Astrophysics
New submissions
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New submissions for Wed, 11 Dec 19
- [1] arXiv:1912.04284 [pdf, other]
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Title: The Young Suns Exoplanet Survey: Detection of a wide orbit planetary mass companion to a solar-type Sco-Cen memberAuthors: A. J. Bohn, M. A. Kenworthy, C. Ginski, C. F. Manara, M. J. Pecaut, J. de Boer, C. U. Keller, E. E. Mamajek, T. Meshkat, M. Reggiani, K. O. Todorov, F. SnikComments: Accepted for publication in MNRAS (15 pages, 9 figures)Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
The Young Suns Exoplanet Survey (YSES) consists of a homogeneous sample of 70 young, solar-mass stars located in the Lower Centaurus-Crux subgroup of the Scorpius-Centaurus association with an average age of $15\pm3\,$Myr. We report the detection of a co-moving companion around the K3IV star TYC 8998-760-1 (2MASSJ13251211-6456207) that is located at a distance of $94.6\pm0.3\,$pc using SPHERE/IRDIS on the VLT. Spectroscopic observations with VLT/X-SHOOTER constrain the mass of the star to $1.00\pm0.02\,M_{\odot}$ and an age of $16.7\pm1.4\,$Myr. The companion TYC 8998-760-1 b is detected at a projected separation of 1.71'', which implies a projected physical separation of $162\,$au. Photometric measurements ranging from $Y$ to $M$ band provide a mass estimate of $14\pm3\,M_\mathrm{jup}$ by comparison to BT-Settl and AMES-dusty isochrones, corresponding to a mass ratio of $q=0.013\pm0.003$ with respect to the primary. We rule out additional companions to TYC 8998-760-1 that are more massive than $12\,M_\mathrm{jup}$ and farther than $12\,$au away from the host. Future polarimetric and spectroscopic observations of this system with ground and space based observatories will facilitate testing of formation and evolution scenarios shaping the architecture of the circumstellar environment around this 'young Sun'.
- [2] arXiv:1912.04286 [pdf, other]
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Title: Upper Limits on Planet Occurrence around Ultracool Dwarfs with K2Comments: Submitted to AAS Journals. Machine-readable table in sourceSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
The occurrence of planets orbiting ultracool dwarfs is poorly constrained. We present results from a Guest Observer program on NASA's K2 spacecraft to search for transiting planets orbiting a sample of 827 ultracool dwarfs. Having found no transiting planets in our sample, we determined an upper limit on the occurrence of planets. We simulated planets orbiting our sample for a range of orbital periods and sizes. For the simulated planets that transit their host, we injected the transit light curve into the real K2 light curves, then attempted to recover the injected planets. For a given occurrence rate, we calculated the probability of seeing no planets, and use the results to place an upper limit on planet occurrence as a function of planet radius and orbital period. We find that short period, mini-Neptune- and Jupiter-sized planets are rare around ultracool dwarfs, consistent with results for early- and mid-type M dwarf stars. We constrain the occurrence rate $\eta$ for planets between $0.5$ and $10$ R$_{\oplus}$ with orbital periods between 1 and 26.3 days.
- [3] arXiv:1912.04287 [pdf, other]
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Title: Constraining Orbital Periods from Nonconsecutive Observations: Period Estimates for Long-Period Planets in Six Systems Observed by K2 During Multiple CampaignsComments: 10 pages, 5 figures; accepted for publication in AJSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Most planetary discoveries with the K2 and TESS missions are restricted to short periods because of the limited duration of observation. However, the re-observation of sky area allows for the detection of longer period planets. We describe new transits detected in six candidate planetary systems which were observed by multiple K2 mission campaigns. One of these systems is a multiplanet system with four candidate planets; we present new period constraints for two planets in this system. In the other five systems, only one transit is observed in each campaign, and we derive period constraints from this new data. The period distributions are highly multimodal resulting from missed potential transits in the gap between observations. Each peak in the distribution corresponds to transits at an integer harmonic of the two observed transits. We further detail a generalized procedure to constrain the period for planets with multiple observations with intervening gaps. Because long period photometrically discovered planets are rare, these systems are interesting targets for follow-up observations and confirmation. Specifically, all six systems are bright enough (V = 10.4-12.7) to be amenable to radial velocity follow-up. This work serves as a template for period constraints in a host of similar yet-to-be-discovered planets in long baseline, temporally gapped observations conducted by the TESS mission.
- [4] arXiv:1912.04288 [pdf, other]
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Title: A new implementation of the Schwarzschild method for constructing observationally-driven dynamical models of galaxies of all morphological typesComments: accepted by ApJ; the code is available at this http URLSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present Forstand, a new code for constructing dynamical models of galaxies with the Schwarzschild orbit-superposition method. These models are constrained by line-of-sight kinematic observations and applicable to galaxies of all morphological types, including disks and triaxial rotating bars. Our implementation has several novel and improved features, is computationally efficient, and made publicly available. Using mock datasets taken from N-body simulations, we demonstrate that the pattern speed of a bar can be recovered with an accuracy of 10-20%, regardless of orientation, if the 3D shape of the galaxy is known or inferred correctly.
- [5] arXiv:1912.04289 [pdf, other]
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Title: Electromagnetic signals from the decay of free neutrons in the first hours of neutron star mergersSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The first hours following a neutron star merger are considered to provide several UV/optical/NIR signals: $ \beta $-decay emission from free neutrons, radioactive decay of shocked heavy elements in the cocoon and cocoon's cooling emission. Here we consider two additional emission sources: $ \beta $-decay of free neutrons in the cocoon and synchrotron by the $ \beta $-decay electrons. We present 3D RHD simulations of jets that propagate in a multi-layer ejecta from the merger and calculate semi-analytically the resulting light curves. We find that the free neutrons emission at high latitudes is enhanced by the cocoon by a factor of a few to power a wide ($ \lesssim 60^\circ $) and brief ($ \sim 1 $ hour) UV signal that can reach an absolute magnitude of $\gtrsim$ -15, comparable with the cooling emission. If the ejected neutron matter mass is $ M_n \gtrsim 10^{-4}{\rm M_\odot} $, the synchrotron emission may yield a long ($ \sim 8 $ hours) quasi-isotropic UV/optical signal with an absolute magnitude between -12 and -15, depending on the magnetic field. Such a high mass of a mildly-relativistic component may partly obscure the cocoon's shocked r-process elements, thereby attenuating its radioactive decay emission. Future observations on these timescales, including null detections, may place constraints on the ejected neutron matter mass and shed light on the ejecta and jet-cocoon characteristics.
- [6] arXiv:1912.04290 [pdf, other]
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Title: Variations in the slope of the resolved star-forming main sequence: a tool for constraining the mass of star-forming regionsAuthors: Maan H. Hani, Christopher C. Hayward, Matthew E. Orr, Sara L. Ellison, Paul Torrey, Norm Murray, Andrew Wetzel, Claude-André Faucher-GiguèreComments: submitted to MNRAS-LettersSubjects: Astrophysics of Galaxies (astro-ph.GA)
The correlation between galaxies' integrated stellar masses and star formation rates (the `star formation main sequence'; SFMS) is a well-established scaling relation. Recently, surveys have found a relationship between the star formation rate and stellar mass surface densities on kpc and sub-kpc scales (the `resolved SFMS'; rSFMS). In this work, we demonstrate that the rSFMS emerges naturally in FIRE-2 zoom-in simulations of Milky Way-mass galaxies. We make SFR and stellar mass maps of the simulated galaxies at a variety of spatial resolutions and star formation averaging time-scales and fit the rSFMS using multiple methods from the literature. While the absolute value of the SFMS slope depends on the fitting method, the slope is steeper for longer star formation time-scales and lower spatial resolutions regardless of the fitting method employed. We present a toy model that quantitatively captures the dependence of the simulated galaxies' rSFMS slope on spatial resolution and use it to illustrate how this dependence can be used to constrain the characteristic mass of star-forming clumps.
- [7] arXiv:1912.04296 [pdf, other]
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Title: A robust estimate of the Milky Way mass from rotation curve dataComments: 31 pages, 9 figures, 6 tablesSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph)
We present a new estimate of the mass of the Milky Way, inferred via a Bayesian approach from tracers of the circular velocity in the disk plane and stars in the stellar halo. We use the rotation curve method to determine the dark matter density profile, together with the total stellar mass, which is constrained by surface stellar density and microlensing measurements. We also include uncertainties on the baryonic morphology via Bayesian model averaging, thus converting a potential source of systematic error into a more manageable statistical uncertainty. We evaluate the robustness of our result against various possible systematics, including rotation curve data selection, uncertainty on the Sun's velocity $V_0$, dependence on the dark matter profile assumptions, and choice of priors. We find the Milky Way's virial mass to be $\log_{10}M_{200}/ {\rm M_\odot} = 11.92^{+0.06}_{-0.05}{\rm(stat)}\pm{0.28}\pm0.27{\rm(syst)}$ and the total mass to be $\log_{10}M_{\rm tot}/ {\rm M_\odot} = 11.95^{+0.04}_{-0.04}{\rm(stat)}\pm{0.25}\pm0.25{\rm(syst)}$ ($M_{200}=8.3^{+1.2}_{-0.9}{\rm(stat)}\times10^{11}\,{\rm M_\odot}$ and $M_{\rm tot}=8.9^{+1.0}_{-0.8}{\rm(stat)}\times10^{11}\,{\rm M_\odot}$). We also apply our framework to Gaia DR2 rotation curve data and find good statistical agreement with the above results.
- [8] arXiv:1912.04299 [pdf, other]
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Title: Predicting dark matter halo formation in N-body simulations with deep regression networksComments: 10 pages, 8 figures, 1 table, submitted to MNRAS, comments welcomeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Dark matter haloes play a fundamental role in cosmological structure formation. The most common approach to model their assembly mechanisms is through N-body simulations. In this work we present an innovative pathway to predict dark matter halo formation from the initial density field using a Deep Learning algorithm. We implement and train a Deep Convolutional Neural Network (DCNN) to solve the task of retrieving Lagrangian patches from which dark matter halos will condense. The volumetric multi-label classification task is turned into a regression problem by means of the euclidean distance transformation. The network is complemented by an adaptive version of the watershed algorithm to form the entire protohalo identification pipeline. We show that splitting the segmentation problem into two distinct sub-tasks allows for training smaller and faster networks, while the predictive power of the pipeline remains the same. The model is trained on synthetic data derived from a single full N-body simulation and achieves deviations of ~10% when reconstructing the dark matter halo mass function at z=0. This approach represents a promising framework for learning highly non-linear relations in the primordial density field. As a practical application, our method can be used to produce mock dark matter halo catalogues directly from the initial conditions of N-body simulations.
- [9] arXiv:1912.04301 [pdf, other]
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Title: Constraints on Aquatic Photosynthesis for Terrestrial Planets Around Other StarsComments: 6 pages; 3 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Aquatic photosynthesis plays a major role in carbon fixation and O$_2$ production on Earth. In this paper, we analyze the prospects for oxygenic photosynthesis in aquatic environments on Earth-analogs around F-, G-, K- and M-type stars. Our analysis takes into account the spectral type of the host star, attenuation of light by aquatic organisms, and rates of respiration and photosynthesis. We study the compensation depth ($\mathcal{Z}_\mathrm{CO}$) and the critical depth ($\mathcal{Z}_\mathrm{CR}$), defined respectively as the locations where the net growth rates and vertically integrated net growth rates of photoautotrophs become zero. Our analysis suggests that $\mathcal{Z}_\mathrm{CO}$ declines by more than an order of magnitude as one moves from the habitable zones around Sun-like stars to late-type M-dwarfs, but $\mathcal{Z}_\mathrm{CR}$ decreases by only a modest amount ($\sim 10\%$). For M-dwarf exoplanets, we propose that the photosynthetic red edge may constitute a more robust biosignature of aquatic photosynthesis compared to atmospheric O$_2$.
- [10] arXiv:1912.04304 [pdf, ps, other]
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Title: Resonance sweeping by a decelerating barComments: 21 pages, 23 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We provide the first quantitative evidence for the deceleration/growth of the Galactic bar from local stellar kinematics thus confirming dynamical friction within expectations for a typical dark matter halo. The kinematic response of the stellar disk to a decelerating bar is studied using secular perturbation theory and test particle simulations. We show that the velocity distribution at any point in the disk affected by a naturally slowing bar is qualitatively different from that perturbed by a steadily rotating bar with the same current pattern speed $\Omega_p$ and amplitude. When the bar slows with rate $d\Omega_p/dt$, its resonances sweep through phase space. Depending on $d{\Omega}_p/dt$, they trap and drag along a portion of previously free orbits. This enhances occupation on resonances, but also changes the distribution of stars within the resonant region. Helped by this accumulation of orbits near the boundary of the resonant region, the decelerating bar model reproduces with its corotation resonance the offset and strength of the Hercules stream in the local $v_R-v_\varphi$ plane and the double-peaked structure of $<v_R>$ in the $L_z-\varphi$ plane. On the outer/inner Lindblad resonances and other higher order resonances, resonant dragging by a slowing bar is associated with a continuing increase in radial action. We compare the model to data in the action plane, identifying multiple resonance ridges. This work shows models using a constant bar pattern speed ($d\Omega_p/dt=0$) likely lead to qualitatively wrong conclusions. Most importantly we provide the first quantitative estimate of the slowing rate of the bar: $d\Omega_p/dt = (-5.0 \pm 2.5)$ km/s/kpc/Gyr.
- [11] arXiv:1912.04307 [pdf, other]
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Title: The Sheet of Giants: Unusual Properties of the Milky Way's Immediate NeighbourhoodComments: 18 pages, 11 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
We quantify the shape and overdensity of the galaxy distribution in the `Local Sheet' within a sphere of $R=8$ Mpc, and compare these properties with the expectations of the $\Lambda$CDM model. We measure ellipsoidal axis ratios of $c/a\approx0.16$ and $b/a\approx0.79$, indicating that the distribution of galaxies in the Local Volume can be approximated by a flattened oblate ellipsoid, consistent with the `sheet'-like configuration noted in previous studies. In contrast with previous estimates that the Local Sheet has a density close to average, we find that the number density of faint and bright galaxies in the Local Volume is $\approx1.7$ and $\approx5.2$ times denser, respectively, than the mean number density of galaxies of the same luminosity. Comparison with simulations shows that the number density contrasts of bright and faint galaxies within $8$ Mpc alone make the Local Volume a $\approx 2.5\sigma$ outlier in the $\Lambda$CDM cosmology. Our results indicate that the cosmic neighbourhood of the Milky Way may be unusual for galaxies of similar luminosity. The impact of the peculiar properties of our neighbourhood on the properties of the Milky Way and other nearby galaxies is not yet understood and warrants further study.
- [12] arXiv:1912.04311 [pdf, other]
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Title: Setting the scene for BUFFALO: A study of the matter distribution in the HFF galaxy cluster MACS J0416.1-2403 and its parallel fieldAuthors: Elizabeth J. Gonzalez, Martín Chalela, Mathilde Jauzac, Dominique Eckert, Matthieu Schaller, David Harvey, Anna Niemiec, Anton M. Koekemoer, David Barnes, Doug Clowe, Thomas Connor, José M. Diego, Juan D. Remolina Gonzalez, Charles L. SteinhardtComments: 15 pages, 8 figures, 3 tables, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
In the context of the BUFFALO (Beyond Ultra-deep Frontier Fields And Legacy Observations) survey, we present a new analysis of the merging galaxy cluster MACS\,J0416.1-2403 ($z = 0.397$) and its parallel field using the data collected by the Hubble Frontier Fields (HFF) campaign. In this work, we measure the surface mass density from a weak-lensing analysis, and characterise the overall matter distribution in both the cluster and parallel fields. The surface mass distribution derived for the parallel field shows clumpy overdensities connected by filament-like structures elongated in the direction of the cluster core. We also characterise the X-ray emission of the cluster, and compare it with the lensing mass distribution. We identify five substructures at the $>5\sigma$ level over the two fields, four of them being in the cluster one. Furthermore, three of them are located close to the edges of the field of view, and border issues can significantly hamper the determination of their physical parameters. Finally, we compare our results with the predicted subhalo distribution of one of the Hydrangea/C-EAGLE simulated cluster. Significant differences are obtained suggesting the simulated cluster is at a more advanced evolutionary state than MACS\,J0416.1-2403. Our results anticipate the upcoming BUFFALO observations that will link the two HFF fields, extending further the \emph{HST} coverage, and thus allowing a better characterisation of the reported substructures.
- [13] arXiv:1912.04312 [pdf, other]
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Title: Galactic Archaeology with asteroseismic ages part II: Confirmation of a delayed gas infall using Bayesian analysis based on MCMC methodsComments: 11 pages, 13 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
With the wealth of information from large surveys and observational campaigns in the contemporary era, it is critical to properly exploit the data to constrain the parameters of Galactic chemical evolution models and quantify the associated uncertainties. We aim at constraining the two-infall chemical evolution models for the solar annulus using the measured chemical abundance ratios and seismically inferred age of stars in the APOKASC sample. In the revised two-infall chemical evolution models by Spitoni et al. (2019), a significant delay of $\sim 4.3$ Gyr has been invoked between the two episodes of gas accretion. In this work, we wish to test its robustness and statistically confirm/quantify the delay. For the first time, a Bayesian framework based on Markov Chain Monte Carlo methods has been used for fitting the two-infall chemical evolution models to the data. In addition to fitting the data for stars in the APOKASC sample, our best fit models also reproduce other important observational constraints of the chemical evolution of the disk: i) present day stellar surface density; ii) present day supernova and star formation rates; iii) the metallicity distribution function; and iv) solar abundance values. We found a significant delay between the two gas accretion episodes for various models explored with different values for the star formation efficiencies. The values for the delay lie in the range $4.5-5.5$ Gyr. The results suggest that the APOKASC sample carries the signature of delayed gas-rich merger, with the dilution as main process determining the shape of low-$\alpha$ stars in the abundance ratios space.
- [14] arXiv:1912.04313 [pdf, other]
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Title: An asymmetric explosion mechanism may explain the diversity of Si II line widths in type Ia supernovaeComments: 16 pages, 13 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
Near maximum brightness, the spectra of type Ia supernovae (SNe Ia) present typical absorption features of Silicon II observed at roughly 6100A and 5750A. The 2-D distribution of the pseudo-equivalent widths (pEWs) of these features is a useful tool for classifying SNe Ia spectra (Branch plot). Comparing the observed distribution of SNe on the Branch plot to results of simulated explosion models, we find that 1-D models fail to cover most of the distribution. In contrast, we find that TARDIS radiative transfer simulations of the WD head-on collision models along different lines of sight almost fully cover the distribution. We use several simplified approaches to explain this result. We perform order-of-magnitude analysis and model the opacity of the Si lines using LTE and NLTE approximations. Introducing a simple toy model of spectral feature formation, we show that the pEW is a good tracer for the extent of the absorption region in the ejecta. Using radiative transfer simulations of synthetic SNe ejecta, we reproduce the observed Branch plot distribution by varying the luminosity of the SN and the Si density profile of the ejecta. We deduce that the success of the collision model in covering the Branch plot is a result of its asymmetry, which allows for a significant range of Si density profiles along different viewing angles, uncorrelated with a range of $^{56}$Ni yields that cover the observed range of SNe Ia luminosity. We use our results to explain the shape and boundaries of the Branch plot distribution.
- [15] arXiv:1912.04314 [pdf, other]
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Title: The role of galaxies and AGN in reionising the IGM -- III : IGM-galaxy cross-correlations at z~6 from 8 quasar fields with DEIMOS and MUSEAuthors: Romain A. Meyer, Koki Kakiichi, Sarah E. I. Bosman, Richard S. Ellis, Nicolas Laporte, Brant E. Robertson, Emma V. Ryan-Weber, Ken Mawatari, Adi ZitrinComments: Submitted to MNRAS. 17 pages, 18 figures, 3 tables + appendices. Key results: Figs. 6,13,14Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present improved results of the measurement of the correlation between galaxies and the intergalactic medium (IGM) transmission at the end of reionisation. We have gathered a sample of $13$ spectroscopically confirmed Lyman-break galaxies (LBGs) and $21$ Lyman-$\alpha$ emitters (LAEs) at angular separations $20'' \lesssim \theta \lesssim 10'$ ($\sim 0.1-4$ pMpc at $z\sim 6$) from the sightlines to $8$ background $z\gtrsim 6$ quasars. We report for the first time the detection of an excess of Lyman-$\alpha$ transmission spikes at $\sim 10-60$ cMpc from LAEs ($3.6\sigma$) and LBGs ($3.1\sigma$). We interpret the data with an improved model of the galaxy-Lyman-$\alpha$ transmission and two-point cross-correlations which includes the enhanced photoionisation due to clustered faint sources, enhanced gas densities around the central bright objects and spatial variations of the mean free path. The observed LAE(LBG)-Lyman-$\alpha$ transmission spike two-point cross-correlation function (2PCCF) constrains the luminosity-averaged escape fraction of all galaxies contributing to reionisation to $\langle f_{\rm esc} \rangle_{M_{\rm UV}<-12} = 0.10_{-0.05}^{+0.17}\,(0.18_{-0.06}^{+0.52})$. We investigate if the 2PCCF measurement can determine whether bright or faint galaxies are the dominant contributors to reionisation. Our results show that a contribution from faint galaxies ($M_{\rm UV} > -20 \, (2\sigma)$) is necessary to reproduce the observed 2PCCF and that reionisation might be driven by different sub-populations around LBGs and LAEs at $z\sim 6$.
- [16] arXiv:1912.04325 [pdf, other]
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Title: A model independent comparison of supernova and strong lensing cosmography: implications for the Hubble constant tensionComments: 13 pages, 11 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
We use supernovae measurements, calibrated by the local determination of the Hubble constant $H_0$ by SH0ES, to interpolate the distance-redshift relation using Gaussian process regression. We then predict, independent of the cosmological model, the distances that are measured with strong lensing time delays. We find excellent agreement between these predictions and the measurements. The agreement holds when we consider only the redshift dependence of the distance-redshift relation, independent of the value of $H_0$. Our results disfavor the possibility that lens mass modeling contributes a 10\% bias or uncertainty in the strong lensing analysis, as suggested recently in the literature. In general our analysis strengthens the case that residual systematic errors in both measurements are below the level of the current discrepancy with the CMB determination of $H_0$, and supports the possibility of new physical phenomena on cosmological scales. With additional data our methodology can provide more stringent tests of unaccounted for systematics in the determinations of the distance-redshift relation in the late universe.
- [17] arXiv:1912.04336 [pdf, ps, other]
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Title: Spatially separated continuum sources revealed by microlensing in the gravitationally lensed broad absorption line quasar SDSSJ081830.46+060138.0Comments: Accepted for publication in Astronomy and AstrophysicsSubjects: Astrophysics of Galaxies (astro-ph.GA)
Gravitational microlensing is a powerful tool for probing the inner structure of distant quasars. In this context, we have obtained spectropolarimetric observations of the two images of the broad absorption line (BAL) quasar SDSSJ081830.46+060138.0 (J0818+0601) at redshift $z \simeq$ 2.35. We first show that J0818+0601 is actually gravitationally lensed, and not a binary quasar. A strong absorption system detected at $z$ = 1.0065$\pm$0.0002 is possibly due to the lensing galaxy. Microlensing is observed in one image and it magnifies the emission lines, the continuum, and the BALs differently. By disentangling the part of the spectrum that is microlensed from the part that is not microlensed, we unveil two sources of continuum that must be spatially separated: a compact one, which is microlensed, and an extended one, which is not microlensed and contributes to two thirds of the total continuum emission. J0818+0601 is the second BAL quasar in which an extended source of rest-frame ultraviolet continuum is found. We also find that the images are differently polarized, suggesting that the two continua might be differently polarized. Our analysis provides constraints on the BAL flow. In particular, we find that the outflow is seen with a nonzero onset velocity, and stratified according to ionization.
- [18] arXiv:1912.04349 [pdf, other]
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Title: Kinematics of filaments in cooling flow clusters and heating by mixingComments: Will be submitted in 2 days to allow comments by readersSubjects: Astrophysics of Galaxies (astro-ph.GA)
We compare a recent study of the kinematics of optical filaments in three cooling flow clusters of galaxies with previous numerical simulations of jet-inflated hot bubbles, and conclude that the velocity structure functions of the filaments better fit direct excitation by the jets than by turbulent cascade from the largest turbulent eddies. The observed velocity structure functions of the optical filaments in the three clusters are steeper than that expected from a classical cascade in turbulent dissipation. Our three-dimensional (3D) hydrodynamical simulations show that as the jets inflate bubbles in the intracluster medium (ICM), they form vortexes in a large range of scales. These vortexes might drive the ICM turbulence with eddies of over more than an order of magnitude in size. A direct excitation of turbulence by the vortexes that the jets form and the slow turbulent dissipation imply that heating the ICM by mixing with hot bubbles is more efficient than heating by turbulent dissipation.
- [19] arXiv:1912.04354 [pdf, other]
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Title: A Systematic Search for Reddest Far-infrared and Sub-millimeter Galaxies: revealing dust-embedded starbursts at high redshiftsComments: submitted to ApJSSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Experiment (hep-ex)
We present the results of our systematic search for the reddest far-infrared (FIR) and sub-millimeter (sub-mm) galaxies using the data from the Herschel Multi-tiered Extragalactic Survey (HerMES) and the SCUBA2 Cosmological Legacy Survey (S2CLS). The red FIR galaxies are "500 um risers", whose spectral energy distributions (SEDs) increase with wavelength across the three FIR passbands of the Spectral and Photometric Imaging REceiver (SPIRE) at Herschel. Within 106.5 sq.deg of the HerMES fields, we have selected 629 highly reliable 500 um risers. The red sub-mm galaxies are "SPIRE-dropouts", which are prominent detections in the S2CLS 850 um data but are extremely weak or invisible in the SPIRE bands. Within the 2.98 sq.deg common area of HerMES and S2CLS, we have selected 95 such objects. These very red sources could be dusty starbursts at high redshifts (z>6) because the peak of their cold-dust emission heated by star formation is shifted to the reddest FIR/sub-mm bands. The surface density of 500 um risers is ~8.2 per sq.deg at above 20 mJy level in 500 um, while that of SPIRE-dropouts is ~ 19.3 per sq.deg at above 5 mJy level in 850 um. Using deep radio data in these field, we find that the surface density of z>6 objects is 5.5 per sq.deg among 500 um risers and is 0.8--13.6 per sq.deg among SPIRE-dropouts. The dust-embedded star formation processes in such objects contribute comparably as Lyman-break galaxies to the global star formation rate density at $z>6$.
- [20] arXiv:1912.04355 [pdf, other]
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Title: Debris Disks in Multi-Planet Systems: Are Our Inferences Compromised by Unseen Planets?Comments: 24 pages, 20 figures, revised in response to referee reportSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Resolved debris disk features (e.g., warps, offsets, edges and gaps, azimuthal asymmetries, radially thickened rings, scale heights) contain valuable information about the underlying planetary systems, such as the posited planet's mass, semi-major axis, and other orbital parameters. Most existing models assume a single planet is sculpting the disk feature, but recent observations of mature planetary systems (e.g., by radial velocity surveys or \textit{Kepler}) have revealed that many planets reside in multi-planet systems. Here we investigate if/how planet properties inferred from single-planet models are compromised when multiple planets reside in the system. For each disk feature, we build a two-planet model that includes a planet b with fixed parameters and a planet c with a full range of possible parameters. We investigate these two-planet systems and summarize the configurations for which assuming a single planet (i.e., planet b) leads to significantly flawed inferences of that planet's properties. We find that although disk features are usually primarily dominated by a single planet, when using single-planet models we are at risk of misinterpreting planet properties by orders of magnitude in extreme cases. Specifically, we are at high risk of misinterpreting planet properties from disk warps; at moderate risk from disk edges and gaps, radially thickened rings, and scale height features; and at low risk from host star-disk center offsets and azimuthal asymmetries. We summarize situations where we can infer the need to use a multi-planet model instead of a single-planet one from disk morphology dissimilarities.
- [21] arXiv:1912.04361 [pdf, other]
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Title: Origin of Earth's water: sources and constraintsComments: Chapter to appear in Planetary Astrobiology (Editors: Victoria Meadows, Giada Arney, David Des Marais, and Britney Schmidt). 32 pages, 12 figures. Abstract shortened to fitSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); Geophysics (physics.geo-ph)
We review the state of knowledge on the origin of Earth's water. Empirical constraints come from chemical and isotopic measurements of solar system bodies and of Earth itself. Dynamical models have revealed pathways for water delivery to Earth during its formation; most are anchored to specific models for terrestrial planet formation. Meanwhile, disk chemical models focus on determining how the isotopic ratios of the building blocks of planets varied as a function of radial distance and time, defining markers of material transported along those pathways. Carbonaceous chondrite meteorites -- representative of the outer asteroid belt -- match Earth's water isotopes (although mantle plumes have been measured at lower D/H). But how was this connection established -- did Earth's water originate among the asteroids (as in the classical model of terrestrial planet formation)? Or, more likely, was Earth's water delivered from the same parent population as the hydrated asteroids (e.g., external pollution, as in the Grand Tack model)? We argue that the outer asteroid belt -- the boundary between the inner and outer solar system -- is the next frontier for new discoveries. The outer asteroid belt contains a population of icy bodies with volatile-driven activity seen on twelve main belt comets (MBCs); seven of which exhibit sublimation-driven activity on repeated perihelion passages. Measurements of the isotopic characteristics of MBCs would provide essential missing links in the chain between disk models and dynamical models. Finally, we extrapolate to rocky exoplanets. Migration is the only mechanism likely to produce very water-rich planets with more than a few percent water by mass (and even with migration, some planets are pure rock). While water loss mechanisms remain to be studied in more detail, we expect that water should be delivered to the vast majority of rocky exoplanets.
- [22] arXiv:1912.04371 [pdf, other]
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Title: Galaxy interactions in IllustrisTNG-100, I: The power and limitations of visual identificationAuthors: Kelly Blumenthal, Jorge Moreno, Joshua E. Barnes, Lars Hernquist, Paul Torrey, Zachary Claytor, Vicente Rodriguez-Gomez, Federico Marinacci, Mark VogelsbergerComments: 20 pages, 11 figures, thumbnail catalog of interacting pairs sampleSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present a sample of 446 galaxy pairs constructed using the cosmological simulation IllustrisTNG-100 at z = 0, with M$_{FoF, dm}$ = 10$^{11}$-10$^{13.5}$ M$_{\odot}$. We produce ideal mock SDSS g-band images of all pairs to test the reliability of visual classification schema employed to produce samples of interacting galaxies. We visually classify each image as interacting or not based on the presence of a close neighbour, the presence of stellar debris fields, disturbed discs, and/or tidal features. By inspecting the trajectories of the pairs, we determine that these indicators correctly identify interacting galaxies $\sim45\%$ of the time. We subsequently split the sample into the visually identified interacting pairs (VIP; 38 pairs) and those which are interacting but are not visually identified (nonVIP; 47 pairs). We find that VIP have undergone a close passage nearly twice as recently as the nonVIP, and typically have higher stellar masses. Further, the VIP sit in dark matter haloes that are approximately 2.5 times as massive, in environments nearly 2 times as dense, and are almost a factor of 10 more affected by the tidal forces of their surroundings than the nonVIP. These factors conspire to increase the observability of tidal features and disturbed morphologies, making the VIP more likely to be identified. Thus, merger rate calculations which rely on stellar morphologies are likely to be significantly biased toward massive galaxy pairs which have recently undergone a close passage.
- [23] arXiv:1912.04372 [pdf, other]
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Title: On Post-Starburst Galaxies Dominating Tidal Disruption EventsAuthors: Renyue Cen (Princeton)Comments: 21 pages, 4 figures, to appear in ApJ LettersSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
A starburst induced by a galaxy merger may create a relatively thin central stellar disk at radius $\le 100$pc. We calculate the rate of tidal disruption events (TDEs) by the inspiraling secondary supermassive black (SMBH) through the disk. With a small enough stellar velocity dispersion ($\sigma/v_c \le 0.1$) in the disk, it is shown that $10^5-10^6$ TDEs of solar-type main sequence stars per post-starburst galaxy (PSB) can be produced to explain their dominance in producing observed TDEs. Although the time it takes to bring the secondary SMBH to the disk apparently varies in the range of $\sim 0.1-1$Gyr since the starburst, depending on its landing location and subsequently due to dynamical friction with stars exterior to the central stellar disk in question, the vast majority of TDEs by the secondary SMBH in any individual PSB occurs within a space of time shorter than $\sim 30$Myr. Five unique testable predictions of this model are suggested.
- [24] arXiv:1912.04386 [pdf, other]
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Title: Carbon and Oxygen Isotopic Ratios. II. Semiregular Variable M GiantsAuthors: Thomas Lebzelter, Kenneth H. Hinkle, Oscar Straniero, David L. Lambert, Catherine A. Pilachowski, Kristie A. NaultJournal-ref: Astrophysical Journal, 2019, 886, 117Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Carbon and oxygen isotopic ratios are reported for a sample of 51 SRb- and Lb-type variable asymptotic giant branch stars. Vibration-rotation first- and second-overtone CO lines in 1.5-2.5 mum spectra were measured to derive isotopic ratios for 12C/13C, 16O/17O, and 16O/18O. Comparisons with previous measurements for individual stars and with various samples of evolved stars, as available in the extant literature, are discussed. Using the oxygen isotopic ratios, the masses of the SRb stars can be derived. Combining the masses with Gaia luminosities, the SRb stars are shown to be antecedents of the Mira variables. The limiting parameters where plane-parallel, hydrostatic equilibrium model atmospheres can be used for abundance analysis of M giants are explored.
- [25] arXiv:1912.04389 [pdf, other]
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Title: The Influence of Stellar Contamination on the Interpretation of Near Infrared Transmission Spectra of Sub-Neptune Worlds around M-DwarfsComments: Resubmitted after 2nd round of minor revisions, 12/06/2019Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
The impact of unocculted stellar surface heterogeneities in the form of cool spots and hot faculae on the spectrum of a transiting planet has been a daunting problem for the characterization of exoplanet atmospheres. The wavelength-dependent nature of stellar surface heterogeneities imprinting their signatures on planetary transmission spectra are of concern particularly for systems of sub-Neptunes orbiting M-dwarfs. Here we present a systematic exploration of the impact of this spot-contamination on simulated near infrared transmission spectra of sub-Neptune planets. From our analysis, we find that improper correction of stellar surface heterogeneities on transmission spectra can lead to significant bias when inferring planetary atmospheric properties. However, this bias is negligible for lower fractions of heterogeneities (<1%). Additionally, we find that acquiring a priori knowledge of stellar heterogeneities does not improve precision in constraining planetary parameters if the heterogeneities are appropriately marginalized within a retrieval---however these are conditional on our confidence of stellar atmospheric models being accurate representations of the true photosphere. In sum, to acquire unbiased constraints when characterizing planetary atmospheres with the James Webb Space Telescope, we recommend performing joint retrievals of both the disk-integrated spectrum of the star and the stellar contamination corrected transmission spectrum.
- [26] arXiv:1912.04410 [pdf, other]
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Title: Ionization correction factors for sodium, potassium, and calcium in planetary nebulaeComments: 18 pages, 14 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
We use a large grid of photoionization models that are representative of observed planetary nebulae (PNe) to derive ionization correction factors (ICFs) for sodium, potassium, and calcium. In addition to the analytical expressions of the ICFs, we provide the range of validity where the ICFs can be safely used and an estimate of the typical uncertainties associated with the ICFs. We improved the previous ICFs for calcium and potassium in the literature and suggest for the first time an ICF for sodium. We tested our ICFs with a sample of 39 PNe with emission lines of some ion of these elements. No obvious trend is found between the derived abundances and the degree of ionization, suggesting that our ICFs do not seem to be introducing an artificial bias in the results. The abundances found in the studied PNe range from -2.88$^{+0.21}_{-0.22}$ to -2.09$\pm$0.21 in log(Na/O), from -4.20$^{+0.31}_{-0.45}$ to -3.05$^{+0.26}_{-0.47}$ in log(K/O), and from -3.71$^{+0.41}_{-0.34}$ to -1.57$^{+0.33}_{-0.47}$ in log(Ca/O). These numbers imply that some of the studied PNe have up to 65, 75, or 95 per cent of their Na, K, and/or Ca atoms condensed into dust grains, respectively. As expected, the highest depletions are found for calcium which is the element with the highest condensation temperature.
- [27] arXiv:1912.04412 [pdf, other]
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Title: Probabilistic cosmic web classification using fast-generated training dataComments: 22 pages, 16 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
We present a novel method of robust probabilistic cosmic web particle classification in three dimensions using a supervised machine learning algorithm. Training data was generated using a simplified $\Lambda$CDM toy model with pre-determined algorithms for generating halos, filaments, and voids. While this model lacks physical detail, it can be generated substantially more quickly than an N-body simulation without loss in classification accuracy. For each particle in this dataset, measurements were taken of the local density field and directionality. These measurements were used to train a random forest algorithm with, which was used to assign class probabilities to each particle in a $\Lambda$CDM, dark matter-only N-body simulation with $256^3$ particles, as well as on another toy model data set. By comparing the trends in the ROC curves and other statistical metrics of predictions made on each of the datasets using different feature sets, we demonstrate that the combination of measurements of the local density field magnitude and directionality enables accurate and consistent classification of halo, filament, and void particles in varied environments. We also show that this combination of training features ensures that the construction of our toy model does not affect classification. The use of a fully supervised algorithm allows greater control over the information deemed important for classification, preventing issues arising from hyperparameters and mode collapse in deep learning models. Due to the speed of training data generation, our method is highly scalable, making it particularly suited for classifying large datasets, including observed data.
- [28] arXiv:1912.04414 [pdf, other]
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Title: CCCP and MENeaCS: (updated) weak-lensing masses for 100 galaxy clustersAuthors: Ricardo Herbonnet, Cristóbal Sifón, Henk Hoekstra, Yannick Bahé, Remco F. J. van der Burg, Jean-Baptiste Melin, Anja von der Linden, David Sand, Scott Kay, David BarnesComments: 20 pages, 9 figures, 4 tables, submitted to MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Large area surveys have detected significant samples of galaxy clusters that can be used to constrain cosmological parameters, provided that the masses of the clusters are measured robustly. To improve the calibration of cluster masses using weak gravitational lensing we present new results for 48 clusters at $0.05<z<0.15$, observed as part of the Multi Epoch Nearby Cluster Survey (MENeaCS), and reevaluate the mass estimates for 52 clusters from the Canadian Cluster Comparison Project (CCCP). Updated high-fidelity photometric redshift catalogues of reference deep fields are used in combination with advances in shape measurements and state-of-the-art cluster simulations, yielding an average systematic uncertainty in the lensing signal below 5%, similar to the statistical uncertainty for our cluster sample. We derive a scaling relation with Planck measurements for the full sample and find a bias in the Planck masses of $1-b=0.84 \pm 0.04$. We find no statistically significant trend of the mass bias with redshift or cluster mass, but find that different selections could change the bias by up to 1.5$\sigma$. We find a gas fraction of $0.139 \pm 0.014$ for 8 relaxed clusters in our sample, which can also be used to infer cosmological parameters.
- [29] arXiv:1912.04431 [pdf, other]
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Title: Swift monitoring of M51: A 38-day super-orbital period for the pulsar ULX7 and a new transient ULXAuthors: Murray Brightman, Hannah Earnshaw, Felix Fürst, Fiona A. Harrison, Marianne Heida, Gianluca Israel, Sean Pike, Daniel Stern, Dominic J. WaltonComments: Submitted to ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present the results from a monitoring campaign made with the Neil Gehrels Swift Observatory of the M51 galaxies, which contain several variable ultraluminous X-ray sources (ULXs). The ongoing campaign started in May 2018, and we report here on $\sim1.5$ years of observations. The campaign, which consists of 105 observations, has a typical cadence of 3--6 days, and has the goal of determining the long-term X-ray variability of the ULXs. Two of the most variable sources were ULX7 and ULX8, both of which are known to be powered by neutron stars that are exceeding their isotropic Eddington luminosities by factors of up to 100. This is further evidence that neutron star powered ULXs are the most variable. Our two main results are, first, that ULX7 exhibits a periodic flux modulation with a period of 38 days varying over a magnitude and a half in flux from peak to trough. Since the orbital period of the system is known to be 2 days, the modulation is super-orbital, which is a near-ubiquitous property of ULX pulsars. Secondly we identify a new transient ULX, M51 XT-1, the onset of which occurred during our campaign, reaching a peak luminosity of $\sim10^{40}$ erg s$^{-1}$, before gradually fading over the next $\sim200$ days until it slipped below the detection limit of our observations. Combined with the high-quality Swift/XRT lightcurve of the transient, serendipitous observations made with Chandra and XMM-Newton provide insights into the onset and evolution of a likely super-Eddington event.
- [30] arXiv:1912.04474 [pdf, other]
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Title: Dependence of Gravitational Wave Transient Rates on Cosmic Star Formation and Metallicity Evolution HistoryComments: Accepted by MNRAS, 5 pages, 2 figures, 2 tablesSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
We compare the impacts of uncertainties in both binary population synthesis models and the cosmic star formation history on the predicted rates of Gravitational Wave compact binary merger (GW) events. These uncertainties cause the predicted rates of GW events to vary by up to an order of magnitude. Varying the volume-averaged star formation rate density history of the Universe causes the weakest change to our predictions, while varying the metallicity evolution has the strongest effect. Double neutron-star merger rates are more sensitive to assumed neutron-star kick velocity than the cosmic star formation history. Varying certain parameters affects merger rates in different ways depending on the mass of the merging compact objects; thus some of the degeneracy may be broken by looking at all the event rates rather than restricting ourselves to one class of mergers.
- [31] arXiv:1912.04509 [pdf, ps, other]
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Title: Formation rate of LB-1-like systems through dynamical interactionsComments: 9 pages, 1 figureSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We estimate formation rates of LB-1-like systems through dynamical interactions in the framework of the theory of stellar evolution before the discovery of the LB-1 system. The LB-1 system contains $\sim 70M_\odot$ black hole (BH), so-called pair instability (PI)-gap BH, and B-type star with solar metallicity, and has nearly zero eccentricity. The most efficient formation mechanism is as follows. In an open cluster, a naked helium (He) star (with $\sim 20M_\odot$) collides with a heavy main-sequence (MS) star (with $\sim 50M_\odot$) which has a B-type companion. The collision results in a binary consisting of the collision product and B-type star with a high eccentricity. The binary can be circularized through the dynamical tide with radiative damping of the collision-product envelope. Finally, the collision product collapses to a PI-gap BH, avoiding pulsational pair instability and pair instability supernovae because its He core is as massive as the pre-colliding naked He star. We find that the number of LB-1-like systems in the Milky Way galaxy is $\sim 0.1 (\rho_{\rm oc} / 10^4 M_\odot \mbox{pc}^{-3})$, where $\rho_{\rm oc}$ is the initial mass densities of open clusters. If we take into account LB-1-like systems with O-type companion stars, the number increases to $\sim 0.3 (\rho_{\rm oc} / 10^4 M_\odot \mbox{pc}^{-3})$. This mechanism can form LB-1-like systems at least 100 times more efficiently than the other mechanisms: captures of B-type stars by PI-gap BHs, stellar collisions between other type stars, and stellar mergers in hierarchical triple systems.
- [32] arXiv:1912.04510 [pdf, other]
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Title: PopSyCLE: A New Population Synthesis Code for Compact Object Microlensing EventsAuthors: Casey Y. Lam (UC Berkeley), Jessica R. Lu (UC Berkeley), Matthew W. Hosek, Jr. (UCLA), William A. Dawson (LLNL), Nathan R. Golovich (LLNL)Comments: 33 pages, 22 figures, accepted to ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
We present a new Milky Way microlensing simulation code, dubbed PopSyCLE (Population Synthesis for Compact object Lensing Events). PopSyCLE is the first resolved microlensing simulation to include a compact object distribution derived from numerical supernovae explosion models and both astrometric and photometric microlensing effects. We demonstrate the capabilities of PopSyCLE by investigating the optimal way to find black holes (BHs) with microlensing. Candidate BHs have typically been selected from wide-field photometric microlensing surveys, such as OGLE, by selecting events with long Einstein crossing times ($t_E>120$ days). These events can be selected at closest approach and monitored astrometrically in order to constrain the mass of each lens; PopSyCLE predicts a BH detection rate of ~40% for such a program. We find that the detection rate can be enhanced to ~85% by selecting events with both $t_E>120$ days and a microlensing parallax of $\pi_E<0.08$. Unfortunately, such a selection criterion cannot be applied during the event as $\pi_E$ requires both pre- and post-peak photometry. However, historical microlensing events from photometric surveys can be revisited using this new selection criteria in order to statistically constrain the abundance of BHs in the Milky Way. The future WFIRST microlensing survey provides both precise photometry and astrometry and will yield individual masses of $\mathcal{O}(100-1000) black holes, which is at least an order of magnitude more than is possible with individual candidate follow-up with current facilities. The resulting sample of BH masses from WFIRST will begin to constrain the shape of the black hole present-day mass function, BH multiplicity, and BH kick velocity distributions.
- [33] arXiv:1912.04522 [pdf, other]
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Title: The Impact of Merging on The Origin of Kinematically Misaligned and Counter-rotating Galaxies in MaNGAAuthors: Song-lin Li, Yong Shi, Dmitry Bizyaev, Christopher Duckworth, Ren-bin Yan, Yan-mei Chen, Long-ji Bing, Jian-hang Chen, Xiao-ling Yu, Rogemar A. RiffelComments: 11 pages, 5 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
Galaxy mergers and interactions are expected to play a significant role leading to offsets between gas and stellar motions in galaxies. Herein we crossmatch galaxies in MaNGA MPL-8 with the Dark Energy Spectroscopic Instrument (DESI) Legacy Surveys and identify 538 galaxies with merging/interacting features to investigate their position angle offsets ($\Delta$PA) between gas and stellar rotation. We find that there is a much higher merging/interacting fraction in misaligned galaxies (30$^\circ$ $\leqslant$ $\Delta$PA $<$150$^\circ$) than that in co-rotators ($\Delta$PA $<$ 30$^\circ$). This result corroborates that merging/interacting is one of the sources to produce misaligned galaxies and recent merging events can contribute to maximum 40\% of such misalignment. Furthermore, the marginal merging/interacting fraction in star-forming (SF) counter-rotators ($\Delta$PA $\geqslant$ 150$^\circ$) indicates the minor role of merging in the origin of SF counter-rotators. In addition, the slightly smaller merging/interacting fraction in non star-forming (non-SF) counter-rotators (0.14$\pm$0.039) than that in non-SF misaligned galaxies (0.22$\pm$0.031) agrees with that counter-rotating is a stable state, where tidal features disappear. Finally, the ratio of co-rotators to counter-rotators in non-SF merging/interacting galaxies is about 8:1, much larger than the prediction from the isotropic merging (1:1), which supports the speculation that gas and stars prefer to be aligned during merging, as the orbital angular momentum transfers to gas and stellar spin.
- [34] arXiv:1912.04525 [pdf, other]
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Title: A radio parallax to the black hole X-ray binary MAXI J1820+070Authors: P. Atri, J. C. A. Miller-Jones, A. Bahramian, R. M. Plotkin, A. T. Deller, P. G. Jonker, T. J. Maccarone, G. R. Sivakoff, R. Soria, D. Altamirano, T. Belloni, R. Fender, E. Koerding, D. Maitra, S. Markoff, S. Migliari, D. Russell, T. Russell, C. L. Sarazin, A. J. Tetarenko, V. TudoseComments: 5 pages, 3 figures, Submitted in MNRAS, Comments welcomeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Using the Very Long Baseline Array and the European Very Long Baseline Interferometry Network we have made a precise measurement of the radio parallax of the black hole X-ray binary MAXI\,J1820+070, providing a model-independent distance to the source. Our parallax measurement of $0.348\pm0.033$ mas for MAXI\,J1820+070 translates to a distance of $2.96\pm0.33$ kpc. This distance implies that the source reached $15\pm3\%$ of the Eddington luminosity at the peak of its outburst. Further, we use this distance to refine previous estimates of the jet inclination angle, jet velocity and the mass of the black hole in MAXI J1820+070 to be $62\pm3^{\circ}$, $0.88\pm0.09c$ and $9.5\pm1.4 M_{\odot}$, respectively
- [35] arXiv:1912.04541 [pdf, ps, other]
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Title: Unravelling the unusually curved X-ray spectrum of RGB J0710+591 using AstroSat observationsAuthors: Pranjupriya Goswami, Atreyee Sinha, Sunil Chandra, Ranjeev Misra, Varsha Chitnis, Rupjyoti Gogoi, Sunder Sahayanathan, C.S. Stalin, K.P. Singh, J.S. YadavComments: 9 pages, 3 figures. Accepted for publication in MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We report the analysis of simultaneous multi-wavelength data of the high energy peaked blazar RGB J0710+591 from the LAXPC, SXT and UVIT instruments on-board AstroSat. The wide band X-ray spectrum (0.35 -- 30 keV) is modelled as synchrotron emission from a non-thermal distribution of high energy electrons. The spectrum is unusually curved, with a curvature parameter $\beta_p \sim 6.4$ for a log parabola particle distribution, or a high energy spectral index $p_2 > 4.5$ for a broken power-law distribution. The spectrum shows more curvature than an earlier quasi-simultaneous analysis of Swift-XRT/NuSTAR data where the parameters were $\beta_p \sim 2.2$ or $p_2 \sim 4$. It has long been known that a power-law electron distribution can be produced from a region where particles are accelerated under Fermi process and the radiative losses in acceleration site decide the maximum attainable Lorentz factor, $\gamma_{max}$. Consequently, this quantity decides the energy at which the spectrum curves steeply. We show that such a distribution provides a more natural explanation for the AstroSat data as well as the earlier XRT/NuSTAR observation, making this as the first well constrained determination of the photon energy corresponding to $\gamma_{max}$. This in turn provides an estimate of the acceleration time-scale as a function of magnetic field and Doppler factor. The UVIT observations are consistent with earlier optical/UV measurements and reconfirm that they plausibly correspond to a different radiative component than the one responsible for the X-ray emission.
- [36] arXiv:1912.04560 [pdf, other]
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Title: Model-Independent Determination of the Cosmic Growth FactorAuthors: Sophia Haude (1), Shabnam Salehi (1), Sofía Vidal (1), Matteo Maturi (1), Matthias Bartelmann (2) ((1) Theoretical Astrophysics, ZAH, Heidelberg University, (2) Theoretical Physics, Heidelberg University)Comments: 21 pages, 5 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Since the discovery of the accelerated cosmic expansion, one of the most important tasks in observational cosmology is to determine the nature of the dark energy. We should build our understanding on a minimum of assumptions in order to avoid biases from assumed cosmological models. The two most important functions describing the evolution of the universe and its structures are the expansion function E(a) and the linear growth factor D_+(a). The expansion function has been determined in previous papers in a model-independent way using distance moduli to type-Ia supernovae and assuming only a metric theory of gravity, spatial isotropy and homogeneity. Here, we extend this analysis in three ways: (1) We extend the data sample by combining the Pantheon measurements of type-Ia supernovae with measurements of baryonic acoustic oscillations; (2) we substantially simplify and generalise our method for reconstructing the expansion function; and (3) we use the reconstructed expansion function to determine the linear growth factor of cosmic structures, equally independent of specific assumptions on an underlying cosmological model other than the usual spatial symmetries. We show that the result is quite insensitive to the initial conditions for solving the growth equation, leaving the present-day matter-density parameter {\Omega}_m0 as the only relevant parameter for an otherwise purely empirical and accurate determination of the growth factor.
- [37] arXiv:1912.04585 [pdf, other]
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Title: Limits on Kaluza-Klein dark matter annihilation in the Sun from recent IceCube resultsSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex)
We interpret recent IceCube results on searches for dark matter accumulated in the sun in terms of the lightest Kaluza-Klein excitation (assumed here to be the Kaluza-Klein photon, $B^1$), obtaining improved limits on the annihilation rate in the Sun, the resulting neutrino flux at the Earth and on the $B^1$-proton cross-sections, for $B^1$ masses in the range 30--3000 GeV. These results improve previous results from IceCube in its 22-string configuration by up to an order of magnitude, depending on mass, but also extend the results to $B^1$ masses as low as 30 GeV.
- [38] arXiv:1912.04589 [pdf, other]
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Title: A study of the blue straggler population of the old open cluster Collinder 261Comments: Accepted for publication in the Astronomical Journal (16 pages, 8 figures)Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Blue Stragglers are stars located in an unexpected region of the color-magnitude diagram of a stellar population, as they appear bluer and more luminous than the stars in the turnoff region. They are ubiquitous, since they have been found among Milky Way field stars, in open and globular clusters, and also in other galaxies of the Local Group. Here we present a study on the blue straggler population of the old and metal-rich open cluster Collinder 261, based on Gaia DR2 data and on a multi-epoch radial velocity survey conducted with FLAMES@VLT. We also analyze the radial distribution of the blue straggler population to probe the dynamical status of the cluster. Blue straggler candidates were identified first with Gaia DR2, according to their position on the CMD, proper motions, and parallaxes. Their radial distribution was compared with those of the main sequence, red giant, and red clump stars, to evaluate mass segregation. Additionally, their radial velocities (and the associated uncertainties) were compared with the mean radial velocity and the velocity dispersion of the cluster. When possible, close binaries and long-period binaries were also identified, based on the radial velocity variations for the different epochs. We also looked for yellow stragglers, i.e., possible evolved blue stragglers. We found 53 blue stragglers members of Collinder 261, six of them already identified in previous catalogs. Among the blue straggler candidates with radial velocity measurements, we found one long-period binary, five close-binary systems, three non-variable stars; we also identified one yellow straggler.
- [39] arXiv:1912.04593 [pdf, ps, other]
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Title: Resonances in the Earth's Space EnvironmentComments: 38 pages, 9 figures, submitted to Communications in Nonlinear Science and Numerical SimulationSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Dynamical Systems (math.DS); Space Physics (physics.space-ph)
We study the presence of resonances in the region of space around the Earth. We consider a massless body (e.g, a dust particle or a small space debris) subject to different forces: the gravitational attraction of the geopotential, the effects of Sun and Moon. We distinguish different types of resonances: tesseral resonances are due to a commensurability involving the revolution of the particle and the rotation of the Earth, semi-secular resonances include the rates of variation of the mean anomalies of Moon and Sun, while secular resonances just depend on the rates of variation of the arguments of perigee and the longitudes of the ascending nodes of the perturbing bodies. We characterize such resonances, giving precise statements on the regions where the resonances can be found and provide examples of some specific commensurability relations.
- [40] arXiv:1912.04602 [pdf, ps, other]
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Title: How far can we trust published TESS periods?Comments: 6 pages, 4 figures, will be published in Contrib. Astron. Obs. Skalnate Pleso, 2020Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Possible inaccuracies in the determination of periods from short-term time series caused by disregard of the real course of light curves and instrumental trends are documented on the example of the period analysis of simulated TESS-like light curve by notorious Lomb-Scargle method.
- [41] arXiv:1912.04615 [pdf, other]
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Title: The Athena space X-ray Observatory and the astrophysics of hot plasmaAuthors: Didier Barret (IRAP), Anne Decourchelle (CEA), Andy Fabian (IOA), Matteo Guainazzi (ESA), Kirpal Nandra (MPE), Randall Smith (SAO), Jan-Willem den Herder (SRON)Comments: 12 pages, 9 figures, Proceedings of the XMM-Newton 2019 science workshop "Astrophysics of hot plasma in extended X -ray sources", accepted for publication in Astronomische NachrichtenSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
The properties (temperature, density, chemical composition, velocity) of hot astrophysical plasma and the physical processes affecting them (heating/cooling, turbulence, shocks, acceleration) can be probed by high resolution X-ray spectroscopy, to be complemented by high spatial resolution imaging. The paper presents a status of the ESA's Advanced Telescope for High Energy Astrophysics (Athena) mission, particularly focusing on the science performance of its two focal plane instruments for the studies of extended X-ray sources: the Wide Field Imager (WFI) and the X-ray Integral Field Unit (X-IFU). This paper then provides a brief summary of the breakthroughs expected with Athena on the astrophysics of hot plasma, building on the vast heritage of the discoveries and revolutionary results obtained by Chandra and XMM-Newton in this field. As of November 12th, 2019, Athena successfully concluded its feasibility study, and has since then moved into the definition phase, with a launch date scheduled in the early 2030s.
- [42] arXiv:1912.04651 [pdf, other]
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Title: Peering into the formation history of beta Pictoris b with VLTI/GRAVITY long baseline interferometryAuthors: GRAVITY Collaboration, M. Nowak, S. Lacour, P. Mollière, J. Wang, B. Charnay, E.F. van Dishoeck, R. Abuter, A. Amorim, J.P. Berger, H. Beust, M. Bonnefoy, H. Bonnet, W. Brandner, A. Buron, F. Cantalloube, C. Collin, F. Chapron, Y. Clenet, V. Coude du Foresto, P.T. de Zeeuw, R. Dembet, J. Dexter, G. Duvert, A. Eckart, F. Eisenhauer, N.M. Forster Schreiber, P. Fédou, R. Garcia Lopez, F. Gao, E. Gendron, R. Genzel, S. Gillessen, F. Haußmann, T. Henning, S. Hippler, Z. Hubert, L. Jocou, P. Kervella, A.-M. Lagrange, V. Lapeyrere, J.-B. Le Bouquin, P. Lena, A.-L. Maire, T. Ott, T. Paumard, C. Paladini, K. Perraut, G. Perrin, L. Pueyo, O. Pfuhl, S. Rabien, C. Rau, G. Rodriguez-Coira, G. Rousset, S. Scheithauer, J. Shangguan, O. Straub, C. Straubmeier, E. Sturm, L.J. Tacconi, F. Vincent, et al. (6 additional authors not shown)Comments: 14 pages + 7 page appendix, 7 figures, accepted for pulicationSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Our objective is to estimate the C/O ratio in the atmosphere of beta Pictoris b and obtain an estimate of the dynamical mass of the planet, as well as to refine its orbital parameters using high-precision astrometry. We used the GRAVITY instrument with the four 8.2 m telescopes of the Very Large Telescope Interferometer to obtain K-band spectro-interferometric data on $\beta$ Pic b. We extracted a medium resolution (R=500) K-band spectrum of the planet and a high-precision astrometric position. We estimated the planetary C/O ratio using two different approaches (forward modeling and free retrieval) from two different codes (ExoREM and petitRADTRANS, respectively). Finally, we used a simplified model of two formation scenarios (gravitational collapse and core-accretion) to determine which can best explain the measured C/O ratio. Our new astrometry disfavors a circular orbit for $\beta$ Pic b ($e=0.15^{+0.05}_{-0.04}$). Combined with previous results and with Hipparcos/GAIA measurements, this astrometry points to a planet mass of $M = 12.7\pm{}2.2\,M_\mathrm{Jup}$. This value is compatible with the mass derived with the free-retrieval code petitRADTRANS using spectral data only. The forward modeling and free-retrieval approches yield very similar results regarding the atmosphere of beta Pic b. In particular, the C/O ratios derived with the two codes are identical ($0.43\pm{}0.05$ vs $0.43^{+0.04}_{-0.03}$). We argue that if the stellar C/O in $\beta$ Pic is Solar, then this combination of a very high mass and a low C/O ratio for the planet suggests a formation through core-accretion, with strong planetesimal enrichment.
- [43] arXiv:1912.04657 [pdf, other]
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Title: A SkyMapper view of the Large Magellanic Cloud: The dynamics of stellar populationsComments: 14 pages, 12 figures. Accepted by MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present the first SkyMapper stellar population analysis of the Large Magellanic Cloud (hereafter LMC),including the identification of 3578 candidate Carbon Stars through their extremely red $g-r$ colours. Coupled with Gaia astrometry, we analyse the distribution and kinematics of this Carbon Star population, finding the LMC to be centred at $(R.A., Dec.) = (80.90^{\circ}\pm{0.29}, -68.74^{\circ}\pm{0.12})$, with a bulk proper motion of $(\mu_{\alpha},\mu_{\delta}) = (1.878\pm0.007,0.293\pm0.018) \mathrm{mas\ yr^{-1}}$ and a disk inclination of $i = 25.6^{\circ}\pm1.1$ at position angle $\theta = 135.6^{\circ}\pm 3.3^{\circ}$. We complement this study with the identification and analysis of additional stellar populations, finding that the dynamical centre for Red Giant Branch (RGB) stars is similar to that seen for the Carbon Stars, whereas for young stars the dynamical centre is significantly offset from the older populations. This potentially indicates that the young stars were formed as a consequence of a strong tidal interaction, probably with the Small Magellanic Cloud (SMC). In terms of internal dynamics, the tangential velocity profile increases linearly within $\sim3\ \mathrm{kpc}$, after which it maintains an approximately constant value of $V_{rot} = 83.6\pm 1.7 \mathrm{km\ s^{-1}}$ until $\sim7 \mathrm{kpc}$. With an asymmetric drift correction, we estimate the mass within $7 \mathrm{kpc}$ to be $M_{\rm LMC}(<7\mathrm{kpc}) = (2.5\pm0.1)\times10^{10}\ \mathrm{M}_{\odot}$ and within the tidal radius ($\sim 30\ \mathrm{kpc}$) to be $M_{\rm LMC}(<30\mathrm{kpc}) = (1.06 \pm 0.32)\times10^{11}\ \mathrm{M}_{\odot}$, consistent with other recent measurements.
- [44] arXiv:1912.04662 [pdf, other]
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Title: A companion star launching jets in the wind acceleration zone of a giant starComments: Will be submitted in 2 days to allow comments by readersSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
By conducting three-dimensional (3D) hydrodynamical simulations we find that jets that a main sequence companion launches as it orbits inside the wind acceleration zone of an asymptotic giant branch (AGB) star can efficiently remove mass from that zone. We assume that during the intensive wind phase a large fraction of the gas in the acceleration zone does not reach the escape velocity. Therefore, in the numerical simulations we blow the wind with a velocity just below the escape velocity. We assume that a main sequence companion accretes mass from the slow wind via an accretion disk, and launches two opposite jets perpendicular to the equatorial plane. This novel flow interaction shows that by launching jets a companion outside a giant star, but close enough to be in the acceleration zone of a slow intensive wind, can enhance the mass loss rate from the giant by ejecting some gas that would otherwise fall back onto the giant star. The jets are bent inside the wind acceleration zone and eject mass in a belt on the two sides of the equatorial plane. The jet-wind interaction contains instabilities that mix shocked jets' gas with the wind, leading to energy transfer from the jets to the wind. As well, our new simulations add to the rich variety of jet-induced outflow morphologies from evolved stars.
- [45] arXiv:1912.04676 [pdf, other]
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Title: Three dimensional structure of mean motion resonances beyond NeptuneAuthors: Tabare GallardoComments: 29 pages, 26 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
We propose a semianalytical method for the calculation of widths, libration centers and small amplitude libration periods of the mean motion resonances k_p:k in the framework of the circular restricted three body problem valid for arbitrary eccentricities and inclinations. Applying the model to the trans Neptunian region (TNR) we obtain several atlas of resonances between 30 and 100 au showing their domain in the plane (a,e) for different orbital inclinations. The resonance width may change substantially when varying the argument of the perihelion of the resonant object and in order to take into account these variations we introduce the concept of resonance fragility. Resonances 1:k and 2:k are the widest, strongest, most isolated ones and with lower fragility for all interval of inclinations and eccentricities. We discuss about the existence of high k_p:k resonances. We analyze the distribution of the resonant populations inside resonances 1:1, 2:3, 3:5, 4:7, 1:2 and 2:5. We found that the populations are in general located near the regions of the space (e,i) where the resonances are wider and less fragile with the notable exception of the population inside the resonance 4:7 and in a lesser extent the population inside 3:5 which are shifted to lower eccentricities.
- [46] arXiv:1912.04682 [pdf, other]
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Title: Improved model-independent constraints on the recombination era and development of a direct projection methodComments: 17 pages, 20 figures, 7 tables; submitted to MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The precision of recent experiments such as ${\it Planck}$ have allowed us to constrain standard and non-standard physics (e.g., due to dark matter annihilation or varying fundamental constants) during the recombination epoch. However, we can also probe this era of cosmic history using model-independent variations of the free electron fraction, $X_{\rm e}$, which in turn affects the temperature and polarization anisotropies of the cosmic microwave background. In this paper, we improve on the previous efforts to construct and constrain these generalised perturbations in the ionization history, deriving new optimized eigenmodes based on the full Planck 2015 likelihood data, introducing the new module 'FEARec++'. We develop a direct likelihood sampling method for attaining the numerical derivatives of the standard and non-standard parameters, and discuss complications arising from the stability of the likelihood code. We improve the amplitude constraints of the ${\it Planck}$ 2015 principal components constructed here, $\mu_1=-0.09\pm0.12$, $\mu_2=-0.17\pm0.20$ and $\mu_3=-0.30\pm0.35$, finding no indication for departures from the standard recombination scenario. The third mode error is reduced by $60\%$. We utilise an efficient eigen-analyser that keeps the cross-correlations of the first three eigenmodes to $\xi_{\mu,\mu'}<0.1\%$ after marginalisation for all the considered data combinations. We also propose a new projection method for estimating constraints on the parameters of non-standard recombination. Using our eigenmodes, this allows us to recreate the ${\it Planck}$ constraint on the two-photon decay rate, $A_{\rm 2s1s}=7.60\pm0.64$, giving an estimate to within $\simeq 0.05\sigma$ of the full MCMC result. The improvements on the analysis using the ${\it Planck}$ data will allow us to implement this new method for analysis with fundamental constant variations in the future.
- [47] arXiv:1912.04687 [pdf, other]
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Title: A novel formulation of the PBH mass functionComments: 11 pages, 1 figureSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
Computations of the primordial black hole (PBH) mass function discussed in the literature have conceptual issues. They stem from that the mass function is a differential quantity and the standard criterion of the PBH formation from the seed primordial fluctuations cannot be directly applied to the computation of the differential quantities. We propose a new criterion of the PBH formation which is an addition of one extra condition to the existing one. By doing this, we derive a formal expression of the PBH mass function without introducing any ambiguous interpretations which exist in the previous studies. Once the underlying primordial fluctuations are specified, the PBH mass function can be in principle determined by the new formula. As a demonstration of our formulation, we compute the PBH mass function analytically for the case where the perturbations are Gaussian and the space is one dimension.
- [48] arXiv:1912.04717 [pdf, other]
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Title: Feeding of active galactic nuclei by dynamical perturbationsComments: 13 pages, 14 figures, accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
There possibly was an AGN episode in the Galactic Centre about 6 Myr ago, powerful enough to produce the Fermi bubbles. We present numerical simulations of a possible scenario giving rise to an activity episode: a collision between a central gas ring surrounding the supermassive black hole (SMBH) and an infalling molecular cloud. We investigate different initial collision angles between the cloud and the ring. We follow the hydrodynamical evolution of the system following the collision using Gadget-3 hybrid N-body/SPH code and calculate the feeding rate of the SMBH accretion disc. This rate is then used as an input for a 1D thin $\alpha$-disc model in order to calculate the AGN luminosity. By varying the disc feeding radii we determine the limiting values for possible AGN accretion disc luminosity. Small angle collisions do not result in significant mass transport to the centre of the system, while models with highest collision angles transport close to $40\%$ of the initial matter to the accretion disc. Even with ring and cloud masses equal to $10^4 \, M_\odot$, which is the lower limit of present-day mass of the Circumnuclear ring in the Galactic Centre, the energy released over an interval of 1.5 Myr can produce $\sim 10\%$ of that required to inflate the Fermi bubbles. If the gas ring in the Galactic Centre 6 Myr ago had a mass of at least $10^5 \, M_\odot$, our proposed scenario can explain the formation of the Fermi bubbles. We estimate that such high-impact collisions might occur once every $\sim 10^8$ yr in our Galaxy.
- [49] arXiv:1912.04729 [pdf, ps, other]
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Title: Accurate OH Maser Positions From The SPLASH Survey III: The Final 96 Square DegreesAuthors: Hai-Hua Qiao, Shari L. Breen, Jose F. Gomez, J. R. Dawson, Andrew J. Walsh, James A. Green, Simon P. Ellingsen, Hiroshi Imai, Zhi-Qiang ShenComments: 22 pages, 12 figures. arXiv admin note: text overlap with arXiv:1809.09304Subjects: Astrophysics of Galaxies (astro-ph.GA)
We present high spatial resolution observations of ground-state OH masers achieved with the Australia Telescope Compact Array (ATCA). These observations targeted 253 pointing centres containing OH maser candidates at all four ground-state OH transitions identified in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) across 96 square degrees of the Southern Galactic plane (332\degree$<l<$334\degree and $-$2\degree$<b<+$2\degree, 344\degree$<l<$355\degree and $-$2\degree$<b<+$2\degree, 358\degree$<l<$4\degree and $+$2\degree$<b<+$6\degree, 5\degree$<l<$10\degree and $-$2\degree$<b<+$2\degree). We detect maser emission towards 236 fields and suggest that 7 out of 17 non-detections are due to the slightly lower sensitivity of the ATCA observations, combined with some temporal variability. The superior resolution provided by the ATCA data has allowed us to identify 362 OH maser sites in the 236 target fields. Almost half (160 of 362) of these masers have been detected for the first time. Comparison between these 362 maser sites with information presented in the literature allowed us to categorize 238 sites as evolved star sites (66\%), 63 as star formation (17\%), eight as supernova remnants and 53 unknown maser sites (15\%). We present analysis of the OH masers across the full SPLASH survey range (176 square degrees) and find that the detection rate of 1.7 GHz radio continuum sources (18\%) is lower than that previously found at 8.2 and 9.2 GHz (38\%). We also find that the velocity separations of evolved star sites with symmetric 1612 MHz maser profiles are generally smaller than those with asymmetric profiles.
- [50] arXiv:1912.04732 [pdf, other]
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Title: Charge Constraints of Macroscopic Dark MatterAuthors: Jagjit Singh SidhuComments: 16 pages, 8 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Macroscopic dark matter (macros) refers to a broad class of alternative candidates to particle dark matter with still unprobed regions of parameter space. Prior work on macros has considered elastic scattering to be the dominant energy transfer mechanism in deriving constraints on the abundance of macros for some range of masses $M_x$ and (geometric) cross-sections $\sigma_x$ However, macros with a significant amount of electric charge would, through Coulomb interactions, interact strongly enough to have produced observable signals on terrestrial, galactic and cosmological scales. We determine the expected signals and constrain the corresponding regions of parameter space, based on the lack of these signals in observations.
- [51] arXiv:1912.04751 [pdf, other]
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Title: Characterisation of the ground layer of turbulence at Paranal using a robotic SLODAR systemSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
We describe the implementation of a robotic SLODAR instrument at the Cerro Paranal observatory. The instrument measures the vertical profile of the optical atmospheric turbulence strength, in 8 resolution elements, to a maximum altitude ranging between 100 m and 500 m. We present statistical results of measurements of the turbulence profile on a total of 875 nights between 2014 and 2018. The vertical profile of the ground layer of turbulence is very varied, but in the median case most of the turbulence strength in the ground layer is concentrated within the first 50 m altitude, with relatively weak turbulence at higher altitudes up to 500 m. We find good agreement between measurements of the seeing angle from the SLODAR and from the Paranal DIMM seeing monitor, and also for seeing values extracted from the Shack-Hartmann active optics sensor of VLT UT1, adjusting for the height of each instrument above ground level. The SLODAR data suggest that a median improvement in the seeing angle from 0.689 arcsec to 0.481 arcsec at wavelength 500 nm would be obtained by fully correcting the ground-layer turbulence between the height of the UTs (taken as 10 m) and altitude 500 m.
- [52] arXiv:1912.04763 [pdf, other]
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Title: First evidence of enhanced recombination in astrophysical environments and the implications for plasma diagnosticsAuthors: A. Nemer (1,2), N. C. Sterling (3), J. Raymond (4), A. K. Dupree (4), J. García-Rojas (5,6), Qianxia Wang (1,7), M. S. Pindzola (1), C. P. Ballance (8), S. D. Loch (1) ((1) Auburn University, USA, (2) Princeton University, USA, (3) University of West Georgia, USA, (4) CfA, Harvard, USA, (5) IAC, Spain, (6) ULL, Spain, (7) Rice University, USA, (8) Queen's University Belfast, UK)Comments: 3 Figures, 2 Tables. Published in The Astrophysical Journal Letters. 2019 December 10Journal-ref: ApJL, 887, L9 (2019)Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); Atomic Physics (physics.atom-ph)
We report the first unambiguous observational evidence of Rydberg Enhanced Recombination (RER), a potentially important recombination mechanism that has hitherto been unexplored in low-temperature photoionized plasmas. RER shares similarities with dielectronic recombination, with the difference that the electron is captured into a highly excited state below the ionization threshold -- rather than above the threshold -- of the recombining ion. We predict transitions of carbon and oxygen ions that are formed via the RER process, and their relative strengths with collisional-radiative spectral models. Optical C II RER features are detected in published high-resolution spectra of eight planetary nebulae, and a C III transition has been found in the ultraviolet spectrum in a symbiotic star system. The relative intensities of these lines are consistent with their production by this recombination mechanism. Because RER has not previously been accounted for in photoionized plasmas, its inclusion in models can significantly impact the predicted ionization balance and hence abundance calculations of important astrophysical species. Calculations for C+ suggest that the enhancement in the total recombination rate can amount to a factor of 2.2 at 8100 K, increasing to 7.5 at T = 3500 K. These results demonstrate the importance of including RER in models of photoionized astrophysical plasmas and in elemental abundance determinations.
- [53] arXiv:1912.04765 [pdf, other]
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Title: Formation of moon systems around giant planets: Capture and ablation of planetesimals as foundation for a pebble accretion scenarioComments: 20 pages, 13 figures; accepted for publication in A&ASubjects: Earth and Planetary Astrophysics (astro-ph.EP)
The four major satellites of Jupiter, known as the Galilean moons, and Saturn's most massive satellite, Titan, are believed to have formed in a predominantly gaseous circum-planetary disk, during the last stages of formation of their parent planet. Pebbles from the protoplanetary disk are blocked from flowing into the circumplanetary disk by the positive pressure gradient at the outer edge of the planetary gap, so the gas drag assisted capture of planetesimals should be the main contributor to the delivery of solids onto circum-planetary disks. However, a consistent framework for the subsequent accretion of the moons remains to be built. Here we use numerical integrations to show that most planetesimals being captured within a circum-planetary disk are strongly ablated due to the frictional heating they experience, thus supplying the disk with small dust grains, whereas only a small fraction 'survives' their capture. We then construct a simple model of a circum-planetary disk supplied by ablation, where the flux of solids through the disk is at equilibrium with the ablation supply rate, and investigate the formation of moons in such disks. We show that the growth of satellites is driven mainly by accretion of the pebbles that coagulate from the ablated material. The pebble-accreting protosatellites rapidly migrate inward and pile up in resonant chains at the inner edge of the circum-planetary disk. We propose that dynamical instabilities in these resonant chains are at the origin of the different architectures of Jupiter's and Saturn's moon systems. The assembly of moon systems through pebble accretion can therefore be seen as a down-scaled manifestation of the same process that forms systems of super-Earths and terrestrial-mass planets around solar-type stars and M-dwarfs.
- [54] arXiv:1912.04794 [pdf, ps, other]
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Title: Spritz: a new fully general-relativistic magnetohydrodynamic codeComments: 36 pages, 17 figures, submitted to Classical and Quantum GravitySubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
The new era of multimessenger astrophysics requires the capability of studying different aspects of the evolution of compact objects. In particular, the merger of neutron star binaries is a strong source of gravitational waves and electromagnetic radiation, from radio to $\gamma$-rays, as demonstrated by the detection of GW170817 and its electromagnetic counterparts. In order to understand the physical mechanisms involved in such systems, it is necessary to employ fully general relativistic magnetohydrodynamic (GRMHD) simulations able to include the effects of a composition and temperature dependent equation of state describing neutron star matter as well as neutrino emission and reabsorption. Here, we present our new code named Spritz that solves the GRMHD equations in 3D Cartesian coordinates and on a dynamical spacetime. The code can support tabulated equations of state, taking into account finite temperature effects and allowing for the inclusion of neutrino radiation. In this first paper, we present the general features of the code and a series of tests performed in special and general relativity to assess the robustness of the basic GRMHD algorithms implemented. Among these tests, we also present the first comparison between a non-staggered and a staggered formulation of the vector potential evolution, which is used to guarantee the divergence-less character of the magnetic field.
- [55] arXiv:1912.04803 [pdf, other]
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Title: Compensation of tropospheric and ionospheric effects in gravitational sessions of the spacecraft RadioAstronComments: 10 pages, 10 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc); Atmospheric and Oceanic Physics (physics.ao-ph); Space Physics (physics.space-ph)
The possibility of compensating atmospheric influence in an experiment on precision measurement of gravitational redshift using the "RadioAstron" spacecraft (SC) is discussed. When a signal propagates from a ground-based tracking station to a spacecraft and back, interaction with the ionosphere and troposphere makes considerable contribution to the frequency shift. A brief overview of the physical effects determining this contribution is given, and the principles of calculation and compensation of the corresponding frequency distortions of radio signals are described. Then these approaches are used to reduce the atmospheric frequency shift of the "RadioAstron" spacecraft signal. The spacecraft hardware allows working in two communication modes: "one-way" and "two-way", in addition, two communication channels at different frequencies work simultaneously. "One-way" (SC - ground-based tracking station) communication mode, a signal is synchronized by the on board hydrogen frequency standard. The "two-way" (SC - ground-based tracking station - SC ) mode is synchronized by the ground hydrogen standard. The calculations performed allow us to compare the quality of compensation of atmospheric fluctuations performed by various methods and choose the optimal one.
- [56] arXiv:1912.04812 [pdf, other]
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Title: The LOFAR view of NGC 3998, a sputtering AGNAuthors: Sarrvesh S. Sridhar, Raffaella Morganti, Kristina Nyland, Bradley S. Frank, Jeremy Harwood, Tom OosterlooComments: Accepted for publication in Astronomy & AstrophysicsSubjects: Astrophysics of Galaxies (astro-ph.GA)
Low-power radio sources dominate the radio sky. They tend to be small in size and core-dominated, but the origin of their properties and the evolution of their radio plasma are not well constrained. Interestingly, there is mounting evidence that low-power radio sources can significantly impact their surrounding gaseous medium and, therefore, may be more relevant for galaxy evolution than previously thought. In this paper, we present low radio frequency observations obtained with LOFAR at 147 MHz of the radio source hosted by NGC 3998. This is a rare example of a low-power source which is extremely core-dominated, but which has two large-scale lobes of low surface brightness. We combine the new 147 MHz image with available 1400 MHz data to derive the spectral index over the source. Despite the low surface brightness, reminiscent of remnant structures, the lobes show an optically thin synchrotron spectral index (~ 0.6). We interpret this as being due to rapid decollimation of the jets close to the core, to high turbulence of the plasma flow, and entrainment of thermal gas. This could be the result of intermittent activity of the central AGN, or, more likely, temporary disruption of the jet due to the interaction of the jet with the rich circumnuclear ISM. Both would result in sputtering energy injection from the core which would keep the lobes fed, albeit at a low rate. We discuss these results in connection with the properties of low-power radio sources in general. Our findings show that amorphous, low surface brightness lobes should not be interpreted, by default, as remnant structures. Large, deep surveys (in particular the LOFAR 150 MHz LoTSS and the recently started 1400 MHz Apertif survey) will identify a growing number of objects similar to NGC 3998 where these ideas can be further tested.
- [57] arXiv:1912.04839 [pdf, ps, other]
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Title: Homogeneous Analysis of Globular Clusters from the APOGEE Survey with the BACCHUS Code. II. The Southern Clusters and OverviewAuthors: Szabolcs Mészáros, Thomas Masseron, D. A. García-Hernández, Carlos Allende Prieto, Timothy C. Beers, Dmitry Bizyaev, Drew Chojnowski, Roger E. Cohen, Katia Cunha, Flavia Dell'Agli, Garrett Ebelke, José G. Fernández-Trincado, Peter Frinchaboy, Doug Geisler, Sten Hasselquist, Fred Hearty, Jon Holtzman, Jennifer Johnson, Richard R. Lane, Ivan Lacerna, Penelopé Longa-Peña, Steven R. Majewski, Sarah L. Martell, Dante Minniti, David Nataf, David L. Nidever, Kaike Pan, Ricardo P. Schiavon, Matthew Shetrone, Verne V. Smith, Jennifer S. Sobeck, Guy S. Stringfellow, László Szigeti, Baitian Tang, John C. Wilson, Olga ZamoraComments: Accepted for publication in MNRAS, 31 pages, 24 figures, 7 tablesSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
We investigate the Fe, C, N, O, Mg, Al, Si, K, Ca, Ce and Nd abundances of 2283 red giant stars in 31 globular clusters from high-resolution spectra observed in both the northern and southern hemisphere by the SDSS-IV APOGEE-2 survey. This unprecedented homogeneous dataset, largest to date, allows us to discuss the intrinsic Fe spread, the shape and statistics of Al-Mg and N-C anti-correlations as a function of cluster mass, luminosity, age and metallicity for all 31 clusters. We find that the Fe spread does not depend on these parameters within our uncertainties including cluster metallicity, contradicting earlier observations. We do not confirm the metallicity variations previously observed in M22 and NGC 1851. Some clusters show a bimodal Al distribution, while others exhibit a continuous distribution as has been previously reported in the literature. We confirm more than 2 populations in $\omega$ Cen and NGC 6752, and find new ones in M79. We discuss the scatter of Al by implementing a correction to the standard chemical evolution of Al in the Milky Way. After correction, its dependence on cluster mass is increased suggesting that the extent of Al enrichment as a function of mass was suppressed before the correction. We observe a turnover in the Mg-Al anti-correlation at very low Mg in $\omega$ Cen, similar to the pattern previously reported in M15 and M92. $\omega$ Cen may also have a weak K-Mg anti-correlation, and if confirmed, it would be only the third cluster known to show such a pattern.
- [58] arXiv:1912.04872 [pdf, other]
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Title: Amending halo model to satisfy cosmological conservation lawsComments: 9 pages, 6 figures, comments are welcomeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
One of the most powerful tools in the arsenal of theoretical cosmologists is the halo model of large scale structure, which provides a phenomenological description of nonlinear structure in our universe. However, it is well known that there is no simple way to impose conservation laws in the halo model. This can severely impair the predictions on large scales for observables such as weak lensing or the kinematic Sunyaev-Zel'dovich effect, which should satisfy mass and momentum conservations, respectively. For example, the standard halo model overpredicts weak lensing power spectrum by $> 8\%$ on scales $>20$ degrees. To address this problem, we present an $Amended ~ Halo ~ Model$, explicitly separating the linear perturbations from $compensated$ halo profiles. This is guaranteed to respect conservation laws, as well as linear theory predictions on large scales. We then provide a simple fitting function for the compensated halo profiles, and discuss the modified predictions for 1-halo and 2-halo terms, as well as other cosmological observations such weak lensing power spectrum. We further argue that the amended halo model provides a more accurate framework to capture physical effects that happen in the process of cosmological structure formation.
- [59] arXiv:1912.04880 [pdf, other]
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Title: Quantifying concordance of correlated cosmological data setsComments: 26 pages, 11 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
We develop estimators of agreement and disagreement between correlated cosmological data sets. These account for data correlations when computing the significance of both tensions and excess confirmation while remaining statistically optimal. We discuss and thoroughly characterize different approaches commenting on the ones that have the best behavior in practical applications. We complement the calculation of their statistical distribution within the Gaussian model with one estimator that takes non-Gaussianities fully into account. To illustrate the use of our techniques, we apply these estimators to supernovae measurements of the distance-redshift relation, absolutely calibrated by the local distance ladder. The suite of best estimators that we discuss finds results that are in excellent agreement between estimators and find no indications of significant internal inconsistencies in this data set above the $1\%$ probability threshold. This shows the robustness of local determinations of the Hubble constant to features in the distance-redshift relation.
- [60] arXiv:1912.04887 [pdf, other]
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Title: A thick disc as massive as it gets: the vertical structure of the enormous edge-on lenticular galaxy NGC7572Comments: 16 pages, 10 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
Galactic discs are known to have a complex multi-layer structure. An in-depth study of the stellar population properties of the thin and thick components can elucidate the formation and evolution of disc galaxies. Even though thick discs are ubiquitous, their origin is still debated. Here we probe the thick disc formation scenarios by investigating NGC7572, an enormous edge-on galaxy having $R_{25}\approx 25$ kpc and $V_{rot} \approx 370$ km/s, which substantially exceeds the Milky Way size and mass. We analysed DECaLS archival imaging and found that the disc of NGC7572 contains two flaring stellar discs (a thin and a thick disc) with similar radial scales. We collected deep long-slit spectroscopic data using the 6-m Russian BTA telescope and analysed them with a novel technique. We first reconstructed a non-parametric stellar line-of-sight velocity distribution along the radius of the galaxy and then fitted it with two kinematic components accounting for the orbital distribution of stars in thin and thick discs. The old thick disc turned out to be 2.4 times as massive as the intermediate-age thin component, $1.9\cdot 10^{11}$ Msun vs. $7.8\cdot10^{10}$ Msun, which is very unusual. The different duration of the formation epochs evidenced by the [Mg/Fe] values of +0.3 dex and +0.15 dex for the thick and thin discs respectively, their kinematics and the mass ratio suggest that in NGC7572 we observe a rapidly formed very massive thick disc and an under-developed thin disc, whose formation ended prematurely due to the exhaustion of the cold gas likely because of environmental effects.
- [61] arXiv:1912.04890 [pdf, other]
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Title: Large Scale Structures in the CANDELS Fields: The Role of the Environment in Star Formation ActivityAuthors: Nima Chartab, Bahram Mobasher, Behnam Darvish, Steven L. Finkelstein, Yicheng Guo, Dritan Kodra, Kyoung-Soo Lee, Jeffrey A. Newman, Camilla Pacifici, Casey Papovich, Zahra Sattari, Abtin Shahidi, Mark E. Dickinson, Sandra M. Faber, Henry C. Ferguson, Mauro Giavalisco, Marziye jafariyazaniComments: 17 pages, 10 figures, 3 tables, accepted for publication in the ApJ. Catalogs of the environment measurements and the density maps will be available with the final published paper in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present a robust method, weighted von Mises kernel density estimation, along with boundary correction to reconstruct the underlying number density field of galaxies. We apply this method to galaxies brighter than $\rm HST/F160w\le 26$ AB mag at the redshift range of $0.4\leq z \leq 5$ in the five CANDELS fields (GOODS-N, GOODS-S, EGS, UDS, and COSMOS). We then use these measurements to explore the environmental dependence of the star formation activity of galaxies. We find strong evidence of environmental quenching for massive galaxies ($\rm M \gtrsim 10^{11} \rm {M}_\odot$) out to $z\sim 3.5$ such that an over-dense environment hosts $\gtrsim 20\%$ more massive quiescent galaxies compared to an under-dense region. We also find that environmental quenching efficiency grows with stellar mass and reaches $\sim 60\%$ for massive galaxies at $z\sim 0.5$. The environmental quenching is also more efficient in comparison to the stellar mass quenching for low mass galaxies ($\rm M \lesssim 10^{10} \rm {M}_\odot$) at low and intermediate redshifts ($z\lesssim 1.2$). Our findings concur thoroughly with the "over-consumption" quenching model where the termination of cool gas accretion (cosmological starvation) happens in an over-dense environment and the galaxy starts to consume its remaining gas reservoir in depletion time. The depletion time depends on the stellar mass and could explain the evolution of environmental quenching efficiency with the stellar mass.
- [62] arXiv:1912.04892 [pdf, other]
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Title: Tidal Evolution of Eccentric Binaries Driven by Convective Turbulent ViscosityComments: 15 pages, 11 figures, submittedSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Tidal dissipation due to convective turbulent viscosity shapes the evolution of a variety of astrophysical binaries. For example, this type of dissipation determines the rate of orbital circularization in a binary with a post-main sequence star that is evolving toward a common envelope phase. Viscous dissipation can also influence binaries with solar-type stars, or stars with a close-in giant planet. In general, the effective viscosity in a convective stellar envelope depends on the tidal forcing frequency $\omega_{\rm tide}$; when $\omega_{\rm tide}$ is larger than the turnover frequency of convective eddies, the viscosity is reduced. Previous work has focused on binaries in nearly circular orbits. However, for eccentric orbits, the tidal potential has many forcing frequencies. In this paper, we develop a formalism for computing tidal dissipation that captures the effect of frequency-dependent turbulent viscosity and is valid for arbitrary binary eccentricities. We also present an alternative simpler formulation that is suitable for very high eccentricities. We apply our formalisms to a red giant branch (RGB) star model and a solar-type star model. We find that a range of pseudosynchronous rotation rates are possible for both stellar models, and the pseudosynchronous rate can differ from the prediction of the commonly-used weak tidal friction theory by up to a factor of a few. We also find that tidal decay and circularization due to turbulent viscosity can be a few orders of magnitude faster than predicted by weak tidal friction in RGB stars on eccentric, small pericentre orbits, but is suppressed by a few orders of magnitude in solar-type stars due to viscosity reduction.
Cross-lists for Wed, 11 Dec 19
- [63] arXiv:1910.02147 (cross-list from hep-th) [pdf, ps, other]
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Title: Distance, de Sitter and Trans-Planckian Censorship conjectures: the status quo of Warm InflationAuthors: Suratna DasComments: 3 pgs, double column, no figures. Comments are welcome, v2: typos corrected, few references and comments added, v3: minor changes, references added, accepted for publication in Physics of the Dark UniverseSubjects: 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)
In this short note, we pointed out that Warm inflationary scenario remains to be favoured over its cold counterpart by the recently proposed conjectures, which aim to overrule de Sitter like constructions in String Landscapes. On the other hand, the canonical cold (single-field slow-roll) inflationary models, which were in tension with the previously proposed de Sitter conjecture, have now become even more unlikely to realise in String Landscapes as these scenarios fail to cope up with both the conjectures, de Sitter and trans-Planckian censorship, at one go.
- [64] arXiv:1912.04272 (cross-list from physics.ins-det) [pdf, other]
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Title: Broadband, millimeter-wave antireflection coatings for large-format, cryogenic aluminum oxide opticsAuthors: A. Nadolski, J. D. Vieira, J. A. Sobrin, A. M. Kofman, P. A. R. Ade, Z. Ahmed, A. J. Anderson, J. S. Avva, R. Basu Thakur, A. N. Bender, B. A. Benson, L. Bryant, J. E. Carlstrom, F. W. Carter, T. W. Cecil, C. L. Chang, J. R. Cheshire IV, G. E. Chesmore, J. F. Cliche, A. Cukierman, T. de Haan, M. Dierickx, J. Ding, D. Dutcher, W. Everett, J. Farwick, K. R. Ferguson, L. Florez, A. Foster, J. Fu, J. Gallicchio, A. E. Gambrel, R. W. Gardner, J. C. Groh, S. Guns, R. Guyser, N. W. Halverson, A. H. Harke-Hosemann, N. L. Harrington, R. J. Harris, J. W. Henning, W. L. Holzapfel, D. Howe, N. Huang, K. D. Irwin, O. Jeong, M. Jonas, A. Jones, M. Korman, J. Kovac, D. L. Kubik, S. Kuhlmann, C.-L. Kuo, A. T. Lee, A. E. Lowitz, J. McMahon, J. Meier, S. S. Meyer, D. Michalik, J. Montgomery, T. Natoli, H. Nguyen, et al. (27 additional authors not shown)Comments: 16 pages, 9 figures; submitted to Applied Optics (05 Dec 2019)Subjects: Instrumentation and Detectors (physics.ins-det); Instrumentation and Methods for Astrophysics (astro-ph.IM)
We present two prescriptions for broadband (~77 - 252 GHz), millimeter-wave antireflection coatings for cryogenic, sintered polycrystalline aluminum oxide optics: one for large-format (700 mm diameter) planar and plano-convex elements, the other for densely packed arrays of quasi-optical elements, in our case 5 mm diameter half-spheres (called "lenslets"). The coatings comprise three layers of commercially-available, polytetrafluoroethylene-based, dielectric sheet material. We review the fabrication processes for both prescriptions then discuss laboratory measurements of their transmittance and reflectance. In addition, we present the inferred refractive indices and loss tangents for the coating materials and the aluminum oxide substrate.
- [65] arXiv:1912.04276 (cross-list from physics.ins-det) [pdf, other]
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Title: Benefits of bolometer Joule stepping and Joule pulsingComments: Accepted for publication in the Journal of Low Temperature PhysicsSubjects: Instrumentation and Detectors (physics.ins-det); Instrumentation and Methods for Astrophysics (astro-ph.IM)
We introduce the `Joule stepping' technique, whereupon a constantly-biased bolometer has its bias voltage modified by a small additional step. We demonstrate this technique using a composite NTD semiconductor bolometer and a pulsing device which sends an extra step in voltage. We demonstrate the results of the technique over a range of bias voltages at 100, 200, and 300 mK. We find that Joule stepping allows us to directly measure long thermal tails with low amplitudes in the bolometer response, and could be a useful tool for quickly and easily understanding response functions of bolometric detectors. We also show that the derivative of the Joule step is equivalent to the bolometer response to a $\delta$-pulse (or Joule pulse), which allows for greater understanding of fast transient behaviour.
- [66] arXiv:1912.04283 (cross-list from hep-th) [pdf, other]
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Title: Inflation, Higher Spins and the SwamplandAuthors: Marco ScalisiComments: 12 pages, 2 figuresSubjects: 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)
We study the implications on inflation of an infinite tower of higher-spin states with masses falling exponentially at large field distances, as dictated by the Swampland Distance Conjecture. We show that the Higuchi lower bound on the mass of the tower automatically translates into an upper bound on the inflaton excursion. Strikingly, the mere existence of all spins in the tower forbids any scalar displacement whatsoever, at arbitrarily small Hubble scales, and it turns out therefore incompatible with inflation. A certain field excursion is allowed only if the tower has a cut-off in spin. Finally, we show that this issue is circumvented in the case of a tower of string excitations precisely because of the existence of such a cut-off, which decreases fast enough in field space.
- [67] arXiv:1912.04295 (cross-list from hep-ph) [pdf, other]
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Title: Searching for Earth/Solar Axion HalosAuthors: Abhishek Banerjee, Dmitry Budker, Joshua Eby, Victor V. Flambaum, Hyungjin Kim, Oleksii Matsedonsky, Gilad PerezComments: 23 pages, 9 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Atomic Physics (physics.atom-ph)
We discuss the sensitivity of the present and near-future axion dark matter experiments to a halo of axions or axion-like particles gravitationally bound to the Earth or the Sun. The existence of such halos, assuming they are formed, renders a significant gain in the sensitivity of axion searches while satisfying all the present experimental bounds. The structure and coherence properties of these halos also imply novel signals, which can depend on the latitude or orientation of the detector. We demonstrate this by analysing the sensitivity of several distinct types of axion dark matter experiments.
- [68] arXiv:1912.04306 (cross-list from gr-qc) [pdf, other]
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Title: Initial Conditions of Inflation in a Bianchi I UniverseAuthors: Kieran FinnComments: 5 pages 1 figureSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We investigate the initial conditions of inflation in a Bianchi~I universe that is homogeneous but not isotropic. We use the Eisenhart lift to describe such a theory geometrically as geodesics on a field space manifold. We construct the phase-space manifold of the theory by considering the tangent bundle of the field space and equipping it with a natural metric. We find that the total volume of this manifold is finite for a wide class of inflationary models. We therefore take the initial conditions to be uniformly distributed over it in accordance with Laplace's principle of indifference. This results in a normalisable, reparametrisation invariant measure on the set of initial conditions of inflation in a Bianchi~I universe. We find that this measure favours an initial state in which the inflaton field is at or near its minimum, with a mild preference for some initial anisotropy. Since inflation requires an initial field value with a large displacement from its minimum, we therefore conclude that the theory of inflation requires finely tuned initial conditions.
- [69] arXiv:1912.04727 (cross-list from hep-ph) [pdf, other]
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Title: Cosmology and Dark MatterAuthors: V.A.RubakovComments: Lectures at European School on High Energy Physics ESHEP2019, Saint-Petersburg, Russia, September 2019. arXiv admin note: text overlap with arXiv:1804.11230Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Cosmology and astroparticle physics give strongest possible evidence for the incompleteness of the Standard Model of particle physics. Leaving aside misterious dark energy, which may or may not be just the cosmological constant, two properties of the Universe cannot be explained by the Standard Model: dark matter and matter-antimatter asymmtery. Dark matter particles may well be discovered in foreseeable future; this issue is under intense experimental investigation. Theoretical hypotheses on the nature of the dark matter particles are numerous, so we concentrate on several well motivated candidates, such as WIMPs, axions and sterile neutrinos, and also give examples of less motivated and more elusive candidates such as fuzzy dark matter. This gives an idea of the spectrum of conceivable dark matter candidates, while certainly not exhausting it. We then consider the matter-antimatter asymmetry and discuss whether it may result from physics at 100~GeV -- TeV scale. Finally, we turn to the earliest epoch of the cosmological evolution. Although the latter topic does not appear immediately related to contemporary particle physics, it is of great interest due to its fundamental nature. We emphasize that the cosmological data, notably, on CMB anisotropies, unequivocally show that the well understood hot stage was not the earliest one. The best guess for the earlier stage is inflation, which is consistent with everything known to date; however, there are alternative scenarios. We discuss the ways to study the earliest epoch, with emphasis on future cosmological observations.
Replacements for Wed, 11 Dec 19
- [70] arXiv:1712.03969 (replaced) [pdf, ps, other]
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Title: Conformal gravity: light deflection revisited and the galactic rotation curve failureComments: 16 pages, 1 figure. Revised version according to the referees comments. The results reported in the original version remain unchangedJournal-ref: Class. Quantum Grav. 36 (2019) 245014 (16pp)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [71] arXiv:1903.08798 (replaced) [pdf, other]
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Title: Emulators for the non-linear matter power spectrum beyond $Λ$CDMAuthors: Hans Winther, Santiago Casas, Marco Baldi, Kazuya Koyama, Baojiu Li, Lucas Lombriser, Gong-Bo ZhaoComments: 12 pages, 10 figures. Version accepted for publication in PRD. Data can be found at this https URLSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [72] arXiv:1904.03097 (replaced) [pdf, other]
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Title: 21-cm observations and warm dark matter modelsComments: matches published versionJournal-ref: Phys. Rev. D 100, 123005 (2019)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
- [73] arXiv:1904.12018 (replaced) [pdf, other]
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Title: Self-intersection of the Fallback Stream in Tidal Disruption EventsComments: 19 pages, 16 figures, plus appendices. MNRAS accepted after minor revisionSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [74] arXiv:1905.09338 (replaced) [pdf, other]
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Title: H0LiCOW XII. Lens mass model of WFI2033-4723 and blind measurement of its time-delay distance and $H_0$Authors: Cristian E. Rusu, Kenneth C. Wong, Vivien Bonvin, Dominique Sluse, Sherry H. Suyu, Christopher D. Fassnacht, James H. H. Chan, Stefan Hilbert, Matthew W. Auger, Alessandro Sonnenfeld, Simon Birrer, Frederic Courbin, Tommaso Treu, Geoff C.-F. Chen, Aleksi Halkola, Leon V. E. Koopmans, Philip J. Marshall, Anowar J. ShajibComments: Version accepted by MNRAS. 29 pages including appendix, 17 figures, 6 tables. arXiv admin note: text overlap with arXiv:1607.01403Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [75] arXiv:1906.10466 (replaced) [pdf, other]
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Title: Inelastic dark matter nucleus scatteringComments: 28 pages, 8 figures, version accepted for publication in JCAPSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [76] arXiv:1907.04771 (replaced) [pdf, other]
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Title: How cold gas continuously entrains mass and momentum from a hot windComments: 23 pages, 22 figures; videos available at this http URL; published in MNRSSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [77] arXiv:1907.07199 (replaced) [pdf, other]
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Title: An independent assessment of significance of annual modulation in COSINE-100 dataComments: 7 pages, 2 figures. Analysis code and data available from this https URLSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex)
- [78] arXiv:1907.10635 (replaced) [pdf, other]
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Title: Sub-MeV Dark Matter and the Goldstone Modes of Superfluid HeliumComments: 5 pages, 3 figures; v2: references updated and typos correctedJournal-ref: Phys. Rev. D 100, 116007 (2019)Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex)
- [79] arXiv:1907.11896 (replaced) [pdf, other]
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Title: Constraints on primordial curvature perturbations from primordial black hole dark matter and secondary gravitational wavesComments: 15 pages, 3 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [80] arXiv:1908.08056 (replaced) [pdf, other]
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Title: The Progenitors of Calcium-Strong TransientsComments: Accepted to ApJ. Minor changes and updates to previous version. Main conclusions remain unchangedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
- [81] arXiv:1909.01373 (replaced) [pdf, other]
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Title: Gravitational Waves from the Inspiral of Supermassive Black Holes in Galactic-scale SimulationsComments: 22 pages, 10 figures, published in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
- [82] arXiv:1909.04168 (replaced) [pdf, other]
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Title: Visible Sterile Neutrinos as the Earliest Relic Probes of CosmologyComments: 7 pages, 1 figure; v3: publication versionJournal-ref: Phys.Lett. B800 (2019) 135113Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex)
- [83] arXiv:1909.07968 (replaced) [pdf, other]
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Title: Fate of a neutron star with an endoparasitic black hole and implications for dark matterComments: 13 pages, 9 figures; revised to match PRD versionJournal-ref: Phys. Rev. D 100, 124026 (2019)Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
- [84] arXiv:1910.10156 (replaced) [pdf, other]
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Title: Reality or Mirage? Observational Test and Implications for the Claimed Extremely Magnified Quasar at $z = 6.3$Comments: Published in ApJ: 8 pages, 4 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
- [85] arXiv:1911.02765 (replaced) [pdf, other]
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Title: Electric sails are potentially more effective than light sails near most starsComments: Accepted for publication in Acta Astronautica; 20 pages; 4 figuresSubjects: Space Physics (physics.space-ph); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
- [86] arXiv:1911.07457 (replaced) [pdf, other]
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Title: Calibrating the power of relativistic jetsAuthors: L. Foschini, M. L. Lister, T. Hovatta, Y. Y. Kovalev, P. Romano, S. Vercellone, A. Lähteenmäki, T. K. Savolainen, M. Tornikoski, E. Angelakis, M. Berton, V. Braito, S. Ciroi, M. Kadler, P. R. BurdComments: 7 pages, 4 figures. Poster presented at High Energy Phenomena in Relativistic Outflows (HEPRO) VII, Barcelona (Spain), July 9-12, 2019. Accepted for publication on Proceedings of Science (PoS)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
- [87] arXiv:1911.10207 (replaced) [pdf, other]
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Title: Cosmological Decoherence from Thermal GravitonsComments: 30 pages, 6 figures; comments welcomeSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)
- [88] arXiv:1911.10740 (replaced) [pdf, other]
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Title: The FLASHES Survey I: Integral Field Spectroscopy of the CGM around 48 $z=2.3-3.1$ QSOsAuthors: Donal O'Sullivan, Christopher Martin, Mateusz Matuszewski, Keri Hoadley, Erika Hamden, James D Neill, Zeren Lin, Prachi PariharComments: Submitted to ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [89] arXiv:1911.11450 (replaced) [pdf, other]
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Title: Expanding Core-Collapse Supernova Search Horizon of Neutrino DetectorsAuthors: Odysse Halim, Carlo Vigorito, Claudio Casentini, Giulia Pagliaroli, Marco Drago, Viviana FafoneComments: 4 pages, 2 figures. this contribution was accepted by IOP Conference Series for the conference: TAUP2019, Toyama, Japan. this http URLSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex); Data Analysis, Statistics and Probability (physics.data-an)
- [90] arXiv:1911.11804 (replaced) [pdf, other]
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Title: A seismic scaling relation for stellar age II: The red giant branchAuthors: Earl Patrick BellingerComments: 5 pages, 4 figures. Accepted for publication in MNRAS Letters. Source code providedSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [91] arXiv:1912.01061 (replaced) [pdf, other]
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Title: On the slope of curvature power spectrum in non-attractor inflationComments: 62 pages, 17 figures, v2, new references added, typos corrected, discussion in section 4 and 5 is improvedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
- [92] arXiv:1912.03082 (replaced) [pdf, ps, other]
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Title: Analysis of Quiescent Corona X-ray Spectra from SphinX during the 2009 Solar MinimumSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
- [93] arXiv:1912.03392 (replaced) [pdf, other]
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Title: Iterative removal of redshift space distortions from galaxy clusteringComments: 21 pages, 12 figures, 1 table; submitted to MNRAS; comments welcomeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [94] arXiv:1912.04103 (replaced) [pdf, ps, other]
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Title: On using inspiralling supermassive binary black holes in the PTA frequency band as standard sirens to constrain dark energyComments: Accepted for publication in ApJ, 11 pages, 10 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [95] arXiv:1912.04167 (replaced) [pdf, ps, other]
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Title: KIC 8840638: A new Eclipsing Binary Consisting of a $δ$ Scuti star with multiperiodic pulsationsComments: Comments are welcomedSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
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