We gratefully acknowledge support from
the Simons Foundation and Leiden University.

Astrophysics

New submissions

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New submissions for Tue, 18 Feb 20

[1]  arXiv:2002.06197 [pdf, other]
Title: An Improved Measurement of the Secondary Cosmic Microwave Background Anisotropies from the SPT-SZ + SPTpol Surveys
Comments: Submitted to ApJ, 16 pages. arXiv admin note: text overlap with arXiv:1408.3161
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We report new measurements of millimeter-wave power spectra in the angular multipole range $2000 \le \ell \le 11,000$ (angular scales $5^\prime \gtrsim \theta \gtrsim 1^\prime$). By adding 95 and 150\,GHz data from the low-noise 500 deg$^2$ SPTpol survey to the SPT-SZ three-frequency 2540 deg$^2$ survey, we substantially reduce the uncertainties in these bands. These power spectra include contributions from the primary cosmic microwave background, cosmic infrared background, radio galaxies, and thermal and kinematic Sunyaev-Zel'dovich (SZ) effects. The data favor a thermal SZ (tSZ) power at 143\,GHz of $D^{\rm tSZ}_{3000} = 3.42 \pm 0.54~ \mu {\rm K}^2$ and a kinematic SZ (kSZ) power of $D^{\rm kSZ}_{3000} = 3.0 \pm 1.0~ \mu {\rm K}^2$. This is the first measurement of kSZ power at $\ge 3\,\sigma$. We study the implications of the measured kSZ power for the epoch of reionization, finding the duration of reionization to be $\Delta z_{re} = 1.0^{+1.6}_{-0.7}$ ($\Delta z_{re}< 4.1$ at 95% confidence), when combined with our previously published tSZ bispectrum measurement.

[2]  arXiv:2002.06207 [pdf, ps, other]
Title: Spectroscopic Confirmation of a Coma Cluster Progenitor at z ~ 2.2
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We report the spectroscopic confirmation of a new protocluster in the COSMOS field at $z$ $\sim$ 2.2, COSMOS Cluster 2.2 (CC2.2), originally identified as an overdensity of narrow-band selected H$\alpha$ emitting candidates. With only two masks of Keck/MOSFIRE near-IR spectroscopy in both $H$ ($\sim$ 1.47-1.81 $\mu$m) and $K$ ($\sim$ 1.92-2.40 $\mu$m) bands ($\sim$ 1.5 hour each), we confirm 35 unique protocluster members with at least two emission lines detected with S/N $>$ 3. Combined with 12 extra members from the zCOSMOS-deep spectroscopic survey (47 in total), we estimate a mean redshift and a line-of-sight velocity dispersion of $z_{mean}$=2.23224 $\pm$ 0.00101 and $\sigma_{los}$=645 $\pm$ 69 km s$^{-1}$ for this protocluster, respectively. Assuming virialization and spherical symmetry for the system, we estimate a total mass of $M_{vir}$ $\sim$ $(1-2) \times$10$^{14}$ $M_{\odot}$ for the structure. We evaluate a number density enhancement of $\delta_{g}$ $\sim$ 7 for this system and we argue that the structure is likely not fully virialized at $z$ $\sim$ 2.2. However, in a spherical collapse model, $\delta_{g}$ is expected to grow to a linear matter enhancement of $\sim$ 1.9 by $z$=0, exceeding the collapse threshold of 1.69, and leading to a fully collapsed and virialized Coma-type structure with a total mass of $M_{dyn}$($z$=0) $\sim$ 9.2$\times$10$^{14}$ $M_{\odot}$ by now. This observationally efficient confirmation suggests that large narrow-band emission-line galaxy surveys, when combined with ancillary photometric data, can be used to effectively trace the large-scale structure and protoclusters at a time when they are mostly dominated by star-forming galaxies.

[3]  arXiv:2002.06209 [pdf, other]
Title: Probing the Bright End of the Rest-Frame Ultraviolet Luminosity Function at z = 8-10 with Hubble Pure-Parallel Imaging
Comments: Accepted to the Astrophysical Journal, 23 pages, 10 Figures
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Looking for bright galaxies born in the early universe is fundamental to investigating the Epoch of Reionization, the era when the first stars and galaxies ionized the intergalactic medium. We utilize Hubble Space Telescope pure parallel imaging to select galaxy candidates at a time 500 to 650 million years after the Big Bang, which corresponds to redshifts z ~ 8-10. These data come from the Brightest of Reionizing Galaxies Survey (BoRG) Cycle 22 dataset, which consists of pure-parallel imaging in ~ 90 different lines of sight that sum up to an area of ~ 420 arcmin^2. This survey uses five filters and has the advantage (compared to the Cycle 21 BoRG program) of including imaging in the JH140 band, covering continuous wavelengths from the visible to near-infrared (lambda = 0.35um - 1.7um). This allows us to perform reliable selection of galaxies at z>8 using the photometric redshift technique. We use these galaxy candidates to constrain the bright end of the rest-frame ultraviolet luminosity function in this epoch. These candidates are excellent targets for follow-up observations, particularly with the James Webb Space Telescope.

[4]  arXiv:2002.06211 [pdf, other]
Title: Testing Physical Models for Cosmic Ray Transport Coefficients on Galactic Scales: Self-Confinement and Extrinsic Turbulence at GeV Energies
Authors: Philip F. Hopkins (Caltech), Jonathan Squire (Otago), T. K. Chan (ICC Durham), Eliot Quataert (Berkeley), Suoqing Ji (Caltech), Dusan Keres (UCSD), Claude-Andre Faucher-Giguere (Northwestern)
Comments: 22 pages, 10 figures (+6 page, 2 figures in appendices). Submitted to MNRAS. Comments welcome
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)

The microphysics of ~GeV cosmic ray (CR) transport on galactic scales remain deeply uncertain, with almost all studies adopting simple prescriptions (e.g. constant-diffusivity). We explore different physically-motivated, anisotropic, dynamical CR transport scalings in high-resolution cosmological FIRE simulations of dwarf and ~$L_{\ast}$ galaxies where scattering rates vary with local plasma properties motivated by extrinsic turbulence (ET) or self-confinement (SC) scenarios, with varying assumptions about e.g. turbulent power spectra on un-resolved scales, Alfven-wave damping, etc. We self-consistently predict observables including $\gamma$-rays ($L_{\gamma}$), grammage, residence times, and CR energy densities to constrain the models. We demonstrate many non-linear dynamical effects (not captured in simpler models) tend to enhance confinement. For example, in multi-phase media, even allowing arbitrary fast transport in neutral gas does not substantially reduce CR residence times (or $L_{\gamma}$), as transport is rate-limited by the ionized WIM and 'inner CGM' gaseous halo ($10^{4}-10^{6}$ K gas within 10-30 kpc), and $L_{\gamma}$ can be dominated by trapping in small 'patches.' Most physical ET models contribute negligible scattering of ~1-10 GeV CRs, but it is crucial to account for anisotropy and damping (especially of fast modes) or else scattering rates would violate observations. We show that the most widely-assumed scalings for SC models produce excessive confinement by factors >100 in the WIM and inner CGM, where turbulent and Landau damping dominate. This suggests either a breakdown of quasi-linear theory used to derive the CR transport parameters in SC, or that other novel damping mechanisms dominate in intermediate-density ionized gas.

[5]  arXiv:2002.06214 [pdf, other]
Title: Two new Double-lined Spectroscopic Binary White Dwarfs
Comments: MNRAS, in press
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We present radial velocity observations of four binary white dwarf candidates identified through their over-luminosity. We identify two new double-lined spectroscopic binary systems, WD 0311-649 and WD 1606+422, and constrain their orbital parameters. WD 0311-649 is a 17.7 h period system with a mass ratio of $1.44 \pm 0.06$ and WD 1606+422 is a 20.1 h period system with a mass ratio of $1.33 \pm 0.03$. An additional object, WD 1447-190, is a 43 h period single-lined white dwarf binary, whereas WD 1418-088 does not show any significant velocity variations over timescales ranging from minutes to decades. We present an overview of the 14 over-luminous white dwarfs that were identified by Bedard et al., and find the fraction of double- and single-lined systems to be both 31%. However, an additional 31% of these over-luminous white dwarfs do not show any significant radial velocity variations. We demonstrate that these must be in long-period binaries that may be resolved by Gaia astrometry. We also discuss the over-abundance of single low-mass white dwarfs identified in the SPY survey, and suggest that some of those systems are also likely long period binary systems of more massive white dwarfs.

[6]  arXiv:2002.06218 [pdf, other]
Title: The Life Cycle of the Central Molecular Zone. II: Distribution of atomic and molecular gas tracers
Comments: 19 pages, 11 figures, accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We use the hydrodynamical simulation of our inner Galaxy presented in Armillotta et al. (2019) to study the gas distribution and kinematics within the CMZ. We use a resolution high enough to capture the gas emitting in dense molecular tracers such as NH3 and HCN, and simulate a time window of 50 Myr, long enough to capture phases during which the CMZ experiences both quiescent and intense star formation. We then post-process the simulated CMZ to calculate its spatially-dependent chemical and thermal state, producing synthetic emission data cubes and maps of both HI and the molecular gas tracers CO, NH3 and HCN. We show that, as viewed from Earth, gas in the CMZ is distributed mainly in two parallel and elongated features extending from positive longitudes and velocities to negative longitudes and velocities. The molecular gas emission within these two streams is not uniform, and it is mostly associated to the region where gas flowing towards the Galactic Center through the dust lanes collides with gas orbiting within the ring. Our simulated data cubes reproduce a number of features found in the observed CMZ. However, some discrepancies emerge when we use our results to interpret the position of individual molecular clouds. Finally, we show that, when the CMZ is near a period of intense star formation, the ring is mostly fragmented as a consequence of supernova feedback, and the bulk of the emission comes from star-forming molecular clouds. This correlation between morphology and star formation rate should be detectable in observations of extragalactic CMZs.

[7]  arXiv:2002.06231 [pdf, other]
Title: The orbital content of bars: The origin of 'non-x1-tree', bar-supporting orbits
Comments: 20 pages, 16 figures, 4 tables with small figures, published in Monthly Notices of the Royal Astronomical Society
Journal-ref: MNRAS 490, pp.2740-2759, 2020
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Recently, many orbital studies in barred galaxy potentials have revealed the existence of orbits which are not trapped around x1 tree orbits, but could be potentially appropriate building blocks for bars. These findings question the uniqueness of the x1 family as the standard paradigm of orbital motion in galactic bars. The main goal of this paper is to investigate the role that such orbits could play in shaping the morphology of bars. We trace the morphological patterns appearing in the face-on and edge-on views of the non-periodic orbits presented in these studies and we show that they are introduced in the system by second type bifurcations of x1. For this purpose, we use a typical 3D Ferrers bar model and follow the radial and vertical bifurcations of the x1 family considered as being multi periodic, with multi = 2, 3, 5. The variation of the stability indices of x1 in the multi = 2, 3 cases give us also the four- and six- periodic orbits, respectively. We tabulate these orbits including all information necessary to assess their role as appropriate building blocks. We discuss their stability and their extent, as well as their size and morphological evolution, as a function of energy. We conclude that even the most important of the multi-periodic orbits presented in Tables 2 to 5 are less appropriate building blocks for bars than the families of the x1 tree at the same energy.

[8]  arXiv:2002.06234 [pdf, other]
Title: A Cross-Correlation Study of High-energy Neutrinos and Tracers of Large-Scale Structure
Comments: 10 pages, 6 figures. Comments welcome
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

The origin of the bulk of the astrophysical neutrinos detected by the IceCube Observatory remains a mystery. Previous source-finding analyses compare the directions of IceCube events and individual sources in astrophysical catalogs. The source association method is technically challenging when the number of source candidates is much larger than the number of the observed astrophysical neutrinos. We show that in this large source number regime, a cross-correlation analysis of neutrino data and source catalog can instead be used to constrain potential source populations for the high-energy astrophysical neutrinos, and provide spatial evidence for the existence of astrophysical neutrinos. We present an analysis of the cross-correlation of the IceCube 2010-2012 point-source data and a WISE-2MASS galaxy sample. While we find no significant detection of cross-correlation with the publicly available neutrino dataset, we show that, when applied to the full IceCube data, which has a longer observation time and higher astrophysical neutrino purity, our method has sufficient statistical power to detect a cross-correlation signal if the neutrino sources trace the Large Scale Structure of the Universe.

[9]  arXiv:2002.06240 [pdf, other]
Title: Gravitational waves from r-mode instability of massive young sub- and super-Chandrasekhar white dwarfs
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)

In the present work we investigate the r-mode instability windows, spindown and spindown rates of sub- and super-Chandrasekhar magnetized white dwarfs in presence of Landau quantization of the electron gas and magnetic braking. The gravitational wave strain amplitudes due to r-mode instability is also calculated. The dominant damping mechanism is taken to be the shear viscosity arising due to scattering of the degenerate electrons from the ion liquid. We find that the critical frequencies of Landau quantized magnetized white dwarfs are the lowest, those of non-Landau quantized ones are higher and those of non-magnetized ones are the highest at the same temperature. This implies that magnetic braking and Landau quantization both enhance r-mode instability. We have also seen that there is rapid spindown of magnetized white dwarfs due to additional magnetic braking term but there is no considerable effect of Landau quantization on the spindown and spindown rates for magnetic field strengths relevant for white dwarf interiors. We find that the r-mode gravitational wave strain amplitude for a rapidly rotating super-Chandrasekhar white dwarf at 1 kpc is $\sim 10^{-27}$ making isolated massive rapidly rotating hot magnetized white dwarfs prime candidates for search of gravitational waves in the future.

[10]  arXiv:2002.06249 [pdf, other]
Title: Coronal Dimming as a Proxy for Stellar Coronal Mass Ejections
Comments: 8 pages, 4 figures, to appear in the Proceedings of IAU Symposium No. 354 - Solar and Stellar Magnetic Fields: Origins and Manifestations
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)

Solar coronal dimmings have been observed extensively in the past two decades and are believed to have close association with coronal mass ejections (CMEs). Recent study found that coronal dimming is the only signature that could differentiate powerful ares that have CMEs from those that do not. Therefore, dimming might be one of the best candidates to observe the stellar CMEs on distant Sun-like stars. In this study, we investigate the possibility of using coronal dimming as a proxy to diagnose stellar CMEs. By simulating a realistic solar CME event and corresponding coronal dimming using a global magnetohydrodynamics model (AWSoM: Alfven-wave Solar Model), we first demonstrate the capability of the model to reproduce solar observations. We then extend the model for simulating stellar CMEs by modifying the input magnetic flux density as well as the initial magnetic energy of the CME flux rope. Our result suggests that with improved instrument sensitivity, it is possible to detect the coronal dimming signals induced by the stellar CMEs.

[11]  arXiv:2002.06294 [pdf, ps, other]
Title: The gluon condensation effect in the cosmic hadron spectra
Comments: 24 pages, 9 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)

Hardening of cosmic proton- and nuclei-spectra is explained by using the gluon condensation (GC) model, which states that a large amount of gluons in proton may condense near the high energy threshold. The results present the universality of the GC-effect, which may be a common origin of a series of anomalous astrophysical phenomena including the broken power-law in gamma-ray spectra, the excess in positron- and electron-spectra and hardening of proton- and nuclei-spectra.

[12]  arXiv:2002.06297 [pdf, ps, other]
Title: Characterizing X-ray properties of the gamma-ray pulsar PSR J1418$-$6058 in the Rabbit pulsar wind nebula
Comments: 7 pages, 3 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We report on X-ray studies of the gamma-ray pulsar PSR J1418$-$6058 in the Rabbit pulsar wind nebula (PWN) carried out using archival Chandra and XMM-Newton observations. A refined timing analysis performed with the 120-ks XMM-Newton data finds significant ($p\approx10^{-7}$) pulsation at $P\approx110$ ms which is consistent with that measured with the Fermi large area telescope (LAT). In the Chandra image, we find extended emission around the pulsar similar to those seen around other pulsars in young PWNe, which further argues for association between PSR J1418$-$6058 and the Rabbit PWN. The X-ray spectrum of the pulsar is hard and similar to those of soft-gamma pulsars. Hence PSR J1418$-$6058 may add to the list of soft-gamma pulsars.

[13]  arXiv:2002.06321 [pdf, other]
Title: Cascade Model for Planetesimal Formation by Turbulent Clustering
Comments: 26 pages, 11 figures, 3 tables, accepted for publication by The Astrophysical Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

We use a newly developed cascade model of turbulent concentration of particles in protoplanetary nebulae to calculate several properties of interest to the formation of primitive planetesimals and to the meteorite record. The model follows, and corrects, calculations of the primary planetesimal Initial Mass Function (IMF) by Cuzzi et al. (2010), in which an incorrect cascade model was used. Here we use the model of Hartlep et al. (2017), which has been validated against several published numerical simulations of particle concentration in turbulence. We find that, for a range of nebula and particle properties, planetesimals may be "born big", formed as sandpiles with diameters in the 10-100 km range, directly from freely floating particles. The IMFs have a modal nature, with a well-defined peak rather than a powerlaw size dependence. Predictions for the inner and outer nebula behave similarly in these regards, and observations of inner and outer nebula primitive bodies support such modal IMFs. Also, we present predictions of local particle concentrations on several lengthscales in which particles "commonly" find themselves, which have significance for meteoritical observations of the redox state and isotopic fractionation in regions of chondrule formation. An important difference between these results, and those of Cuzzi et al. (2010), is that particle growth-by-sticking must proceed to at least the 1-few cm radius range for the IMF and meteoritical properties to be most plausibly satisfied. That is, as far as the inner nebula goes, the predominant "particles" must be aggregates of chondrules (or chondrule-size precursors) rather than individual chondrules themselves.

[14]  arXiv:2002.06354 [pdf, other]
Title: Constraints on Cosmological and Galaxy Parameters from Strong Gravitational Lensing Systems
Comments: 22 Pages, 7 Figures and 6 Tables. Comments are welcome
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Strong gravitational lensing along with the distance sum rule method can constrain both cosmological parameters as well as density profiles of galaxies without assuming any fiducial cosmological model. To constrain galaxy parameters and cosmic curvature, we use a newly compiled database of $161$ galactic scale strong lensing systems for distance ratio data. For the luminosity distance in the distance sum rule method, we use databases of supernovae type-Ia (Pantheon) and Gamma Ray Bursts (GRBs). We use a general lens model, namely the Extended Power-Law lens model. We consider three different parametrisations of mass density power-law index $(\gamma)$ to study the dependence of $\gamma$ on redshift. We find that parametrisations of $\gamma$ have a negligible impact on the best fit value of cosmic curvature parameter.
Furthermore, measurement of time delay can provide a promising cosmographic probe via the "time delay distance" that includes the ratio of distances between the observer, lens and the source. We use the distance sum rule method with $12$ datapoints of time-delay distance data to put constraints on the Cosmic Distance Duality Relation (CDDR) and the cosmic curvature parameter. For this we consider three different parametrisations of distance duality parameter $(\eta)$. Our results indicate that a flat universe can be accommodated within $95\%$ confidence level for all the parametrisations of $\eta$. Further, we find that within 95\% confidence level, there is no violation of CDDR if $\eta$ is assumed to be redshift dependent but CDDR is violated if $\eta$ is considered redshift independent. Hence, we need a larger sample of strong gravitational lensing systems in order to improve the constraints on the cosmic curvature and distance duality parameter.

[15]  arXiv:2002.06373 [pdf, other]
Title: Stellar activity consequence on the retrieved transmission spectra through chromatic Rossiter-McLaughlin observations
Comments: 8 pages, 10 figures, 2 tables, accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Mostly multiband photometric transit observations have been used so far to retrieve broadband transmission spectra of transiting exoplanets in order to study their atmosphere. An alternative method has been proposed and has only been used once to recover transmission spectra using chromatic Rossiter-McLaughlin observations. Stellar activity has been shown to potentially imitate narrow and broadband features in the transmission spectra retrieved from multiband photometric observations; however, there has been no study regarding the influence of stellar activity on the retrieved transmission spectra through chromatic Rossiter-McLaughlin. In this study with the modified SOAP3.0 tool, we consider different types of stellar activity features (spots and plages), and we generated a large number of realistic chromatic Rossiter-McLaughlin curves for different types of planets and stars. We were then able to retrieve their transmission spectra to evaluate the impact of stellar activity on them. We find that chromatic Rossiter-McLaughlin observations are also not immune to stellar activity, which can mimic broadband features, such as Rayleigh scattering slope, in their retrieved transmission spectra. We also find that the influence is independent of the planet radius, orbital orientations, orbital period, and stellar rotation rate. However, more general simulations demonstrate that the probability of mimicking strong broadband features is lower than 25% and that can be mitigated by combining several Rossiter-McLaughlin observations obtained during several transits.

[16]  arXiv:2002.06381 [pdf, ps, other]
Title: Measurements of $H_0$ in modified gravity theories
Comments: 8 pages, 3 figures, 3 tables. Comments are welcome
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)

In this work, we obtain measurements of the Hubble constant in the context of modified gravity theories. We set up our theoretical framework by considering viable cosmological $f(R)$ and $f(T)$ models, and we analyzed them through the use of geometrical data sets obtained in model-independently way, namely, gravitationally lensed quasars with measured time delays, standard clocks from cosmic chronometers, and standard candles from the Pantheon Supernovae Ia sample. We find $H_0=(72.4\pm 1.4)$ km s$^{-1}$ Mpc$^{-1}$ and $H_0=(71.5\pm 1.3)$ km s$^{-1}$ Mpc$^{-1}$ for the $f(R)$ and $f(T)$ models, respectively. Our results represent 1.9\% and 1.8\% measurements of the Hubble constant, which are fully consistent with the local estimate of $H_0$ by the Hubble Space Telescope. We do not find significant departures from general relativity, as our study shows that the characteristic parameters of the extensions of gravity beyond general relativity are compatible with the $\Lambda$CDM cosmology. Moreover, within the standard cosmological framework, our joint analysis suggests that it is possible to measure the dark energy equation of state parameter at 1.2\% accuracy, although we find no statistical evidence for deviations from the cosmological constant case.

[17]  arXiv:2002.06388 [pdf, other]
Title: Blueshifted absorption lines from X-ray reflection in IRAS 13224-3809
Comments: 6 pages, 5 figures, accepted for publication in MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We explore a disc origin for the highly-blueshifted, variable absorption lines seen in the X-ray spectrum of the Narrow Line Seyfert 1 galaxy IRAS13224-3809. The blueshift corresponds to a velocity of about 0.25c. Such features in other Active Galactic Nuclei are often interpreted as UltraFast Outflows (UFOs). The velocity is of course present in the orbital motions of the inner disk. The absorption lines in IRAS13224-3809 are best seen when the flux is low and the reflection component of the disk is strong relative to the power-law continuum. The spectra are consistent with a model in which the reflection component passes through a thin, highly-ionized absorbing layer at the surface of the inner disc, the blue-shifted side of which dominates the flux due to relativistic aberration (the disc inclination is about 70 deg). No fast outflow need occur beyond the disc.

[18]  arXiv:2002.06408 [pdf, other]
Title: Classification of Photospheric Emission in Short GRBs
Comments: Submitted for publication in Ap.J
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

In order to better understand the physical origin of short duration gamma-ray bursts (GRBs), we perform time-resolved spectral analysis on a sample of 70 pulses in 68 short GRBs with burst duration $T_{90}\lesssim2$~s detected by the \textit{Fermi}/GBM during the first 11 years of its mission. We apply Bayesian analysis to all spectra that have statistical significance $S\ge15$ within each pulse and apply a cut-off power law (CPL) model. For our analysis, we identify the maximal values of the low energy spectral index, $\alpha_{\rm max}$. Under the assumption that the main emission mechanism is the same throughout each pulse, such an analysis is indicative of pulse emission. We find that $\sim$1/3 of short GRBs are consistent with a pure, non-dissipative photospheric model, at least, around the peak of the pulse. This fraction is larger compare to the corresponding one (1/4) obtained for long GRBs. For those bursts which are compatible with a pure photospheric origin, we find (i) a bi-modal distribution in the values of the Lorentz factors and the hardness ratios; (ii) an anti-correlation between $T_{90}$ and the peak energy, $E_{\rm pk}$: $T_{90} \propto E_{\rm pk}^{-0.35\pm0.01}$. This correlation disappears when we consider the entire short GRB sample. Our results thus imply that short GRB population may in fact be composed of two separate populations: a continuation of the long GRB population to shorter duration, and a separate population with distinct physical properties. Furthermore, thermal emission is initially ubiquitous, but is accompanied at longer times by additional radiation (likely synchrotron), making time-resolved spectroscopy absolutely necessary in analyzing GRB pulses.

[19]  arXiv:2002.06414 [pdf, other]
Title: The optical luminosity function of LOFAR radio-selected quasars at $1.4\leq z\leq5.0$ in the NDWFS-Boötes field
Comments: 29 pages, 24 figures. Accepted in A&A
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We present an estimate of the optical luminosity function (OLF) of LOFAR radio-selected quasars (RSQs) at $1.4<z<5.0$ in the $9.3\:\textrm{deg}^{2}$ NOAO Deep Wide-field survey (NDWFS) of the Bo\"otes field. The selection was based on optical/mid-ir photometry used to train three different machine learning (ML) algorithms. Objects taken as quasars by the ML algorithms are required to be detected at $5\sigma$ significance in deep radio maps to be classified as candidate quasars. The optical imaging came from the SDSS and the PS1 $3\pi$ survey; mid-ir photometry was taken from the SDWFS survey; and radio data was obtained from deep LOFAR imaging of the NDWFS-Bo\"otes field. The requirement of a $5\sigma$ LOFAR detection allowed us to reduce the stellar contamination in our sample by two orders of magnitude. The sample comprises 134 objects, including both photometrically selected candidate quasars (47) and spectroscopically confirmed quasars (83). The depth of our LOFAR observations allowed us to detect the radio-emission of quasars that would be otherwise classified as radio-quiet. Around $65\%$ of the quasars in the sample are fainter than $M_{\textrm{1450}}<-24.0$, a regime where the OLF of quasars selected through their radio emission, has not been investigated in detail. It has been demonstrated that in cases where mid-ir wedge-based AGN selection is not possible due to a lack of appropriate data, the selection of quasars using ML algorithms trained with optical/mid-ir photometry in combination with LOFAR data provides an excellent approach for obtaining samples of quasars. We demonstrate that RSQs show an evolution similar to the exhibited by faint quasars $(M_{\textrm{1450}}<-22.0)$. Finally, we find that RSQs may compose up to $\sim20\%$ of the whole faint quasar population (radio-detected plus radio-undetected).

[20]  arXiv:2002.06434 [pdf, ps, other]
Title: The Warm Gas in the MW: A Kinematical Model
Comments: Accepted by ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We develop a kinematical model for the Milky Way Si IV-bearing gas to determine its density distribution and kinematics. This model is constrained by a column density line shape sample extracted from the {\it HST}/COS archival data, which contains 186 AGN sight lines. We find that the Si IV ion density distribution is dominated by an extended disk along the $z$-direction (above or below the midplane), i.e., $n(z)=n_0\exp(-(z/z_0)^{0.82})$, where $z_0$ is the scale height of $6.3_{-1.5}^{+1.6}$ kpc (northern hemisphere) and $3.6_{-0.9}^{+1.0}$ kpc (southern hemisphere). The density distribution of the disk in the radial direction shows a sharp edge at $15-20$ kpc given by, $n(r_{\rm XY})=n_0\exp(-(r_{\rm XY}/r_0)^{3.36})$, where $r_0 \approx 12.5\pm0.6$ kpc. The difference of density distributions over $r_{\rm XY}$ and $z$ directions indicates that the warm gas traced by \ion{Si}{4} is mainly associated with disk processes (e.g., feedback or cycling gas) rather than accretion. We estimate the mass of the warm gas (within 50 kpc) is $\log (M(50 {\rm kpc})/M_\odot)\approx8.1$ (assuming $Z\approx0.5Z_\odot$), and a $3\sigma$ upper limit of $\log (M(250 {\rm kpc})/M_\odot)\approx9.1$ (excluding the Magellanic system). Kinematically, the warm gas disk is nearly co-rotating with the stellar disk at $v_{\rm rot}=215\pm3\rm~km~s^{-1}$, which lags the midplane rotation by about $8\rm~km~s^{-1}~kpc^{-1}$ (within 5 kpc). Meanwhile, we note that the warm gas in the northern hemisphere has significant accretion with $v_{\rm acc}$ of $69\pm 7\rm ~km~s^{-1}$ at 10 kpc (an accretion rate of $-0.60_{-0.13}^{+0.11}~M_\odot\rm~yr^{-1}$), while in the southern hemisphere, there is no measurable accretion, with an upper limit of $0.4~M_\odot\rm~yr^{-1}$.

[21]  arXiv:2002.06435 [pdf, ps, other]
Title: New and improved rotational periods of magnetic CP stars from ASAS-3, KELT and MASCARA data
Comments: 19 pages, 4 tables, 8 figures; the complete light curve figures are available from the authors and in the final publication; accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

Magnetic chemically peculiar (mCP) stars allow the investigation of such diverse phenomena as atomic diffusion, magnetic fields and stellar rotation. The aim of the present investigation is to enhance our knowledge of the rotational properties of mCP stars by increasing the sample of objects with accurately determined rotational periods. To this end, archival photometric time-series data from the ASAS-3, KELT and MASCARA surveys were employed to improve existing rotational period information and derive rotational periods for mCP stars hitherto not known to be photometric variables. Our final sample consists of 294 mCP stars, a considerable amount of which (more than 40%) are presented here as photometric variables for the first time. In addition, we identified 24 mCP star candidates that show light variability in agreement with rotational modulation but lack spectroscopic confirmation. The rotational period distribution of our sample agrees well with the literature.Most stars are between 100Myr and 1Gyr old, with an apparent lack of very young stars. No objects were found on the zero age main sequence; several stars seem to have evolved to the subgiant stage, albeit well before the first dredge-up. We identified four eclipsing binaries (HD 244391, HD 247441, HD 248784 and HD 252519), which potentially host an mCP star. This is of great interest because mCP stars are very rarely found in close binary systems, particularly eclipsing ones. Using archival spectra, we find strong evidence that the HD 252519 system indeed harbours an mCP star component.

[22]  arXiv:2002.06446 [pdf, ps, other]
Title: Constraints on the muon fraction and density profile in neutron stars
Comments: 12 pages including 9 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)

Muons in neutron stars (NSs) play especially important roles in addressing several interesting new physics questions associated with detecting as well as understanding interactions and astrophysical effects of muonphilic dark matter particles. The key model inputs for studying the latter are the total muon mass $M_{\mu}$, the muon mass fraction $M_{\mu}/M_{\rm NS}$ over the NS mass $M_{\rm NS}$ and the muon radial density profile $\rho_{\mu}(r)$ in NSs of varying masses. We investigate these quantities within a minimum model for the core of NSs consisting of neutrons, protons, electrons, and nuons using an explicitly isospin-dependent parametric Equation of State (EOS) constrained by available nuclear laboratory experiments and the latest astrophysical observations of NS masses, radii and tidal deformabilities. We found that the absolutely maximum muon mass $M_{\mu}$ and its mass fraction $M_{\mu}/M_{\rm NS}$ in the most massive NSs allowed by causality are about 0.025 $M_\odot$ and 1.1\%, respectively. For the most massive NS of mass 2.14 $M_\odot$ observed so far, they reduce to about 0.020 $M_\odot$ and 0.9\%, respectively. We also study respective effects of individual parameters describing the EOS of high-density neutron-rich nucleonic matter on the muon contents in NSs with varying masses. We found that the most important but uncertain nuclear physics ingredient for determining the muon contents in NSs is the high-density nuclear symmetry energy.

[23]  arXiv:2002.06466 [pdf, other]
Title: Coupled Thermal and Compositional Evolution of Photo Evaporating Planet Envelopes
Comments: 13 Pages, 6 Figures. Submitted to Apj, and edited based off of the reviewer's suggestions. Any community comments welcome. We plan to resubmit to Apj shortly, pending community suggestions
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Photo-evaporative mass loss sculpts the atmospheric evolution of tightly-orbiting sub-Neptune-mass exoplanets. To date, models of the mass loss from warm Neptunes have assumed that the atmospheric abundances remain constant throughout the planet's evolution. However, the cumulative effects of billions of years of escape modulated by diffusive separation and preferential loss of hydrogen can lead to planetary envelopes that are enhanced in helium and metals relative to hydrogen (Hu et al. 2015). We have performed the first self-consistent calculations of the coupled thermal, mass-loss, and compositional evolution of hydrogen-helium envelopes surrounding sub-Neptune mass planets. We extended the MESA (Modules for Experiments in Stellar Astrophysics) stellar evolution code to model the evolving envelope abundances of photo-evaporating planets. We find that GJ 436b, the planet that originally inspired Hu et al. (2015) to propose the formation of helium enhanced planetary atmospheres, requires a primordial envelope that is too massive to become helium enhanced. Nonetheless, we show that helium enhancement is possible for planets with masses similar to GJ 436b after only several Gyr of mass loss. These planets have $R_p\lesssim 3.00~R_\oplus$, initial $f_{\rm env} < 0.5\%$, irradiation flux $\sim$10$^1$-10$^3$ times that of Earth, and obtain final helium fractions in excess of Y=0.40 in our models. The results of preferential envelope loss may have observable consequences on mass-radius relations and atmospheric spectra for sub-Neptune populations.

[24]  arXiv:2002.06475 [pdf, other]
Title: An Andean Deep-Valley Detector for High-Energy Tau Neutrinos
Comments: 15 pages, 6 figures, white paper submitted to the Latin American Strategy Forum for Research Infrastructure (LASF4RI)
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)

High-energy astrophysical neutrinos, recently discovered by IceCube up to energies of several PeV, opened a new window to the high-energy Universe. Yet much remains to be known. IceCube has excellent muon flavor identification, but tau flavor identification is challenging. This limits its ability to probe neutrino physics and astrophysics. To address this limitation, we present a concept for a large-scale observatory of astrophysical tau neutrinos in the 1-100 PeV range, where a flux is guaranteed to exist. Its detection would allow us to characterize the neutrino sources observed by IceCube, to discover new ones, and test neutrino physics at high energies. The deep-valley air-shower array concept that we present provides highly background-suppressed neutrino detection with pointing resolution <1 degree, allowing us to begin the era of high-energy tau-neutrino astronomy.

[25]  arXiv:2002.06479 [pdf, other]
Title: The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XXI. Binaries among multiple stellar populations
Comments: 13 pages, 11 figures, published in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

A number of scenarios for the formation of multiple populations in globular clusters (GCs) predict that second generation (2G) stars form in a compact and dense subsystem embedded in a more extended first-generation (1G) system. If these scenarios are accurate, a consequence of the denser 2G formation environment is that 2G binaries should be more significantly affected by stellar interactions and disrupted at a larger rate than 1G binaries. The fractions and properties of binary stars can thus provide a dynamical fingerprint of the formation epoch of multiple-population GCs and their subsequent dynamical evolution. We investigate the connection between binaries and multiple populations in five GCs, NGC 288, NGC 6121 (M 4), NGC 6352, NGC 6362, and NGC 6838 (M 71). To do this, we introduce a new method based on the comparison of Hubble Space Telescope observations of binaries in the F275W, F336W, F438W, F606W and F814W filters with a large number of simulated binaries. In the inner regions probed by our data we do not find large differences between the local 1G and the 2G binary incidences in four of the studied clusters, the only exception being M 4 where the 1G binary incidence is about three times larger than the 2G incidence. The results found are in general agreement with the results of simulations predicting significant differences in the global 1G and 2G incidences and in the local values in the clusters' outer regions but similar incidences in the inner regions. The significant difference found in M 4 is consistent with simulations with a larger fraction of wider binaries. Our analysis also provides the first evidence of mixed (1G-2G) binaries, a population predicted by numerical simulations to form in a cluster's inner regions as a result of stellar encounters during which one component of a binary is replaced by a star of a different population.

[26]  arXiv:2002.06492 [pdf, ps, other]
Title: Image formation for extended sources with the solar gravitational lens
Comments: 37 pages, 15 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Detectors (physics.ins-det); Optics (physics.optics)

We study the image formation process with the solar gravitational lens (SGL) in the case of an extended, resolved source. An imaging telescope, modeled as a convex lens, is positioned within the image cylinder formed by the light received from the source. In the strong interference region of the SGL, this light is greatly amplified, forming the Einstein ring around the Sun, representing a distorted image of the extended source. We study the intensity distribution within the Einstein ring observed in the focal plane of the convex lens. For any particular telescope position in the image plane, we model light received from the resolved source as a combination of two signals: light received from the directly imaged region of the source and light from the rest of the source. We also consider the case when the telescope points away from the extended source or, equivalently, it observes light from sources in sky positions that are some distance away from the extended source, but still in its proximity. At even larger distances from the optical axis, in the weak interference or geometric optics regions, our approach recovers known models related to microlensing, but now obtained via the wave-optical treatment. We then derive the power of the signal and related photon fluxes within the annulus that contains the Einstein ring of the extended source, as seen by the imaging telescope. We discuss the properties of the deconvolution process, especially its effects on noise in the recovered image. We compare anticipated signals from realistic exoplanetary targets against estimates of noise from the solar corona and estimate integration times needed for the recovery of high-quality images of faint sources. The results demonstrate that the SGL offers a unique, realistic capability to obtain resolved images of exoplanets in our galactic neighborhood.

[27]  arXiv:2002.06500 [pdf, ps, other]
Title: The Formation of the Double Gaussian Line Profiles of the Symbiotic Star AG Peg
Comments: 9 pages, 9 figures, and 4 tables
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We analyze high dispersion emission lines of the symbiotic nova AG Peg, observed in 1998, 2001, and 2002. The H$\alpha$ and H$\beta$ lines show three components, two narrow and one underlying broad line components, but most other lines, such as HI, HeI, and HeII lines, show two blue- and red-shifted components only. A recent study by Lee & Hyung (2018) suggested that the double Gaussian lines emitted from a bipolar conic shell is likely to form Raman scattering lines observed in 1998. In this study, we show that the bipolar cone with an opening angle of 74$^{o}$, which expands at a velocity of 70 kms$^{-1}$ along the polar axis of the white dwarf, can accommodate the observed double line profiles in 1998, 2001, and 2002. We conclude that the emission zone of the bipolar conic shell, which formed along the bipolar axis of the white dwarf due to the collimation by the accretion disk, is responsible for the double Gaussian profiles.

[28]  arXiv:2002.06537 [pdf, ps, other]
Title: Discovery of a new supernova remnant G21.8-3.0
Comments: 8 pages, 4 figures (figure quality is reduced due to the size limit), accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph)

Sensitive radio continuum surveys of the Galactic plane are ideal for discovering new supernova remnants (SNRs). From the Sino-German {\lambda}6 cm polarisation survey of the Galactic plane, an extended shell-like structure has been found at l = 21.8 degree, b = -3.0 degree, which has a size of about 1 degree. New observations were made with the Effelsberg 100-m radio telescope at {\lambda}11 cm to estimate the source spectrum together with the Urumqi {\lambda}6 cm and the Effelsberg {\lambda}21 cm data. The spectral index of G21.8-3.0 was found to be {\alpha} = -0.72 {\pm} 0.16. Polarised emission was mostly detected in the eastern half of G21.8-3.0 at both {\lambda}6 cm and {\lambda}11 cm. These properties, together with the H{\alpha} filament along its northern periphery and the lack of infrared emission, indicate that the emission is non-thermal as is usual in shell-type SNRs.

[29]  arXiv:2002.06550 [pdf, other]
Title: Oscillations of the baseline of solar magnetic field and solar irradiance on a millennial timescale
Comments: 7 pages, 5 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)

Recently discovered long-term oscillations of the solar background magnetic field associated with double dynamo waves generated in inner and outer layers of the Sun indicate that the solar activity is heading in the next three decades (2019-2055) to a Modern grand minimum similar to Maunder one. On the other hand, a reconstruction of solar total irradiance suggests that since the Maunder minimum there is an increase in the cycle-averaged total solar irradiance (TSI) by a value of about $1-1.5$ $Wm^{-2}$ closely correlated with an increase of the baseline (average) terrestrial temperature. In order to understand these two opposite trends, we calculated the double dynamo summary curve of magnetic field variations backward one hundred thousand years allowing us to confirm strong oscillations of solar activity in regular (11 year) and recently reported grand (350-400 year) solar cycles caused by actions of the double solar dynamo. In addition, oscillations of the baseline (zero-line) of magnetic field with a period of $1950\pm95$ years (a super-grand cycle) are discovered by applying a running averaging filter to suppress large-scale oscillations of 11 year cycles. Latest minimum of the baseline oscillations is found to coincide with the grand solar minimum (the Maunder minimum) occurred before the current super-grand cycle start. Since then the baseline magnitude became slowly increasing towards its maximum at $~$2700 to be followed by its decrease and minimum at $~$3700. These oscillations of the baseline solar magnetic field are found associated with a long-term solar inertial motion about the barycenter of the solar system that can lead to a further natural increase of the terrestrial temperature by 2.5-3.0$^\circ$C.

[30]  arXiv:2002.06566 [pdf, other]
Title: Asteroseismology of evolved stars to constrain the internal transport of angular momentum. III. Using the rotation rates of intermediate-mass stars to test the Fuller-formalism
Comments: Accepted in A&A as letter (reference: AA/2020/37568)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Context: The internal characteristics of stars, such as their core rotation rates, are obtained via asteroseismic observations. A comparison of core rotation rates found in this way with core rotation rates as predicted by stellar evolution models demonstrate a large discrepancy. This means that there must be a process of angular momentum transport missing in the current theory of stellar evolution. A new formalism was recently proposed to fill in for this missing process, which has the Tayler instability as its starting point (hereafter referred to as `Fuller-formalism'). Aims: We investigate the effect of the Fuller-formalism on the internal rotation of stellar models with an initial mass of 2.5 Mo. Methods: Stellar evolution models, including the Fuller-formalism, of intermediate-mass stars were calculated to make a comparison between asteroseismically obtained core rotation rates in the core He burning phase and in the white dwarf phase. Results: Our main results show that models including the Fuller-formalism can match the core rotation rates obtained for the core He burning phases. However, these models are unable to match the rotation rates obtained for white dwarfs. When we exclude the Fuller-formalism at the end of the core He burning phase, the white dwarf rotation rates of the models match the observed rates. Conclusions: We conclude that in the present form, the Fuller-formalism cannot be the sole solution for the missing process of angular momentum transport in intermediate-mass stars.

[31]  arXiv:2002.06600 [pdf, other]
Title: Two-dimensional Multi-fiber Spectrum Image Correction Based on Machine Learning Techniques
Comments: 10 pages, 14 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Artificial Intelligence (cs.AI)

Due to limited size and imperfect of the optical components in a spectrometer, aberration has inevitably been brought into two-dimensional multi-fiber spectrum image in LAMOST, which leads to obvious spacial variation of the point spread functions (PSFs). Consequently, if spatial variant PSFs are estimated directly , the huge storage and intensive computation requirements result in deconvolutional spectral extraction method become intractable. In this paper, we proposed a novel method to solve the problem of spatial variation PSF through image aberration correction. When CCD image aberration is corrected, PSF, the convolution kernel, can be approximated by one spatial invariant PSF only. Specifically, machine learning techniques are adopted to calibrate distorted spectral image, including Total Least Squares (TLS) algorithm, intelligent sampling method, multi-layer feed-forward neural networks. The calibration experiments on the LAMOST CCD images show that the calibration effect of proposed method is effectible. At the same time, the spectrum extraction results before and after calibration are compared, results show the characteristics of the extracted one-dimensional waveform are more close to an ideal optics system, and the PSF of the corrected object spectrum image estimated by the blind deconvolution method is nearly central symmetry, which indicates that our proposed method can significantly reduce the complexity of spectrum extraction and improve extraction accuracy.

[32]  arXiv:2002.06627 [pdf, other]
Title: Orbital ingredients for cooking X-structures in edge-on galaxies
Comments: Accepted for publication in ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA)

X-structures are often observed in galaxies hosting the so-called B/PS (boxy/peanuts) bulges and are visible from the edge-on view. They are the most notable features of B/PS bulges and appear as four rays protruding from the disk of the host galaxy and distinguishable against the B/PS bulge background. In some works their origin is thought to be connected with the so-called banana-shaped orbits with a vertical resonance 2:1. A star in such an orbit performs two oscillations in the vertical direction per one revolution in the bar frame. Several recent studies that analyzed ensembles of orbits arising in different $N$-body models do not confirm the dominance of the resonant 2:1 orbits in X-structures. In our work we analyze two $N$-body models and show how the X-structure in our models is gradually assembled from the center to the periphery from orbits with less than 2:1 frequency ratio. The most number of such orbits is enclosed in a 'farfalle'-shape (Italian pasta) form and turns out to be non-periodic. We conclude that the X-structure is only the envelope of regions of high density caused by the crossing or folding of different types of orbits at their highest points, and does not have a "backbone" similar to that of the in-plane bar. Comparing the orbital structure of two different numerical models, we show that the dominance of one or another family of orbits with a certain ratio of the vertical oscillations frequency to the in-plane frequency depends on the parameters of the underlying galaxy and ultimately determines the morphology of the X-structure and the opening angle of its rays.

[33]  arXiv:2002.06646 [pdf, other]
Title: Relationships between Photospheric Vertical Electric Currents and Hard X-Ray Sources in Solar Flares: Statistical Study
Comments: 56 pages, 21 figures, accepted in ApJ
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

There are still debates whether particle acceleration in solar flares may occur due to interruption of electric currents flowing along magnetic loops. To contribute to this problem, we performed the first statistical study of relationships between flare hard X-ray (HXR; $50-100$ keV) sources observed by the \textit{Ramaty High-Energy Solar Spectroscopic Imager} (RHESSI) and photospheric vertical electric currents (PVECs, $j_{r}$) calculated using vector magnetograms obtained with the Helioseismic and Magnetic Imager (HMI) on-board the \textit{Solar Dynamics Observatory} (SDO). A sample of 48 flares, from C3.0 to X3.1 class, observed in central part of the solar disk by both instruments in 2010--2015 was analyzed. We found that $\approx 70$\% of all HXR sources overlapped with islands or ribbons of enhanced ($\left| j_{r} \right| \gtrsim 10^{4}$ statampere~cm$^{-2}$) PVECs. However, less than $\approx 40$\% of the HXR sources overlapped with PVEC maxima, with an accuracy of $\pm 3^{\prime\prime}$. More than in half of the flares there were HXR sources outside regions of enhanced PVECs. We found no correlation between intensity of the HXR sources and PVEC density or total PVEC under them. No systematic dissipation of PVECs under the HXR sources was found during the flares. Collectively, the results do not support the current-interruption flare models. However, the results indicate the importance of the presence of longitudinal currents in flare regions. Understanding of their specific role in the processes of energy release, plasma heating, and acceleration of particles requires further investigation.

[34]  arXiv:2002.06651 [pdf, other]
Title: Cycles on the Solar-Type Stars and Cooler Dwarfs
Comments: Accepted by Geomagnetism and Aeronomy, 2019, V.59, No 7. 7 pages, 4 figures, 1 table
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Features of the development of activity cycles in the solar-type stars and fast-rotating cool dwarfs have been considered for 65 stars observed in some decades. Cycles with duration of 7-18 years compared to the solar cycle were found for about 50% of the studied stars. In cooler dwarfs with rotation periods of less than 5 days, cyclic changes in brightness occur on longer scales, up to 80 years. Activity of the highest level is produced on K dwarfs; their main cycles are long and have the highest amplitudes. Both old and young solar-type stars show a similar tendency in increasing the cycle length with a slower rotation. No evidence for a relation between the rotation period and duration of cycles was found for cool dwarfs with $P_{rot} < 5$ days.

[35]  arXiv:2002.06656 [pdf, other]
Title: Enhanced spectrum of primordial perturbations, galaxy formation and small scale structure
Comments: 23 pages and 17 figures. Comments welcomed
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

The standard structure formation scenario is successful on linear scales. Several apparent problems affect it however at galactic scales, such as the small scale problems at low redshift and more recent issues involving early massive galaxy and black hole formation. As these problems arise where complex baryonic physics becomes important, the associated unknowns are often assumed to be behind the problems. But the same scales are also those where the primordial spectrum is relatively unconstrained, and there are several ways in which it can be modified. We focus on that arising from effects possibly associated with the crossing of high energy cutoff scale by fluctuation modes during inflation. Elementary arguments show that adiabatic evolution cannot modify the near scale invariance, we thus discuss a simple model for the contrary extreme of sudden transition. Numerical calculations and simple arguments suggest that its predictions, for parameters considered here, are more generic than may be expected, with significant modifications requiring a rapid transition. We examine the implications of such a scenario, in this simplest form of sudden jump, on the matter power spectrum and halo mass function in light of the limitations imposed by particle production. We show that enhancement and oscillation in the power spectrum on currently nonlinear scales can potentially simultaneously alleviate both the apparent problem of early structure formation and, somewhat counterintuitively, problems at low redshift such as the apparent dearth of dwarf galaxies. We discuss consequences that can observationally constrain the scenario and its parameters, including an inflationary Hubble scale $\lesssim 10^{-8} M_{\rm Pl}$, while touching on the possibility of simultaneous modification of power on the largest scales.

[36]  arXiv:2002.06693 [pdf, other]
Title: Bringing high spatial resolution to the Far-infrared -- A giant leap for astrophysics
Comments: White Paper, submitted to ESA in August 2019 in response to the "Voyage 2050" process; 24 pages, 12 figures, 1 table; three references updated from preprint to journal status, one reference added in comparison to the version submitted to ESA
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det)

The far-infrared (FIR) regime is one of the few wavelength ranges where no astronomical data with sub-arcsecond spatial resolution exist. Neither of the medium-term satellite projects like SPICA, Millimetron nor O.S.T. will resolve this malady. For many research areas, however, information at high spatial and spectral resolution in the FIR, taken from atomic fine-structure lines, from highly excited carbon monoxide (CO), light hydrids, and especially from water lines would open the door for transformative science. A main theme will be to trace the role of water in proto-planetary disks, to observationally advance our understanding of the planet formation process and, intimately related to that, the pathways to habitable planets and the emergence of life. Furthermore, key observations will zoom into the physics and chemistry of the star-formation process in our own Galaxy, as well as in external galaxies. The FIR provides unique tools to investigate in particular the energetics of heating, cooling and shocks. The velocity-resolved data in these tracers will reveal the detailed dynamics engrained in these processes in a spatially resolved fashion, and will deliver the perfect synergy with ground-based molecular line data for the colder dense gas.

[37]  arXiv:2002.06698 [pdf, other]
Title: How massive are the superfluid cores in the Crab and Vela pulsars and why their glitch-events are accompanied with under and overshootings?
Comments: 9 pages, 10 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Superconductivity (cond-mat.supr-con); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

The Crab and Vela are well-studied glitching pulsars and the data obtained sofar should enable us to test the reliability of models of their internal structures. Very recently it was proposed that glitching pulsars are embedded in bimetric spacetime: their incompressible superfluid cores (SuSu-cores) are embedded in flat spacetime, whereas the ambient compressible and dissipative media are enclosed in Schwarzschild spacetime.
In this letter we apply this model to the Crab and Vela pulsars and show that a newly born pulsar initially of $1.25\text{M}_{\odot}$ and an embryonic SuSu-core of $0.029\text{M}_{\odot}$ could evolve into a \ARZL{Crab-like}\ARZR pulsar after 1000 years and into a \ARZL{Vela-like}\ARZR pulsar 10000 years later to finally fade away as an invisible dark energy object after roughly 10 Myr. Based thereon we infer that the Crab and the Vela pulsars should have SuSu-cores of $0.15\text{M}_{\odot}$ and $0.55\text{M}_{\odot}$, respectively.
Futhermore, the under- and overshootings phenomena observed to accompany the glitch events of the Vela pulsar are rather a common phenomenon of glitching pulsars that can be well-explained within the framework of bimetric spacetime.

[38]  arXiv:2002.06711 [pdf, other]
Title: A method of enhancing source detection sensitivity in Gaussian noise, with application to PSR 1937+21 and GW150914
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

The Gaussian phase noise of intensity time series is demonstrated to be drastically reduced when the raw voltage data are digitally filtered through an arbitrarily large number $n$ of orthornormal bandpass profiles (eigen-filters) sharing the same intensity bandwidth, and the resulting intensity series are co-added. Specifically, the relative noise variance of the summed series at the resolution of one coherence time or less, goes down with increasing $n$ as $1/n$, although (consistent with the radiometer equation) the advantage gradually disappears when the series is bin averaged to lower resolution. Thus the algorithm is designed to enhance the sensitivity of detecting transients that are smoothed out by time averaging and too faint to be visible in the noisy unaveraged time series, as demonstrated by the simulation of a weak embedded time varying signal of either a periodic nature or a fast and unrepeated pulse. The algorithm is then applied to a 10 minute observation of the pulsar PSR 1937+21 by the VLA, where the theoretical predictions were verified by the data. Moreover, it is shown that microstructures within the time profile are better defined as the number $n$ of filters used increases, and a periodic signal of period $1.86 \times 10^{-5}$~s ($53.9$~kHz) is discovered in the pulse profile. Lastly, we apply the algorithm to the first binary black hole merger detected by LIGO, GW150914. We find the SNR of the mean peak intensity increases as $\sqrt{n}$ and cross correlation of the event between the LIGO-Hanford-Livingston detector pair increases with filter order $n$.

[39]  arXiv:2002.06720 [pdf]
Title: Color, Composition, and Thermal Environment of Kuiper Belt Object (486958) Arrokoth
Comments: 31 pages, 8 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

The outer Solar System object (486958) Arrokoth (provisional designation 2014 MU$_{69}$) has been largely undisturbed since its formation. We study its surface composition using data collected by the New Horizons spacecraft. Methanol ice is present along with organic material, which may have formed through radiation of simple molecules. Water ice was not detected. This composition indicates hydrogenation of carbon monoxide-rich ice and/ or energetic processing of methane condensed on water ice grains in the cold, outer edge of the early Solar System. There are only small regional variations in color and spectra across the surface, suggesting Arrokoth formed from a homogeneous or well-mixed reservoir of solids. Microwave thermal emission from the winter night side is consistent with a mean brightness temperature of 29$\pm$5 K.

[40]  arXiv:2002.06722 [pdf, ps, other]
Title: Two Component Jets of GRB160623A as Shocked Jet cocoon afterglow
Comments: Accepted to ApJ Letters; 8 pages, 4 figures, 1 table
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Two components of jets associated with the afterglow of the gamma-ray burst GRB 160623A were observed with multi-frequency observations including long-term monitoring in a sub-millimetre range (230 GHz) using the SMA. The observed light curves with temporal breaks suggests on the basis of the standard forward-shock synchrotron radiation model that the X-ray radiation is narrowly collimated with an opening angle $\theta_{n,j}<\sim6^{\circ}$ whereas the radio radiation originated from wider jets ($\sim27^{\circ}$). The temporal and spectral evolutions of the radio afterglow agree with those expected from a synchrotron radiation modelling with typical physical parameters except for the fact that the observed wide jet opening angle for the radio emission is significantly larger than the theoretical maximum opening angle. By contrast, the opening angle of the X-ray afterglow is consistent with the typical value of GRB jets. Since the theory of the relativistic cocoon afterglow emission is similar to that of a regular afterglow with an opening angle of $\sim30^{\circ}$, the observed radio emission can be interpreted as the shocked jet cocoon emission. This result therefore indicates that the two components of the jets observed in the GRB 160623A afterglow is caused by the jet and the shocked jet cocoon afterglows.

[41]  arXiv:2002.06730 [pdf, ps, other]
Title: SED modelling of broadband emission in the pulsar wind nebula 3C 58
Comments: Accepted for publication in Astronomische Nachrichten
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We investigate broadband emission properties of the pulsar wind nebula (PWN) 3C 58 using a spectral energy distribution (SED) model. We attempt to match simultaneously the broadband SED and spatial variations of X-ray emission in the PWN. We further the model to explain a possible far-IR feature of which a hint is recently suggested in 3C 58: a small bump at $\sim$$10^{11}$ GHz in the PLANCK and Herschel band. While external dust emission may easily explain the observed bump, it may be internal emission of the source implying an additional population of particles. Although significance for the bump is not high, here we explore possible origins of the IR bump using the emission model and find that a population of electrons with GeV energies can explain the bump. If it is produced in the PWN, it may provide new insights into particle acceleration and flows in PWNe.

[42]  arXiv:2002.06749 [pdf, ps, other]
Title: Angular Expansion of Nova Shells
Comments: 8 pages, 2 figures, 3 tables. Accepted for publication in ApJ
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Nova shells can provide us with important information on their distance, their interactions with the circumstellar and interstellar media, and the evolution in morphology of the ejecta. We have obtained narrow-band images of a sample of five nova shells, namely DQHer, FHSer, TAur, V476Cyg, and V533Her, with ages in the range from 50 to 130 years. These images have been compared with suitable available archival images to derive their angular expansion rates. We find that all the nova shells in our sample are still in the free expansion phase, which can be expected, as the mass of the ejecta is 7-45 times larger than the mass of the swept-up circumstellar medium. The nova shells will keep expanding freely for time periods up to a few hundred years, reducing their time dispersal into the interstellar medium.

[43]  arXiv:2002.06754 [pdf, other]
Title: Velocity Gradient in the Presence of Self-Gravity: Identifying Gravity-induced Inflow and Determining Collapsing Stage
Comments: 25 pages, 18 figures, submitted to ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Understanding how star formation is regulated requires studying the energy balance between turbulence, magnetic fields, feedback, and gravity within molecular clouds. However, identifying the transition region where the gravity takes over and collapse occurs remains elusive. Recent studies of the Velocity Gradient Technique (VGT), which is an advanced tool for magnetic field studies, reveal that the velocity gradient changes its direction by 90 degrees with respect to the magnetic field in the regions of gravitational collapse. In this study, we confirm that the self-gravity induces the change of orientation and high gradient amplitude for both the velocity gradient and intensity gradient. We explore two ways of identifying self-gravitating regions through the double-peak feature in the histogram of gradients' orientation and the curvature of gradients. We show that velocity gradients' morphology and amplitude can be synthetically used to trace the convergent inflows. By comparing with the column density Probability Density Functions method, we show that VGT is a powerful new tool for studying the gas dynamics and tracing magnetic field in star-forming regions. By analogy with VGT, we extend the Intensity Gradient Technique (IGT) to locate the gravitational collapsing region and shock. We show that the synergy of VGT and IGT can determine the collapsing stages in a star-forming region. We conclude that star formation can happen very successfully in strongly magnetized and fully ionized media.

[44]  arXiv:2002.06782 [pdf, ps, other]
Title: Reducing the $H_{0}$ tension with generalized Proca theory
Comments: 13 pages, 5 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

We investigate the cosmological viability of the generalized proca theory. We first implement the background and linear perturbation equations of motion in the Boltzmann code and then study the constraints on the parameters of the generalized proca theory after running MCMC against the cosmological data set. With Planck + HST data, we obtain the constraint $h=0.7334_{-0.0269}^{+0.0246}$, which indicates that the tension between early universe and late time universe within this theory is removed. By adding other late-time data sets (BAO, RSD, etc.) we show that the tension is reduced, as the 2$\sigma$ allowed region for $h$ in Proca, $h=0.7041_{-0.0087}^{+0.0094}$, overlaps with the 2$\sigma$ region of the HST data.

[45]  arXiv:2002.06787 [pdf, ps, other]
Title: Observational Evidence for Stochastic Shock Drift Acceleration of Electrons at the Earth's Bow Shock
Comments: 7 pages, 4 figures. Published in PRL
Journal-ref: Phys. Rev. Lett., 124, 065101, 2020
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Earth and Planetary Astrophysics (astro-ph.EP); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)

The first-order Fermi acceleration of electrons requires an injection of electrons into a mildly relativistic energy range. However, the mechanism of injection has remained a puzzle both in theory and observation. We present direct evidence for a novel stochastic shock drift acceleration theory for the injection obtained with Magnetospheric Multiscale (MMS) observations at Earth's bow shock. The theoretical model can explain electron acceleration to mildly relativistic energies at high-speed astrophysical shocks, which may provide a solution to the long-standing issue of electron injection.

[46]  arXiv:2002.06814 [pdf, other]
Title: Segmenting the Universe into dynamically coherent basins
Comments: 8 pages, 11 figures, submitted to MNRAS
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

This article explores in depth a watershed concept to partition the universe, introduced in \cite{2019MNRAS.489L...1D} and applied to the {\it Cosmicflows-3} observational dataset. We present a series of tests conducted with cosmological dark matter simulations. In particular we are interested in quantifying the evolution with redshift of large scale structures when defined as segmented basins of attraction. This new dynamical definition in the field of measuring standard rulers demonstrates robustness since all basins show a density contrast $\delta$ above one (mean universe density) independently of the simulation spatial resolution or the redshift. Another major finding is that density profiles of the basins show universality in slope. Consequently, there is a unique definition of what is a gravitational watershed at large scale, that can be further used as a probe for cosmology studies.

[47]  arXiv:2002.06833 [pdf, ps, other]
Title: Morphology of TeV gamma-ray emission from the kpc scale jets in radio galaxies
Authors: W. Bednarek
Comments: 20 pages, 14 figures, ApJ, accepted
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

TeV gamma rays are observed from a few nearby radio galaxies whose jets are viewed at relatively large angles towards the observer. This emission can be produced in the kpc scale jets whose Lorentz factors are decelerated from values of the order of several at the parsec scale distances. We consider in detail the model in which TeV gamma-ray emission is produced by the relativistic electrons in the kpc scale jet which comptonize strongly beamed radiation from the inner (parsec scale) jet. As an example, we study morphology of the TeV gamma-ray emission from the decelerated kpc scale jet in the nearby radio galaxy Cen~A. It is shown that TeV gamma-ray emission can extend throughout the kpc scale distances, being relatively smoothly distributed along the jet for some parameters of the considered model. Investigation of the morphological structure of such specific gamma-ray emission by the future Cherenkov Telescope Array (e.g. CTA) should provide important constraints on the content and dynamics of the kpc scale jet in Cen~A.

[48]  arXiv:2002.06844 [pdf, ps, other]
Title: Stellar masks and bisector's shape for M-type stars observed in the GAPS Programme with HARPS-N at TNG
Comments: 13 pages, 8 figures Accepted for publication in Experimental Astronomy
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

The HARPS/HARPS-N Data Reduction Software (DRS) relies on the cross-correlation between the observed spectra and a suitable stellar mask to compute a cross-correlation function (CCF) to be used both for the radial velocity (RV) computation and as an indicator of stellar lines asymmetry, induced for example by the stellar activity. Unfortunately the M2 mask currently used by the HARPS/HARPS-N DRS for M-type stars results in heavily distorted CCFs. We created several new stellar masks in order to decrease the errors in the RVs and to improve the reliability of the activity indicators as the bisector's span. We obtained very good results with a stellar mask created from the theoretical line list provided by the VALD3 database for an early M-type star (T$_{\mathrm{eff}}$=3500~K and $\log{g}=4.5$). The CCF's shape and relative activity indicators improved and the RV time-series allowed us to recover known exoplanets with periods and amplitudes compatible with the results obtained with HARPS-TERRA.

[49]  arXiv:2002.06857 [pdf, other]
Title: CS Depletion in Prestellar Cores
Authors: Shinyoung Kim (1, 2), Chang Won Lee (1, 2), Maheswar Gopinathan (3), Mario Tafalla (4), Jungjoo Sohn (5), Gwanjeong Kim (6), Mi-Ryang Kim (1), Archana Soam (7), Philip C. Myers (8) ((1) Korea Astronomy and Space science Institute, (2) University of Science and Technology, Korea, (3) Indian Institute of Astrophysics, (4) IGN, Observatorio Astronómico Nacional, (5) Korea National University of Education, (6) National Astronomical Observatory of Japan, (7) SOFIA Science Center, USRA, NASA Ames Research Center, (8) Center for Astrophysics, Harvard & Smithsonian)
Comments: 20 pages, 9 figures, Accepted for publication in ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

The CS molecule is known to be absorbed onto dust in the cold and dense conditions, causing it to get significantly depleted in the central region of cores. This study is aimed to investigate the depletion of the CS molecule using the optically thin C$^{34}$S molecular line observations. We mapped five prestellar cores, L1544, L1552, L1689B, L694-2, and L1197 using two molecular lines, C$^{34}$S $(J=2-1)$ and N$_2$H$^+$ $(J=1-0)$ with the NRO 45-m telescope, doubling the number of cores where the CS depletion was probed using C$^{34}$S. In most of our targets, the distribution of C$^{34}$S emission shows features that suggest that the CS molecule is generally depleted in the center of the prestellar cores. The radial profile of the CS abundance with respect to H$_2$ directly measured from the CS emission and the Herschel dust emission indicates that the CS molecule is depleted by a factor of $\sim$3 toward the central regions of the cores with respect to their outer regions. The degree of the depletion is found to be even more enhanced by an order of magnitude when the contaminating effect introduced by the presence of CS molecules in the surrounding envelope that lie along the line-of-sight is removed. Except for L1197 which is classified as relatively the least evolved core in our targets based on its observed physical parameters, we found that the remaining four prestellar cores are suffering from significant CS depletion at their central region regardless of the relative difference in their evolutionary status.

[50]  arXiv:2002.06871 [pdf, ps, other]
Title: Protostellar Outflows at the EarliesT Stages (POETS). IV. Statistical properties of the 22 GHz H2O masers
Comments: 8 pages, 6 figures, accepted for publication in Astronomy & Astrophysics
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

We wish to perform a statistical study of the location and motion of individual 22 GHz water maser cloudlets, characterized by sizes that are within a few au, with respect to the radio thermal emission from young stellar objects (YSO). For this purpose, we have been carrying out the Protostellar Outflows at the EarliesT Stages (POETS) survey of a sample (38) of high-mass YSOs. The water maser positions and three-dimensional (3D) velocities were determined through Very Long Baseline Array observations with accuracies of a few milliarcsec (mas) and a few km/s, respectively. The position of the ionized core of the protostellar wind, marking the YSO, was determined through sensitive continuum Jansky Very Large Array observations with a typical error of 20 mas. The statistic of the separation of the water masers from the radio continuum shows that 84% of the masers are found within 1000 au from the YSO and 45% of them are within 200 au. Therefore, we can conclude that the 22 GHz water masers are a reliable proxy for the YSO position. The distribution of maser luminosity is strongly peaked towards low values, indicating that about half of the maser population is still undetected with the current Very Long Baseline Interferometry detection thresholds of 50-100 mJy/beam. Next-generation, sensitive radio interferometers will exploit these weak masers for an improved sampling of the velocity and magnetic fields around the YSOs. The average direction of the water maser proper motions provides a statistically-significant estimate for the orientation of the jet emitted by the YSO: 55% of the maser proper motions are directed on the sky within an angle of 30 deg from the jet axis. Finally, we show that our measurements of 3D maser velocities statistically support models in which water maser emission arises from planar shocks with propagation direction close to the plane of the sky.

[51]  arXiv:2002.06881 [pdf, other]
Title: Galaxy kinematics across different environments in the RXJ1347-1145 cluster complex
Comments: 25 pages, 11 figures. Accepted for publication in A&A (06.02.2020)
Subjects: Astrophysics of Galaxies (astro-ph.GA)

In order to understand the role of the different processes that drive galaxy evolution in clusters, we need comprehensive studies that simultaneously examine several of the most important characteristics of galaxies. In this work we examine the physical properties of cluster galaxies at z=0.45 attending to the degree of distortion of their rotation curves. Regular rotating galaxies were included in our Tully-Fisher analysis while the distorted ones were used to study the role of cluster-specific interactions with respect to star formation and AGN activity. We report a higher fraction of galaxies with irregular gas kinematics in the cluster environment than in the field. Cluster galaxies with regular rotation display a moderate brightening in the B-band Tully-Fisher relation compatible with the gradual evolution of the stellar populations with lookback time, and no significant evolution in the stellar-mass Tully-Fisher relation, in line with previous studies at similar redshift. Average specific star formation rate (sSFR) values are slightly lower in our cluster sample (-0.15 dex) with respect to the main sequence of star-forming galaxies, confirming the role of the environment in the early quenching of star formation in clusters. Finally, we carried out an exploratory observational study on the stellar-to-halo mass relation finding that cluster galaxies tend to have slightly lower stellar mass values for a fixed halo mass compared to their field counterparts.

[52]  arXiv:2002.06892 [pdf, other]
Title: The evidence for a spatially flat Universe
Comments: submitted to MNRAS
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

We revisit the observational constraints on spatial curvature following recent claims that the Planck data favour a closed Universe. We use a new and statistically powerful Planck likelihood to show that the Planck temperature and polarization spectra are consistent with a spatially flat Universe, though because of a geometrical degeneracy cosmic microwave background spectra on their own do not lead to tight constraints on the curvature density parameter Omega_K. When combined with other astrophysical data, particularly geometrical measurements of baryon acoustic oscillations, the Universe is constrained to be spatially flat to extremely high precision, with Omega_ K = 0.0004 +/-0.0018 in agreement with the 2018 results of the Planck team. In the context of inflationary cosmology, the observations offer strong support for models of inflation with a large number of e-foldings and disfavour models of incomplete inflation.

[53]  arXiv:2002.06902 [pdf, other]
Title: TICs 167692429 and 220397947: The first compact hierarchical triple stars discovered with TESS
Comments: Accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)

We report the discovery and complex analyses of the first two compact hierarchical triple star systems discovered with TESS in or near its southern continuous viewing zone during Year 1. Both TICs 167692429 and 220397947 were previously unknown eclipsing binaries, and the presence of a third companion star was inferred from eclipse timing variations exhibiting signatures of strong 3rd-body perturbations and, in the first system, also from eclipse depth variations. We carried out comprehensive analyses, including the simultaneous photodynamical modelling of TESS and archival ground-based WASP lightcurves, as well as eclipse timing variation curves. Also, for the first time, we included in the simultaneous fits multiple star spectral energy distribution data and theoretical PARSEC stellar isochrones, taking into account Gaia DR2 parallaxes and cataloged metallicities. We find that both systems have twin F-star binaries and a lower mass tertiary star. In the TIC 167692429 system the inner binary is moderately inclined ($i_{mut}=27^o$) with respect to the outer orbit, and the binary vs. outer (triple) orbital periods are 10.3 vs. 331 days, respectively. The mutually inclined orbits cause a driven precession of the binary orbital plane which leads to the disappearance of binary eclipses for long intervals. In the case of TIC 220397947 the two orbital planes are more nearly aligned and the inner vs. outer orbital periods are 3.5 and 77 days, respectively. In the absence of radial velocity observations, we were unable to calculate highly accurate masses and ages for the two systems. According to stellar isochrones TIC 167692429 might be either a pre-main sequence or an older post-MS system. In the case of TIC 220397947 our solution prefers a young, pre-MS scenario.

[54]  arXiv:2002.06913 [pdf, other]
Title: R-process enrichment in ultrafaint dwarf galaxies
Comments: 9 pages, 6 figures, resubmitted to MNRAS after first revision
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We study the enrichment and mixing of r-process elements in ultrafaint dwarf galaxies (UFDs). We assume that r-process elements are produced by neutron-star mergers (NSMs), and examine multiple models with different natal kick velocities and explosion energies. To this end, we perform cosmological simulations of galaxy formation to follow mixing of the dispersed r-process elements driven by star formation and the associated stellar feedback in progenitors of UFDs. We show that the observed europium abundance in Reticulum II is reproduced by our inner explosion model where a NSM is triggered at the centre of the galaxy, whereas the relatively low abundance in Tucana III is reproduced if a NSM occurs near the virial radius of the progenitor galaxy. The latter case is realised only if the neutron-star binary has a large natal kick velocity and travels over a long distance of a kilo-parsec before merger. In both the inner and outer explosion cases, it is necessary for the progenitor galaxy to sustain prolonged star formation over a few hundred million years after the NSM, so that the dispersed r-process elements are well mixed within the inter-stellar medium. Short-duration star formation results in inefficient mixing, and then a large variation is imprinted in the stellar europium abundances, which is inconsistent with the observations of Reticulum II and Tucana III.

[55]  arXiv:2002.06917 [pdf, other]
Title: Modelling and simulations of supernova remnants: a short review focused on recent progress in morphological studies
Authors: Gilles Ferrand
Comments: Invited talk at XMM workshop "Astrophysics of hot plasma in extended X-ray sources" Accepted for publication in Astronomische Nachrichten
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Supernova remnants (SNRs) are the outcome of supernovae (SNe, either core-collapse or thermonuclear). The remnant results from the interaction between the stellar ejecta and the ambient medium around the progenitor star. Young SNRs are characterized by strong shocks that heat and ionize the gas, generate magneto-hydrodynamic turbulence, and accelerate particles to relativistic energies. They radiate at all wavelengths, especially in the X-ray domain, where spectro-imaging observations can provide a wealth of information. This paper presents recent progress in the modelling of SNRs, particularly by the means of numerical simulations, and with a focus on three-dimensional aspects. In the first part we will consider SNRs as producers of cosmic rays (CRs). If SNRs are accelerators efficient enough to power the Galactic component of CRs, this must have a visible impact on their dynamics, and therefore on the thermal emission from the plasma, as well as on their non-thermal emission. In the second part we will consider SNRs as probes of the explosion mechanism. The time has come to connect multi-dimensional simulations of SNe and simulations of SNRs, opening the possibility to study the explosion mechanism via the dynamics and morphology of SNRs.

[56]  arXiv:2002.06918 [pdf, ps, other]
Title: Can we constrain the extragalactic magnetic field from very high energy observations of GRB 190114C?
Comments: 4 pages, 2 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Primary very high energy $\gamma$-rays from $\gamma$-ray bursts (GRBs) are partially absorbed on extragalactic background light (EBL) photons with subsequent formation of intergalactic electromagnetic cascades. Characteristics of the observable cascade $\gamma$-ray signal are sensitive to the strength and structure of the extragalactic magnetic field (EGMF). GRB 190114C was recently detected with the MAGIC imaging atmospheric Cherenkov telescopes, for the first time allowing to estimate the observable cascade intensity for various EGMF configurations. We inquire whether any constraints on the EGMF strength and structure could be obtained from publicly-available $\gamma$-ray data on GRB 190114C. We present detailed calculations of the observable cascade signal for various EGMF configurations. We show that the sensitivity of the Fermi-LAT space $\gamma$-ray telescope is not sufficient to obtain such constraints on the EGMF parameters.

[57]  arXiv:2002.06924 [pdf, other]
Title: New constraints on the magnetization of the cosmic web using LOFAR Faraday rotation observations
Comments: 12 pages, 7 figures, 2 tables. Submitted to MNRAS. Comments welcome
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)

Measuring the properties of extragalactic magnetic fields through the effect of Faraday rotation provides a means to understand the origin and evolution of cosmic magnetism. Here we use data from the LOFAR Two-Metre Sky Survey (LoTSS) to calculate the Faraday rotation measure (RM) of close pairs of extragalactic radio sources. By considering the RM difference ($\Delta$RM) between physical pairs (e.g. double-lobed radio galaxies) and non-physical pairs (i.e. close projected sources on the sky), we statistically isolate the contribution of extragalactic magnetic fields to the total RM variance along the line of sight. We find a difference in the rms of $\Delta$RM between non-physical and physical pairs of 0.4$\pm$0.3 rad/m$^2$, and a difference in the corresponding median |$\Delta$RM| values of 0.3$\pm$0.4 rad/m$^2$. This enables us to place an upper limit on the co-moving cosmological magnetic field strength of $B < 2.5$ nG on Mpc scales. This limit is obtained by exploring a wide range of input magnetic field strengths in a model of cosmic over-densities that realistically reflects the observed matter inhomogeneities on large scales. We also compare the LOFAR RM data with a suite of cosmological MHD simulations, that explore different magnetogenesis scenarios. Both magnetization of the large scale structure by astrophysical processes such as galactic and AGN outflows, and simple primordial scenarios with seed field strengths of $B\lesssim0.5$ nG cannot be rejected by the current data, while stronger primordial fields or models with dynamo amplification in filaments are disfavoured. In general, LOFAR polarized sources are typically located in regions of the Universe with low RM variance, making them excellent probes of the weak magnetization of cosmic filaments and voids far from galaxy cluster environments.

[58]  arXiv:2002.06925 [pdf, other]
Title: SMM J04135+10277: A distant QSO-starburst system caught by ALMA
Comments: Accepted by MNRAS; 14 pages, 9 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

The gas content of galaxies is a key factor for their growth, starting from star formation and black hole accretion to galaxy mergers. Thus, characterising its properties via observations of tracers like the CO emission line is of big importance in order to understand the bigger picture of galaxy evolution. We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of dust continuum, CO(5-4) and CO(8-7) line emission in the quasar--star-forming companion system SMM J04135+10277 (z=2.84). Earlier low-$J$ CO studies of this system found a huge molecular gas reservoir associated to the companion galaxy, while the quasar appeared gas-poor. Our CO observations revealed that the host galaxy of the quasar is also gas-rich, with an estimated molecular gas mass of $\sim(0.7-2.3)\times10^{10}$ M$_{\odot}$. The CO line profiles of the companion galaxy are broad ($\sim1000$ km s$^{-1}$), and show signs of rotation of a compact, massive system. In contrast to previous far-infrared observations, we resolve the continuum emission and detect both sources, with the companion galaxy dominating the dust continuum and the quasar having a $\sim25\%$ contribution to the total dust emission. By fitting the infrared spectral energy distribution of the sources with \textsc{MR-MOOSE} and empirical templates, the infrared luminosities of the quasar and the companion are in the range of $L_{\rm IR, QSO}\sim(2.1-9.6)\times10^{12}$ L$_{\odot}$ and $L_{\rm IR, Comp.}\sim(2.4-24)\times10^{12}$ L$_{\odot}$, while the estimated star formation rates are $\sim210-960$ M$_{\odot}$ yr$^{-1}$ and $\sim240-2400$ M$_{\odot}$ yr$^{-1}$, respectively. Our results demonstrate that non-detection of low-$J$ CO transition lines in similar sources does not necessarily imply the absence of massive molecular gas reservoir but that the excitation conditions favour the excitation of high-$J$ transitions.

[59]  arXiv:2002.06939 [pdf, other]
Title: Empirical Line Lists in the ExoMol Database
Journal-ref: Atoms 2020, 8(1), 7
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Chemical Physics (physics.chem-ph)

The ExoMol database aims to provide comprehensive molecular line lists for exoplanetary and other hot atmospheres. The data are expanded by inclusion of empirically derived line lists taken from the literature for a series of diatomic molecules, namely CH, NH, OH, AlCl, AlF, OH$^+$, CaF, MgF, KF, NaF, LiCl, LiF, MgH, TiH, CrH, FeH, C$_2$, CP, CN, CaH, and triplet N$_2$. Generally, these line lists are constructed from measured spectra using a combination of effective rotational Hamiltonian models for the line positions and ab initio (transition) dipole moments to provide intensities. This work results in the inclusion of 22 new molecules (36 new isotopologues) in the ExoMol database.

[60]  arXiv:2002.06966 [pdf, other]
Title: MHD-shock structures of astrospheres: \textlambda~Cephei-like astrospheres
Comments: 14 pages, 9 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)

The interpretation of recent observations of bow shocks around O-stars and the creation of corresponding models require a detailed understanding of the associated (magneto-)hydrodynamic structures. We base our study on three-dimensional numerical magneto-)hydrodynamical models, which are analyzed using the dynamically relevant parameters, in particular, the (magneto)sonic Mach numbers. The analytic Rankine-Hugoniot relation for HD and MHD are compared with those obtained by the numerical model. In that context we also show that the only distance which can be approximately determined is that of the termination shock, if it is a hydrodynamical shock. For MHD shocks the stagnation point does not, in general, lie on the inflow line, which is the line parallel to the inflow vector and passing through the star. Thus an estimate via the Bernoulli equation as in the HD case is, in general, not possible. We also show that in O-star astrospheres, distinct regions exist in which the fast, slow, Alfv\'enic, and sonic Mach numbers become lower than one, implying sub-slow magnetosonic as well as sub-fast and sub-sonic flows. Nevertheless, the analytic MHD Rankine Hugoniot relations can be used for further studies of turbulence and cosmic ray modulation.

[61]  arXiv:2002.06971 [pdf, other]
Title: Formation of complex molecules in translucent clouds: Acetaldehyde, vinyl alcohol, ketene, and ethanol via nonenergetic processing of C2H2 ice
Comments: 17 pages, 12 figures, 2 tables
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)

Complex organic molecules (COMs) have been identified toward high- and low-mass protostars as well as molecular clouds, suggesting that these interstellar species originate from the early stage(s) of starformation. The reaction pathways resulting in COMs described by the formula C$_2$H$_\text{n}$O are still under debate. In this work, we investigate the laboratory possible solid-state reactions that involve simple hydrocarbons and OH-radicals along with H$_2$O ice under translucent cloud conditions (1$\leq$A$_V$$\leq$5 and \textit{n}$_\text{H}$$\sim$10$^3$ cm$^{-3}$). We focus on the interactions of C$_2$H$_2$ with H-atoms and OH-radicals, which are produced along the H$_2$O formation sequence on grain surfaces at 10 K. Ultra-high vacuum (UHV) experiments were performed to study the surface chemistry observed during C$_2$H$_2$ + O$_2$ + H codeposition, where O$_2$ was used for the in-situ generation of OH-radicals. Reflection absorption infrared spectroscopy (RAIRS) was applied to in situ monitor the initial and newly formed species. After that, a temperature-programmed desorption experiment combined with a Quadrupole mass spectrometer (TPD-QMS) was used as a complementary analytical tool. The investigated 10 K surface chemistry of C$_2$H$_2$ with H-atoms and OH-radicals not only results in semi and fully saturated hydrocarbons, such as ethylene (C$_2$H$_4$) and ethane (C$_2$H$_6$), but it also leads to the formation of COMs, such as vinyl alcohol, acetaldehyde, ketene, ethanol, and possibly acetic acid. It is concluded that OH-radical addition reactions to C$_2$H$_2$, acting as a molecular backbone, followed by isomerization (i.e., keto-enol tautomerization) via an intermolecular pathway and successive hydrogenation provides a so far experimentally unreported solid-state route for the formation of these species without the need of energetic input.

[62]  arXiv:2002.06980 [pdf, other]
Title: ProSpect: Generating Rapid Spectral Energy Distributions with Complex Star Formation and Metallicity Histories
Comments: 24 pages, 35 figures, 8 tables. Submitted to MNRAS in Dec 2019- having waited two months, posting now for ESOz 2020 meeting
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)

We introduce ProSpect, a generative galaxy spectral energy distribution code that can also be used for parameter inference. ProSpect comes with two popular families of stellar population libraries (BC03 and EMILES), and a large variety of methods to construct star formation and metallicity histories. It models dust through the use of a Charlot & Fall (2000) attenuation model with re-emission using Dale, et al. (2014) far-infrared templates. It also has the ability to model AGN through the inclusion of a simple AGN and hot torus model. Finally, it makes use of MAPPINGS-III photoionisation tables to produce line emission features. We test the generative and inversion utility of ProSpect through application to the Shark semi-analytic code, and informed by these results produce fits to the final photometric catalogues produces by the Galaxy and Mass Assembly Survey (GAMA). As part of the testing of ProSpect, we also produce a range of simple photometric stellar mass approximations covering a range of filters for both observed frame and rest frame photometry.

[63]  arXiv:2002.07004 [pdf, other]
Title: Seeds of Life in Space (SOLIS).VII. Discovery of a cold dense methanol blob toward the L1521F VeLLO system
Comments: 11 pages, 7 figures, 3 tables, accepted for publication by A&A
Subjects: Astrophysics of Galaxies (astro-ph.GA)

The SOLIS (Seeds Of Life In Space) IRAM/NOEMA Large Program aims at studying a set of crucial complex organic molecules in a sample of sources, with well-known physical structure, covering the various phases of Solar-type star formation. One representative object of the transition from the prestellar core to the protostar phases has been observed toward the Very Low Luminosity Object (VeLLO) called L1521F. This type of source is important to study to make the link between prestellar cores and Class 0 sources and also to constrain the chemical evolution during the process of star formation. Two frequency windows (81.6-82.6 GHz and 96.65-97.65 GHz) were used to observe the emission from several complex organics toward the L1521F VeLLO. Only 2 transitions of methanol (A+, E2) have been detected in the narrow window centered at 96.7 GHz (with an upper limit on E1) in a very compact emission blob (~7'' corresponding to ~1000au) toward the NE of the L1521F protostar. The CS 2-1 transition is also detected within the WideX bandwidth. Consistently, with what has been found in prestellar cores, the methanol emission appears ~1000au away from the dust peak. The location of the methanol blob coincides with one of the filaments previously reported in the literature. The Tex of the gas inferred from methanol is (10$\pm$2) K, while the H2 gas density (estimated from the detected CS 2-1 emission and previous CS 5-4 ALMA obs.) is a factor >25 higher than the density in the surrounding environment (n(H2) >10$^{7}$ cm$^{-3}$). From its compactness, low excitation temperature and high gas density, we suggest that the methanol emission detected with NOEMA is either a cold and dense shock-induced blob, recently formed ($\leq$ few hundred years) by infalling gas or a cold and dense fragment that may have just been formed as a result of the intense gas dynamics found within the L1521F VeLLO system.

[64]  arXiv:2002.07022 [pdf, other]
Title: Tidally induced warps of spiral galaxies in IllustrisTNG
Comments: 13 pages, 11 figures, submitted to MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Warps are common features in both stellar and gaseous disks of nearby spiral galaxies with the latter usually easier to detect. Several theories have been proposed in the literature to explain their formation and prevalence, including tidal interactions with external galaxies. Observational correlations also suggest the importance of tides for warp formation. Here, we use the TNG100 run from the magnetohydrodynamical cosmological simulation suite IllustrisTNG to investigate the connection between interactions and the formation of gas warps. We find that in the sample of well-resolved gas-rich spiral galaxies ($10^{10}\lesssim\mathrm{M_{*}/M_{\odot}}\lesssim10^{11}$ at $z=0$) from the simulation TNG100-1, about $16\%$ possess the characteristic S-shaped warp. Around one third of these objects have their vertical morphology induced by interactions with other galaxies. Half of these interactions end with the perturber absorbed by the host. Warps formed in interactions are more asymmetrical than the remaining sample, however after the interaction the asymmetry decreases with time. We find that warps induced by interactions survive on average for $<1$ Gyr. The angle between the orbital angular momentum of the perturber and the angular momentum of the host's disk that most likely leads to warp formation is around 45 degrees. While our main goal is to investigate tidally induced warps, we find that during interactions in addition to tides, new gas that is accreted from infalling satellites also can contribute to warp formation.

[65]  arXiv:2002.07061 [pdf, other]
Title: Power Law Plateau Inflation Potential In The RS $II$ Braneworld Evading Swampland Conjecture
Comments: 14 pages, 6 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

In the recent time, inflationary cosmology is facing an existential crisis due to the proposed Swampland criterion which aims to evade any (meta-)stable de Sitter construction within the String landscape. It is been realised that a single field slow roll inflation is inconsistent with the Swampland criterion unless the inflationary model in realised in some non standard scenario such as Warm inflation or the Braneworld scenario. In \cite{Dimopoulos}, Dimopoulos and Owen introduced a new class of model of inflation dubbed as the power law plateau inflation in the standard cold inflationary scenario. But to realise this model in the standard scenario consistent with observation, they had to introduce a phase of thermal inflation. In this paper we have analysed this model in the braneworld scenario to show that for some choice of the parameters defining the model class, one can have an observationally consistent power law plateau without any phase of thermal inflation. We have also shown that, for the correct choice of model parameters, one can easily satisfy the Swampland criterion. Besides, for a particular choice of the potential one can also satisfy the recently proposed Trans-Planckian Censorship Conjecture.

Cross-lists for Tue, 18 Feb 20

[66]  arXiv:2002.06212 (cross-list from stat.ML) [pdf, other]
Title: Ensemble Slice Sampling
Subjects: Machine Learning (stat.ML); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG); Computation (stat.CO)

Slice Sampling has emerged as a powerful Markov Chain Monte Carlo algorithm that adapts to the characteristics of the target distribution with minimal hand-tuning. However, Slice Sampling's performance is highly sensitive to the user-specified initial length scale hyperparameter. Moreover, Slice Sampling generally struggles with poorly scaled or strongly correlated distributions. This paper introduces Ensemble Slice Sampling, a new class of algorithms that bypasses such difficulties by adaptively tuning the length scale. Furthermore, Ensemble Slice Sampling's performance is immune to linear correlations by exploiting an ensemble of parallel walkers. These algorithms are trivial to construct, require no hand-tuning, and can easily be implemented in parallel computing environments. Empirical tests show that Ensemble Slice Sampling can improve efficiency by more than an order of magnitude compared to conventional MCMC methods on highly correlated target distributions such as the Autoregressive Process of Order 1 and the Correlated Funnel distribution.

[67]  arXiv:2002.06225 (cross-list from gr-qc) [pdf, other]
Title: SphericalNR: A dynamical spacetime and general relativistic MHD evolution framework in spherical coordinates for the Einstein Toolkit
Comments: 28 pages, 12 figures, submitted to Physical Review D
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Computational Physics (physics.comp-ph)

We present SphericalNR, a new framework for the publicly available Einstein Toolkit that numerically solves the Einstein field equations coupled to the equations of general relativistic MHD (GRMHD) in a 3+1 split of spacetime in spherical coordinates without symmetry assumptions. The spacetime evolution is performed using reference-metric versions of either the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) equations or the fully covariant and conformal Z4 (fCCZ4) system with constraint damping. We have developed a reference-metric version of the Valencia formulation of GRMHD with a vector potential method, guaranteeing the absence of magnetic monopoles during the evolution. In our framework, every dynamical field (both spacetime and matter) is evolved using its components in an orthonormal basis with respect to the spherical reference metric. Furthermore, all geometric information about the spherical coordinate system is encoded in source terms appearing in the evolution equations. This allows for the straightforward extension of Cartesian high-resolution shock-capturing finite volume codes to use spherical coordinates with our framework. To this end, we have adapted GRHydro, a Cartesian finite volume GRMHD code already available in the Einstein Toolkit, to use spherical coordinates. We present the full evolution equations of the framework, as well as details of its implementation in the Einstein Toolkit. We validate SphericalNR by demonstrating it passes a variety of challenging code tests in static and dynamical spacetimes.

[68]  arXiv:2002.06937 (cross-list from hep-ph) [pdf, other]
Title: A Dark Matter Interpretation of Excesses in Multiple Direct Detection Experiments
Comments: 20 pages, 7 figures. Preparing for journal submission
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Materials Science (cond-mat.mtrl-sci); High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

We present a novel unifying interpretation of excess event rates observed in several dark matter direct-detection experiments that utilize single-electron threshold semiconductor detectors. Despite their different locations, exposures, readout techniques, detector composition, and operating depths, these experiments all observe statistically significant excess event rates of $\sim$ 10 Hz/kg. However, none of these persistent excesses has yet been reported as a dark matter signal because their common spectral shapes are inconsistent with dark matter particles scattering elastically off detector nuclei or electrons. We show that these results can be reconciled if the semiconductor detectors are seeing a collective inelastic process known as a plasmon. We further show that plasmon excitation could arise in two compelling dark matter scenarios, both of which can explain rates of existing signal excesses in germanium and, at least at the order of magnitude level, across several traditional WIMP searches and single-electron threshold detectors. Both dark matter scenarios motivate a radical rethinking of the standard interpretations of dark matter-electron scattering from recent experiments.

[69]  arXiv:2002.06988 (cross-list from gr-qc) [pdf, other]
Title: Anisotropic Fluid Cosmology: an Alternative to Dark Matter?
Comments: 20 pages, 1 figure
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

We use anisotropic fluid cosmology to describe the present, dark energy-dominated, universe. Similarly to what has been proposed for galactic dynamics, the anisotropic fluid gives an effective description of baryonic matter, dark energy and their possible interaction, without assuming the presence of dark matter. The resulting anisotropic fluid spacetime naturally generates inhomogeneities at small scales, triggered by an anisotropic stress, and could therefore be responsible for structure formation at these scales. Solving the cosmological equations, we show that the dynamics of the scale factor $a$ is described by usual FLRW cosmology and decouples completely from that describing inhomogeneities. We assume that the cosmological anisotropic fluid inherits the equation of state from that used to describe galaxy rotation curves. We show that, in the large scale regime, the fluid can be described as a generalized Chaplygin gas and fits well the distance modulus experimental data of type Ia supernovae, thus correctly modelling the observed accelerated expansion of the universe. Conversely, in the small scale regime, we use cosmological perturbation theory to derive the power spectrum $P(k)$ for mass density distribution. At short wavelengths, we find a $1/k^4$ behaviour, in good accordance with the observed correlation function for matter distribution at small scales.

[70]  arXiv:2002.07105 (cross-list from hep-ph) [pdf, other]
Title: Quantum Effects in Palatini Higgs Inflation
Comments: 20 pages, 2 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

We study quantum effects in Higgs inflation in the Palatini formulation of gravity, in which the metric and connection are treated as independent variables. We exploit the fact that the cutoff, above which perturbation theory breaks down, is higher than the scale of inflation. Unless new physics above the cutoff leads to unnaturally large corrections, we can directly connect low-energy physics and inflation. On the one hand, the lower bound on the top Yukawa coupling due to collider experiments leads to an upper bound on the non-minimal coupling of the Higgs field to gravity: $\xi \lesssim 10^8$. On the other hand, the Higgs potential can only support successful inflation if $\xi \gtrsim 10^6$. This leads to a fairly strict upper bound on the top Yukawa coupling of $0.925$ (defined in the $\overline{\text{MS}}$-scheme at the energy scale $173.2\,\text{GeV}$) and constrains the inflationary prediction for the tensor-to-scalar ratio. Additionally, we compare our findings to metric Higgs inflation.

[71]  arXiv:2002.07126 (cross-list from cond-mat.soft) [pdf, other]
Title: Pressure and temperature dependence of solubility and surface adsorption of nitrogen in the liquid hydrocarbon bodies on Titan
Comments: 9 pages, 8 figures. arXiv admin note: text overlap with arXiv:1910.13343
Subjects: Soft Condensed Matter (cond-mat.soft); Earth and Planetary Astrophysics (astro-ph.EP); Chemical Physics (physics.chem-ph)

We have studied the pressure and temperature dependence of solubility of nitrogen in methane and ethane using vapor-liquid equilibrium simulations of binary mixtures of nitrogen in methane and ethane for a range of pressures between 1.5 atm and 3.5 atm and temperatures between 90 K and 110 K, thermodynamic conditions that may exist on the Saturn's moon, Titan. We find that the solubility of nitrogen in methane increases linearly with pressure while the solubility of nitrogen in ethane increases exponentially with pressure at temperature 90 K. Solubility of nitrogen in both methane and ethane exhibits an exponential decrease with temperature at a pressure of 3 atm. The solubility of nitrogen in methane is much larger compared to that in ethane in the range of pressure and temperature studied here. Our results are in quantitative agreement with the available experimental measurements of the solubility of nitrogen in methane and ethane. Furthermore, we find that the surface adsorption of nitrogen increases with increasing pressure at temperature 90 K, while the adsorption free energy increases with increasing pressure. Moreover, we find that the surface tension decreases linearly with pressure for both nitrogen-methane and nitrogen-ethane systems. The rate of decrease of surface tension with pressure for nitrogen-ethane system is much larger as compared to the nitrogen-methane system. Finally, we find that the absorption of a nitrogen molecule into the liquid-phase from the interface is diffusive and does not involve any appreciable energy barrier. Our results suggest that homogeneous nucleation of bubbles is unlikely on Titan and the bubble formation in the lakes on Titan must arise from heterogeneous nucleation of bubbles.

[72]  arXiv:2002.07133 (cross-list from gr-qc) [pdf, other]
Title: Is Modified Newtonian Dynamics a fractional theory?
Authors: Andrea Giusti
Comments: 5 pages, 1 figure, comments are welcome
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

I provide a derivation of Milgrom's Modified Newtonian Dynamics from a fractional version of Newton's theory based on the fractional Poisson equation. I employ the properties of the fractional Laplacian to investigate the features of the fundamental solution of the proposed model. Taking advantage of the Tully-Fisher relation I then connect the fundamental length scale $\ell$, emerging from this modification of Newton's gravity, with the critical acceleration $a_0$ of MOND. Finally, implications for galaxy rotation curves of a variable-order version of the model are discussed.

Replacements for Tue, 18 Feb 20

[73]  arXiv:1803.03303 (replaced) [pdf, other]
Title: Kepler-78 and the Ultra-Short-Period Planets
Comments: fixed error in Eq. (4)
Journal-ref: New Astronomy Reviews 83 (2018) 37-48
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[74]  arXiv:1804.03182 (replaced) [pdf, other]
Title: PUSHing Core-Collapse Supernovae to Explosions in Spherical Symmetry II: Explodability and Global Properties
Comments: 24 pages, 18 figures, 5 tables. Accepted to ApJ
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
[75]  arXiv:1807.04290 (replaced) [pdf, other]
Title: The Halo's Ancient Metal-Rich Progenitor Revealed with BHB Stars
Comments: 11 pages, 8 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[76]  arXiv:1808.06623 (replaced) [pdf, other]
Title: Beyond $Λ$CDM with Low and High Redshift Data: Implications for Dark Energy
Comments: v3: 10 pages, 12 .pdf figure, matching the published version
Journal-ref: Gen.Rel.Grav. 52 (2020) no.2, 15
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
[77]  arXiv:1811.04445 (replaced) [pdf, other]
Title: Linear cosmological perturbations in Scalar-tensor-vector gravity
Comments: 7 pages, accepted version
Journal-ref: Physics Letters B, Volume 802, 2020, 135238
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[78]  arXiv:1812.07916 (replaced) [pdf, other]
Title: Overshooting in simulations of compressible convection
Authors: Petri J. Käpylä (Georg-August-Universität Göttingen, ReSoLVE Center of Excellence/Aalto)
Comments: 15 pages, 13 figures, published in Astron. Astrophys
Journal-ref: A&A 631, A122 (2019)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[79]  arXiv:1901.00787 (replaced) [pdf, other]
Title: Turbulent viscosity and effective magnetic Prandtl number from simulations of isotropically forced turbulence
Authors: Petri J. Käpylä (1,2), Matthias Rheinhardt (2), Axel Brandenburg (3,4,5,6), Maarit J. Käpylä (2,7) ((1) Göttingen University, (2) ReSoLVE Center of Excellence, Aalto, (3) NORDITA, (4) Stockholm University, (5) JILA, (6) LASP, (7) Max-Planck-Institut für Sonnensystemforschung)
Comments: 13 pages, 12 figures, accepted in Astron. Astrophys
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Fluid Dynamics (physics.flu-dyn)
[80]  arXiv:1902.02374 (replaced) [pdf, other]
Title: Photometric Biases in Modern Surveys
Comments: 35 pages, 13 figures, accepted to AJ; code and data available online at this https URL
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
[81]  arXiv:1903.04363 (replaced) [pdf, other]
Title: Effects of small-scale dynamo and compressibility on the $Λ$ effect
Authors: Petri J. Käpylä (Göttingen University, ReSoLVE Center of Excellence/Aalto)
Comments: 8 pages, 7 figures, published in Astron. Nachr
Journal-ref: Astron. Nachr,, 340, 744 (2019)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Fluid Dynamics (physics.flu-dyn)
[82]  arXiv:1905.00361 (replaced) [pdf, other]
Title: Measuring dark matter-neutrino relative velocity on cosmological scales
Comments: 6 pages, 2 figures, 1 table, published version
Journal-ref: Phys. Rev. D 101, 023525 (2020)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
[83]  arXiv:1905.00437 (replaced) [pdf, ps, other]
Title: Bubble mapping with the Square Kilometer Array -- I. Detecting galaxies with Euclid, JWST, WFIRST and ELT within ionized bubbles in the intergalactic medium at z>6
Comments: 18 pages, 7 figures, v.2: Accepted for publications in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[84]  arXiv:1905.02213 (replaced) [pdf, other]
Title: Probing Axions with Event Horizon Telescope Polarimetric Measurements
Comments: 7 pages, 3 figures, published version
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
[85]  arXiv:1905.05122 (replaced) [pdf, other]
Title: Assessing non-linear models for galaxy clustering II: model validation and forecasts for Stage IV surveys
Comments: 23 pages, 21 figures, MNRAS accepted version
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[86]  arXiv:1905.10771 (replaced) [pdf, ps, other]
Title: The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
Comments: Fits tables can be found at this ftp URL
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[87]  arXiv:1907.00043 (replaced) [pdf, other]
Title: The Reconstructed Power Spectrum in the Zeldovich Approximation
Comments: 46 pages, 15 figures, updated to match version accepted by JCAP. Corrected a typo in Equation 4.11
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[88]  arXiv:1907.02901 (replaced) [pdf, other]
Title: Ice Giant Circulation Patterns: Implications for Atmospheric Probes
Comments: 29 pages, 8 figures, review article accepted to SSRv special issue on "In Situ Exploration of the Ice Giants"
Journal-ref: Space Science Reviews (2020)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[89]  arXiv:1907.09542 (replaced) [pdf, other]
Title: Testing fundamental physics with photon frequency shift
Comments: 7 pages, 2 figures, 1 table. Version accepted for publication in EPJC Letters
Subjects: General Relativity and Quantum Cosmology (gr-qc); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics - Theory (hep-th); Quantum Physics (quant-ph)
[90]  arXiv:1907.12225 (replaced) [pdf, other]
Title: New test on General Relativity using galaxy-galaxy lensing with astronomical surveys
Comments: 6 pages, 1 figure, comments are welcome. Updated with discussions on systematics
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
[91]  arXiv:1908.03098 (replaced) [pdf, other]
Title: Quantifying the impacts of future gravitational-wave data on constraining interacting dark energy
Comments: 16 pages, 5 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
[92]  arXiv:1908.04995 (replaced) [pdf, ps, other]
Title: Cylindrically symmetric static $n$-dimensional (un)charged (anti-)de Sitter black holes in generic $f(T)$ gravity
Comments: 7 pages, 2 figures, extended version
Journal-ref: Europhysics Letters (EPL) vol. 129 (2020) 20003
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Mathematical Physics (math-ph)
[93]  arXiv:1909.02427 (replaced) [pdf, other]
Title: The Discovery of the Long-Period, Eccentric Planet Kepler-88 d and System Characterization with Radial Velocities and Photodynamical Analysis
Comments: 23 pages, 11 figures, submitted to AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[94]  arXiv:1909.02504 (replaced) [pdf, other]
Title: Modelling the matter bispectrum at small scales in modified gravity
Comments: 44 pages, 16 figures, 4 tables. JCAP accepted version
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[95]  arXiv:1909.07742 (replaced) [pdf, other]
Title: The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 LRG sample: structure growth rate measurement from the anisotropic LRG correlation function in the redshift range 0.6 < z < 1.0
Comments: Accepted on the 5th December 2019, 28 pages,27 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[96]  arXiv:1909.10899 (replaced) [pdf, ps, other]
Title: Static and rotating white dwarfs at finite temperatures
Comments: 5 pages, 3 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
[97]  arXiv:1910.05682 (replaced) [pdf, other]
Title: Neutrino oscillations in supernovae: angular moments and fast instabilities
Comments: 7 pages, 3 figures
Journal-ref: Phys. Rev. D 101, 043009 (2020)
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE)
[98]  arXiv:1910.06011 (replaced) [pdf, ps, other]
Title: Constraints on nature of ultra light dark matter particles with 21cm forest
Comments: 13 pages, 9 figures. Published in PRD
Journal-ref: Phys. Rev. D 101, 043516 (2020)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[99]  arXiv:1910.08958 (replaced) [pdf, other]
Title: PUSHing core-collapse supernovae to explosions in spherical symmetry IV: Explodability, remnant properties and nucleosynthesis yields of low metallicity stars
Comments: 22 pages, 16 figures, 6 tables. Accepted to ApJ
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
[100]  arXiv:1910.12873 (replaced) [pdf, other]
Title: Lensing by Kerr Black Holes
Comments: 28 pages, 9 figures. v2: minor edits, matches published version
Journal-ref: Phys. Rev. D 101, 044031 (2020)
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
[101]  arXiv:1910.12881 (replaced) [pdf, other]
Title: The Null Geodesics of the Kerr Exterior
Comments: 24 pages, 4 figures. v2: minor edits, matches published version
Journal-ref: Phys. Rev. D 101, 044032 (2020)
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
[102]  arXiv:1910.13779 (replaced) [pdf, ps, other]
Title: Large-scale dynamics of winds originated from black hole accretion flows: (II) Magnetohydrodynamics
Authors: Can Cui, Feng Yuan
Comments: Accepted for Publication in ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[103]  arXiv:1910.13838 (replaced) [pdf, other]
Title: Large-scale dynamics of winds originated from black hole accretion flows: (I) Hydrodynamics
Authors: Can Cui, Feng Yuan, Bo Li
Comments: 14 pages, 9 figures, accepted for publication in ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[104]  arXiv:1911.04010 (replaced) [pdf, other]
Title: Multi-Epoch Modeling of TXS 0506+056 and Implications for Long-Term High-Energy Neutrino Emission
Comments: 24 pages, 8 figures, 11 tables, accepted for publication in ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[105]  arXiv:1911.04356 (replaced) [pdf, other]
[106]  arXiv:1911.06040 (replaced) [pdf, ps, other]
Title: Cuscuton gravity as a classically stable limiting curvature theory
Comments: 23 pages; v2: minor changes, references added; v3: minor typos corrected, matches published version
Journal-ref: JCAP02(2020)016
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
[107]  arXiv:1911.07568 (replaced) [pdf, other]
Title: Neutrino Production Associated with Late Bumps in Gamma-Ray Bursts and Potential Contribution to Diffuse Flux at IceCube
Comments: 9 pages, 4 figures, 1 table, revised version
Journal-ref: Astrophys. J. 890 (2020) 83
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
[108]  arXiv:1911.07695 (replaced) [pdf, ps, other]
Title: Silhouettes of invisible black holes
Comments: 22 pages, 24 figures, added references, improvements in the interpretation, accepted for publication in Physics Uspekhi
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
[109]  arXiv:1911.07853 (replaced) [pdf, other]
Title: Imprints of the Early Universe on Axion Dark Matter Substructure
Comments: 35 pages, 13 figures. Matches published version
Journal-ref: Phys. Rev. D 101, 035002 (2020)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
[110]  arXiv:1911.08545 (replaced) [pdf, other]
Title: A comparison of cosmological filaments catalogues
Comments: 14 pages, 17 figures. Accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[111]  arXiv:1911.10721 (replaced) [pdf, ps, other]
Title: A More Efficient Search for H2O Megamaser Galaxies : The Power of the X-ray and Mid-infrared Photometry
Comments: 22 pages, 11 figures, 4 tables, Accepted by ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[112]  arXiv:1912.13316 (replaced) [pdf, other]
Title: MIRACLES: atmospheric characterization of directly imaged planets and substellar companions at 4-5 $μ$m. I. Photometric analysis of $β$ Pic b, HIP 65426 b, PZ Tel B and HD 206893 B
Comments: 25 pages, 15 figures, accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
[113]  arXiv:1912.13333 (replaced) [pdf, other]
Title: Horizonless ultracompact objects and dark matter in quadratic gravity
Comments: v2: 28 pages, 2 figures. v2 has an updated list of references and minor modifications, it matches the published version
Journal-ref: JCAP 2002 (2020) 018
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
[114]  arXiv:2001.04868 (replaced) [pdf, other]
Title: Lightening Gravity-Mediated Dark Matter
Comments: 39 pages, 8 figures, v2: references and unitarity bounds added
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
[115]  arXiv:2001.05776 (replaced) [pdf, other]
Title: Environmental processing in cluster core galaxies at z=1.7
Comments: 6 pages, 3 figures, accepted for publication in A&A Letters
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[116]  arXiv:2001.07012 (replaced) [pdf, other]
Title: Gauss-Bonnet Inflation after Planck2018
Comments: 52 pages, 16 figures, 16 tables
Journal-ref: The Astrophysical Journal, 890:58 (33pp), 2020
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
[117]  arXiv:2002.00147 (replaced) [pdf, other]
Title: On-sky SiPM Performance Measurements for Millisecond to Sub-Microsecond Optical Source Variability Studies
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
[118]  arXiv:2002.01920 (replaced) [pdf, other]
Title: FRB-periodicity: mild pulsar in tight O/B-star binary
Authors: Maxim Lyutikov, Maxim Barkov, Dimitrios Giannios (Purdue University)
Comments: 13 pages, 4 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[119]  arXiv:2002.02275 (replaced) [pdf, other]
Title: The Gaia-ESO Survey: detection and characterization of single line spectroscopic binaries
Comments: 27 pages, 24 figures, accepted for publication in A&A
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[120]  arXiv:2002.02546 (replaced) [pdf, other]
Title: Convective boundary mixing in low- and intermediate-mass stars I. Core properties from pressure-mode asteroseismology
Comments: 20 Pages, 9 Figures, 4 Tables and supplementary material. Accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[121]  arXiv:2002.02553 (replaced) [pdf, other]
Title: Orbital-induced spin precession as an origin of periodicity in periodically-repeating fast radio bursts
Comments: 11 pages, 4 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
[122]  arXiv:2002.05563 (replaced) [pdf, other]
Title: Neutrino mass and mass hierarchy in various dark energy
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[123]  arXiv:2002.05735 (replaced) [pdf, other]
Title: Spacetime Tomography Using The Event Horizon Telescope
Comments: Accepted to ApJ (17 pages, 15 figures) (revised edition corrected some affiliations)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
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