolk, M.D. Lucas, M. Marengo, D.T. BrittComments: 41 Pages, 5 Figures, 5 Tables, Accepted for publication in the Astrophysical JournalSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
We report here time domain infrared spectroscopy and optical photometry of the HD145263 silica-rich circumstellar disk system taken from 2003 through 2014. We find an F4V host star surrounded by a stable, massive 1e22 - 1e23 kg (M_Moon to M_Mars) dust disk. No disk gas was detected, and the primary star was seen rotating with a rapid ~1.75 day period. After resolving a problem with previously reported observations, we find the silica, Mg-olivine, and Fe-pyroxene mineralogy of the dust disk to be stable throughout, and very unusual compared to the ferromagnesian silicates typically found in primordial and debris disks. By comparison with mid-infrared spectral features of primitive solar system dust, we explore the possibility that HD 145263's circumstellar dust mineralogy occurred with preferential destruction of Fe-bearing olivines, metal sulfides, and water ice in an initially comet-like mineral mix and their replacement by Fe-bearing pyroxenes, amorphous pyroxene, and silica. We reject models based on vaporizing optical stellar megaflares, aqueous alteration, or giant hypervelocity impacts as unable to produce the observed mineralogy. Scenarios involving unusually high Si abundances are at odds with the normal stellar absorption near-infrared feature strengths for Mg, Fe, and Si. Models involving intense space weathering of a thin surface patina via moderate (T < 1300 K) heating and energetic ion sputtering due to a stellar superflare from the F4V primary are consistent with the observations. The space weathered patina should be reddened, contain copious amounts of nanophase Fe, and should be transient on timescales of decades unless replenished.
- [30] arXiv:2003.06881 [pdf]
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Title: Transformative Science from the Lunar Farside: Observations of the Dark Ages and Exoplanetary Systems at Low Radio FrequenciesAuthors: Jack O. BurnsComments: 11 pages, 9 figures, 1 table, to be submitted to Philosophical Transactions of the Royal Society ASubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
The farside of the Moon is a pristine, quiet platform to conduct low radio frequency observations of the early Universe's Dark Ages, as well as space weather and magnetospheres associated with habitable exoplanets. In this paper, NASA-funded concept studies will be described including a lunar-orbiting spacecraft, DAPPER, that will measure the 21 cm global spectrum at redshifts 40-80, and an array of low frequency dipoles on the lunar farside surface, FARSIDE. DAPPER observations (17-38 MHz), using a single cross-dipole antenna, will measure the amplitude of the 21 cm spectrum to the level required to distinguish the standard {\Lambda}CDM cosmological model from those of additional cooling models possibly produced by exotic physics such as dark matter interactions. FARSIDE has a notional architecture consisting of 128 dipole antennas deployed across a 10 km area by a rover. FARSIDE would image the entire sky each minute in 1400 channels over 0.1-40 MHz. This would enable monitoring of the nearest stellar systems for the radio signatures of coronal mass ejections and energetic particle events, and would also detect the magnetospheres of the nearest candidate habitable exoplanets. In addition, FARSIDE would determine the Dark Ages global 21 cm signal at yet lower frequencies and provide a pathfinder for power spectrum measurements.
- [31] arXiv:2003.06889 [pdf, other]
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Title: A Deep Exposure in High Resolution X-Rays Reveals the Hottest Plasma in the $ζ\,$Puppis WindAuthors: David P. Huenemoerder (1), Richard Ignace (2), Nathan A. Miller (3), Kenneth G. Gayley (4), Wolf-Rainer Hamann (5), Jennifer Lauer (6), Anthony F.J. Moffat (7), Yaël Nazé (8), Joy S. Nichols (6), Lidia Oskinova (5), Noel D. Richardson (9), Wayne Waldron (10) ( (1) Massachusetts Institute of Technology, (2) East Tennessee State University, (3) University of Wisconsin--Eau Claire, (4) University of Iowa, (5) University of Potsdam, (6) Harvard-Smithsonian Center for Astrophysics, (7) Université de Montréal, (8) Université de Liège, (9) Embry-Riddle Aeronautical University, (10) Eureka Scientific, Inc. )Comments: 18 pages, 4 figures; accepted for publication in the Astrophysical JournalSubjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
We have obtained a very deep exposure (813 ks) of $\zeta\,$Puppis (O4 supergiant) with the Chandra/HETG Spectrometer. Here we report on analysis of the 1-9 \r{A} region, especially well suited for Chandra, which has a significant contribution from continuum emission between well separated emission lines from high-ionization species. These data allow us to study the hottest plasma present through the continuum shape and emission line strengths. Assuming a powerlaw emission measure distribution which has a high-temperature cut-off, we find that the emission is consistent with a thermal spectrum having a maximum temperature of 12 MK. This implies an effective wind shock velocity of $900\,\mathrm{km\,s^{-1}}$, well below the wind terminal speed of $2250\,\mathrm{km\,s^{-1}}$. For X-ray emission which forms close to the star, the speed and X-ray flux are larger than can be easily reconciled with strictly self-excited line-deshadowing-instability models, suggesting a need for a fraction of the wind to be accelerated extremely rapidly right from the base. This is not so much a dynamical instability as a nonlinear response to changing boundary conditions.
- [32] arXiv:2003.06896 [pdf, ps, other]
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Title: MACHO 311.37557.169: A VY Scl starComments: 7 pages, 5 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
Optical surveys, such as the MACHO project, often uncover variable stars whose classification requires followup observations by other instruments. We performed X-ray spectroscopy and photometry of the unusual variable star MACHO 311.37557.169 with \XMM\ in April 2018, supplemented by archival X-ray and optical spectrographic data. The star has a bolometric X-ray luminosity of about $1\times 10^{32}$ erg s$^{-1}$ cm$^{-2}$ and a heavily absorbed two-temperature plasma spectrum. The shape of its light curve, its overall brightness, its X-ray spectrum, and the emission lines in its optical spectrum suggest that it is most likely a VY~Scl cataclysmic variable.
- [33] arXiv:2003.06925 [pdf, other]
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Title: A comparison of UV and optical metallicities in star-forming galaxiesAuthors: Nell Byler (1 and 2), Lisa J Kewley (1 and 2), Jane R Rigby (3), Ayan Acharyya (1 and 2), Danielle A Berg (4 and 5), Matthew Bayliss (6), Keren Sharon (7). ((1) Australian National University, (2) ASTRO 3D, (3) NASA's Goddard Space Flight Center, (4) University of Wisconsin, (5) The Ohio State University, (6) MIT Kavli Institute for Astrophysics and Space Research, (7) University of Michigan)Comments: ApJ acceptedSubjects: Astrophysics of Galaxies (astro-ph.GA)
Our ability to study the properties of the interstellar medium (ISM) in the earliest galaxies will rely on emission line diagnostics at rest-frame ultraviolet (UV) wavelengths. In this work, we identify metallicity-sensitive diagnostics using UV emission lines. We compare UV-derived metallicities with standard, well-established optical metallicities using a sample of galaxies with rest-frame UV and optical spectroscopy. We find that the He2-O3C3 diagnostic (He II 1640 / C III 1906,1909 vs. O III 1666 / C III 1906,1909) is a reliable metallicity tracer, particularly at low metallicity (12+log(O/H) < 8), where stellar contributions are minimal. We find that the Si3-O3C3 diagnostic (Si III 1883 / C III 1906,1909 vs. O III 1666 / C III 1906,1909) is a reliable metallicity tracer, though with large scatter (0.2-0.3 dex), which we suggest is driven by variations in gas-phase abundances. We find that the C4-O3C3 diagnostic (C IV 1548,1550 / O III 1666 vs. O III 1666 / C III 1906,1909) correlates poorly with optically-derived metallicities. We discuss possible explanations for these discrepant metallicity determinations, including the hardness of the ionizing spectrum, contribution from stellar wind emission, and non-solar-scaled gas-phase abundances. Finally, we provide two new UV oxygen abundance diagnostics, calculated from polynomial fits to the model grid surface in the He2-O3C3 and Si3-O3C3 diagrams.
- [34] arXiv:2003.06956 [pdf, other]
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Title: A roadmap to hadronic supercriticalities: a comprehensive study of the parameter space for high-energy astrophysical sourcesComments: 17 pages, 14 figures, 2 tables, submitted to MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Hadronic supercriticalities are radiative instabilities that appear when large amounts of energy are stored in relativistic protons. When the proton energy density exceeds some critical value, a runaway process is initiated resulting in the explosive transfer of the proton energy into electron-positron pairs and radiation and the increase of the photon-to-proton efficiency. We perform a comprehensive study of the parameter space by investigating the onset of hadronic supercriticalities for a wide range of source parameters (i.e., magnetic field strengths of 1 G$- 100$ kG and radii of $10^{11}$ cm$-10^{16}$ cm) and maximum proton Lorentz factors ($10^3-10^9$). We show that supercriticalities are possible for the whole range of source parameters related to compact astrophysical sources, like gamma-rays bursts, cores and jets of active galactic nuclei. We also provide an in-depth look at the physical mechanisms of hadronic supercriticalities and show that magnetized relativistic plasmas are excellent examples of non-linear dynamical systems in high-energy astrophysics.
- [35] arXiv:2003.06998 [pdf, ps, other]
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Title: In-flight calibration of the Insight-Hard X-ray Modulation TelescopeAuthors: Xiaobo Li, Xufang Li, Ying Tan, Yanji Yang, Mingyu Ge, Juan Zhang, Youli Tuo, Baiyang Wu, Jinyuan Liao, Yifei Zhang, Liming Song, Shu Zhang, Jinlu Qu, Shuang-nan Zhang, Fangjun Lu, Yupeng Xu, Congzhan Liu, Xuelei Cao, Yong Chen, Jianyin Nie, Haisheng Zhao, Chengkui LiComments: 14 pages, 28 figures, accepted by Journal of High Energy AstrophysicsSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
We present the calibration of the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) X-ray satellite, which can be used to perform timing and spectral studies of bright X-ray sources. Insight-HXMT carries three main payloads onboard: the High Energy X-ray telescope (HE), the Medium Energy X-ray telescope (ME) and the Low Energy X-ray telescope (LE). In orbit, the radioactive sources, activated lines, the fluorescence lines and celestial sources are used to calibrate the energy scale and energy resolution of the payloads. The Crab nebular is adopted as the primary effective area calibrator and empirical functions are constructed to modify the simulated effective areas of the three payloads respectively. The systematic errors of HE, compared to the model of the Crab nebular, are less than 2% in 28--120 keV and 2%--10% above 120 keV. The systematic errors of ME are less than 1.5% in 10--35 keV. The systematic errors of LE are less than 1% in 1--7 keV except the Si K--edge (1.839 keV, up to 1.5%) and less than 2% in 7--10 keV.
- [36] arXiv:2003.07006 [pdf, ps, other]
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Title: Long-term orbital evolution of Galactic satellites and the effects on their star formation historiesComments: 10 pages, 10 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
We investigate the orbital motions of dwarf spheroidal galaxies (dSphs) in the halo of the Milky Way (MW) to understand their possible effects on the diversity of the star formation histories seen in these MW satellites. In this work, we explicitly consider a time-varying gravitational potential due to the growth of the MW's dark halo mass to calculate the long-term orbital evolutions of the dSphs, guided with {\it Gaia} DR2 proper motions, over the past 13.5 billion years. We find that the infall time of a satellite, defined at which the galaxy first crosses within the growing virial radius of the MW's halo, coincides well with the time when the star formation rate (SFR) is peaked for the sample of classical dSphs. On the other hand, ultra-faint dSphs already finished their SF activity prior to their infall times as already suggested in previous works, but there is a signature that their earlier SF histories are affected by interaction with the growing MW's halo to some extent. We also find, for classical dSphs, that the relative fraction of stars formed after the peak of the SFR to the current stellar mass is smaller for the smaller pericentric radius of the galaxy at its first infall. These results suggest that the infalling properties of the dSphs into the MW and the resultant environmental effects such as ram-pressure stripping and/or tidal disturbance in the MW's dark halo containing hot gas play important roles in their star formation histories.
- [37] arXiv:2003.07067 [pdf, other]
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Title: Disk structure around the Class I protostar L1489 IRS revealed by ALMA: a warped disk systemAuthors: Jinshi Sai, Nagayoshi Ohashi, Kazuya Saigo, Tomoaki Matsumoto, Yusuke Aso, Shigehisa Takakuwa, Yuri Aikawa, Ippei Kurose, Hsi-Wei Yen, Kohji Tomisaka, Kengo Tomida, Masahiro N. MachidaComments: 26 pages, 18 figures, accepted by ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
We have observed the Class I protostar L1489 IRS with the Atacama Millimeter/submillimeter Array (ALMA) in Band 6. The C$^{18}$O $J=$2-1 line emission shows flattened and non-axisymmetric structures in the same direction as its velocity gradient due to rotation. We discovered that the C$^{18}$O emission shows dips at a radius of ~200-300 au while the 1.3 mm continuum emission extends smoothly up to r~400 au. At the radius of the C$^{18}$O dips, the rotational axis of the outer portion appears to be tilted by ~15 degrees from that of the inner component. Both the inner and outer components with respect to the C$^{18}$O dips exhibit the $r^{-0.5}$ Keplerian rotation profiles until r~600 au. These results not only indicate that a Keplerian disk extends up to ~600 au but also that the disk is warped. We constructed a three dimensional warped disk model rotating at the Keplerian velocity, and demonstrated that the warped disk model reproduces main observed features in the velocity channel maps and the PV diagrams. Such a warped disk system can form by mass accretion from a misaligned envelope. We also discuss a possible disk evolution scenario based on comparisons of disk radii and masses between Class I and Class II sources.
- [38] arXiv:2003.07090 [pdf, ps, other]
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Title: 180$^\circ$ Rotations in the Polarization Angle for BlazarsComments: Accepted for publication in Astronomy & AstrophysicsSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Rotations of the electric vector position angle (EVPA) in blazars are often close to an integral multiple of 180$^\circ$. There are multiple examples of this in the literature, and our analysis here, of the optical polarization data from the RoboPol monitoring program, strengthens the evidence by showing that $n\pi$ rotations occur more frequently than expected by chance. We explain this with a model consisting of two polarized emission components: a "jet" that is constant in time, and a "burst" that is variable. The EVPA of the combination is $\rm EVPA_{jet}$ at both the beginning and the end of the burst, so the net rotation across the burst must be $n\pi$. Examples are analyzed on the Stokes plane, where the winding number for the Stokes vector of the combination gives the value of $n$. The main conclusion is that the EVPA rotation can be much larger than the physical rotation of the emission region around the axis of the jet, but this requires the EVPAs of the jet and the burst to be nearly orthogonal. A shock-in-jet calculation by Zhang et al. can provide a physical model for our toy model, and in addition automatically gives the needed orthogonality. The model is illustrated with data on OJ287 published by Myserlis et al., and we suggest that the large rapid EVPA rotation seen there might be a phase effect and not representative of a physical rotation.
- [39] arXiv:2003.07091 [pdf, other]
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Title: Plasma Diagnostics From Active Region and Quiet Sun Spectra Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian DistributionComments: 23 pages, 8 figures, 4 tablesSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
We perform plasma diagnostics, including that of the non-Maxwellian $\kappa$-distributions, in several structures observed in the solar corona by the Extreme-Ultraviolet Imaging Spectrometer (EIS) onboard the Hinode spacecraft. To prevent uncertainties due to the in-flight calibration of EIS, we selected spectral atlases observed shortly after the launch of the mission. One spectral atlas contains an observation of an active region, while the other is an off-limb quiet Sun region. To minimize the uncertainties of the diagnostics, we rely only on strong lines and we average the signal over a spatial area within selected structures. Multiple plasma parameters are diagnosed, such as the electron density, differential emission measure, and the non-Maxwellian parameter $\kappa$. To do that, we use a simple, well-converging iterative scheme based on refining the initial density estimates via the DEM and $\kappa$. We find that while the quiet Sun spectra are consistent with a Maxwellian distribution, the coronal loops and moss observed within active region are strongly non-Maxwellian with $\kappa$ $\lessapprox$ 3. These results were checked by calculating synthetic ratios using DEMs obtained as a function of $\kappa$. Ratios predicted using the DEMs assuming $\kappa$-distributions converged to the ratios observed in the quiet Sun and coronal loops. To our knowledge, this work presents a strong evidence of a presence of different electron distributions between two physically distinct parts of the solar corona.
- [40] arXiv:2003.07136 [pdf, ps, other]
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Title: In Search for Infall Motion in molecular clumps II: HCO+ (1-0) and HCN (1-0) Observations toward a Sub-sample of Infall CandidatesSubjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Gravitational accretion accumulates the original mass, and this process is crucial for us to understand the initial phases of star formation. Using the specific infall profiles in optically thick and thin lines, we searched the clumps with infall motion from the Milky Way Imaging Scroll Painting (MWISP) CO data in previous work. In this study, we selected 133 sources of them as a sub-sample for further research and identification. The excitation temperatures of these sources are between 7.0 and 38.5 K, while the H_2 column densities are between 10^21 and 10^23 cm^-2. We have observed optically thick lines HCO+ (1-0) and HCN (1-0) using the DLH 13.7-m telescope, and found 56 sources of them with blue profile and no red profile in these two lines, which are likely to have infall motions, with the detection rate of 42\%. It suggests that using CO data to restrict sample can effectively improve the infall detection rate. Among these confirmed infall sources, there are 43 associated with Class 0/I young stellar objects (YSOs), and 13 are not. These 13 sources are probably associated with the sources in earlier evolutionary stage. By comparison, the confirmed sources which are associated with Class 0/I YSOs have higher excitation temperatures and column densities, while the other sources are colder and have lower column densities. Most infall velocities of the sources we confirmed are between 10^-1 to 10^0 km s^-1, which is consistent with previous studies.
- [41] arXiv:2003.07154 [pdf, other]
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Title: The OTELO survey: Nature and mass-metallicity relation for H$α$ emitters at $z\sim\,0.4$Authors: Jakub Nadolny, Maritza A. Lara-López, Miguel Cerviño, Ángel Bongiovanni, Jordi Cepa, José A. de Diego, Ana María Pérez García, Ricardo Pérez Martínez, Miguel Sánchez-Portal, Emilio Alfaro, Héctor O. Castañeda, Jesús Gallego, J. Jesús González, J. Ignacio González-Serrano, Carmen P. Padilla Torres, Irene Pintos-Castro, Mirjana PovićComments: 17 Pages, 14 Figures, Accepted in Astronomy & AstrophysicsSubjects: Astrophysics of Galaxies (astro-ph.GA)
A sample of low-mass H$\alpha$ emission line sources (ELS) at $z\,\sim\,0.4$ was studied in the context of the mass-metallicty relation (MZR) and its possible evolution. We drew our sample from the OSIRIS Tunable Emission Line Object (OTELO) survey, which exploits the red tunable filter of OSIRIS at the Gran Telescopio Canarias to perform a blind narrow-band spectral scan in a selected field of the Extended Groth Strip. We were able to directly measure emission line fluxes and equivalent widths from the analysis of OTELO pseudo-spectra. This study aims to explore the MZR in the very low-mass regime. Our sample reaches stellar masses ($M_*$) as low as $10^{6.8}\,M_\odot$, where 63\% of the sample have $M_*\,<10^9\,M_\odot$. We also explore the relation of the star formation rate (SFR) and specific SFR (sSFR) with $M_*$ and gas-phase oxygen abundances, as well as the $M_*$-size relation and the morphological classification. The $M_*$ were estimated using synthetic rest-frame colours. Using an $\chi^2$ minimization method, we separated the contribution of \Nii$\lambda$6583 to the H$\alpha$ emission lines. Using the N2 index, we separated active galactic nuclei from star-forming galaxies (SFGs) and estimated the gas metallicity. We studied the morphology of the sampled galaxies qualitatively (visually) and quantitatively (automatically) using high-resolution data from the \textit{Hubble Space Telescope}-ACS. The physical size of the galaxies was derived from the morphological analysis using \texttt{GALAPAGOS2/GALFIT}, where we fit a single-S\'ersic 2D model to each source.
- [42] arXiv:2003.07187 [pdf, other]
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Title: Chemodynamics of Green Pea galaxies -- I. Outflows and turbulence driving the escape of ionising photons and chemical enrichmentAuthors: L. Hogarth, R. Amorín, J. M. Vílchez, G. F. Hägele, M. Cardaci, E. Pérez-Montero, V. Firpo, A. Jaskot, R. ChávezComments: 23 pages, 21 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
We investigate the ionised gas kinematics, physical properties and chemical abundances of $J142947$, a Green Pea galaxy at $z\sim 0.17$ with strong, double-peak Ly$\alpha$ emission and indirect evidence of Lyman continuum (LyC) escape. Using deep high-dispersion long-slit spectroscopy, we perform a multi-component Gaussian analysis of optical emission-line profiles. Our model consistently fits all relevant emission lines as a narrow component with intrinsic velocity dispersion $\sigma\sim 40\ kms^{-1}$, and two broader blue-shifted components with $\sigma\sim 90\ kms^{-1}$ and $\sim 250\ kms^{-1}$. Emission-line ratios are used to find electron densities and temperatures, excitation and ionisation conditions, and direct O/H and N/O abundances for each component. A highly ionised ([OIII]/[OII] $\sim 10$), metal-poor, young and compact starburst dominates narrow emission, showing evidence of hard radiation fields and elevated N/O. The blue-shifted broader components are consistent with highly turbulent, possibly clumpy ionised gas at the base of a strong photoionised outflow, which accounts for $\gtrsim$ 50% of the integrated emission-line fluxes. The outflow is dense and metal-enriched compared to the HII regions, with expansion velocities larger than those obtained from UV interstellar absorption lines and the escape velocity under standard assumptions. Some of these metals may be able to escape, with mass- and metal-loading factors of the outflow in line with those found in high-$z$ galaxies of similar $\Sigma_{SFR}$. Our findings depict a two-stage starburst picture; hard radiation fields from the younger star clusters illuminate a turbulent and clumpy ISM that has been eroded by SNe feedback. We propose that ionising LyC photons are able to escape into the halo through low HI density channels or filaments in the ISM approaching density-bounded conditions, traced by outflowing gas.
- [43] arXiv:2003.07199 [pdf, other]
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Title: Optical Identification of Four Hard X-ray Sources from the INTEGRAL Sky SurveysAuthors: D.I. Karasev, S.Yu.Sazonov, A. Yu. Tkachenko, G. A. Khorunzhev, R. A. Krivonos, P. S. Medvedev, I.A.Zaznobin, I. A. Mereminskiy, R. A. Burenin, M. N. Pavlinsky, M. V. EselevichComments: 11 pages, 6 figuresJournal-ref: Astronomy Letters, 2019, Vol. 45, No. 12, pp. 836-846Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We continue the study begun in Karasev et al. (2018) and present the results of our optical identifications of four hard X-ray sources from the INTEGRAL sky surveys. Having first improved the positions of these objects in the sky with the X-ray telescope (XRT) of the Swift observatory, we have identified their counterparts using optical and infrared sky survey data. Then, we have obtained optical spectra for the supposed counterparts with the RTT-150 Russian-Turkish telescope and the AZT-33IK telescope. This has allowed the nature of the objects under study to be established. The sources IGR J11079+7106 and IGR J12171+7047 have turned out to be extragalactic in nature and be Seyfert 1 and 2 galaxies, respectively, with the second object being characterized by a large absorption column density. The source IGR J18165-3912 is most likely an intermediate polar with a very high luminosity. The fourth source, IGR J20596+4303, is a chance superposition of two objects - a Seyfert 2 galaxy and a cataclysmic variable.
- [44] arXiv:2003.07228 [pdf]
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Title: Design of the HARMONI Pyramid WFS moduleAuthors: Noah Schwartz, Jean-François Sauvage, Edgard Renault, Carlos Correia, Benoit Neichel, Thierry Fusco, Kjetil Dohlen, Kacem El Hadi, Cyril Petit, Elodie Choquet, Vincent Chambouleyron, Jerome Paufique, Fraser Clarke, Niranjan Thatte, Ian BrysonComments: 12 pages, 17 figures, AO4ELT6 Proceedings, Adaptive Optics for Extremely Large Telescopes 6, Conference Proceeding, Qu\'ebec City, Canada, Spain, June 9-14, 2019Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Atmospheric and Oceanic Physics (physics.ao-ph)
Current designs for all three extremely large telescopes show the overwhelming adoption of the pyramid wavefront sensor (P-WFS) as the WFS of choice for adaptive optics (AO) systems sensing on natural guide stars (NGS) or extended objects. The key advantages of the P-WFS over the Shack-Hartmann are known and are mainly provided by the improved sensitivity (fainter NGS) and reduced sensitivity to spatial aliasing. However, robustness and tolerances of the P-WFS for the ELTs are not currently well understood. In this paper, we present simulation results for the single-conjugate AO mode of HARMONI, a visible and near-infrared integral field spectrograph for the European Extremely Large Telescope. We first explore the wavefront sensing issues related to the telescope itself; namely the island effect (i.e. differential piston) and M1 segments phasing errors. We present mitigation strategies to the island effect and their performance. We then focus on some performance optimisation aspects of the AO design to explore the impact of the RTC latency and the optical gain issues, which will in particular affect the high-contrast mode of HARMONI. Finally, we investigate the influence of the quality of glass pyramid prism itself, and of optical aberrations on the final AO performance. By relaxing the tolerances on the fabrication of the prism, we are able to reduce hardware costs and simplify integration. We show the importance of calibration (i.e. updating the control matrix) to capture any displacement of the telescope pupil and rotation of the support structure for M4. We also show the importance of the number of pixels used for wavefront sensing to relax tolerances of the pyramid prism. Finally, we present a detailed optical design of the pyramid prism, central element of the P-WFS.
- [45] arXiv:2003.07235 [pdf, other]
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Title: The X-ray outburst of the Galactic Center magnetar over six years of Chandra observationsAuthors: N. Rea, F. Coti Zelati, D. Vigano' (CSIC, IEEC), A. Papitto (INAF), F. Baganoff (MIT), A. Borghese (CSIC, IEEC), S. Campana (INAF), P. Esposito (INAF, IUSS), D. Haggard (McGill), G.L. Israel, S. Mereghetti, R. Mignani (INAF), R. Perna (Stony Brook), J.A. Pons (U. Alicante), G. Ponti, L. Stella (INAF), D.F. Torres (ICREA, CSIC, IEEC), R. Turolla (U. Padova), S. Zane (MSSL)Comments: 11 pages, 6 figures. Submitted to ApJ on November 15th, referee's comments includedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The magnetar SGR J1745-2900 discovered at parsecs distance from the Milky Way central black hole, Sagittarius A*, represents the closest pulsar to a supermassive black hole ever detected. Furthermore, its intriguing radio emission has been used to study the environment of the black hole, as well as to derive a precise position and proper motion for this object. The discovery of SGR J1745-2900 has opened interesting debates about the number, age and nature of pulsars expected in the Galactic center region. In this work, we present extensive X-ray monitoring of the outburst of SGR J1745-2900 using the Chandra X-ray Observatory, the only instrument with the spatial resolution to distinguish the magnetar from the supermassive black hole (2.4" angular distance). It was monitored from its outburst onset in April 2013 until August 2019, collecting more than fifty Chandra observations for a total of more than 2.3 Ms of data. Soon after the outburst onset, the magnetar emission settled onto a purely thermal emission state that cooled from a temperature of about 0.9 to 0.6 keV over 6 years. The pulsar timing properties showed at least two changes in the period derivative, increasing by a factor of about 4 during the outburst decay. We find that the long-term properties of this outburst challenge current models for the magnetar outbursts.
- [46] arXiv:2003.07237 [pdf, other]
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Title: An XMM-Newton X-ray View of Supernova Remnant W49B: Revisiting its Recombining Plasmas and Progenitor TypeComments: 29 pages, 9 figures, accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present a comprehensive X-ray spectroscopy and imaging study of supernova remnant W49B using archival XMM-Newton observations. The overionization state of the shocked ejecta in W49B is clearly indicated by the radiative recombination continua of Si XIV, S XV, and Fe XXV, combined with the Ly$\alpha$ lines of Ca and Fe. The line flux images of W49B indicate high emission measures of the central bar-like region for almost all the emission lines, while the equivalent width maps reveal a stratified structure for the metal abundance distributions. The global spectrum of W49B is well reproduced by a model containing one collisional ionization equilibrium (CIE) plasma component and two recombining plasma (RP) components. The CIE plasma represents the shocked interstellar medium, which dominates the X-ray emitting volume in W49B with a mass $\sim450M_\odot$. The two RP components with a total mass $\sim4.6M_\odot$ are both dominated by the ejecta material, but characterized by different electron temperatures ($\sim1.60$ keV and $\sim0.64$ keV). The recombination ages of the RP components are estimated as $\sim6000$ yr and $\sim3400$ yr, respectively. We then reveal the possibility of a thermal conduction origin for the high-temperature RP in W49B by calculating the conduction timescale. The metal abundance ratios of the ejecta in W49B are roughly consistent with a core-collapse explosion model with a $\lesssim15M_\odot$ progenitor, except for a rather high Mn/Fe. A Type Ia origin can explain the Mn abundance, while it predicts much higher ejecta masses than observed values for all the metal species considered in our analysis.
- [47] arXiv:2003.07251 [pdf, ps, other]
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Title: First observations and magnitude measurement of SpaceX's DarksatAuthors: J. Tregloan-Reed, A. Otarola, E. Ortiz, V. Molina, J. Anais, R. González, J. P. Colque, E. Unda-SanzanaComments: Letter submitted to A&A. 5 Pages, 3 figures and 4 tablesSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Measure the Sloan g' magnitudes of the SpaceX STARLINK-1130 (Darksat) and 1113 LEO communication satellites and determine the effectiveness of the Darksat darkening treatment at 475.4\,nm. Two observations of the SpaceX STARLINK Darksat LEO communication satellite were conducted on 2020/02/08 and 2020/03/06 using a Sloan r' and g' respectively. While a second satellite, STARLINK-1113 was observed on 2020/03/06 using a Sloan g' filter. The initial observation on 2020/02/08 was a test observation when Darksat was still manoeuvring to its nominal orbit and orientation. Based on the successful test observation, the first main observation was conducted on 2020/03/06 along with an observation of a second STARLINK satellite. The calibration, image processing and analysis of the Darksat Sloan g' image gives an estimated Sloan g' magnitude of $\mathbf{7.57\pm0.04}$ at a range of 976.50\,km. For STARLINK-1113 an estimated Sloan g' magnitude of $\mathbf{6.69\pm0.05}$ at a range of 941.62\,km was found. When scaled to a range of 550\,km, a reduction of (55\,\%\,$\pm$\,4.8\,\%) is seen in the reflected solar flux between Darksat and STARLINK-1113. The data and results presented in this work, show that the special darkening "treatment" used by SpaceX for Darksat has reduced the Sloan g' magnitude by $0.88\pm0.05$\,mag (55\,\%\,$\pm$\,4.8\,\%), when the range is equal to a nominal orbital height (550\,km). This result will serve members of the astronomical community modelling the satellite mega-constellations, to ascertain their true impact on both the amateur and professional astronomical communities. Concurrent and further observations are planned to cover the full optical and NIR spectrum, from an ensemble of instruments, telescopes and observatories.
- [48] arXiv:2003.07275 [pdf, other]
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Title: Periodic Fast Radio Bursts from Axion Emission by Cosmic SuperstringsComments: 15 pages, 1 figureSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We propose that the periodic fast radio bursts of FRB 180916.J0158+65 are sourced by axion emission (mass $m_{a} \sim 10^{-14}$ eV) from cosmic superstrings. Some of the emitted axions are converted to photons by magnetic fields as they travel along the line of sight to Earth. An impulsive burst of axion emission generates a photon signal typically lasting for milliseconds and varying with frequency in the observed manner. We find a range of parameters in our cosmic string network model consistent with the properties of FRB 180916.J0158+65. We suggest followup gravitational wave observations to test our model.
- [49] arXiv:2003.07284 [pdf, ps, other]
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Title: Application of a helicity proxy to edge-on galaxiesComments: 6 pages, 4 figures, 2 tables, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We propose to detect a proxy of the magnetic helicity in galaxies by observing the dust polarization of the edge-on galaxy NGC 891. Our numerical results of mean-field dynamo calculations show that there should be a large-scale component of the rotationally invariant parity-odd B polarization that we predict to be negative in the first and third quadrants, and positive in the second and fourth quadrants. The large-scale parity-even E polarization is predicted to be negative near the axis and positive further away in the outskirts.
- [50] arXiv:2003.07290 [pdf, other]
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Title: The White Dwarf Binary Pathways Survey III: contamination from hierarchical triples containing a white dwarfAuthors: F. Lagos, M.R. Schreiber, S.G. Parsons, A. Zurlo, D. Mesa, B.T. Gänsicke, R. Brahm, C. Caceres, H. Canovas, M-S. Hernandez, A. Jordan, D. Koester, L. Schmidtobreick, C. Tappert, M. ZorotovicComments: accepted for publication in MNRASSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
The White Dwarf Binary Pathways Survey aims at increasing the number of known detached A, F, G and K main sequence stars in close orbits with white dwarf companions (WD+AFGK binaries) to refine our understanding about compact binary evolution and the nature of Supernova Ia progenitors. These close WD+AFGK binary stars are expected to form through common envelope evolution, in which tidal forces tend to circularize the orbit. However, some of the identified WD+AFGK binary candidates show eccentric orbits, indicating that these systems are either formed through a different mechanism or perhaps they are not close WD+AFGK binaries. We observed one of these eccentric WD+AFGK binaries with SPHERE and find that the system TYC 7218-934-1 is in fact a triple system where the WD is a distant companion. The inner binary likely consists of the G-type star plus an unseen low mass companion in an eccentric orbit. Based on this finding, we estimate the fraction of triple systems that could contaminate the WD+AFGK sample. We find that less than 15 per cent of our targets with orbital periods shorter than 100 days might be hierarchical triples.
- [51] arXiv:2003.07293 [pdf, other]
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Title: Ion acceleration in non-relativistic quasi-parallel shocks using fully kinetic simulationsComments: 17 pages, 9 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Computational Physics (physics.comp-ph)
The formation of collisionless shock fronts is an ubiquitous phenomenon in space plasma environments. In the solar wind shocks might accompany coronal mass ejections, while even more violent events, such as supernovae, produce shock fronts traveling at relativistic speeds. While the basic concepts of shock formation and particle acceleration in their vicinity are known, many details on a micro-physical scope are still under discussion. In recent years the hybrid kinetic simulation approach has allowed to study the dynamics and acceleration of protons and heavier ions in great detail. However, Particle-in-Cell codes allow to study the process including also electron dynamics and the radiation pressure. Additionally a further numerical method allows for crosschecking results. We therefore investigate shock formation and particle acceleration with a fully kinetic particle-in-cell code. Besides electrons and protons we also include helium and carbon ions in our simulations of a quasi-parallel shock. We are able to reproduce characteristic features of the energy spectra of the particles, such as the temperature ratios of the different ion species in the downstream which scale with the ratio of particle mass to charge. We also find that approximately 12-15% of the energy of the unperturbed upstream is transferred to the accelerated particles escaping the shock.
- [52] arXiv:2003.07295 [pdf, other]
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Title: Soft proton scattering at grazing incidence from X-ray mirrors: analysis of experimental data in the framework of the non-elastic approximationAuthors: R. Amato, T. Mineo, A. D'Aì, S. Diebold, V. Fioretti, A. Guzman, S. Lotti, C. Macculi, S. Molendi, E. Perinati, C. Tenzer, A. SantangeloSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Astronomical X-ray observatories with grazing incidence optics face the problem of pseudo-focusing of low energy protons from the mirrors towards the focal plane. Those protons constitute a variable, unpredictable component of the non X-ray background that strongly affects astronomical observations and a correct estimation of their flux at the focal plane is then essential. For this reason, we investigate how they are scattered from the mirror surfaces when impacting with grazing angles. We compare the non-elastic model of reflectivity of particles at grazing incidence proposed by Remizovich et al. (1980) with the few available experimental measurements of proton scattering from X-ray mirrors. We develop a semi-empirical analytical model based on the fit of those experimental data with the Remizovich solution. We conclude that the scattering probability weakly depends on the energy of the impinging protons and that the relative energy losses are necessary to correctly model the data. The model we propose assumes no dependence on the incident energy and can be implemented in particle transport simulation codes to generate, for instance, proton response matrices for specific X-ray missions. Further laboratory measurements at lower energies and on other mirror samples, such as ATHENA Silicon Pore Optics, will improve the resolution of the model and will allow us to build the proper proton response matrices for a wider sample of X-ray observatories.
- [53] arXiv:2003.07306 [pdf, other]
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Title: On-sky calibration of a SKA1-low station in the presence of mutual couplingAuthors: Josef Borg, Alessio Magro, Kristian Zarb Adami, Eloy de lera Acedo, Adrian Sutinjo, Daniel UngSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det)
This paper deals with the calibration of the analogue chains of a Square Kilometre Array (SKA) phased aperture array station, using embedded element patterns (one per antenna in the array, thus accounting for the full effects of mutual coupling) or average element patterns to generate model visibilities. The array is composed of 256 log-periodic dipole array antennas. A simulator capable of generating such per-baseline model visibility correlation matrices was implemented. This allowed for a direct comparison of calibration results using StEFCal (Statistically Efficient and Fast Calibration) with both pattern types. Calibrating the array with StEFCal using simulator-generated model visibilities was successful and thus constitutes a possible routine for calibration of an SKA phase aperture array station. However, results indicate that there was no significant advantage in calibrating with embedded element patterns, with StEFCal successfully retrieving similar per-element coefficients with model visibilities generated with either pattern type. Data from the AAVS-1 (Aperture Array Verification System 1) prototype station in Western Australia was used for demonstration purposes.
- [54] arXiv:2003.07324 [pdf, other]
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Title: The Milky Way's rotation curve with superfluid dark matterComments: 19 pages, 5 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
Recent studies have shown that dark matter with a superfluid phase in which phonons mediate a long-distance force gives rise to the phenomenologically well-established regularities of Modified Newtonian Dynamics (MOND). Superfluid dark matter, therefore, has emerged as a promising explanation for astrophysical observations by combining the benefits of both particle dark matter and MOND, or its relativistic completions, respectively. We here investigate whether superfluid dark matter can reproduce the observed Milky Way rotation curve for $ R < 25\,\rm{kpc}$ and are able to answer this question in the affirmative. Our analysis demonstrates that superfluid dark matter fits the data well with parameters in reasonable ranges. The most notable difference between superfluid dark matter and MOND is that superfluid dark matter requires about $ 20\% $ less total baryonic mass (with a suitable interpolation function). Our analysis further allows us to estimate the radius of the Milky Way's superfluid core and the total mass of dark matter in both the superfluid and the normal phase.
- [55] arXiv:2003.07355 [pdf, other]
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Title: Early Dark Energy Does Not Restore Cosmological ConcordanceComments: 36 pages, 23 figures. CLASS_EDE code publicly available at this https URLSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
Current cosmological data exhibit a tension between inferences of the Hubble constant, $H_0$, derived from early and late-universe measurements. One proposed solution is to introduce a new component in the early universe, which initially acts as "early dark energy" (EDE), thus decreasing the physical size of the sound horizon imprinted in the cosmic microwave background (CMB) and increasing the inferred $H_0$. Previous EDE analyses have shown this model can relax the $H_0$ tension, but the CMB-preferred value of the density fluctuation amplitude, $\sigma_8$, increases in EDE as compared to $\Lambda$CDM, increasing tension with large-scale structure (LSS) data. We show that the EDE model fit to CMB and SH0ES data yields scale-dependent changes in the matter power spectrum compared to $\Lambda$CDM, including $10\%$ more power at $k = 1~h$/Mpc. Motivated by this observation, we reanalyze the EDE scenario, considering LSS data in detail. We also update previous analyses by including $Planck$ 2018 CMB likelihoods, and perform the first search for EDE in $Planck$ data alone, which yields no evidence for EDE. We consider several data set combinations involving the primary CMB, CMB lensing, SNIa, BAO, RSD, weak lensing, galaxy clustering, and local distance-ladder data (SH0ES). While the EDE component is weakly detected (3$\sigma$) when including the SH0ES data and excluding most LSS data, this drops below 2$\sigma$ when further LSS data are included. Further, this result is in tension with strong constraints imposed on EDE by CMB and LSS data without SH0ES, which show no evidence for this model. We also show that physical priors on the fundamental scalar field parameters further weaken evidence for EDE. We conclude that the EDE scenario is, at best, no more likely to be concordant with all current cosmological data sets than $\Lambda$CDM, and appears unlikely to resolve the $H_0$ tension.
Cross-lists for Tue, 17 Mar 20
- [56] arXiv:2003.06445 (cross-list from gr-qc) [pdf, other]
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Title: Stationary black holes and light ringsComments: 5 pages, 3 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
The ringdown and shadow of the astrophysically significant Kerr Black Hole (BH) are both intimately connected to a special set of bound null orbits known as Light Rings (LRs). Does it hold that a generic equilibrium BH must possess such orbits? In this letter we prove the following theorem. A stationary, axi-symmetric, asymptotically flat black hole spacetime in 1+3 dimensions, with a non-extremal, topologically spherical, Killing horizon admits, at least, one standard LR outside the horizon for each rotation sense. The proof relies on a topological argument and assumes $C^2$-smoothness and circularity, but makes no use of the field equations. The argument is also adapted to recover a previous theorem establishing that a horizonless ultra-compact object must admit an even number of non-degenerate LRs, one of which is stable.
- [57] arXiv:2003.06604 (cross-list from physics.ins-det) [pdf, other]
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Title: Measurements of the neutral particle spectra on Mars by MSL/RAD from 2015-11-15 to 2016-01-15Authors: Jingnan Guo, Cary Zeitlin, Robert Wimmer-Schweingruber, Donald M. Hassler, Jan Koehler, Bent Ehresmann, Stephan Boettcher, Eckart Boehm, David E. BrinzaJournal-ref: J. Guo*, C. Zeitlin, R. Wimmer-Schweingruber et al. (2017). Measurements of the neutral particle spectra on Mars by MSL/RAD from 2015-11-15 to 2016-01-15 , LSSR, 14, 12-17Subjects: Instrumentation and Detectors (physics.ins-det); Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
The Radiation Assessment Detector (RAD), onboard the Mars Science Laboratory (MSL) rover Curiosity, has been measuring the energetic charged and neutral particles and the radiation dose rate on the surface of Mars since the landing of the rover in August 2012. In contrast to charged particles, neutral particles (neutrons and gamma-rays) are measured indirectly: the energy deposition spectra produced by neutral particles are complex convolutions of the incident particle spectra with the detector response functions. An inversion technique has been developed and applied to jointly unfold the deposited energy spectra measured in two scintillators of different types (CsI for high gamma detection efficiency, and plastic for neutrons) to obtain the neutron and gamma-ray spectra. This result is important for determining the biological impact of the Martian surface radiation contributed by neutrons, which interact with materials differently from the charged particles. These first in-situ measurements on Mars provide (1) an important reference for assessing the radiation-associated health risks for future manned missions to the red planet and (2) an experimental input for validating the particle transport codes used to model the radiation environments within spacecraft or on the surface of planets. Here we present neutral particle spectra as well as the corresponding dose and dose equivalent rates derived from RAD measurement during a period (November 15, 2015 to January 15, 2016) for which the surface particle spectra have been simulated via different transport models.
- [58] arXiv:2003.06629 (cross-list from cond-mat.mtrl-sci) [pdf]
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Title: Thermodynamic anomalies and three distinct liquid-liquid transitions in warm dense liquid hydrogenComments: 34 pages, 7 figures, with Supplementary MaterialJournal-ref: Physical Review B 100, 134109 (2019)Subjects: Materials Science (cond-mat.mtrl-sci); Earth and Planetary Astrophysics (astro-ph.EP); Computational Physics (physics.comp-ph)
The properties of hydrogen at high pressure have wide implications in astrophysics and high-pressure physics. Its phase change in the liquid is variously described as a metallization, H2-dissociation, density discontinuity or plasma phase transition. It has been tacitly assumed that these phenomena coincide at a first-order liquid-liquid transition (LLT). In this work, the relevant pressure-temperature conditions are thoroughly explored with first-principles molecular dynamics. We show there is a large dependency on exchange-correlation functional and significant finite size effects. We use hysteresis in a number of measurable quantities to demonstrate a first-order transition up to a critical point, above which molecular and atomic liquids are indistinguishable. At higher temperature beyond the critical point, H2-dissociation becomes a smooth cross-over in the supercritical region that can be modelled by a pseudo-transition, where the H2-2H transformation is localized and does not cause a density discontinuity at metallization. Thermodynamic anomalies and counter-intuitive transport behavior of protons are also discovered even far beyond the critical point, making this dissociative transition highly relevant to the interior dynamics of Jovian planets. Below the critical point, simulation also reveals a dynamic H2-2H chemical equilibrium with rapid interconversion, showing that H2 and H are miscible. The predicted critical temperature lies well below the ionization temperature. Our calculations unequivocally demonstrate that there are three distinct regimes in the liquid-liquid transition of warm dense hydrogen.
- [59] arXiv:2003.06671 (cross-list from gr-qc) [pdf, ps, other]
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Title: Aspects of Axion $F(R)$ GravityComments: Invited perspective-review paper from EPL, EPL AcceptedSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We provide a compact review on recent developments on axion $F(R)$ gravity. The axion field is a string theory originating theoretical particle that is a perfect candidate for low-mass particle dark matter. In this review we present how a viable inflationary phenomenology and a viable late-time evolution can be described by an axion $F(R)$ gravity theory, in which the $F(R)$ gravity part can drive in a geometric way the inflationary and the late-time era, and the axion field behaves as dark matter, with its energy density $\rho_a$ behaving as a function of the scale factor as $\rho_a\sim a^{-3}$. We also briefly discuss the effect of a non-trivial axion Chern-Simons coupling on the inflationary phenomenology of the $R^2$ model. Finally, we briefly discuss the effects of a non-minimal coupling of the axion field with the curvature on neutron stars, and also the propagation of gravity waves in Chern-Simons axion gravity.
- [60] arXiv:2003.06874 (cross-list from physics.ins-det) [pdf, other]
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Title: A dark matter telescope probing the 6 to 60 GHz bandAuthors: Javier De Miguel-HernándezComments: 24 pp., 7 figsSubjects: Instrumentation and Detectors (physics.ins-det); High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)
In this article we present the Dark-photons&Axion-Like particles Interferometer (DALI), a novel experiment designed for the detection of photon-mixing cold dark matter in the microwave band between 6 and 60 GHz. DALI is a haloscope for the simultaneous search for axions, ALPs and dark photons, with a number of novelties that make it unique. First, it is a dark matter telescope, with a capacity for pointing, tracking and rastering objects and areas in the sky. This potentially allows one to detect accelerated dark matter particles, substructures and flows, without compromising the simultaneous scanning for dark matter relic particles present in the laboratory. Second, it has been designed using commercial technology. This will allow feasible manufacture at a reasonable cost, thereby mitigating the need for R&D and facilitating maintenance. Finally, it benefits from a high sensitivity over a broad band of frequencies with only minimal reconfiguration.
- [61] arXiv:2003.07145 (cross-list from gr-qc) [pdf, ps, other]
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Title: Testing binary dynamics in gravity at the sixth post-Newtonian levelComments: 13 pages LatexSubjects: General Relativity and Quantum Cosmology (gr-qc); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics - Theory (hep-th)
We calculate the motion of binary mass systems in gravity up to the sixth post--Newtonian order to the $G_N^3$ terms ab initio using momentum expansions within an effective field theory approach based on Feynman amplitudes in harmonic coordinates. For these contributions we construct a canonical transformation to isotropic and to EOB coordinates at 5PN and agree with the results in the literature \cite{Bern:2019nnu,Damour:2019lcq}. At 6PN we compare to the Hamiltonians in isotropic coordinates either given in \cite{Bern:2019nnu} or resulting from the scattering angle. We find a canonical transformation from our Hamiltonian in harmonic coordinates to \cite{Bern:2019nnu}, but not to \cite{Damour:2019lcq}. This implies that we also agree on all observables with \cite{Bern:2019nnu} to the sixth post--Newtonian order to $G_N^3$.
- [62] arXiv:2003.07173 (cross-list from gr-qc) [pdf, ps, other]
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Title: On the quantization of the extremal Reissner-Nordstrom black holeComments: 6 pages, submitted to Phys. Rev. DSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th); Quantum Physics (quant-ph)
Following Rosen's quantization rules, two of the Authors (CC and FF) recently described the Schwarzschild black hole (BH) formed after the gravitational collapse of a pressureless "star of dust" in terms of a "gravitational hydrogen atom". Here we generalize this approach to the gravitational collapse of a charged object, namely, to the geometry of a Reissner-Nordstrom BH (RNBH) and calculate the gravitational potential, the Schr\"odinger equation and the exact solutions of the energy levels of the gravitational collapse. By using the concept of BH effective state, previously introduced by one of us (CC), we describe the quantum gravitational potential, the mass spectrum and the energy spectrum for the extremal RNBH. The area spectrum derived from the mass spectrum finds agreement with a previous result by Bekenstein. The stability of these solutions, described with the Majorana approach to the Archaic Universe scenario, show the existence of oscillatory regimes or exponential damping for the evolution of a small perturbation from a stable state.
- [63] arXiv:2003.07184 (cross-list from hep-th) [pdf, ps, other]
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Title: Role of trans-Planckian modes in cosmologyComments: 33 pages, comments welcomeSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
Motivated by the old trans-Planckian (TP) problem of inflationary cosmology, it has been conjectured that any consistent effective field theory should keep TP modes `hidden' behind the Hubble horizon, so as to prevent them from turning classical and thereby affecting macroscopic observations. In this paper we present two arguments against the Hubble horizon being a scale of singular significance as has been put forward in the TP Censorship Conjecture (TCC). First, refinements of TCC are presented that allow for the TP modes to grow beyond the horizon while still keeping the de-Sitter conjecture valid. Second, we show that TP modes can turn classical even well within the Hubble horizon, which, as such, negates this rationale behind keeping them from crossing it. The role of TP modes is known to be less of a problem in warm inflation, because fluctuations start out usually as classical. This allows warm inflation to be more resilient to the TP problem compared to cold inflation. To understand how robust this is, we identity limits where quantum modes can affect the primordial power spectrum in one specific case.
Replacements for Tue, 17 Mar 20
- [64] arXiv:1707.01020 (replaced) [pdf]
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Title: Astrometric accuracy during the past 2000 yearsAuthors: Erik HøgComments: 4 pages, 2 figures, update of the report from 2017 in arxiv:1707.01020v1Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); History and Philosophy of Physics (physics.hist-ph)
- [65] arXiv:1807.09397 (replaced) [pdf, other]
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Title: Singularities of plane gravitational waves and their memory effectsComments: revtex4-1, one figure. Corrected some typos. Gen. Relativ. Grav. 52 (2020) 21Journal-ref: Gen. Relativ. Grav. 52 (2020) 21Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
- [66] arXiv:1810.12712 (replaced) [pdf, other]
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Title: A New Class of Non-canonical Conformal Attractors for Multifield InflationComments: 23 pages, 5 figures, Published versionJournal-ref: JCAP 2003 (2020) no.03, 022Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [67] arXiv:1811.11478 (replaced) [pdf, ps, other]
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Title: Artificial neural networks for selection of pulsar candidates from the radio continuum surveysAuthors: Naoyuki Yonemaru, Keitaro Takahashi, Hiroki Kumamoto, Shi Dai, Shintaro Yoshiura, Shinsuke IdeguchiComments: 11 pages, 13 figures, 3 tables, accepted for publication in MNRASSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [68] arXiv:1812.06516 (replaced) [pdf]
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Title: Response to Wright et al. 2018: Even more serious problems with NEOWISEAuthors: Nathan P. MyhrvoldSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [69] arXiv:1902.00519 (replaced) [pdf, other]
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Title: Asymptotic Behavior of Cosmologies with $Λ>0$ in 2+1 DimensionsComments: 18 pages, 3 figures; v2: minor corrections, CMP published versionSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); Differential Geometry (math.DG)
- [70] arXiv:1902.03580 (replaced) [pdf, ps, other]
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Title: Cosmic Anisotropy and Fast Radio BurstsComments: 16 pages, 6 figures, revtex4; v2: discussions added, Class. Quant. Grav. in pressSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [71] arXiv:1902.09554 (replaced) [pdf, other]
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Title: The MOSDEF Survey: Kinematic and Structural Evolution of Star-Forming Galaxies at $1.4\leq z\leq 3.8$Authors: Sedona H. Price, Mariska Kriek, Guillermo Barro, Alice E. Shapley, Naveen A. Reddy, William R. Freeman, Alison L. Coil, Irene Shivaei, Mojegan Azadi, Laura de Groot, Brian Siana, Bahram Mobasher, Ryan L. Sanders, Gene C. K. Leung, Tara Fetherolf, Tom O. Zick, Hannah Übler, Natascha M. Förster SchreiberComments: Accepted to ApJ. Added Figure 9, corrected sample size (main results unchanged). 28 pages, 13 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [72] arXiv:1903.00426 (replaced) [pdf, other]
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Title: On Frequency-Dependent Dispersion Measures and Extreme Scattering EventsAuthors: M. T. Lam, T. J. W. Lazio, T. Dolch, M. L. Jones, M. A. McLaughlin, D. R. Stinebring, M. SurnisComments: 16 pages, 7 figures, accepted by ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [73] arXiv:1905.11339 (replaced) [pdf, other]
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Title: Magnetic Fields and Afterglows of BdHNe: Inferences from GRB 130427A, GRB 160509A, GRB 160625B, GRB 180728A and GRB 190114CComments: 7 figures, 3 tables, submitted to ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [74] arXiv:1906.10589 (replaced) [pdf, other]
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Title: Measuring Limb Darkening of Stars in high magnification Microlensing Events by the Finite Element MethodComments: 15 pages, 21 figures, accepted in MNRASSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [75] arXiv:1906.11840 (replaced) [pdf, other]
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Title: Heavy Spinning Particles from Signs of Primordial Non-Gaussianities: Beyond the Positivity BoundsComments: 27 pages, 4 figures; v2: references added, minor changes, version published in JHEPSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [76] arXiv:1907.03778 (replaced) [pdf, other]
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Title: A local resolution of the Hubble tension: The impact of screened fifth forces on the cosmic distance ladderComments: 20 pages, 7 figures; correction to Cepheid--TRGB distance test, H0 results weakened slightlyJournal-ref: Phys. Rev. D 100, 043537 (2019)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
- [77] arXiv:1908.03001 (replaced) [pdf, ps, other]
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Title: Type Ia SN 2019ein: New Insights into the Similarities and diversities among High-Velocity SNe IaAuthors: Miho Kawabata, Keiichi Maeda, Masayuki Yamanaka, Tatsuya Nakaoka, Koji Kawabata, Ryo Adachi, Hiroshi Akitaya, Umut Burgaz, Hidekazu Hanayama, Takashi Horiuchi, Ryohei Hosokawa, Kota Iida, Fumiya Imazato, Keisuke Isogai, Ji-an Jiang, Noriyuki Katoh, Hiroki Kimura, Masaru Kino, Daisuke Kuroda, Hiroyuki Maehara, Kazuya Matsubayashi, Kumiko Morihana, Katsuhiro Murata, Takashi Nagao, Masafumi Niwano, Daisaku Nogami, Motoki Oeda, Tatsuharu Ono, Hiroki Onozato, Masaaki Otsuka, Tomoki Saito, Mahito Sasada, Kazuki Shiraishi, Haruki Sugiyama, Kenta Taguchi, Jun Takahashi, Kengo Takagi, Seiko Takagi, Masaki Takayama, Miyako Tozuka, Kazuhiro SekiguchiComments: 15 pages, 12 figres, Accepted to ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [78] arXiv:1908.07284 (replaced) [pdf]
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Title: The gravity field and interior structure of DioneAuthors: Marco Zannoni (1), Doug Hemingway (2 and 3), Luis Gomez Casajus (1), Paolo Tortora (1) ((1) Dipartimento di Ingegneria Industriale, Università di Bologna, Forlì, Italy, (2) Department of Earth & Planetary Science, University of California Berkeley, Berkeley, California, USA, (3) Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC, USA)Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Space Physics (physics.space-ph)
- [79] arXiv:1908.10590 (replaced) [pdf, other]
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Title: Cosmological parameter estimation from large-scale structure deep learningAuthors: Shuyang Pan, Miaoxin Liu, Jaime Forero-Romero, Cristiano G. Sabiu, Zhigang Li, Haitao Miao, Xiao-Dong LiComments: 17 pages, 10 figures, 1 tablesSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [80] arXiv:1908.10867 (replaced) [pdf, other]
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Title: Voracious vortexes in cataclysmic variables: II. Evidence for the expansion of accretion disc material beyond the accretor's Roche-lobeComments: 13 pages, 12 figures, 2 tables. This is the second paper of a series of two. The first paper can be found here arXiv:1506.04753. Submitted to A&A. This version addressed referee's comments, Section 5 is expanded and divided into 3 sections 5-7, 3 new figures (4,10,11) are addedSubjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
- [81] arXiv:1909.01527 (replaced) [pdf, other]
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Title: Choked accretion onto a Schwarzschild black hole: A hydrodynamical jet-launching mechanismComments: 24 pages, 18 figures, accepted for publication in the ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [82] arXiv:1910.00066 (replaced) [pdf, other]
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Title: Core and crust contributions in overshooting glitches: the Vela pulsar 2016 glitchComments: 7 pages, 5 figures, 2 tablesSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [83] arXiv:1910.13560 (replaced) [pdf, other]
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Title: Symmetries of post-Galilean expansionsComments: 6 pagesJournal-ref: Phys. Rev. Lett. 124, 081602 (2020)Subjects: High Energy Physics - Theory (hep-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [84] arXiv:1911.02179 (replaced) [pdf, other]
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Title: Weak cosmic growth in coupled dark energy with a Lagrangian formulationComments: 14 pages, 2 figures with correctionsSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
- [85] arXiv:1911.02398 (replaced) [pdf, other]
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Title: Detecting the relativistic galaxy bispectrumAuthors: Roy Maartens, Sheean Jolicoeur, Obinna Umeh, Eline M. De Weerd, Chris Clarkson, Stefano CameraComments: 13 pages, 10 figures, Version accepted by JCAPSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [86] arXiv:1911.11495 (replaced) [pdf, ps, other]
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Title: Entropy Production in Affine InflationComments: To appear in PRDSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
- [87] arXiv:1911.11783 (replaced) [pdf, other]
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Title: Probing delayed-end reionization histories with the 21cm-LAE cross-power spectrumAuthors: Lewis H. Weinberger (IoA, Cambridge), Girish Kulkarni (TIFR, Mumbai), Martin G. Haehnelt (IoA, Cambridge)Comments: 17 pages, 10 figures, 3 tables, 4 appendices. Accepted by MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
- [88] arXiv:1912.01256 (replaced) [pdf, other]
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Title: Evidence from high mass X-ray binaries that Galactic WR components of WR+O binaries end their life with a supernova explosionComments: 7 pages, 3 figures, accepted for publication in A&A; accepted versionSubjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
- [89] arXiv:1912.02976 (replaced) [pdf, other]
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Title: Hunting the Glashow Resonance with PeV Neutrino TelescopesComments: 12 pages, 7 figures; matches the published version in JCAPJournal-ref: JCAP03(2020)005Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE)
- [90] arXiv:1912.03868 (replaced) [pdf, other]
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Title: Search for traversable wormholes in active galactic nuclei using X-ray dataComments: 10 pages, 7 figures. v2: refereed versionJournal-ref: Phys. Rev. D 101, 064030 (2020)Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
- [91] arXiv:1912.07406 (replaced) [pdf, other]
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Title: Discreteness effects, $N-$body chaos and the onset of radial-orbit instabilityComments: 9 pages, 7 figures. Matching the version accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); Chaotic Dynamics (nlin.CD)
- [92] arXiv:2001.04864 (replaced) [pdf, other]
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Title: QED meson description of the X17 particle and dark matterAuthors: Cheuk-Yin WongComments: 8 pages, 1 figureSubjects: Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
- [93] arXiv:2001.09260 (replaced) [pdf, other]
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Title: Cosmological model insensitivity of local $H_0$ from the Cepheid distance ladderComments: 11 pages, 3 figures, accepted to ApJSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [94] arXiv:2001.11716 (replaced) [pdf, other]
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Title: Point Spread Function Modelling for Wide Field Small Aperture Telescopes with a Denoising AutoencoderComments: 10 pages, 10 figures, Published by MNRASSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG); Image and Video Processing (eess.IV)
- [95] arXiv:2002.02166 (replaced) [pdf, other]
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Title: The Bimodal Distribution in Exoplanet Radii: Considering Varying Core Compositions and $\rm H_{2}$ Envelope's SizesJournal-ref: ApJ 891 158 (2020)Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
- [96] arXiv:2002.06749 (replaced) [pdf, ps, other]
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Title: Angular Expansion of Nova ShellsAuthors: E. Santamaría, M.A. Guerrero, G. Ramos-Larios, J.A.Toalá, L. Sabin, G. Rubio, J.A. Quino-MendozaComments: 8 pages, 2 figures, 3 tables. Accepted for publication in ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
- [97] arXiv:2002.07061 (replaced) [pdf, other]
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Title: Power Law Plateau Inflation Potential In The RS $II$ Braneworld Evading Swampland ConjectureComments: 14 pages, 6 figures, references addedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [98] arXiv:2002.09211 (replaced) [pdf, ps, other]
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Title: Detection and Classification of Astronomical Targets with Deep Neural Networks in Wide Field Small Aperture TelescopesComments: Accepted by Astronomical Journal. The complete code can be downloaded from this https URL This code can be directly used to process images obtained by WFSATs. Images obtained by ordinary sky survey telescopes can also be processed with this code, however more annotated images are required to train the neural networkSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Computer Vision and Pattern Recognition (cs.CV)
- [99] arXiv:2002.11161 (replaced) [pdf, other]
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Title: Low-mass planet migration in three dimensional wind-driven inviscid discs: a negative corotation torqueAuthors: Colin P. McNally, Richard P. Nelson, Sijme-Jan Paardekooper, Pablo Benitez-Llambay, Oliver GresselComments: 19 pages, 19 figures, MNRAS, updated to match published versionSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [100] arXiv:2003.01188 (replaced) [pdf, ps, other]
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Title: Quasinormal modes, stability and shadows of a black hole in the novel 4D Einstein-Gauss-Bonnet gravityComments: RevTex, 9 pages, 8 figures, new essential material and references are addedSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
- [101] arXiv:2003.01511 (replaced) [pdf, ps, other]
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Title: Photometric Redshifts for the Hyper Suprime-Cam Subaru Strategic Program Data Release 2Comments: 12 pages, 7 figures, 4 tables. arXiv admin note: text overlap with arXiv:1704.05988Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [102] arXiv:2003.04644 (replaced) [pdf, ps, other]
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Title: Periodic Fast Radio Bursts as a Probe of Extragalactic Asteroid BeltsComments: 5 pages in emulateapj format, 3 figures, one missed factor 1/(1+q) added in equation (1), results recalculated, main conclusions unchangedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [103] arXiv:2003.04810 (replaced) [pdf, ps, other]
- [104] arXiv:2003.04851 (replaced) [pdf, ps, other]
- [105] arXiv:2003.05472 (replaced) [pdf, other]
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Title: Concerns about ground based astronomical observations:quantifying satellites' constellations damagesAuthors: Stefano Gallozzi (1), Diego Paris (1), Michele Maris (3), Marco Scardia, (4) David Dubois ((1) INAF-Osservatorio Astronomico di Roma, (2) INAF-Osservatorio Astronomico di Trieste, (3) INAF-Osservatorio Astronomici di Brera, (4) NASA-National Aeronautics and Space Administration)Comments: 21 pages, 26 figures, 4 tables and 1 algorithmSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [106] arXiv:2003.05757 (replaced) [pdf, other]
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Title: A Bayesian Approach to the Vertical Structure of the Disk of the Milky WayComments: 7 pages, 6 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [107] arXiv:2003.05777 (replaced) [pdf, other]
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Title: Characterising hot stellar systems with confidenceComments: 9 pages; 9 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR); Applications (stat.AP); Machine Learning (stat.ML)
- [108] arXiv:2003.05883 (replaced) [pdf, other]
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Title: Multipoint correlators in multifield cosmologyComments: 30 pages, 7 figures. v2: references addedSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
- [109] arXiv:2003.06043 (replaced) [pdf, other]
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Title: A magnetar engine for short GRBs and kilonovaeComments: Submitted versionSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [110] arXiv:2003.06090 (replaced) [pdf, other]
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Title: Image simulations for strong and weak gravitational lensingAuthors: Andrés A. PlazasComments: Accepted for publication in Symmetry, MDPI, special Issue on Gravitational LensingSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
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