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

Astrophysics

New submissions

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New submissions for Mon, 16 Mar 20

[1]  arXiv:2003.05940 [pdf, ps, other]
Title: Statistical deprojection of intervelocities, interdistances and masses in the Isolated Galaxy Pair Catalog
Comments: 24 pages, 19 figures, submitted for publication
Subjects: Astrophysics of Galaxies (astro-ph.GA)

In order to study the internal dynamics of actual galaxy pairs, we need to derive the probability distribution function (PDF) of true 3D (orbital) intervelocities and interdistances between pair members from their observed (projected) values, and of the pair masses from Kepler's third law. Our Isolated Galaxy Pair Catalog (IGPC) of 13114 pairs \cite{Nottale2018a} is used here for this research. The algorithms of statistical deprojection elaborated in \cite{Nottale2018b} are applied to these observational data. We derive the orbital velocity PDFs for the whole catalog and for several selected subsamples. The interdistance PDF is deprojected and compared to analytical profiles which are expected from semi-theoretical arguments. The PDF of deprojected pair orbital velocities is characterized by the existence of a main probability peak around $\approx 150$ km.s$^{-1}$ for all subsamples of the IGPC as well as for the UGC pair catalog \cite{Chamaraux2016}. The interdistance PDFs of both the projected and deprojected data are described at large distances by the same power law with exponent $\approx -2$. The whole distributions, including their cores, are fairly fitted by King profiles. The mass deprojection yields a mass/luminosity ratio for the pairs of $M/L=(30 \pm 5)$ in Solar units. The orbital velocity probability peak is observed at the same value, $\approx 150$ km/s, as the main exoplanet velocity peak, which points toward a possible universality of Keplerian structures, whatever the scale. The pair $M/L$ ratio is just 5 times the standard ratio for luminous matter, which does not require the existence of non-baryonic dark matter in these systems.

[2]  arXiv:2003.05942 [pdf, ps, other]
Title: An empirical "high-confidence" candidate zone for $Fermi$ BL Lacertae objects
Comments: Published in ApJ, 2020, 891, 87. 11 pages, 1 figures, 5 tables
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

In the third catalog of active galactic nuclei detected by the $Fermi$ Large Area Telescope Clean (3LAC) sample, there are 402 blazars candidates of uncertain type (BCU). The proposed analysis will help to evaluate the potential optical classification flat spectrum radio quasars (FSRQs) versus BL Lacertae (BL Lacs) objects of BCUs, which can help to understand which is the most elusive class of blazar hidden in the Fermi sample. By studying the 3LAC sample, we found some critical values of $\gamma$-ray photon spectral index ($\Gamma_{\rm ph}$), variability index (VI) and radio flux (${\rm F_R}$) of the sources separate known FSRQs and BL Lac objects. We further utilize those values to defined an empirical "high-confidence" candidate zone that can be used to classify the BCUs. Within such a zone ($\Gamma_{\rm ph}<2.187$, log${\rm F_R}<2.258$ and ${ \rm logVI <1.702}$), we found that 120 BCUs can be classified BL Lac candidates with a higher degree of confidence (with a misjudged rate $<1\%$). Our results suggest that an empirical "high confidence" diagnosis is possible to distinguish the BL Lacs from the Fermi observations based on only on the direct observational data of $\Gamma_{\rm ph}$, VI and ${\rm F_R}$.

[3]  arXiv:2003.05943 [pdf, other]
Title: Strong biases in retrieved atmospheric composition caused by strong day-night chemical heterogeneities
Comments: 13 pages, 10 figures, accepted on March 12 2020 in Astronomy & Astrophysics, section 10. Planets and planetary systems
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Most planets currently amenable to transit spectroscopy are close enough to their host star to exhibit a relatively strong day to night temperature gradient. For hot planets, this leads to cause a chemical composition dichotomy between the two hemispheres. In the extreme case of ultra hot jupiters, some species, such as molecular hydrogen and water, are strongly dissociated on the day-side while others, such as carbon monoxide, are not. However, most current retrieval algorithm rely on 1D forward models that are unable to model this effect. We thus investigate how the 3D structure of the atmosphere biases the abundances retrieved using commonly used algorithms. We study the case of Wasp-121b as a prototypical ultra hot Jupiter. We use the simulations of this planet performed with the SPARC/MIT global climate model (GCM) and generate transmission spectra that fully account for the 3D structure of the atmosphere with Pytmopsh3R. These spectra are then analyzed using the \taurex retrieval code. We find that such ultra hot jupiter's transmission spectra exhibit muted H$_2$O features that originate in the night-side where the temperature, hence the scale-height, is smaller than on the day-side. However, the spectral features of molecules present on the day-side are boosted by both its high temperature and low mean molecular weight. As a result, the retrieved parameters are strongly biased compared to the ground truth. In particular the [CO]/[H$_2$O] is overestimated by one to three orders of magnitude. This must be kept in mind when using such retrieval analysis to infer the C/O ratio of a planet's atmosphere. We also discuss whether indicators can allow us to infer the 3D structure of an observed atmosphere. Finally we show that HST/WFC3 transmission data of Wasp-121b are compatible with the day-night thermal and compositional dichotomy predicted by models.

[4]  arXiv:2003.05944 [pdf, other]
Title: L-GALAXIES 2020: Spatially resolved cold gas phases, star formation and chemical enrichment in galactic discs
Authors: Bruno Henriques (ETH), Rob Yates (MPA), Jian Fu (Shanghai), Qi Guo (Beijing), Guinevere Kauffmann (MPA), Chaichalit Srisawat (Iceland), Peter Thomas (Sussex), Simon White (MPA)
Comments: published in MNRAS. A full description of the model is available as MNRAS online supplementary material and at this https URL Data from the model are publicly released in SQL-queryable form and in flat files at this http URL
Journal-ref: 2020MNRAS.491.5795H
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We have updated the Munich galaxy formation model, L-Galaxies, to follow the radial distributions of stars and atomic and molecular gas in galaxy discs. We include an H2-based star-formation law, as well as a detailed chemical-enrichment model with explicit mass-dependent delay times for SN-II, SN-Ia and AGB stars. Information about the star formation, feedback and chemical-enrichment histories of discs is stored in 12 concentric rings. The new model retains the success of its predecessor in reproducing the observed evolution of the galaxy population, in particular, stellar mass functions and passive fractions over the redshift range 0<=z<=3 and mass range 8<=log(M_*/Msun)<=12, the black hole-bulge mass relation at z=0, galaxy morphology as a function of stellar mass and the mass-metallicity relations of both stellar and gas components. In addition, its detailed modelling of the radial structure of discs allows qualitatively new comparisons with observation, most notably with the relative sizes and masses of the stellar, atomic and molecular components in discs. Good agreement is found with recent data. Comparison of results obtained for simulations differing in mass resolution by more than two orders of magnitude shows that all important distributions are numerically well converged even for this more detailed model. An examination of metallicity and surface-density gradients in the stars and gas indicates that our new model, with star formation, chemical enrichment and feedback calculated self-consistently on local disc scales, reproduces some but not all of the trends seen in recent many-galaxy IFU surveys.

[5]  arXiv:2003.05945 [pdf, other]
Title: No missing photons for reionization: moderate ionizing photon escape fractions from the FIRE-2 simulations
Authors: Xiangcheng Ma (Berkeley), Eliot Quataert (Berkeley), Andrew Wetzel (UC Davis), Philip F. Hopkins (Caltech), Claude-André Faucher-Giguère (Northwestern), Dušan Kereš
Comments: 16 pages, 11 figures, submitted to MNRAS, comments welcome. Core results are shown in Fig 5 and Fig 7
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We present the escape fraction of hydrogen ionizing photons (f_esc) from a sample of 34 high-resolution cosmological zoom-in simulations of galaxies at z>5 in the Feedback in Realistic Environments project, post-processed with a Monte Carlo radiative transfer code for ionizing radiation. Our sample consists of 8500 halos in M_vir~10^8--10^{12} M_sun (M_star~10^4--10^{10} M_sun) at z=5--12. We find the sample average <f_esc> increases with halo mass for M_vir~10^8--10^{9.5} M_sun, becomes nearly constant for M_vir~10^{9.5}--10^{11} M_sun, and decreases at M_vir>10^{11} M_sun. Equivalently, <f_esc> increases with stellar mass up to M_star~10^8 M_sun and decreases at higher masses. Even applying single-star stellar population synthesis models, we find a moderate <f_esc>~0.2 for galaxies at M_star~10^8 M_sun. Nearly half of the escaped ionizing photons come from stars 1--3 Myr old and the rest from stars 3--10 Myr old. Binaries only have a modest effect, boosting <f_esc> by ~25--35% and the number of escaped photons by 60--80%. Most leaked ionizing photons are from vigorously star-forming regions that usually contain a feedback-driven kpc-scale superbubble surrounded by a dense shell. The shell is forming stars while accelerated, so new stars formed earlier in the shell are already inside the shell. Young stars in the bubble and near the edge of the shell can fully ionize some low-column-density paths pre-cleared by feedback, allowing a large fraction of their ionizing photons to escape. The decrease of <f_esc> at the high-mass end is due to dust attenuation, while at the low-mass end, <f_esc> decreases owing to inefficient star formation (and hence feedback). At fixed mass, <f_esc> tends to increase with redshift. Our simulations produce sufficient ionizing photons for cosmic reionization.

[6]  arXiv:2003.05946 [pdf, other]
Title: Constraining the Source of the High Velocity Ejecta in the Type Ia SN 2019ein
Comments: 20 pages, 15 figures, submitted to ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We present multi-wavelength photometric and spectroscopic observations of SN 2019ein, a High Velocity Type Ia supernova discovered in the nearby galaxy NGC 5353 with a two day non-detection limit. SN 2019ein exhibited some of the highest measured expansion velocities of any Type Ia supernovae, with a Si II absorption minimum blueshifted by 24,000 km s$^{-1}$ at 14 days before peak brightness. More unusually, we observed the emission components of the P Cygni profiles to be blueshifted upwards of 10,000 km s$^{-1}$ with respect to the host galaxy redshift before B-band maximum light. This blueshift, among the highest in a sample of other Type Ia supernovae, is greatest at our earliest spectroscopic epoch and subsequently decreases toward maximum light. We discuss models of progenitor systems and explosion mechanisms that could explain these extreme absorption and emission velocities. Radio observations beginning 14 days before B-band maximum light yield non-detections at the position of SN 2019ein, which rules out symbiotic progenitor systems, most models of white dwarfs powering fast optically-thick accretion winds, and optically thin shells of mass $\lesssim 10^{-6}$ M$_\odot$ at radii $< 100$ AU. Comparing our spectra to models and observations of other High Velocity Type Ia supernovae, we find that the observational properties of SN 2019ein match those of a delayed detonation explosion. We propose that the high velocity ejecta and blueshifted emission may be the result of abundance enhancements due to ejecta mixing in an asymmetric explosion, or optical depth effects in the photosphere of the ejecta at early times. These findings may provide evidence for common explosion mechanisms and ejecta geometries among High Velocity Type Ia supernovae.

[7]  arXiv:2003.05950 [pdf, other]
Title: A Link Between Ram Pressure Stripping and Active Galactic Nuclei
Comments: Submitted to ApJL. 10 pages, 4 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

The dense environment of a galaxy cluster can radically transform the content of in-falling galaxies. Recent observations have found a significant population of active galactic nuclei (AGN) within "jellyfish galaxies," galaxies with trailing tails of gas and stars that indicate significant ram pressure stripping. The relationship between AGN and ram pressure stripping is not well understood. In this letter, we investigate the connection between AGN activity and ram pressure in a fully cosmological setting for the first time using the RomulusC simulation, one of the highest resolution simulations of a galaxy cluster to date. We find unambiguous morphological evidence for ram pressure stripping. For lower mass galaxies (with stellar masses < 10^9.5 solar masses) both star formation and black hole accretion are suppressed by ram pressure before they reach pericenter, whereas for more massive galaxies accretion onto the black hole is enhanced during pericentric passage. Our analysis also indicates that as long as the galaxy retains gas, AGN with higher Eddington ratios are more likely to be the found in galaxies experiencing higher ram pressure. We conclude that prior to quenching star formation, ram pressure triggers enhanced accretion onto the black hole, which then produces heating and outflows due to AGN feedback. AGN feedback may in turn serve to aid in the quenching of star formation in tandem with ram pressure.

[8]  arXiv:2003.05951 [pdf, other]
Title: Dynamical mass inference of galaxy clusters with neural flows
Comments: 11 pages, 7 figures, 1 table. For MNRAS submission
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)

We present an algorithm for inferring the dynamical mass of galaxy clusters directly from their respective phase-space distributions, i.e. the observed line-of-sight velocities and projected distances of galaxies from the cluster centre. Our method employs neural flows, a deep neural network capable of learning arbitrary high-dimensional probability distributions, and inherently accounts, to an adequate extent, for the presence of interloper galaxies which are not bounded to a given cluster, the primary contaminant of dynamical mass measurements. We validate and showcase the performance of our neural flow approach to robustly infer the dynamical mass of clusters from a realistic mock cluster catalogue. A key aspect of our novel algorithm is that it yields the probability density function of the mass of a particular cluster, thereby providing a principled way of quantifying uncertainties, in contrast to conventional machine learning approaches. The neural network mass predictions, when applied to a contaminated catalogue with interlopers, have a logarithmic residual scatter which goes down to 0.043 dex for the most massive clusters. This is nearly an order of magnitude improvement over the classical cluster mass scaling relation with the velocity dispersion, and outperforms recently proposed machine learning approaches. We also apply our neural flow mass estimator to a compilation of galaxy observations of some well-studied clusters with robust dynamical mass estimates, further substantiating the efficacy of our algorithm. Such sophisticated approaches would undoubtedly be relevant for robust and efficient dynamical mass inference from upcoming surveys covering unprecedented volumes of the sky.

[9]  arXiv:2003.05953 [pdf, other]
Title: The case for jets in cataclysmic variables
Comments: To appear in New Astronomy Reviews special volume '100 Years of Astrophysical Jets' (eds. Rob Fender and Ralph Wijers)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

For decades cataclysmic variables (CVs) were thought to be one of the few classes of accreting compact objects to not launch jets, and have consequently been used to constrain jet launching models. However, recent theoretical and observational advances indicate that CVs do in fact launch jets. Specifically, it was demonstrated that their accretion-outflow cycle is analogous to that of their higher mass cousins -- the X-ray Binaries (XRBs). Subsequent observations of the CV SS Cygni confirmed this and have consistently shown radio flaring equivalent to that in the XRBs that marks a transient jet. Based on this finding and the emission properties, several studies have concluded that the radio emission is most likely from a transient jet. Observations of other CVs, while not conclusive, are consistent with this interpretation. However, the issue is not yet settled. Later observations have raised a number of questions about this model, as well as about potential alternative radio emission mechanisms. CVs are non-relativistic and many have well-determined distances; these properties would make them ideal candidates with which to address many of our outstanding questions about fundamental jet physics. Here we review the case for jets in CVs, discuss the outstanding questions and issues, and outline the future work necessary to conclusively answer the question of whether CVs launch jets.

[10]  arXiv:2003.05959 [pdf, other]
Title: Local AGN Survey (LASr): I. Galaxy sample, infrared colour selection and predictions for AGN within 100 Mpc
Comments: Accepted for publication in MNRAS. 30 pages, 19 figures. For full, digital versions of Table 1, 2 and 3, see: this https URL
Subjects: Astrophysics of Galaxies (astro-ph.GA)

In order to answer some of the major open questions in the fields of supermassive black hole (SMBH) and galaxy evolution, a complete census of SMBH growth, i.e., active galactic nuclei (AGN), is required. Thanks to deep all-sky surveys, such as those by the Wide-field Infrared Survey Explorer (WISE) and the Spectrum-Roentgen-Gamma (SRG) missions, this task is now becoming feasible in the nearby Universe. Here, we present a new survey, the Local AGN Survey (LASr), with the goal of identifying AGN unbiased against obscuration and determining the intrinsic Compton-thick (CT) fraction. First, we construct the most complete all-sky sample of galaxies within 100 Mpc from astronomical databases (90% completeness for log M_star/M_sun ~9.4), four times deeper than the current local galaxy reference, the Two Micron All-Sky Survey Redshift Survey (2MRS), which turns out to miss 20% of known luminous AGN. These 49k galaxies serve as parent sample for LASr, called LASr-GPS. It contains 4.3k already known AGN, >=82% of these are estimated to have L(12um) < 10^42.3 erg/s, i.e., are low-luminosity AGN. As a first method for identifying Seyfert-like AGN, we use WISE-based infrared colours, finding 221 galaxies at L(12um) >= 10^42.3 erg/s to host an AGN at 90% reliability, This includes 61 new AGN candidates and implies and optical type 2 fraction of 50 to 71%. We quantify the efficiency of this technique and estimate the total number of AGN with L_int(2-10 keV) >= 10^42 erg/s in the volume to be 362^+145_-116 (8.6^+3.5_-2.8 10^-5 Mpc^-3). X-ray brightness estimates indicate the CT fraction to be 40-55% to explain the Swift non-detections of the infrared selected objects. One third of the AGN within 100 Mpc remain to be identified and we discuss the prospects for the eROSITA all-sky survey.

[11]  arXiv:2003.05969 [pdf, other]
Title: Fibre Inflation and Precision CMB Data
Comments: 12 pages, 4 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)

A generic feature of models of inflation obtained from string compactifications is correlations between the model parameters and the post-inflationary evolution of the universe. Thus, the post-inflationary evolution depends on the inflationary model parameters and accurate inflationary predictions require that this be incorporated in the evolution of the primordial spectrum. The fibre inflation model is a promising model of inflation constructed in type IIB string theory. This model has two interesting features in its post-inflationary evolution. The reheating temperature of the model is directly correlated with the model parameters. The model also necessarily predicts some dark radiation, which can be sizable for certain choices of discrete parameters in the model. We analyse this model in detail using publicly available codes - ModeChord and CosmoMC with the latest Planck+BICEP2/Keck array data to constrain the model parameters and $N_{\rm pivot}$ (the number of e-foldings between horizon exit of CMB modes and the end of inflation). Our analysis sets up the basic methods necessary to extract precise inflationary prediction in string models incorporating correlations between model parameters and post-inflationary evolution.

[12]  arXiv:2003.05978 [pdf, other]
Title: Brighter-fatter effect in near-infrared detectors -- III. Fourier-domain treatment of flat field correlations and application to WFIRST
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

Weak gravitational lensing has emerged as a leading probe of the growth of cosmic structure. However, the shear signal is very small and accurate measurement depends critically on our ability to understand how non-ideal instrumental effects affect astronomical images. WFIRST will fly a focal plane containing 18 Teledyne H4RG-10 near infrared detector arrays, which present different instrument calibration challenges from previous weak lensing observations. Previous work has shown that correlation functions of flat field images are effective tools for disentangling linear and non-linear inter-pixel capacitance (IPC) and the brighter-fatter effect (BFE). Here we present a Fourier-domain treatment of the flat field correlations, which allows us to expand the previous formalism to all orders in IPC, BFE, and classical non-linearity. We show that biases in simulated flat field analyses in Paper I are greatly reduced through the use of this formalism. We then apply this updated formalism to flat field data from three WFIRST flight candidate detectors, and explore the robustness to variations in the analysis. We find that the BFE is present in all three detectors, and that its contribution to the flat field correlations dominates over the non-linear IPC. The magnitude of the BFE is such that the effective area of a pixel is increased by $(3.54\pm0.03)\times 10^{-7}$ for every electron deposited in a neighboring pixel. We compare IPC maps from flat field autocorrelation measurements to those obtained from the single pixel reset method and find a median difference of 0.113%. After further diagnosis of this difference, we ascribe it largely to an additional source of cross-talk, the vertical trailing pixel effect, and recommend further work to develop a model for this effect. These results represent a significant step toward calibration of the non-ideal effects in WFIRST detectors.

[13]  arXiv:2003.05981 [pdf, other]
Title: Analytical expression of aperture efficiency affected by Seidel aberrations
Comments: 15 pages, 4 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

The effect of aberrations on the aperture efficiency has not been discussed analytically, though aberrations determine the performance of a wide field-of-view system. Expansion of a wavefront error and a feed pattern into a series of the Zernike polynomials enables us to calculate the aperture efficiency. We explicitly show the aperture efficiency affected by the Seidel aberrations and derive the conditions for reducing the effects of the spherical aberration and coma. In particular, the condition for coma can reduce a pointing error. We performed Physical Optics simulations and found that, if the Strehl ratio is higher than 0.8, the derived expression provides the aperture efficiencies with a precision of < 2%.

[14]  arXiv:2003.05998 [pdf, other]
Title: Asymmetric spatial distribution of sub-solar metallicity stars in the Milky Way nuclear star cluster
Comments: 16 pages, 11 Figures, accepted MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We present stellar metallicity measurements of more than 600 late-type stars in the central 10 pc of the Galactic centre. Together with our previously published KMOS data, this data set allows us to investigate, for the first time, spatial variations of the nuclear star cluster's metallicity distribution. Using the integral-field spectrograph KMOS (VLT) we observed almost half of the area enclosed by the nuclear star cluster's effective radius. We extract spectra at medium spectral resolution, and apply full spectral fitting utilising the PHOENIX library of synthetic stellar spectra. The stellar metallicities range from [M/H]=-1.25 dex to [M/H]> +0.3 dex, with most of the stars having super-solar metallicity. We are able to measure an anisotropy of the stellar metallicity distribution. In the Galactic North, the portion of sub-solar metallicity stars with [M/H]<0.0 dex is more than twice as high as in the Galactic South. One possible explanation for different fractions of sub-solar metallicity stars in different parts of the cluster is a recent merger event. We propose to test this hypothesis with high-resolution spectroscopy, and by combining the metallicity information with kinematic data.

[15]  arXiv:2003.06011 [pdf, other]
Title: Performance limits of adaptive-optics/high-contrast imagers with pyramid wave-front sensors
Comments: 12 pages, 13 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

Advanced AO systems will likely utilise Pyramid wave-front sensors (PWFS) over the traditional Shack-Hartmann sensor in the quest for increased sensitivity, peak performance and ultimate contrast. Here, we wish to bring knowledge and quantify the PWFS theoretical limits as a means to highlight its properties and use cases.
We explore forward models for the PWFS in the spatial-frequency domain for they prove quite useful since a) they emanate directly from physical-optics (Fourier) diffraction theory; b) provide a straightforward path to meaningful error breakdowns, c) allow for reconstruction algorithms with $O (n\,log(n))$ complexity for large-scale systems and d) tie in seamlessly with decoupled (distributed) optimal predictive dynamic control for performance and contrast optimisation. All these aspects are dealt with here. We focus on recent analytical PWFS developments and demonstrate the performance using both analytic and end-to-end simulations.
We anchor our estimates with observed on-sky contrast on existing systems and then show very good agreement between analytical and Monte-Carlo estimates for the PWFS. For a potential upgrade of existing high-contrast imagers on 10\,m-class telescopes with visible or near-infrared PWFS, we show under median conditions at Paranal a contrast improvement (limited by chromatic and scintillation effects) of 2x-5x by replacing the wave-front sensor alone at large separations close to the AO control radius where aliasing dominates, and factors in excess of 10x by coupling distributed control with the PWFS over most of the AO control region, from small separations starting with the Inner Working Angle of typically 1-2 $\lambda/D$ to the AO correction edge (here 20 $\lambda/D$).

[16]  arXiv:2003.06012 [pdf, other]
Title: Multi-Frequency Observations of the Candidate Neutrino Emitting Blazar BZB J0955+3551
Comments: Submitted to ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The recent spatial and temporal coincidence of the blazar TXS 0506+056 with the IceCube detected neutrino event IC-170922A, has opened up a realm of multi-messenger astronomy with blazar jets as a plausible site of cosmic-ray acceleration. After TXS 0505+056, for the first time, a second blazar, BZB J0955+3551, has recently been found to be spatially coincident with the IceCube detected neutrino event IC-200107A and undergoing its brightest X-ray flare measured so far. Here, we present the results of our multi-frequency campaign to study this peculiar event that includes observations from NuSTAR, Swift, NICER, and 10.4 m Gran Telescopio Canaris (GTC). The optical spectroscopic observation from GTC secured its redshift as $z=0.5573$. Both NuSTAR and NICER data reveal a rapid flux variability albeit at low-significance ($\lesssim3.5\sigma$). We explore the origin of the target photon field needed for the photo-pion production using analytical calculations and considering the observed optical-to-X-ray flux level and conclude that seed photons must come from outside the jet, similar to that reported for TXS 0506+056. We find that there could be a sub-dominant hadronic population responsible for the neutrino emission.

[17]  arXiv:2003.06015 [pdf, other]
Title: Accretion-induced prompt black hole formation in asymmetric neutron star mergers, dynamical ejecta and kilonova signals
Comments: 20 pages, 21 figures, 4 tables
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)

We present new numerical relativity results of neutron star mergers with chirp mass $1.188M_\odot$ and mass ratios $q=1.67$ and $q=1.8$ using finite-temperature equations of state (EOS), approximate neutrino transport and a subgrid model for magnetohydrodynamics-induced turbulent viscosity. The EOS are compatible with nuclear and astrophysical constraints and include a new microphysical model derived from ab-initio calculations based on the Brueckner-Hartree-Fock approach. We report for the first time evidence for accretion-induced prompt collapse in high-mass-ratio mergers, in which the tidal disruption of the companion and its accretion onto the primary star determine prompt black hole formation. As a result of the tidal disruption, an accretion disc of neutron-rich and cold matter forms with baryon masses ${\sim}0.15M_\odot$, and it is significantly heavier than the remnant discs in equal-masses prompt collapse mergers. Massive dynamical ejecta of order ${\sim}0.01M_\odot$ also originate from the tidal disruption. They are neutron rich and expand from the orbital plane with a crescent-like geometry. Consequently, bright, red and temporally extended kilonova emission is predicted from these mergers. Our results show that prompt black hole mergers can power bright electromagnetic counterparts for high-mass-ratio binaries, and that the binary mass ratio can be in principle constrained from multimessenger observations.

[18]  arXiv:2003.06032 [pdf, other]
Title: The shape of SN 1993J re-analyzed
Comments: 18 pages, 12 figures, Accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

SN 1993J is one of the best studied Type IIb supernovae. Spectropolarimetric data analyses were published over two decades ago at a time when the field of supernova spectropolarimetry was in its infancy. Here we present a new analysis of the spectropolarimetric data of SN 1993J and an improved estimate of its interstellar polarization (ISP) as well as a critical review of ISP removal techniques employed in the field. The polarization of SN 1993J is found to show significant alignment on the $q-u$ plane, suggesting the presence of a dominant axis and therefore of continuum polarization. We also see strong line polarization features, including $\mathrm{H\beta}$, He\,{\sc i} $\lambda 5876$, $\mathrm{H\alpha}$, He\,{\sc i} $\lambda 6678$, He\,{\sc i} $\lambda 7065$, and high velocity (HV) components of He\,{\sc i} $\lambda 5876$ and $\mathrm{H\alpha}$. SN 1993J is therefore the second example of a stripped envelope supernova, alongside iPTF13bvn, with prominent HV helium polarization features, and the first to show a likely HV \halpha contribution. Overall, we determine that the observed features can be interpreted as the superposition of anisotropically distributed line forming regions over ellipsoidal ejecta. We cannot exclude the possibility of an off-axis energy source within the ejecta. These data demonstrate the rich structures that are inaccessible if solely considering the flux spectra but can be probed by spectropolarimetric observations. In future studies, the new ISP corrected data can be used in conjunction with 3D radiative transfer models to better map the geometry of the ejecta of SN 1993J.

[19]  arXiv:2003.06034 [pdf]
Title: Ammonium salts are a reservoir of nitrogen on a cometary nucleus and possibly on some asteroids
Comments: Main manuscript and Supplementary material document, Accepted for publication in Science on February 14, 2020
Journal-ref: Science 367, (2020) eaaw7462
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

The measured nitrogen-to-carbon ratio in comets is lower than for the Sun, a discrepancy which could be alleviated if there is an unknown reservoir of nitrogen in comets. The nucleus of comet 67P/Churyumov-Gerasimenko exhibits an unidentified broad spectral reflectance feature around 3.2 micrometers, which is ubiquitous across its surface. On the basis of laboratory experiments, we attribute this absorption band to ammonium salts mixed with dust on the surface. The depth of the band indicates that semivolatile ammonium salts are a substantial reservoir of nitrogen in the comet, potentially dominating over refractory organic matter and more volatile species. Similar absorption features appear in the spectra of some asteroids, implying a compositional link between asteroids, comets, and the parent interstellar cloud.

[20]  arXiv:2003.06043 [pdf, other]
Title: A magnetar engine for short GRBs and kilonovae
Comments: Submitted version
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)

The inspiral and merger of two neutron stars (NSs) are among the loudest and most luminous events in the universe. Radioactive material ejected during and after the merger powers a kilonova transient and synthesizes the heaviest elements in the universe. Jetted outflows from the merger remnant can launch a sGRB. The multimessenger observations of GW170817 have confirmed our basic understanding of NS mergers (NSMs) but two key open astrophysics problems for NSMs are how to generate fast-enough outflows to explain the observed blue kilonova component in GW170817 and whether magnetars can launch sGRB jets. Previous simulations have found that baryon pollution of the polar region prevents the launch of a sGRB jet, but these simulations did not include neutrino effects. We have performed dynamical-spacetime general-relativistic (GR) magnetohydrodynamic (MHD) simulations of NSM remnants including a nuclear equation of state (EOS) and neutrino effects. We find that turbulence induced by the magnetorotational instability (MRI) amplifies magnetic fields to beyond magnetar-strength ($\gtrsim 10^{15}\, \mathrm{G}$) and that this field is efficient in launching a relativistic jet from the magnetar. An additional magnetized wind ejects neutron-rich material with a rate of $\dot{M}_{\mathrm{ej}} \simeq 1 \times10^{-1}\, \mathrm{M_{\odot}\, s^{-1}}$ at high velocities. Our simulations demonstrate that magnetars formed in NSMs are a viable engine for both sGRBs and kilonova.

[21]  arXiv:2003.06073 [pdf, other]
Title: Common Envelope Shaping of Planetary Nebulae. II. Magnetic Solutions and Self-Collimated Outflows
Comments: 21 pages, 7 figures, accepted by ApJ
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

Magnetic fields of order $10^1-10^2$ gauss that are present in the envelopes of red giant stars are ejected in common envelope scenarios. These fields could be responsible for the launching of magnetically driven winds in proto-planetary nebulae. Using 2D simulations of magnetized winds interacting with an envelope drawn from a 3D simulation of the common envelope phase, we study the confinement, heating, and magnetic field development of post-common envelope winds. We find that the ejected magnetic field can be enhanced via compression by factors up to $\sim 10^4$ in circumbinary disks during the self-regulated phases. We find values for the kinetic energy of the order of $10^{46}$ erg that explain the large values inferred in proto-planetary nebula outflows. We show that the interaction of the formed circumbinary disk with a spherical, stellar wind produces a "tapered" flow that is almost indistinguishable from an imposed tapered flow. This increases the uncertainty of the origin of proto-planetary nebula winds, which could be either stellar, circumstellar (stellar accretion disk), circumbinary (circumbinary accretion disk), or a combination of all three.
Within this framework, a scenario for self-collimation of weakly magnetized winds is discussed, which can explain the two objects where the collimation process is observationally resolved, HD 101584 and Hen 3-1475. An explanation for the equatorial, molecular hydrogen emission in CRL 2688 is also presented.

[22]  arXiv:2003.06090 [pdf, other]
Title: Image simulations for strong and weak gravitational lensing
Comments: Accepted for publication in Symmetry, MDPI, special Issue on Gravitational Lensing
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Gravitational lensing has been identified as a powerful tool to address fundamental problems in astrophysics at different scales, ranging from exoplanet identification to dark energy and dark matter characterization in cosmology. Image simulations have played a fundamental role in the realization of the full potential of gravitational lensing by providing a means to address needs such as systematic error characterization, pipeline testing, calibration analyses, code validation, and model development. We present a general overview of the generation and applications of image simulations in strong and weak gravitational lensing

[23]  arXiv:2003.06099 [pdf, other]
Title: Evidence for Infalling Gas in a Lyman-$α$ Blob
Comments: 30 pages, 7 figures, submitted to Nature Astronomy. The full-text access to a view-only version of the published paper is available by using the following SharedIt link: this https URL
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Lyman-$\alpha$ blobs (LABs) are spatially extended nebulae of emission in the Ly$\alpha$ line of hydrogen, seen at high redshifts$^{1,2}$, and most commonly found in the dense environment of star-forming galaxies$^{3,4}$. The origin of Ly$\alpha$ emission in the LABs is still unclear and under debate$^{5}$. Proposed powering sources generally fall into two categories: (1) photoionization, galactic super-winds/outflows, resonant scattering of Ly$\alpha$ photons from starbursts or active galactic nuclei (AGNs)$^{6,7,8,9,10}$ and (2) cooling radiation from cold streams of gas accreting onto galaxies$^{12}$. Here we analyze the gas kinematics within a LAB providing rare observational evidence for infalling gas. This is consistent with the release of gravitational accretion energy as cold streams radiate Ly$\alpha$ photons. It also provides direct evidence for possible cold streams feeding the central galaxies. The infalling gas is not important by mass but hints at more than one mechanism to explain the origin of the extended Ly$\alpha$ emission around young galaxies. It is also possible that the infalling gas may represent material falling back to the galaxy from where it originated, forming a galactic fountain.

[24]  arXiv:2003.06104 [pdf, other]
Title: Searching for Dark Matter Signals from Local Dwarf Spheroidal Galaxies at Low Radio Frequencies in the GLEAM Survey
Comments: 11 pages, 7 Figures, Accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)

The search for emission from weakly interacting massive particle (WIMP) dark matter annihilation and decay has become a multi-pronged area of research not only targeting a diverse selection of astrophysical objects, but also taking advantage of the entire electromagnetic spectrum. The decay of WIMP particles into standard model particles has been suggested as a possible channel for synchrotron emission to be detected at low radio frequencies. Here, we present the stacking analysis of a sample of 33 dwarf spheroidal (dSph) galaxies with low-frequency (72 - 231 MHz) radio images from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. We produce radial surface brightness profiles of images centred upon each dSph galaxy with background radio sources masked. We remove ten fields from the stacking due to contamination from either poorly subtracted, bright radio sources or strong background gradients across the field. The remaining 23 dSph galaxies are stacked in an attempt to obtain a statistical detection of any WIMP-induced synchrotron emission in these systems. We find that the stacked radial brightness profile does not exhibit a statistically significant detection above the 95% confidence level of $\sim$1.5 mJy beam$^{-1}$. This novel technique shows the potential of using low-frequency radio images to constrain fundamental properties of particle dark matter.

[25]  arXiv:2003.06135 [pdf, other]
Title: Mass Estimation of Galaxy Clusters with Deep Learning I: Sunyaev-Zel'dovich Effect
Comments: 11 pages, 7 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Machine Learning (cs.LG)

We present a new application of deep learning to infer the masses of galaxy clusters directly from images of the microwave sky. Effectively, this is a novel approach to determining the scaling relation between a cluster's Sunyaev-Zel'dovich (SZ) effect signal and mass. The deep learning algorithm used is mResUNet, which is a modified feed-forward deep learning algorithm that broadly combines residual learning, convolution layers with different dilation rates, image regression activation and a U-Net framework. We train and test the deep learning model using simulated images of the microwave sky that include signals from the cosmic microwave background (CMB), dusty and radio galaxies, instrumental noise as well as the cluster's own SZ signal. The simulated cluster sample covers the mass range 1$\times 10^{14}~\rm M_{\odot}$ $<M_{200\rm c}<$ 8$\times 10^{14}~\rm M_{\odot}$ at $z=0.7$. The trained model estimates the cluster masses with a 1 $\sigma$ uncertainty $\Delta M/M \leq 0.2$, consistent with the input scatter on the SZ signal of 20%. We verify that the model works for realistic SZ profiles even when trained on azimuthally symmetric SZ profiles by using the Magneticum hydrodynamical simulations. We find the model returns unbiased mass estimates for the hydrodynamical simulations with a scatter consistent with the SZ-mass scatter in the light cones.

[26]  arXiv:2003.06137 [pdf, other]
Title: Radio galaxies and feedback from AGN jets
Comments: To appear in New Astronomy Reviews special volume '100 Years of Astrophysical Jets' (eds. Rob Fender and Ralph Wijers). 43 pages
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)

We review current understanding of the population of radio galaxies and radio-loud quasars from an observational perspective, focusing on their large-scale structures and dynamics. We discuss the physical conditions in radio galaxies, their fuelling and accretion modes, host galaxies and large-scale environments, and the role(s) they play as engines of feedback in the process of galaxy evolution. Finally we briefly summarise other astrophysical uses of radio galaxy populations, including the study of cosmic magnetism and cosmological applications, and discuss future prospects for advancing our understanding of the physics and feedback behaviour of radio galaxies.

[27]  arXiv:2003.06140 [pdf, ps, other]
Title: Efficient acceleration of cylindrical jets: effects of radiative cooling and tangled magnetic field
Comments: Accepted for publication in MNRAS, 12 pages, 4 figures, 1 table
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Diverging supersonic flows are accelerating, as in the case of a de Laval nozzle, and the same concept has been applied for acceleration of magnetohydrodynamic flows in the universe. Here, we study the dynamics of "non-diverging" cylindrical supersonic flows and show that they can be accelerated by effects of radiative cooling and the tangled magnetic field. In addition to radiative cooling of the jet materials (cooling effect), conversion of the ordered magnetic field into the turbulent one (conversion effect) and dissipation of the turbulent magnetic field (dissipation effect) are formulated according to our study on pulsar wind nebulae. Although each of the cooling and conversion effects is an ineffective acceleration process, the terminal velocity of magnetized cylindrical jets attains about half of the maximum possible value when the cooling, conversion and dissipation effects work simultaneously. The radiation efficiency is also about half of the total luminosity of the jet in the case of maximal acceleration. The concept for flow acceleration by the non-ideal MHD effects may be useful for studying relativistic jets in active galactic nuclei, in which the region near the jet axis is expected to be cylindrical and kink unstable.

[28]  arXiv:2003.06151 [pdf, other]
Title: Properties of the post in-spiral common envelope ejecta II: dust formation
Comments: 13 pages, 8 figures; submitted to MNRAS; authors welcome comments
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We study the formation of dust in the expanding gas ejected as a result of a common envelope binary interaction. In our novel approach, we apply the dust formation model of Nozawa et al. to the outputs of the 3D hydrodynamic SPH simulation performed by Iaconi et al., that involves a giant of 0.88~\ms \ and 83~\rs, with a companion of 0.6~\ms \ placed on the surface of the giant in circular orbit. After simulating the dynamic in-spiral phase we follow the expansion of the ejecta for $\simeq 18\,000$~days. During this period the gas is able to cool down enough to reach dust formation temperatures. Our results show that dust forms efficiently in the window between $\simeq 300$~days (the end of the dynamic in-spiral) and $\simeq 5000$~days. The dust forms in two separate populations; an outer one in the material ejected during the first few orbits of the companion inside the primary's envelope and an inner one in the rest of the ejected material. The inner dust population dominates the grain size distribution at the end of the simulation. We are able to fit the grain size distribution at the end of the simulation with a double power law. The slope of the power law for smaller grains is flatter than that for larger grains, creating a knee-shaped distribution. The power law indexes are however different from the classical values determined for the interstellar medium. We also estimate that the contribution to cosmic dust by common envelope events is not negligible and comparable to that of novae and supernovae.

[29]  arXiv:2003.06153 [pdf, other]
Title: Ionized outflows in local luminous AGN: what are the real densities and outflow rates?
Comments: Submitted to MNRAS; 25 pages (the last 5 are extra figures in an appendix)
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We report on the determination of electron densities, and their impact on the outflow masses and rates, measured in the central few hundred parsecs of 11 local luminous active galaxies. We show that the peak of the integrated line emission in the AGN is significantly offset from the systemic velocity as traced by the stellar absorption features, indicating that the profiles are dominated by outflow. In contrast, matched inactive galaxies are characterised by a systemic peak and weaker outflow wing. We present three independent estimates of the electron density in these AGN, discussing the merits of the different methods. The electron density derived from the [SII] doublet is significantly lower than than that found with a method developed in the last decade using auroral and transauroral lines, as well as a recently introduced method based on the ionization parameter. The reason is that, for gas photoionized by an AGN, much of the [SII] emission arises in an extended partially ionized zone where the implicit assumption that the electron density traces the hydrogen density is invalid. We propose ways to deal with this situation and we derive the associated outflow rates for ionized gas, which are in the range 0.001--0.5 M$_{\odot}$yr$^{-1}$ for our AGN sample. We compare these outflow rates to the relation between $\dot{M}_{out}$ and $L_{AGN}$ in the literature, and argue that it may need to be modified and rescaled towards lower mass outflow rates.

[30]  arXiv:2003.06163 [pdf, ps, other]
Title: High-resolution spectroscopy of flares and CMES on AD Leo*
Comments: 10 pages, 7 figures, Accepted in A & A
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)

Flares and coronal mass ejections (CMEs) are important for the evolution of the atmospheres of planets and their potential habitability, particularly for planets orbiting M stars at a distance < 0.4 AU. Detections of CMEs on these stars have been sparse and thus previous studies have modeled their occurrence frequency by scaling up solar relations. However, since the topology and strength of the magnetic fields on M stars is different from that of the Sun, it is not obvious that this approach works well. Our aim was to study, using a large amount of high resolution spectra, flares, CMEs and their dynamics of an active M dwarf star AD Leo. The results can then be used as reference for other M dwarfs. We obtained more than 2000 high-resolution spectra (R (35000)) of the highly active M dwarf AD Leo which is viewed nearly pole on. Using this data, we studied the behaviour of the spectral lines H(alpha) , H(beta) , and HeI 5876 in detail and investigated asymmetric features that could be Doppler signatures of CMEs. We detected numerous flares. The largest one emitted 8.32E31 erg in H(beta) and 2.12E32 erg in H(alpha) . Although the spectral lines in this and other events showed a significant blue asymmetry, the velocities associated with it are far below the escape velocity. Although AD Leo shows a high level of flare activity, the number of CMEs is relatively low. It is thus not appropriate to use the same flare to CME relation for M dwarfs as for the Sun.

[31]  arXiv:2003.06169 [pdf, other]
Title: Agile Earth observation satellite scheduling over 20 years: formulations, methods and future directions
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Artificial Intelligence (cs.AI); Signal Processing (eess.SP)

Agile satellites with advanced attitude maneuvering capability are the new generation of Earth observation satellites (EOSs). The continuous improvement in satellite technology and decrease in launch cost have boosted the development of agile EOSs (AEOSs). To efficiently employ the increasing orbiting AEOSs, the AEOS scheduling problem (AEOSSP) aiming to maximize the entire observation profit while satisfying all complex operational constraints, has received much attention over the past 20 years. The objectives of this paper are thus to summarize current research on AEOSSP, identify main accomplishments and highlight potential future research directions. To this end, general definitions of AEOSSP with operational constraints are described initially, followed by its three typical variations including different definitions of observation profit, multi-objective function and autonomous model. A detailed literature review from 1997 up to 2019 is then presented in line with four different solution methods, i.e., exact method, heuristic, metaheuristic and machine learning. Finally, we discuss a number of topics worth pursuing in the future.

[32]  arXiv:2003.06176 [pdf, ps, other]
Title: X-ray Observations of Planetary Nebulae since WORKPLANS I and Beyond
Authors: Martin A Guerrero (Instituto de Astrofisica de Andalucia, IAA-CSIC)
Comments: 7 pages, 3 figures, proceeding of WORKPLANS II (Leiden, The Netherlands, December 2019), accepted for publication by Galaxies
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

Planetary nebulae (PNe) were expected to be filled with hot pressurized gas driving their expansion. ROSAT hinted at the presence of diffuse X-ray emission from these hot bubbles and detected the first sources of hard X-ray emission from their central stars, but it was not until the advent of Chandra and XMM-Newton that we became able to study in detail their occurrence and physical properties. Here I review the progress in the X-ray observations of PNe since the first WORKshop for PLAnetary Nebulae observationS (WORKPLANS) and present the perspective for future X-ray missions with particular emphasis on eROSITA.

[33]  arXiv:2003.06191 [pdf, other]
Title: Continuation of the X-ray monitoring of Sgr A*: the increase in bright flaring rate confirmed
Comments: 15 pages, 15 figures, A&A accepted, abstract shortened
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The supermassive black hole Sagittarius A* (Sgr A*) is located at the dynamical center of the Milky Way. In a recent study of the X-ray flaring activity from Sgr A* using Chandra, XMM-Newton and Swift data from 1999 to 2015, it has been argued that the bright flaring rate has increased from 2014 Aug. 31 while the faint flaring rate decreased from around 2013 Aug. We tested the persistence of these changes in the flaring rates with new X-ray data of Sgr A* obtained in 2016-2018 (total exposure of 1.4Ms). We detected 9 flares in the Chandra data and 5 flares in the Swift data that we added to the set of 107 previously detected flares. We computed the intrinsic distribution of flare fluxes and durations corrected for the sensitivity bias using a new method that allowed us to take the error on the flare fluxes and durations into account. From this intrinsic distribution, we determined the average flare detection efficiency for each Chandra, XMM-Newton, and Swift observation. After correcting each observational exposure for this efficiency, we applied the Bayesian blocks algorithm on the concatenated flare arrival times. As in the above-mentioned study, we also searched for a flux and fluence threshold that might lead to a change in flaring rate. We improved the previous method by computing the average flare detection efficiencies for each flux and fluence range. The Bayesian block algorithm did not detect any significant change in flaring rate of the 121 flares. However, we detected an increase by a factor of about three in the flaring rate of the most luminous and most energetic flares that have occurred since 2014 Aug. 30. The X-ray activity of Sgr A* has increased for more than four years. Additional studies about the overall near-infrared and radio behavior of Sgr A* are required to draw strong results on the multiwavelength activity of the black hole.

[34]  arXiv:2003.06195 [pdf, other]
Title: Inner dusty envelope of the AGB stars W~Hydrae, SW\,Virginis, and R~Crateris using SPHERE/ZIMPOL
Comments: 16 pages, 9 figures, 3 tables
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Stars with initial masses between $\sim0.8$ and 8~$M_\odot$ present copious mass loss during the asymptotic giant branch (AGB) at the end of their lives. The accepted mass-loss mechanism requires radiation pressure acting on dust grains that form in the extended AGB stellar atmospheres. The details of this process are not yet well understood, however. Using the extreme-adaptive-optics imager and polarimeter SPHERE/ZIMPOL, we observed light polarised by grains around W\,Hya, SW\,Vir, and R\,Crt, which have mass-loss rates between 10$^{-7}$ and 10$^{-6}~M_\odot~{\rm yr^{-1}}$. We find the distribution of dust to be asymmetric around the three targets. A biconical morphology is seen for R Crt, with a position angle that is very similar to those inferred from interferometric observations of maser emission and of mid-infrared continuum emission. The cause of the biconical outflow cannot be directly inferred from the ZIMPOL data. The dust grains polarise light more efficiently at 0.65~$\mu$m for R\,Crt and SW\,Vir and at 0.82~$\mu$m for W\,Hya. This indicates that at the time of the observations, the grains around SW\,Vir and R\,Crt had sizes $< 0.1~\mu$m, while those around W\,Hya were larger, with sizes $\gtrsim 0.1~\mu$m. The asymmetric distribution of dust around R\,Crt makes the interpretation more uncertain for this star, however. We find that polarised light is produced already from within the visible photosphere of W~Hya, which we reproduce using models with an inner dust shell that is optically thick to scattering. The radial profile of the polarised light observed around W\,Hya reveal a steep dust density profile. We find the wind-acceleration region of W\,Hya to extend to at least $\sim 7~R_\star$, in agreement with theoretical predictions of acceleration up to $\sim 12~R_\star$.

[35]  arXiv:2003.06198 [pdf, other]
Title: Hunting for hot corinos and WCCC sources in the OMC-2/3 filament
Comments: A&A, in press, 15 pages, 10 figures, 1 appendice (13 pages, 9 figures)
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Context: Solar-like protostars are known to be chemically rich, but it is not yet clear how much their chemical composition can vary and why. So far, two chemically distinct types of Solar-like protostars have been identified: hot corinos, which are enriched in interstellar Complex Organic Molecules (iCOMs), such as methanol (CH$_3$OH) or dimethyl ether (CH$_3$OCH$_3$), and Warm Carbon Chain Chemistry (WCCC) objects, which are enriched in carbon chain molecules, such as butadiynyl (C$_4$H) or ethynyl radical (CCH). However, none of these have been studied so far in environments similar to that in which our Sun was born, that is, one that is close to massive stars. Aims: In this work, we search for hot corinos and WCCC objects in the closest analogue to the Sun's birth environment, the Orion Molecular Cloud 2/3 (OMC-2/3) filament located in the Orion A molecular cloud. Methods: We obtained single-dish observations of CCH and CH$_3$OH line emission towards nine Solar-like protostars in this region. As in other, similar studies of late, we used the [CCH]/[CH$_3$OH] abundance ratio in order to determine the chemical nature of our protostar sample. Results: Unexpectedly, we found that the observed methanol and ethynyl radical emission (over a few thousands au scale) does not seem to originate from the protostars but rather from the parental cloud and its photo-dissociation region, illuminated by the OB stars of the region. Conclusions: Our results strongly suggest that caution should be taken before using [CCH]/[CH$_3$OH] from single-dish observations as an indicator of the protostellar chemical nature and that there is a need for other tracers or high angular resolution observations for probing the inner protostellar layers.

[36]  arXiv:2003.06223 [pdf, other]
Title: The Fraction of Gamma-ray Bursts with an Observed Photospheric Emission Episode
Comments: Accepted: ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

There is no complete description of the emission physics during the prompt phase in gamma-ray bursts. Spectral analyses, however, indicate that many spectra are narrower than what is expected for non-thermal emission models. Here, we reanalyse the sample of 37 bursts in \citet{Yu2019}, by fitting the narrowest time-resolved spectrum in each burst. We perform model comparison between a photospheric and a synchrotron emission model based on Bayesian evidence. We choose to compare the shape of the narrowest expected spectra: emission from the photosphere in a non-dissipative flow and slow-cooled synchrotron emission from a narrow electron distribution. We find that the photospheric spectral shape is preferred by $54 \pm 8 \%$ of the spectra (20/37), while $38 \pm 8 \%$ of the spectra (14/37) prefer the synchrotron spectral shape; three spectra are inconclusive. We hence conclude that GRB spectra are indeed very narrow and that more than half of the bursts have a photospheric emission episode. We also find that a third of all analysed spectra, not only prefer, but are also compatible with a non-dissipative photosphere, confirming previous similar findings.
Furthermore, we notice that the spectra, that prefer the photospheric model, all have a low-energy power-law indices $\alpha > -0.5$. This means that $\alpha$ is a good estimator of which model is preferred by the data.
Finally, we argue that the spectra which statistically prefer the synchrotron model, could equally well be caused by subphotospheric dissipation. If that is the case, photospheric emission during the early, prompt phase would be even more dominant.

[37]  arXiv:2003.06245 [pdf]
Title: The Evolution of the Star-forming Interstellar Medium across Cosmic Time
Comments: To be published in Annual Reviews of Astronomy and Astrophysics
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Over the past decade increasingly robust estimates of the dense molecular gas content in galaxy populations between redshift 0 and the peak of cosmic galaxy/star formation from redshift 1-3 have become available. This rapid progress has been possible due to the advent of powerful ground-based, and space telescopes for combined study of several millimeter to far-IR, line or continuum tracers of the molecular gas and dust components. The main conclusions of this review are:
1. Star forming galaxies contained much more molecular gas at earlier cosmic epochs than at the present time.
2. The galaxy integrated depletion time scale for converting the gas into stars depends primarily on z or Hubble time, and at a given z, on the vertical location of a galaxy along the star-formation rate versus stellar mass "main-sequence" (MS) correlation.
3. Global rates of galaxy gas accretion primarily control the evolution of the cold molecular gas content and star formation rates of the dominant MS galaxy population, which in turn vary with the cosmological expansion. A second key driver may be global disk fragmentation in high-z, gas rich galaxies, which ties local free-fall time scales to galactic orbital times, and leads to rapid radial matter transport and bulge growth. Third, the low star formation efficiency inside molecular clouds is plausibly set by super-sonic streaming motions, and internal turbulence, which in turn may be driven by conversion of gravitational energy at high-z, and/or by local feedback from massive stars at low-z.
4. A simple 'gas regulator' model is remarkably successful in predicting the combined evolution of molecular gas fractions, star formation rates, galactic winds, and gas phase metallicities.

[38]  arXiv:2003.06248 [pdf, other]
Title: High Quality Software for Planetary Science from Space
Comments: presentation at XVI Congresso Nazionale di Scienze Planetarie (National Conference on Planetary Sciences) held at Centro Culturale San Gaetano, via Altinate, 71, Padova, Italy on 3-7 February, 2020 Affiliation: University of Padova, 6 pages, 4 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Software Engineering (cs.SE)

Planetary science space missions need high quality software ed efficient algorithms in order to extract innovative scientific results from flight data. Reliable and efficient software technologies are increasingly vital to improve and prolong the exploiting of the results of a mission, to allow the application of established algorithms and technologies also to future space missions and for the scientific analysis of archived data. Here after will be given an in-depth analysis study accompanied by implementation examples on ESA and ASI missions and some remarkable results fruit of decades of important experience reached by space agencies and research institutes in the field. Space applications software quality analysis is not different from other application contexts, among the hi-tech and hi-reliability fields. We describe here a Software Quality study in general, then we will focus on the quality of space mission software (s/w) with details on some notable cases.

[39]  arXiv:2003.06255 [pdf, other]
Title: How galaxies populate haloes in very low-density environments? An analysis of the Halo Occupation Distribution in cosmic voids
Comments: 11 pages and 12 figures. Submitted to A&A. Comments are welcome
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Evidence shows properties of dark matter haloes may vary with large-scale environment. By studying the halo occupation distribution in cosmic voids it is possible to obtain useful information that can shed light on the subject. The history of the formation of the haloes and galaxies residing in these regions is likely to differ from the global behaviour given their extreme environment. We use two public access simulated galaxy catalogues constructed with different methods: a semi-analytical model and a hydrodynamic simulation. In both, we identify cosmic voids and we measure the halo occupation distribution inside these regions for different absolute magnitude thresholds. We compare these determinations with the overall results and we study the dependence of different characteristics of the voids. Also, we analyze the stellar content and the formation time of the haloes inside voids and confront the general halo population results. Inside the voids, we find a significantly different halo occupation distribution with respect to the general results. This is present in all absolute magnitude ranges explored. We obtain no signs of variation related to void characteristics indicating that the effects depend only on the density of the large-scale environment. Additionally, we find that the stellar mass content also differs within voids, which host haloes with less massive central galaxies (10%) as well as satellites with significantly lower stellar mass content (30%). Finally, we find a slight difference between the formation times of the haloes which are younger in voids than the average population. These characteristics indicate that haloes populating voids have had a different formation history, inducing significant changes on the halo occupation distribution.

[40]  arXiv:2003.06260 [pdf, ps, other]
Title: The Background Model of the Medium Energy X-ray telescope of Insight-HXMT
Comments: to be published in Journal of High Energy Astrophysics
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)

The Medium Energy X-ray Telescope (ME) is one of the main payloads of the Hard X-ray Modulation Telescope (dubbed as Insight-HXMT). The background of Insight-HXMT/ME is mainly caused by the environmental charged particles and the background intensity is modulated remarkably by the geomagnetic field, as well as the geographical location. At the same geographical location, the background spectral shape is stable but the intensity varies with the level of the environmental charged particles. In this paper, we develop a model to estimate the ME background based on the ME database that is established with the two-year blank sky observations of the high Galactic latitude. In this model, the entire geographical area covered by Insight-HXMT is divided into grids of $5^{\circ}\times5^{\circ}$ in geographical coordinate system. For each grid, the background spectral shape can be obtained from the background database and the intensity can be corrected by the contemporary count rate of the blind FOV detectors. Thus the background spectrum can be obtained by accumulating the background of all the grids passed by Insight-HXMT during the effective observational time. The model test with the blank sky observations shows that the systematic error of the background estimation in $8.9-44.0$ keV is $\sim1.3\%$ for a pointing observation with an average exposure $\sim5.5$ ks. We also find that the systematic error is anti-correlated with the exposure, which indicates the systematic error is partly contributed by the statistical error of count rate measured by the blind FOV detectors.

[41]  arXiv:2003.06273 [pdf, other]
Title: Decoherence in LOFAR-VLBI Beamforming
Comments: 14 pages, 5 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

We show that the use of a superstation (a phased array created using multiple stations of an interferometric array) created in post-processing for LOFAR-VLBI observations introduces a direction-dependent loss of signal in the image. We show this effect using simulations and real data. Using the RIME formalism, we characterise it fully, and give limits under which this signal loss is negligible. Finally, we show that we are able to fully predict this effect. We close with guidelines for interferometric observers to avoid this effect in their observations, and a discussion of techniques which could limit this effect or do away with it entirely. The latter in particular will be relevant to the SKA should its long baselines be used to their fullest potential.

[42]  arXiv:2003.06287 [pdf, other]
Title: Can gyrochronological ages be affected by the variation of the magnetic braking index?
Comments: 14 pages, 3 figures, 2 tables. arXiv admin note: text overlap with arXiv:2003.01444
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

The present work attempts to analytically explain the effects on the moment of inertia, $I$, caused by the evolution of stellar velocity in main-sequence stars. We have found that the effects linked to stellar oblateness can be estimated from the variation of the magnetic braking index denoted by $\Delta q$. We have also found that the effect of $\dot{I}$ is here a determining factor for understanding the delicate mechanisms that control the spin-down of stars in this evolutionary phase. We note that our models predict that the behaviour of the variations of the braking index is distinct when the star density decreases. In the present study, we used three sample stellar targets from the archives of the different satellites, such as CoRoT and \textit{Kepler}, to estimate the possible correlations among the parameters extracted from our model and the stellar age. As a result, we find that $\Delta q$ is strongly correlated to the age of stars. In conclusion, we suggest that the variations of the magnetic braking index due to oblateness can be an interesting way to estimate stellar ages.

[43]  arXiv:2003.06306 [pdf]
Title: Earth$'$s polar night boundary layer as an analogue for dark side inversions on synchronously rotating terrestrial exoplanets
Comments: Accepted by Astrophysical Journal Letters; 14 pages, 3 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

A key factor in determining the potential habitability of synchronously rotating planets is the strength of the atmospheric boundary layer inversion between the dark side surface and the free atmosphere. Here we analyse data obtained from polar night measurements at the South Pole and Alert Canada, which are the closest analogues on Earth to conditions on the dark sides of synchronously rotating exoplanets without and with a maritime influence, respectively. On Earth, such inversions rarely exceed 30 K in strength, because of the effect of turbulent mixing induced by phenomena such as so-called mesoscale slope winds, which have horizontal scales of 10s to 100s of km, suggesting a similar constraint to near-surface dark side inversions. We discuss the sensitivity of inversion strength to factors such as orography and the global-scale circulation, and compare them to a simulation of the planet Proxima Centauri b. Our results demonstrate the importance of comparisons with Earth data in exoplanet research, and highlight the need for further studies of the exoplanet atmospheric collapse problem using mesoscale and eddy-resolving models.

[44]  arXiv:2003.06317 [pdf, other]
Title: A telescope control and scheduling system for the Gravitational-wave Optical Transient Observer
Authors: Martin J Dyer
Comments: 344 pages, PhD Thesis (submitted 26 September 2019, awarded 10 January 2020), abstract and some images compressed for space (see this https URL for original)
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

The detection of the first electromagnetic counterpart to a gravitational-wave signal in August 2017 marked the start of a new era of multi-messenger astrophysics. An unprecedented number of telescopes around the world were involved in hunting for the source of the signal, and although more gravitational-wave signals have been since detected, no further electromagnetic counterparts have been found.
In this thesis, I present my work to help build a telescope dedicated to the hunt for these elusive sources: the Gravitational-wave Optical Transient Observer (GOTO). I detail the creation of the GOTO Telescope Control System, G-TeCS, which includes the software required to control multiple wide-field telescopes on a single robotic mount. G-TeCS also includes software that enables the telescope to complete a sky survey and transient alert follow-up observations completely autonomously, whilst monitoring the weather conditions and automatically fixing any hardware issues that arise. I go on to describe the routines used to determine target priorities, as well as how the all-sky survey grid is defined, how gravitational-wave and other transient alerts are received and processed, and how the optimum follow-up strategies for these events were determined.
The GOTO prototype, situated on La Palma, saw first light in June 2017. I detail the work I carried out on the site to help commission the prototype, and how the control software was developed during the commissioning phase. I also analyse the GOTO CCD cameras and optics, building a complete theoretical model of the system to confirm the performance of the prototype. Finally, I describe the results of simulations I carried out predicting the future of the GOTO project, with multiple robotic telescopes on La Palma and in Australia, and how G-TeCS might be modified to operate these telescopes as a single, global observatory.

[45]  arXiv:2003.06322 [pdf, other]
Title: Relativistic Jets of Blazars
Comments: To appear in New Astronomy Reviews special volume '100 Years of Astrophysical Jets' (eds. Rob Fender and Ralph Wijers)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Relativistic jets of active galactic nuclei have been known to exist for 100 years. Blazars with their jet pointing close to our line of sight are some of the most variable and extreme objects in the universe, showing emission from radio to very-high-energy gamma rays. In this review, we cover relativistic jets of blazars from an observational perspective with the main goal of discussing how observations can be used to constrain theoretical models. We cover a range of topics from multiwavelength observations to imaging of jets with a special emphasis on current open questions in the field.

[46]  arXiv:2003.06359 [pdf, other]
Title: Confirmed short periodic variability of subparsec supermassive binary black hole candidate Mrk 231
Comments: Accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

Here we confirm the short periodic variability of a subparsec supermassive binary black hole (SMBBH) candidate Mrk 231 in the extended optical photometric data set collected by the Catalina Real-Time Transient Survey (CRTS) and All-Sky Automated Survey for Supernovae (ASAS-SN). Using the Lomb-Scargle periodogram and 2DHybrid method, we detected the significant periodicity of ~ 1.1 yr beyond a damped random walk model in the CRTS+ASAS-SN optical data set. Mrk 231 has been previously proposed as a SMBBH candidate with a highly unequal mass ratio (q~ 0.03), very tight mutual separation of ~590 AU, and an orbital period of ~1.2 yr. Hence, our result further supports, even though not prove, the intriguing hypothesis that SMBBHs with low mass ratios may be more common than close-equal mass SMBBHs. This result, however, was obtained from the contribution of CRTS data with limited sampling cadence and photometric accuracy, and further monitoring of Mrk 231 is crucial to confirm the periodicity.

[47]  arXiv:2003.06370 [pdf, other]
Title: Spallation of r-Process Nuclei Ejected from a Neutron Star Merger
Comments: 11 pages, 3 figures, NPA-IX proceedings
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)

Neutron star mergers (NSMs) are rapid neutron capture (r-process) nucleosynthesis sites, which eject materials at high velocities, from 0.1c to as high as 0.6c. Thus the r-process nuclei ejected from a NSM event are sufficiently energetic to initiate spallation reactions with the interstellar medium (ISM) particles. With a thick-target model for the propagation of high-speed heavy nuclei in the ISM, we find that spallation reactions may shift the r-process abundance patterns towards solar data, particularly around the low-mass edges of the r-process peaks where neighboring nuclei have very different abundances. The spallation effects depend both on the astrophysical conditions of the r-process nuclei and nuclear physics inputs for the nucleosynthesis calculations and the propagation process. This work extends that of [Wang et al.(2019)] by focusing on the influence of nuclear physics variations on spallation effects.

[48]  arXiv:2003.06371 [pdf, other]
Title: The Bubble Nebula NGC 7635 -- testing the wind-blown bubble theory
Comments: 10 Figures, 1 Table; Accepted to MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We present a multiwavelength study of the iconic Bubble Nebula (NGC 7635) and its ionising star BD$+$60$^{\circ}$2522. We obtained XMM-Newton EPIC X-ray observations to search for extended X-ray emission as in other similar wind-blown bubbles around massive stars. We also obtained San Pedro M\'{a}rtir spectroscopic observations with the Manchester Echelle Spectrometer to study the dynamics of the Bubble Nebula. Although our EPIC observations are deep, we do not detect extended X-ray emission from this wind-blown bubble. On the other hand, BD$+$60$^{\circ}$2522 is a bright X-ray source similar to other O stars. We used the stellar atmosphere code PoWR to characterise BD$+$60$^{\circ}$2522 and found that this star is a young O-type star with stellar wind capable of producing a wind-blown bubble that in principle could be filled with hot gas. We discussed our findings in line with recent numerical simulations proposing that the Bubble Nebula has been formed as the result of the fast motion of BD$+$60$^{\circ}$2522 through the medium. Our kinematic study shows that the Bubble Nebula is composed by a series of nested shells, some showing blister-like structures, but with little signatures of hydrodynamical instabilities that would mix the material producing diffuse X-ray emission as seen in other wind-blown bubbles. Its morphology seems to be merely the result of projection effects of these different shells.

[49]  arXiv:2003.06394 [pdf, other]
Title: The Synthetic Emission Line COSMOS catalog: H$α$ and [OII] galaxy luminosity functions and counts at $0.3<z<2.5$
Comments: 21 pages, 22 figures, accepted for publication in MNRAS. Our catalog is available as "EL-COSMOS" on the ASPIC database, this http URL
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)

Star-forming galaxies with strong nebular and collisional emission lines are privileged target galaxies in forthcoming cosmological large galaxy redshift surveys. We use the COSMOS2015 photometric catalog to model galaxy spectral energy distributions and emission-line fluxes. We adopt an empirical but physically-motivated model that uses information from the best-fitting spectral energy distribution of stellar continuum to each galaxy. The emission-line flux model is calibrated and validated against direct flux measurements in subsets of galaxies that have 3D-HST or zCOSMOS-Bright spectra. We take a particular care in modelling dust attenuation such that our model can explain both H$\alpha$ and [OII] observed fluxes at different redshifts. We find that a simple solution to this is to introduce a redshift evolution in the dust attenuation fraction parameter, $f=E_{\rm star}(B-V)/E_{\rm gas}(B-V)$, as $f(z)=0.44+0.2z$. From this catalog, we derive the H$\alpha$ and [OII] luminosity functions up to redshifts of about 2.5 after carefully accounting for emission line flux and redshift errors. This allows us to make predictions for H$\alpha$ and [OII] galaxy number counts in next-generation cosmological redshift surveys. Our modeled emission lines and spectra in the COSMOS2015 catalog shall be useful to study the target selection for planned next-generation galaxy redshift surveys and we make them publicly available as `EL-COSMOS' on the ASPIC database.

[50]  arXiv:2003.06396 [pdf, other]
Title: Gravity in the Era of Equality: Towards solutions to the Hubble problem without fine-tuned initial conditions
Comments: Summary for busy readers. 26 pages + appendices, 16 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

Discrepant measurements of the Universe's expansion rate ($H_0$) may signal physics beyond the standard cosmological model. Here I describe two early modified gravity mechanisms that reconcile the value of $H_0$ by increasing the expansion rate in the era of matter-radiation equality. These mechanisms, based on viable Horndeski theories, require significantly less fine-tuned initial conditions than early dark energy with oscillating scalar fields. In Imperfect Dark Energy at Equality (IDEE), the initial energy density dilutes slower than radiation but faster than matter, naturally peaking around the era of equality. The minimal IDEE model, a cubic Galileon, is too constrained by the cosmic microwave background (Planck) and baryon acoustic oscillations (BAO) to relieve the $H_0$ tension. In Enhanced Early Gravity (EEG), the scalar field value modulates the cosmological strength of gravity. The minimal EEG model, an exponentially coupled cubic Galileon, gives a Planck+BAO value $H_0=68.7 \pm 1.5$ (68\% c.l.), reducing the tension with SH0ES from $4.4\sigma$ to $2.6\sigma$. Additionally, Galileon contributions to cosmic acceleration may reconcile $H_0$ via Late-Universe Phantom Expansion (LUPE). Combining LUPE, EEG and $\Lambda$ reduces the tension between Planck, BAO and SH0ES to $2.5\sigma$. I will also describe additional tests of coupled Galileons based on local gravity tests, primordial element abundances and gravitational waves. While further model building is required to fully resolve the $H_0$ problem and satisfy all available observations, these examples show the wealth of possibilities to solve cosmological tensions beyond Einstein's General Relativity.

[51]  arXiv:2003.06405 [pdf, other]
Title: 3HSP J095507.9+355101: a flaring extreme blazar coincident in space and time with IceCube-200107A
Comments: Submitted to MNRAS, 5 pages, 4 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The day after the arrival of the IceCube neutrino 200107A 3HSP J095507.9+355101, an extreme blazar with synchrotron peak frequency > 5E17 Hz, z=0.557, and well within the neutrino event error region, was found to exhibit a very hard X-ray flare. We report here on its multi-messenger data and classify the source as an unlikely "masquerading" BL Lac, contrary to TXS 0506+056, the first source so far associated with IceCube neutrinos. Similarly to TXS\,0506+056, however, 3HSP J095507.9+355101 is also way off the so-called "blazar sequence". Finally, we discuss some theoretical implications in terms of neutrino production. We show that, based on all of the above, 3HSP J095507.9+355101 is a very plausible counterpart to an IceCube neutrino.

[52]  arXiv:2003.06407 [pdf, other]
Title: Systematic Phase Curve Study of Known Transiting Systems from Year 1 of the TESS Mission
Comments: 25 pages, 8 figures, submitted to AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

We present a systematic phase curve analysis of known transiting systems observed by the Transiting Exoplanet Survey Satellite during Year 1 of the Primary Mission. Using theoretical predictions for the amplitude of the planetary longitudinal atmospheric brightness modulation, stellar ellipsoidal distortion and Doppler boosting, as well as brightness considerations to select targets with likely detectable signals, we applied a uniform data processing and light curve modeling framework to fit the full-orbit phase curves of 19 transiting systems with planet-mass or brown dwarf companions. Statistically significant secondary eclipse depths and/or atmospheric brightness modulation amplitudes were measured for HIP 65A, WASP-72, WASP-100, WASP-111, and WASP-122/KELT-14. For WASP-100b, we found marginal evidence that the brightest region of the atmosphere is shifted eastward by $14\overset{\circ}{.}2\pm4\overset{\circ}{.}6$ away from the substellar point. We found significant ellipsoidal distortion signals in the light curves of HIP 65A, TOI-503, and WASP-30, with TOI-503 also exhibiting Doppler boosting. The measured amplitudes of these signals agree with the predictions of theoretical models. From our light curve fits, we also measured updated and refined orbital ephemerides and transit shape parameters. Combining the optical secondary eclipse depths with previously published Spitzer 3.6 and 4.5 $\mu$m measurements, we derived dayside brightness temperatures and visible-light geometric albedos for a subset of the analyzed systems. We find a tentative correlation between increasing dayside temperature and increasing geometric albedo in the TESS bandpass, suggesting enhanced atmospheric reflectivity and/or additional opacity sources contributing to the visible-light flux for planets with $T_{\mathrm{day}}>2200$ K.

[53]  arXiv:2003.06411 [pdf, other]
Title: The Halo Void (Dust) Model of Large Scale Structure
Comments: 40 pages, 12 figures. Comments are welcome
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)

Within the Halo Model of large scale structure, all matter is contained in dark matter halos. This simple yet powerful framework has been broadly applied to multiple data sets and enriched our comprehension of how matter is distributed in the Universe. In this work we extend this assumption by allowing for matter to rest not only inside halos but also within cosmic voids and in between halos and voids (which we call 'dust'). This assumption leads to additional contributions (1Void, 2Void, Halo-Void, etc.) to the predictions of correlation functions, spectra and profiles for both halos and voids. Whereas the Halo Model can only make predictions for halo quantities, the Halo Void Model extends those for void statistics and halo-void cross-correlations. We provide recipes for all new ingredients of the Halo Void (Dust) Model, such as the void abundance, linear bias and density profile and test their validity in a N-body simulation. Including voids and dust into the calculations improves the transition between the 1Halo and the 2Halo terms by up to $\sim 6\%$. It also eliminates the need to include low-mass structures on the normalization of large-scale terms, suggesting that halos and voids are complementary cosmic structures to effectively describe matter distribution on large scales of the Universe.

Cross-lists for Mon, 16 Mar 20

[54]  arXiv:2003.05501 (cross-list from hep-th) [pdf, other]
Title: Holographic duality and mode stability of de Sitter space in semiclassical gravity
Comments: 11 pages, one figure
Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

We employ holographic duality to compute $\langle T_{\mu \nu} \rangle$ in strongly coupled $\mathcal N = 4$ supersymmetric Yang-Mills theory and then study evolution of the semiclassical Einstein field equations sourced by $\langle T_{\mu \nu} \rangle$. Linearizing about de Sitter space, we find that the semiclassical equations of motion reduce to a four dimensional scalar wave equation coupled to a five dimensional scalar wave equation. We compute the mode spectrum of these equations and find that there exists a critical value of the Hubble constant $H_c$ for which de Sitter space is unstable when $H < H_c$ and mode stable when $H > H_c$.

[55]  arXiv:2003.05965 (cross-list from physics.atom-ph) [pdf, other]
Title: Two-Electron-One-Photon Processes Can Dominate over Allowed Radiative and Auger Decay in Few-Electron Ions
Authors: Moto Togawa (1), Steffen Kühn (1, 2), Chintan Shah (1, 3), Pedro Amaro (4), René Steinbrügge (5), Jakob Stierhof (6), Natalie Hell (7), Michael Rosner (1, 2), Keisuke Fujii (8), Matthias Bissinger (6), Ralf Ballhausen (6), Moritz Hoesch (5), Jörn Seltmann (5), SungNam Park (9), Filipe Grilo (4), F. Scott Porter (3), José Paulo Santos (4), Moses Chung (9), Thomas Stöhlker (10, 11, 12), Jörn Wilms (6), Thomas Pfeifer (1), Gregory V. Brown (7), Maurice A. Leutenegger (3), Sven Bernitt (1, 10, 11, 12), José R. Crespo López-Urrutia (1) ((1) Max-Planck-Institut für Kernphysik, Heidelberg, Germany, (2) Heidelberg Graduate School of Fundamental Physics, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany, (3) NASA/Goddard Space Flight Center, Greenbelt, USA, (4) Laboratory of Instrumentation, Biomedical Engineering and Radiation Physics (LIBPhys-UNL), Department of Physics, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal, (5) Deutsches Elektronen-Sychrotron DESY, Hamburg, Germany, (6) Dr. Karl Remeis-Sternwarte and Erlangen Centre for Astroparticle Physics (ECAP), Erlangen, Germany, (7) Lawrence Livermore National Laboratory, Livermore, USA, (8) Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Japan, (9) Ulsan National Institute of Science and Technology, Ulsan, South Korea, (10) Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Jena, Germany, (11) GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany, (12) Helmholtz-Institut Jena, Jena, Germany)
Comments: 8 pages, 6 figures (incl. Supplement Materia) submitted to PRL
Subjects: Atomic Physics (physics.atom-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Plasma Physics (physics.plasm-ph)

We resonantly excite the $K$ series of O$^{5+}$ and O$^{6+}$ up to principal quantum number $n=11$ with monochromatic x rays, producing $K$-shell holes, and observe their relaxation by soft x-ray emission. Some photoabsorption resonances of O$^{5+}$ reveal strong two-electron-one-photon (TEOP) transitions. We find that for the $1s\,2s\,5p\, ^1P_1$ state, TEOP relaxation is by far stronger than the competing, and usually much faster, allowed Auger and radiative decay paths. This enhanced TEOP decay arises from a strong correlation with the near-degenerate upper state $1s\,2p\,4s\, ^1P_1$ of a $K\alpha$ satellite. Even in three-electron systems, TEOP transitions can play a dominant role, and the present results should guide further research on the ubiquitous and abundant many-electron ions where various electronic energy degeneracies and level mixings are far more common.

[56]  arXiv:2003.06020 (cross-list from physics.hist-ph) [pdf]
Title: Extreme Space Weather Events Recorded in History
Comments: 19 pages, 8 figures, written in Japanese, a Japanese article for a part of the Solar-Terrestrial Environment Prediction, in press
Journal-ref: Solar-Terrestrial Environment Prediction, 2020
Subjects: History and Philosophy of Physics (physics.hist-ph); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

This section shows an overview of a recent development of the studies on great space weather events in history. Its discussion starts from the Carrington event and compare its intensity with the extreme storms within the coverage of the regular magnetic measurements. Extending its analyses back beyond their onset, this section shows several case studies of extreme storms with sunspot records in the telescopic observations and candidate auroral records in historical records. Before the onset of telescopic observations, this section shows the chronological coverages of the records of unaided-eye sunspot and candidate aurorae and several case studies on their basis.

[57]  arXiv:2003.06284 (cross-list from hep-ex) [pdf, ps, other]
Title: On the possibility of research the photon-photon interaction at the European X-ray Free Electron Laser -- European XFEL
Comments: 5 pages, 4 figures
Journal-ref: Journal of Physics: Conference Series, Volume 1400, Issue 2, article id. 022008 (2019)
Subjects: High Energy Physics - Experiment (hep-ex); High Energy Astrophysical Phenomena (astro-ph.HE)

The possibility of performing the experimental research in the field of fundamental physics based on the unique instrument -- European X-ray Free Electron Laser (E-XFEL) is considered in this paper. The calculations of the reaction $\gamma + \gamma \to e^{+} + e^{-}$ cross section for gamma quanta with $E \sim~(1-100)\,\mbox{GeV}$ energy with X-ray photons are performed. The possibility of experimental registration of reaction $\gamma + \gamma \to e^{+} + e^{-}$ product are reviewed. Also, the optical depth of the interaction between gamma-rays with the E-XFEL's photon pulses is estimated. Astrophysical applications are discussed.

Replacements for Mon, 16 Mar 20

[58]  arXiv:1808.03836 (replaced) [pdf, other]
Title: Distinguishing the nature of comparable-mass neutron star binary systems with multimessenger observations: GW170817 case study
Comments: 8 pages
Journal-ref: Phys. Rev. D 100, 063021 (2019)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[59]  arXiv:1904.03772 (replaced) [pdf, other]
Title: Power law pseudo phase-space density profiles of dark matter halos: fluke of physics?
Comments: ApJ, Accepted
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[60]  arXiv:1907.10328 (replaced) [pdf, other]
Title: Beyond second-order convergence in simulations of magnetised binary neutron stars with realistic microphysics
Comments: 13 pages, 9 figures matches accepted version
Journal-ref: Monthly Notices of the Royal Astronomical Society, Volume 490, Issue 3, December 2019, Pages 3588-3600
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Computational Physics (physics.comp-ph)
[61]  arXiv:1909.04662 (replaced) [pdf, other]
Title: One-loop renormalization in Galileon effective field theory
Comments: 14 pages; typos corrected, references updated, published in JCAP; the divergent off-shell contributions to the 1PI one-loop diagrams for the 2-point, 3-point, 4-point, and 5-point functions are provided in an ancillary file (txt format)
Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
[62]  arXiv:1910.02699 (replaced) [pdf, ps, other]
Title: Scalar-field dark energy nonminimally and kinetically coupled to dark matter
Comments: published version with corrections, 24 pages
Journal-ref: Phys. Rev. D 101 (2020) no.6, 063511
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)
[63]  arXiv:1910.08325 (replaced) [pdf, other]
Title: Time-dependent $G$ in Einstein's equations as an alternative to the cosmological constant
Comments: 9 pages, 2 figures, Phys. Rev. D Published in 12 March 2020 - this https URL
Journal-ref: Phys. Rev. D 101, 063513 Published 12 March 2020
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
[64]  arXiv:1911.00707 (replaced) [pdf, other]
Title: AGN fueling and feedback, from pc to kpc scale
Authors: Francoise Combes
Comments: 8 pages, 4 figures, IAU Symp 356 "Nuclear Activity in Galaxies Across Cosmic Time", ed. M. Povic et al
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[65]  arXiv:1911.01582 (replaced) [pdf, other]
Title: Separating the Intrinsic Alignment Signal and the Lensing Signal using Self-Calibration in Photo-z Surveys with KiDS450 and KV450 Data
Comments: revision
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[66]  arXiv:1911.06050 (replaced) [pdf, other]
Title: Including higher order multipoles in gravitational-wave models for precessing binary black holes
Comments: 13 pages, 8 figures
Journal-ref: Phys. Rev. D 101, 024056 (2020)
Subjects: General Relativity and Quantum Cosmology (gr-qc); Solar and Stellar Astrophysics (astro-ph.SR)
[67]  arXiv:1911.11735 (replaced) [pdf, other]
Title: Asymmetry between galaxies with different spin patterns: A comparison between COSMOS, SDSS, and Pan-STARRS
Authors: Lior Shamir
Comments: Open Astronomy, accepted
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[68]  arXiv:1912.01621 (replaced) [pdf, other]
Title: The ALPINE-ALMA [CII] Survey: Multi-Wavelength Ancillary Data and Basic Physical Measurements
Comments: 48 pages, 33 figures, 7 tables (including Appendix), accepted for publication in ApJS
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[69]  arXiv:1912.04213 (replaced) [pdf, ps, other]
Title: On average properties of inhomogeneous fluids in general relativity III: general fluid cosmologies
Comments: 67 pages, 4 figures, 1 table; matches published version in GRG as `Editor's Choice Research Article'
Journal-ref: Gen. Rel. Grav. 52 (2020) 27
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[70]  arXiv:1912.04636 (replaced) [pdf, other]
Title: Mimetic Black Holes
Comments: 24 pages, 4 figures
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
[71]  arXiv:1912.08213 (replaced) [pdf, other]
Title: A mass threshold for galactic gas discs by spin flips
Comments: 23 pages, 11 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[72]  arXiv:1912.12465 (replaced) [pdf, other]
Title: Combining gravitational and electromagnetic waves observations to investigate the Hubble tension
Comments: 10 pages, 4 figures
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[73]  arXiv:1912.13209 (replaced) [pdf, other]
Title: Accrete, Accrete, Accrete... Bang! (and repeat): The Remarkable Recurrent Novae
Comments: A review article now accepted to appear within The Golden Age of Cataclysmic Variables and Related Objects V, Proceedings of Science. 19 pages, 2 figures, 1 table
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
[74]  arXiv:1912.13220 (replaced) [pdf, ps, other]
Title: Stringy Newton Gravity with $H$-flux
Comments: 6 pages, No figure, v2) Refs added
Journal-ref: Phys. Rev. D 101, 064020 (2020)
Subjects: High Energy Physics - Theory (hep-th); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
[75]  arXiv:2001.06494 (replaced) [pdf, other]
Title: Turbulence in stratified atmospheres: implications for the intracluster medium
Comments: MNRAS accepted version. For simulation movies see: this https URL
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Atmospheric and Oceanic Physics (physics.ao-ph); Fluid Dynamics (physics.flu-dyn)
[76]  arXiv:2001.11146 (replaced) [pdf, other]
Title: ART$^2$: A 3D Parallel Multi-wavelength Radiative Transfer Code for Continuum and Atomic and Molecular Lines
Authors: Yuexing Li (Penn State), Ming F. Gu (UC Berkeley), Hidenobu Yajima (University of Tsukuba), Qirong Zhu (Carnegie Mellon), Moupiya Maji (University of Geneva)
Comments: Accepted for publication in MNRAS; 20 pages, 26 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP)
[77]  arXiv:2002.11735 (replaced) [pdf, other]
Title: The GOGREEN survey: The environmental dependence of the star-forming galaxy main sequence at $1.0<z<1.5$
Comments: Accepted for publication in MNRAS on February 25 2020
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[78]  arXiv:2003.04346 (replaced) [pdf, other]
Title: The $\it{XXL}$ survey: XL. Obscuration properties of red AGN in $\it{XXL-N}$
Comments: A&A accepted, 37 pages, 51 figures, 7 tables
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[79]  arXiv:2003.04940 (replaced) [pdf, other]
Title: The Chemical Nature of the Young 120-Myr-old Nearby Pisces-Eridanus Stellar Stream Flowing through the Galactic Disk
Comments: 13 Pages, 9 Figures, 3 Tables. Submitted to MNRAS, Comments Welcome
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
[80]  arXiv:2003.04951 (replaced) [pdf, other]
Title: Relationship between rotation curves and matter distribution in spiral galaxy discs
Comments: 44 pages, 13 figures, Master thesis, Department of Astrophysics, University of La Laguna (Tenerife, Spain), July 2016
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[81]  arXiv:2003.05010 (replaced) [pdf, other]
Title: Collision between Molecular Clouds I. The effect of the cloud virial ratio in head-on collisions
Comments: 13 pages, 15 figures; Accepted by MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[82]  arXiv:2003.05457 (replaced) [pdf, other]
Title: Fluctuations in galactic bar parameters due to bar-spiral interaction
Comments: 25 p., 19 figures, submitted to MNRAS, Comments welcome
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[83]  arXiv:2003.05499 (replaced) [pdf, other]
Title: Asteroids' Size Distribution and Colors from HiTS
Authors: J. Peña (1,2), C. Fuentes (1,2), F. Förster (3,2), J. Martínez-Palomera (4,1,3), G. Cabrera-Vives (5,2), J.C. Maureira (3), P. Huijse (6, 2), P.A. Estévez (7,2), L. Galbany (8), S. González-Gaitán (9, 3, 2), Th. de Jaeger (4, 1, 2) ((1) Departamento de Astronomía, Universidad de Chile, Las Condes, Santiago, Chile, (2) Millennium Institute of Astrophysics, Chile., (3) Center for Mathematical Modeling, Santiago, Chile, (4) Department of Astronomy, University of California, Berkeley, CA, USA., (5) Department of Computer Science, Universidad de Concepción, Chile, (6) Informatics Institute, Universidad Austral de Chile, Chile, (7) Electrical Engineering Department, University of Chile, Chile, (8) Departamento de Física Teórica y del Cosmos, Universidad de Granada, Granada, Spain, (9) CENTRA, Instituto Superior Técnico, Universidade de Lisboa, Portugal)
Comments: 17 pages, 18 figures
Journal-ref: The Astronomical Journal, Volume 159, Number 4, Page 148, Year 2020
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[84]  arXiv:2003.05714 (replaced) [pdf, other]
Title: SPHERE+: Imaging young Jupiters down to the snowline
Comments: White paper submitted to ESO on Feb. 20th, 2020
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
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