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New submissions for Fri, 3 Jan 20

[1]  arXiv:2001.00018 [pdf, other]

Title: Connecting optical morphology, environment, and HI mass fraction for low-redshift galaxies using deep learning

Authors: John F. Wu

Comments: 10 pages text, 5 figures. All code public at this https URL

Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)

A galaxy's morphological features encode details about its gas content, star formation history, and feedback processes which regulate its growth and evolution. We use deep convolutional neural networks (CNNs) to capture all of a galaxy's morphological information in order to estimate its neutral atomic hydrogen (HI) content directly from SDSS $gri$ image cutouts. We are able to predict a galaxy's HI mass fraction, $\mathcal M \equiv M_{\rm HI}/M_\star$, to within 0.25~dex accuracy using CNNs. The HI-morphology connection learned by the CNN appears to be constant in low- to intermediate-density galaxy environments, but it breaks down in the highest-density environments, i.e., for normalized overdensity parameter $\log(1+\delta_5) \gtrsim 0.5$ for the ALFALFA $\alpha.40$ sample, $\log(1+\delta_5) \gtrsim 0.1$ for the xGASS representative sample. This transition can be physically interpreted as the onset of ram pressure stripping, tidal effects, and other gas depletion processes in clustered environments. We also use a visualization algorithm, Gradient-weighted Class Activation Maps (Grad-CAM), to determine which morphological features are associated with low or high gas content. These results demonstrate that CNNs are powerful tools for understanding the connections between optical morphology and other properties, as well as for probing other latent variables, in a quantitative and interpretable manner.

[2]  arXiv:2001.00025 [pdf, ps, other]

Title: Over 78 000 RR Lyrae Stars in the Galactic Bulge and Disk from the OGLE Survey

Authors: I. Soszyński, A. Udalski, M. Wrona, M. K. Szymański, P. Pietrukowicz, J. Skowron, D. Skowron, R. Poleski, S. Kozłowski, P. Mróz, K. Ulaczyk, K. Rybicki, P. Iwanek, M. Gromadzki

Comments: 17 pages, 5 figures, submitted to Acta Astronomica

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

We present an upgrade of the OGLE Collection of RR Lyrae stars in the Galactic bulge and disk. The size of our sample has been doubled and reached 78 350 RR Lyr variables, of which 56 508 are fundamental-mode pulsators (RRab stars), 21 321 pulsate solely in the first-overtone (RRc stars), 458 are classical double-mode pulsators (RRd stars), and 63 are anomalous RRd variables (including six triple-mode pulsators). For all the newly identified RR Lyr stars, we publish time-series photometry obtained during the OGLE Galaxy Variability Survey.
We present the spatial distribution of RR Lyr stars on the sky, provide a list of globular clusters hosting RR Lyr variables, and discuss the Petersen diagram for multimode pulsators. We find new RRd stars belonging to a compact group in the Petersen diagram (with period ratios P_1O/P_F = 0.74 and fundamental-mode periods P_F = 0.44 d) and we show that their spatial distribution is roughly spherically symmetrical around the Milky Way center.

[3]  arXiv:2001.00049 [pdf, other]

Title: High-resolution Spectra and Biosignatures of Earth-like Planets Transiting White Dwarfs

Authors: Thea Kozakis, Zifan Lin, Lisa Kaltenegger

Comments: 10 pages, 1 table, 4 figures; submitted to ApJL

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

With the first observations of debris disks as well as proposed planets around white dwarfs, the question of how rocky planets around such stellar remnants can be characterized and probed for signs of life becomes tangible. White dwarfs are similar in size to Earth and have relatively stable environments for billions of years after initial cooling, making them intriguing targets for exoplanet searches and terrestrial planet atmospheric characterization. Their small size and the resulting large planet transit signal allows observations with next generation telescopes to probe the atmosphere of such rocky planets, if they exist. We model high-resolution transmission spectra for planets orbiting white dwarfs from as they cool from 6,000-4,000 K, for i) planets receiving equivalent irradiation to modern Earth, and ii) planets orbiting at the distance around a cooling white dwarf which allows for the longest continuous time in the habitable zone. All high-resolution transmission spectra will be publicly available online upon publication of this study and can be used as a tool to prepare and interpret upcoming observations with JWST, the Extremely Large Telescopes as well as mission concepts like Origins, HabEx, and LUVOIR.

[4]  arXiv:2001.00050 [pdf, other]

Title: High resolution Spectra of Earth-Like Planets Orbiting Red Giant Host Stars

Authors: Thea Kozakis, Lisa Kaltenegger

Comments: 12 pages, 1 table, 5 figures, submitted to ApJ

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

In the near future we will have ground- and space-based telescopes that are designed to observe and characterize Earth-like planets. While attention is focused on exoplanets orbiting main sequence stars, more than 150 exoplanets have already been detected orbiting red giants, opening the intriguing question of what rocky worlds orbiting in the habitable zone of red giants would be like and how to characterize them. We model reflection and emission spectra of Earth-like planets orbiting in the habitable zone of red giant hosts with surface temperatures between 5200 and 3900 K at the Earth-equivalent distance, as well as model planet spectra throughout the evolution of their hosts. We present a high-resolution spectral database of Earth-like planets orbiting in the red giant habitable zone from the visible to infrared, to assess the feasibility of characterizing atmospheric features including biosignatures for such planets with upcoming ground- and space-based telescopes such as the Extremely Large Telescopes and the James Webb Space Telescope.

[5]  arXiv:2001.00055 [pdf, other]

Title: Deflating Super-Puffs: Impact of Photochemical Hazes on the Observed Mass-Radius Relationship of Low Mass Planets

Authors: Peter Gao, Xi Zhang

Comments: 32 pages, 25 figures, and 2 tables. Under review at ApJ

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

The observed mass-radius relationship of low-mass planets informs our understanding of their composition and evolution. Recent discoveries of low mass, large radii objects ("super-puffs") have challenged theories of planet formation and atmospheric loss, as their high inferred gas masses make them vulnerable to runaway accretion and hydrodynamic escape. Here we propose that high altitude photochemical hazes could enhance the observed radii of low-mass planets and explain the nature of super-puffs. We construct model atmospheres in radiative-convective equilibrium and compute rates of atmospheric escape and haze distributions, taking into account haze coagulation, sedimentation, diffusion, and advection by an outflow wind. We develop mass-radius diagrams that include atmospheric lifetimes and haze opacity, which is enhanced by the outflow, such that young (~0.1-1 Gyr), warm (T$_{eq}$ $\geq$ 500 K), low mass objects ($M_c$ < 4M$_{\rm Earth}$) should experience the most apparent radius enhancement due to hazes, reaching factors of three. This reconciles the densities and ages of the most extreme super-puffs. For Kepler-51b, the inclusion of hazes reduces its inferred gas mass fraction to <10%, similar to that of planets on the large radius side of the sub-Neptune radius gap. This suggests that Kepler-51b may be evolving towards that population, and that some warm sub-Neptunes may have evolved from super-puffs. Hazes also render transmission spectra of super-puffs and sub-Neptunes featureless, consistent with recent measurements. Our hypothesis can be tested by future observations of super-puffs' transmission spectra at mid-infrared wavelengths, where we predict that the planet radius will be half of that observed in the near-infrared.

[6]  arXiv:2001.00085 [pdf, other]

Title: How planetary surfaces can shape the climate of habitable exoplanets

Authors: Jack Madden, Lisa Kaltenegger

Comments: Submitted to MNRAS, 12 pages, 12 figures

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Large ground- and space-based telescopes will be able to observe Earth-like planets in the near future. We explore how different planetary surfaces can strongly influence the climate, atmospheric composition, and remotely detectable spectra of terrestrial rocky exoplanets in the habitable zone depending on the host star's incident irradiation spectrum for a range of Sun-like host stars from F0V to K7V. We update a well-tested 1D climate-photochemistry model to explore the changes of a planetary environment for different surfaces for different host stars. Our results show that using a wavelength-dependent surface albedo is critical for modeling potentially habitable rocky exoplanets.

[7]  arXiv:2001.00095 [pdf, other]

Title: Creation and Evolution of Impact-generated Reduced Atmospheres of Early Earth

Authors: Kevin Zahnle, Roxana Lupu, David Catling

Comments: Submitted 12/30/2019 to "The Planetary Science Journal"

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

The origin of life on Earth seems to demand a highly reduced early atmosphere, rich in CH4, H2, and NH3, but geological evidence suggests that Earth's mantle has always been relatively oxidized and its emissions dominated by CO2, H2O, and N2. The paradox can be resolved by exploiting the reducing power inherent in the "late veneer," i.e., material accreted by Earth after the Moon-forming impact. Isotopic evidence indicates that the late veneer consisted of extremely dry, highly reduced inner solar system materials, suggesting that Earth's oceans were already present when the late veneer came. The major primary product of reaction between the late veneer's iron and Earth's water was H2. Ocean vaporizing impacts generate high pressures and long cooling times that favor CH4 and NH3. Impacts too small to vaporize the oceans are much less productive of CH4 and NH3, unless (i) catalysts were available to speed their formation, or (ii) additional reducing power was extracted from pre-existing crustal or mantle materials. The transient H2-CH4 atmospheres evolve photochemically to generate nitrogenated hydrocarbons at rates determined by solar radiation and hydrogen escape, on timescales ranging up to tens of millions of years and with cumulative organic production ranging up to half a kilometer. Roughly one ocean of hydrogen escapes. The atmosphere after the methane's gone is typically H2 and CO rich, with eventual oxidation to CO2 rate-limited by water photolysis and hydrogen escape.

[8]  arXiv:2001.00099 [pdf, other]

Title: Galaxies hosting an AGN: a view from the CALIFA survey

Authors: Eduardo A. D. Lacerda, Sebastián F. Sánchez, R. Cid Fernandes, Carlos López-Cobá, Carlos Espinosa-Ponce, L. Galbany

Comments: 19 pages, 10 figures, 2 tables

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We study the presence of optically-selected Active Galactic Nuclei (AGNs) within a sample of 867 galaxies extracted from the extended {\it Calar-Alto Legacy Integral Field spectroscopy Area} (eCALIFA) spanning all morphological classes. We identify 10 Type-I and 24 Type-II AGNs, amounting to $\sim4$ per cent of our sample, similar to the fraction reported by previous explorations in the same redshift range. We compare the integrated properties of the ionized and molecular gas, and stellar population of AGN hosts and their non-active counterparts, combining them with morphological information. The AGN hosts are found in transitory parts (i.e. green-valley) in almost all analysed properties which present bimodal distributions (i.e. a region where reside star-forming galaxies and another with quiescent/retired ones). Regarding morphology, we find AGN hosts among the most massive galaxies, with enhanced central stellar-mass surface density in comparison to the average population at each morphological type. Moreover, their distribution peaks at the Sab-Sb classes and none are found among very late-type galaxies (> Scd). Finally, we inspect how the AGN could act in their hosts regarding the quenching of star-formation. The main role of the AGN in the quenching process appears to be the removal (or heating) of molecular gas, rather than an additional suppression of the already observed decrease of the star-formation efficiency from late-to-early type galaxies.

[9]  arXiv:2001.00125 [pdf, other]

Title: Size and Shape Constraints of (486958) Arrokoth from Stellar Occultations

Authors: Marc W. Buie, Simon B. Porter, Peter Tamblyn, Dirk Terrell, Alex Harrison Parker, David Baratoux, Maram Kaire, Rodrigo Leiva, Anne J. Verbiscer, Amanda M. Zangari, François Colas, Baïdy Demba Diop, Joseph I. Samaniego, Lawrence H. Wasserman, Susan D. Benecchi, Amir Caspi, Stephen Gwyn, J.J. Kavelaars, Adriana C. Ocampo Uría, Jorge Rabassa, M. F. Skrutskie, Alejandro Soto, Paolo Tanga, Eliot F. Young, S. Alan Stern, Bridget C. Andersen, Mauricio E. Arango Pérez, Anicia Arredondo, Rodolfo Alfredo Artola, Abdoulaye Bâ, Romuald Ballet, Ted Blank, Cheikh Tidiane Bop, Amanda S. Bosh, Matías Aarón Camino López, Christian M. Carter, J. H. Castro-Chacón, Alfonso Caycedo Desprez, Nicolás Caycedo Guerra, Steven J. Conard, Jean-Luc Dauvergne, Bryan Dean, et al. (91 additional authors not shown)

Comments: Submitted to Astronomical Journal (revised); 40 pages, 13 figures, 9 tables

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

We present the results from four stellar occultations by (486958) Arrokoth, the flyby target of the New Horizons extended mission. Three of the four efforts led to positive detections of the body, and all constrained the presence of rings and other debris, finding none. Twenty-five mobile stations were deployed for 2017 June 3 and augmented by fixed telescopes. There were no positive detections from this effort. The event on 2017 July 10 was observed by SOFIA with one very short chord. Twenty-four deployed stations on 2017 July 17 resulted in five chords that clearly showed a complicated shape consistent with a contact binary with rough dimensions of 20 by 30 km for the overall outline. A visible albedo of 10% was derived from these data. Twenty-two systems were deployed for the fourth event on 2018 Aug 4 and resulted in two chords. The combination of the occultation data and the flyby results provides a significant refinement of the rotation period, now estimated to be 15.9380 $\pm$ 0.0005 hours. The occultation data also provided high-precision astrometric constraints on the position of the object that were crucial for supporting the navigation for the New Horizons flyby. This work demonstrates an effective method for obtaining detailed size and shape information and probing for rings and dust on distant Kuiper Belt objects as well as being an important source of positional data that can aid in spacecraft navigation that is particularly useful for small and distant bodies.

[10]  arXiv:2001.00133 [pdf, other]

Title: Clumpy AGN outflows due to thermal instability

Authors: Randall Dannen, Daniel Proga, Tim Waters, Sergei Dyda

Comments: 7 pages, 4 figures, 1 table, movies and additional information available on our project webpage: this http URL

Subjects: Astrophysics of Galaxies (astro-ph.GA)

One of the main mechanisms that could drive mass outflows on parsec scales in AGN is thermal driving. The same X-rays that ionize and heat the plasma are also expected to make it thermally unstable. Indeed, it has been proposed that the observed clumpiness in AGN winds is caused by thermal instability (TI). While many studies employing time-dependent numerical simulations of AGN outflows have included the necessary physics for TI, none have so far managed to produce clumpiness. Here we present the first such clumpy wind simulations in 1-D and 2-D, obtained by simulating parsec scale outflows irradiated by an AGN. By combining an analysis of our extensive parameter survey with physical arguments, we show that the lack of clumps in previous numerical models can be attributed to the following three effects: (i) insufficient radiative heating or other physical processes that prevent the outflowing gas from entering the TI zone; (ii) the stabilizing effect of tidal stretching in cases where the gas enters the TI zone; and (iii) a flow speed effect: in circumstances where stretching is inefficient, the flow can still be so fast that it passes through the TI zone too quickly for perturbations to grow. Besides these considerations, we also find that a necessary criterion to trigger TI in an outflow is for the pressure ionization parameter to decrease along a streamline once gas enters a TI zone.

[11]  arXiv:2001.00148 [pdf, ps, other]

Title: Evidence for planetary hypothesis for PTFO 8-8695b with five-year optical/infrared monitoring observations

Authors: Yuta Tanimoto, Takuya Yamashita, Takahiro Ui, Mizuho Uchiyama, Miho Kawabata, Hiroki Mori, Tatsuya Nakaoka, Taisei Abe, Ryosuke Itoh, Yuka Kanda, Kenji Kawaguchi, Naoki Kawahara, Ikki Otsubo, Kensei Shiki, Kengo Takagi, Katsutoshi Takaki, Hiroshi Akitaya, Masayuki Yamanaka, Koji S. Kawabata

Comments: 17 pages, 19 figures, 6 tables, accepted for publication in PASJ

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

PTFO 8-8695b (CVSO 30b) is a young planet candidate whose host star is a $\sim$ 2.6 Myr-old T-Tauri star, and there have been continuous discussions about the nature of this system. To unveil the mystery of this system, we observed PTFO8-8695 for around five years at optical and infrared bands simultaneously using Kanata telescope at the Higashi-Hiroshima Observatory. Through our observations, we found that the reported fading event split into two: deeper but phase-shifted "dip-A" and shallower but equiphase "dip-B". These dips disappeared at different epochs, and then, dip-B reappeared. Based on the observed wavelength dependence of dip depths, a dust clump and a precessing planet are likely origins of dip-A and B, respectively. Here we propose "a precessing planet associated with a dust cloud" scenario for this system. This scenario is consistent with the reported change in the depth of fading events, and even with the reported results, which were thought to be negative evidence to the planetary hypothesis, such as the past non-detection of the Rossiter-McLaughlin effect. If this scenario is correct, this is the third case of a young (<3 Myr) planet around a pre-main sequence star. This finding implies that a planet can be formed within a few Myr.

[12]  arXiv:2001.00168 [pdf, other]

Title: Gas-dust correlations in nearby galaxies: a case study of NGC 3184 and NGC 7793

Authors: Gautam Saikia, Narendra Nath Patra, Nirupam Roy, Chanda J. Jog

Comments: 12 pages, 8 figures. Accepted for publication in MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA)

The study of gas-dust interactions occurring in the interstellar medium of a galaxy is essential for understanding various physical processes taking place within it. A comparison of such events at different locations corresponding to diverse astrophysical environments provides more insight into the star-formation as well as dust destruction conditions and time-scales. We present a case study for two galaxies: NGC 3184 and NGC 7793, which are typical examples of a `grand design spiral' and a `flocculent spiral', respectively. We investigate the gas-dust correlations at various spatially resolved locations within each galaxy, including spiral arms, using archival data. Moreover, we have segregated the neutral gas into wide (warm) and narrow (cold) velocity components to check the correlations with individual dust emission bands. We find a positive correlation between the gas and the dust, with the total atomic gas emission mainly dominated by its warm component in both the galaxies. We also find the dust population in NGC 7793 to have a greater fraction of emission coming from cold and diffuse, larger-sized dust particles as compared to NGC 3184. This nearby galaxy pilot study could serve as a template for similar studies of larger galaxy samples with analogous morphologies.

[13]  arXiv:2001.00177 [pdf, other]

Title: Wave reflection and transmission at interface of convective and stably stratified regions in a rotating star or planet

Authors: Xing Wei

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Fluid Dynamics (physics.flu-dyn)

We use a simplified model to study wave reflection and transmission at interface of convective region and stably stratified region (e.g. radiative zone in star or stratification layer in gaseous planet). Inertial wave in convective region and gravito-inertial wave in stably stratified region are considered. We begin with polar area and then extend to any latitude. Six cases are discussed (see Table 1), and in Case 2 both waves co-exist in both regions. Four configurations are further discussed for Case 2. The angles and energy ratios of wave reflection and transmission are calculated. It is found that wave propagation and transmission depend on the ratio of buoyancy frequency to rotational frequency. In a rapidly rotating star or planet wave propagates across interface and most of energy of incident wave is transmitted to the other region, but in a slowly rotating star or planet wave transmission is inhibited.

[14]  arXiv:2001.00194 [pdf, other]

Title: EDGES signal in presence of magnetic fields

Authors: Pravin Kumar Natwariya, Jitesh R. Bhatt

Comments: 4 pages, 4 figures

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We compute the 21-cm differential brightness temperature of the intergalactic medium in presence of primordial helical magnetic field for redshift $z=30-10$. It is shown that the gas temperature can be lowered to 3.2 degree Kelvin at $z=17$ by the alpha-effect due to the twisting of magnetic field lines by eddies generated due to the turbulence generated at earlier times. Using the EDGES results, we find the upper and lower limits on the primordial magnetic field $6\times 10^{-3}~{\rm nG} $ & $5\times 10^{-4}~{\rm nG}$ respectively. We also discuss the effect of Ly$\alpha$ background on the bounds. Our results do not require any new physics in terms of dark-matter.

[15]  arXiv:2001.00197 [pdf, other]

Title: What determines the formation and characteristics of protoplanetary discs?

Authors: Patrick Hennebelle, Benoît Commerçon, Yueh-Ning Lee, Sébastien Charnoz

Comments: accepted for publication in A&A

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Planets form in protoplanetary discs. Their masses, distribution, and orbits sensitively depend on the structure of the protoplanetary discs. However, what sets the initial structure of the discs in terms of mass, radius and accretion rate is still unknown. We perform non-ideal MHD numerical simulations using the adaptive mesh refinement code Ramses, of a collapsing, one solar mass, molecular core to study the disc formation and early, up to 100 kyr, evolution, paying great attention to the impact of numerical resolution and accretion scheme. We found that while the mass of the central object is almost independent of the numerical parameters such as the resolution and the accretion scheme onto the sink particle, the disc mass, and to a lower extent its size, heavily depend on the accretion scheme, which we found, is itself resolution dependent. This implies that the accretion onto the star and through the disc are largely decoupled. For a relatively large domain of initial conditions (except at low magnetisation), we found that the properties of the disc do not change too significantly. In particular both the level of initial rotation and turbulence do not influence the disc properties provide the core is sufficiently magnetized. After a short relaxation phase, the disc settles in a stationary state. It then slowly grows in size but not in mass. The disc itself is weakly magnetized but its immediate surrounding is on the contrary highly magnetized. Our results show that the disc properties directly depend on the inner boundary condition, i.e. the accretion scheme onto the central object, suggesting that the disc mass is eventually controlled by the small scale accretion process, possibly the star-disc interaction. Because of ambipolar diffusion and its significant resistivity, the disc diversity remains limited and except for low magnetisation, their properties are (abridged).

[16]  arXiv:2001.00205 [pdf, ps, other]

Title: Gravitational wave memory from a propagating relativistic jet: a probe to the interior of gamma-ray burst progenitors

Authors: Yun-Wei Yu

Comments: 5 pages, 4 figures, Happy new year!

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

It is believed that the relativistic jets of gamma-ray bursts (GRBs) should initially propagate through a heavy envelope of the massive progenitor stars or through a merger ejecta formed from the compact binary mergers. The interaction of a jet with a stellar envelope or a merger ejecta can lead to the deceleration of the head material of the jet and, simultaneously, the formation of a hot cocoon. However, this jet-envelope/ejecta interaction is actually undetectable with electromagnetic radiation and can only be inferred indirectly by the structure of the breakout jet. Therefore, as a way out of this difficulty, it is suggested that the jet-envelope/ejecta interaction can produce a gravitational wave memory of an amplitude of $h\sim10^{-27}-10^{-24}$, which could be detected with some future gravitational wave detectors sensitive in the frequency range of $f\sim 0.1-1$ Hz. This provides a potential direct way to probe the jet propagation and then the interior of the GRB progenitors. Moreover, this method is in principle available even if the jet is finally chocked in the stellar envelope or the merger ejecta.

[17]  arXiv:2001.00217 [pdf, other]

Title: Seeds of Life in Space (SOLIS) V. Methanol and acetaldehyde in the protostellar jet-driven shocks L1157-B0 and B1

Authors: C. Codella, C. Ceccarelli, E. Bianchi, N. Balucani, L. Podio, P. Caselli, S. Feng, B. Lefloch, A. López-Sepulcre, R. Neri, S. Spezzano, M. De Simone

Comments: A&A, in press

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

Aim: In the past, observations of protostellar shocks have been able to set constraints on the formation route of formamide (NH2CHO), exploiting its observed spatial distribution and comparison with astrochemical model predictions. In this work, we follow the same strategy to study the case of acetaldehyde (CH3CHO). Method: To this end, we used the data obtained with the IRAM-NOEMA interferometer in the framework of the Large Program SOLIS to image the B0 and B1 shocks along the L1157 blueshifted outflow in methanol (CH3OH) and acetaldehyde line emission. Results: We imaged six CH3OH and eight CH3CHO lines which cover upper level energies up to 30 K. Both species trace the B0 molecular cavity as well as the northern B1 portion, i.e. the regions where the youngest shocks (1000 yr) occurred. The CH$_3$OH and CH$_3$CHO emission peaks towards the B1b clump, where we measured the following column densities and relative abundances: 1.3 x 10^16 cm-2 and 6.5 x 10-6 (methanol), and 7 x 10^13 cm-2 and 3.5 x 10-8 (acetaldehyde). We carried out a non-LTE LVG analysis of the observed CH3OH line: the average kinetic temperature and density of the emitting gas are Tkin = 90 K and nH2 = 4 x 10^5 cm-3, respectively. The CH3OH and CH3CHO abundance ratio towards B1b is 190, varying by less than a factor 3 throughout the whole B0-B1 structure. Conclusions: The comparison of astrochemical model predictions with the observed methanol and acetaldehyde spatial distribution does not allow to distinguish whether acetaldehyde is formed on the grain mantles or rather on the gas-phase, as its gas-phase formation, dominated by the reaction of ethyl radical (CH3CH2) with atomic oxygen, is very fast. Observations of acetaldehyde in younger shocks, e.g. 10^2 yr old, or/and of the ethyl radical, whose frequencies are not presently available, are necessary to settle the issue.

[18]  arXiv:2001.00239 [pdf, ps, other]

Title: A $5/4$ commensurability of KIC 5773205, the smallest eclipsing red dwarf detected by the Kepler mission

Authors: Valeri V. Makarov, Alexey Goldin

Comments: Submitted

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)

KIC 5773205 is the least luminous eclipsing M dwarf found in the Villanova catalog of eclipsing binaries detected by the {\it Kepler} mission. We processed and analyzed the three available quarters of mission data for this star and discovered a persistent periodic variation of the light curve with a period, which is in exact 4:5 commensurability to the orbital period. Three routes of interpretation are considered: 1) non-radial pulsations excited by the tidal interaction at a specific eigenfrequency; 2) a high-order spin-orbit resonance caused by the tides; 3) an ellipsoidal deformation caused by an outer orbiting companion in a mean motion resonance. All three explanations meet considerable difficulties, but the available facts seem to favor the tidally driven pulsation scenario. The star may represent a new type of heartbeat binary with tidally excited pulsations that are close to the orbital motion in frequency.

[19]  arXiv:2001.00261 [pdf, other]

Title: Asymmetric Surface Brightness Structure of Lensed Arc in SDSS J1226+2152: A Case for Dark Matter Substructure

Authors: Liang Dai, Alexander A. Kaurov, Keren Sharon, Michael K. Florian, Jordi Miralda-Escudé, Tejaswi Venumadhav, Brenda Frye, Jane R. Rigby, Matthew Bayliss

Comments: 15 pages including references and appendices, and 11 figures; comments welcome

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We study the highly magnified arc SGAS J122651.3+215220 caused by a star-forming galaxy source at $z_s=2.93$ crossing the lensing caustic cast by the galaxy cluster SDSS J1226+2152 ($z_l=0.43$), using archival Hubble Space Telescope observations. We report in the arc a number of asymmetric surface brightness features consistently seen across four filters, lying at a fraction of an arcsecond from the lensing critical curve and likely to be highly but unequally magnified image pairs of underlying compact sources. One explanation of unequal magnification is strongly coupled microlensing by intracluster stars, which induces independent flux variations in the images of individual or groups of source stars in the lensed galaxy. For a second possibility, intracluster dark matter subhalos invisible to the telescope can effectively perturb lensing magnifications near the critical curve and give rise to persistently unequal image pairs. Our modeling suggests that the microlensing hypothesis is in tension with the absence of notable temporal variation in the asymmetries over a six-year baseline, while subhalos of $\sim 10^6$--$10^8\,M_\odot$ anticipated from structure formation with Cold Dark Matter typically produce stationary and sizable asymmetries. We judge that observations at additional times and more precise lens models are necessary to stringently constrain temporal variability and robustly distinguish between the two possible explanations. The arc under our study is a scheduled target of a Director's Discretionary Early Release Science program of the James Webb Space Telescope, which will provide deep images as well as a high-resolution view with integral field spectroscopy.

[20]  arXiv:2001.00289 [pdf, ps, other]

Title: Repeated state change of variable gamma-ray pulsar, PSR~J2021+4026

Authors: J. Takata, H.H. Wang, L.C.C. Lin, C.-P. Hu, C.Y. Hui, A.K.H. Kong, P.H.T. Tam, K.L. Li, K.S. Cheng

Comments: 20 pages, 6 figures. Accepted for publication in ApJ

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

PSR J2021+4026 is a radio-quiet gamma-ray pulsar and the first pulsar that shows state change of the gamma-ray emission and spin-down rate. The state change of PSR J2021+4026 was first observed at 2011 October, at which the pulsar changes the state from high gamma-ray flux/low spin-down rate state to low gamma-ray flux/high spin-down rate st\ ate. In December 2014, PSR J2021+4026 recovered the state before the 2011 state change over a timescale of a few months. We report that the long term evolution of the gamma-ray flux and timing behavior suggests that PSR J2021+4026 changed the state near 2018 February 1st and entered a new low gamma-ray flux/high spin-down rate state. At the 2018 state change, the averaged flux dropped from $(1.29\pm 0.01)\times 10^{-6} {\rm cts~cm^{-2}s^{-1}}$ to $(1.12\pm 0.01)\times 10^{-6} {\rm cts~cm^{-2}s^{-1\ }}$, which has the similar behavior to the case of 2011 event. The spin-down rate has increased by $\sim 3\%$ in the new state since the 2018 state change. The shapes of pulse profile and spectrum in GeV bands also changed at the 2018 event, and they are consistent with behavior at the 2011 state change. Our results probably suggest that PSR J2021+4026 is switching between different states with a timescale of several years, like some radio pulsars (e.g. PSR~B1828-11). PSR J2021+4026 will provide a unique opportunity to study the mechanism of the state switching.

[21]  arXiv:2001.00318 [pdf, other]

Title: Testing the Prediction of Fuzzy Dark Matter Theory in the Milky Way Center

Authors: Zhi Li, Juntai Shen, Hsi-Yu Schive

Comments: Accepted for publication in ApJ. 14 pages, 7 figures

Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)

The fuzzy dark matter model (FDM, also known as quantum wave dark matter model) argues that light bosons with a mass of $\sim10^{-22}{\;{\rm eV}}$ are a possible candidate for dark matter in the Universe. One of the most important predictions of FDM is the formation of a soliton core instead of a density cusp at the center of galaxies. If FDM is the correct theory of dark matter, then the predicted soliton core can help to form the Central Molecular Zone (CMZ) in the Milky Way. We present high-resolution hydrodynamical simulations of gas flow patterns to constrain the properties of the soliton core based on a realistic Milky Way potential. We find that a dense center is required to form a reasonable CMZ. The size and kinematics of the CMZ offer a relatively strong constraint on the inner enclosed mass profile of the Galaxy. If a soliton core is not considered, a compact nuclear bulge alone with a radially varying mass-to-light ratio can match the observed size and kinematics of the CMZ. A soliton core model with a mass of $\approx4.0\times10^8{\; {\rm M}_{\odot}}$ and a core radius of $\approx0.05{\;{\rm kpc}}$, together with a less massive nuclear bulge with a constant mass-to-light ratio, also agrees nicely with the current data. Such a FDM soliton core corresponds to a boson mass of $\sim2-7\times10^{-22}{\;{\rm eV}}$, which could be further constrained by the improved determination of the mass-to-light ratio in the Galactic center.

[22]  arXiv:2001.00331 [pdf, other]

Title: The Carnegie-Irvine Galaxy Survey. IX. Classification of Bulge Types and Statistical Properties of Pseudo Bulges

Authors: Hua Gao, Luis C. Ho, Aaron J. Barth, Zhao-Yu Li

Comments: Accepted for publication in ApJS; 19 pages (main text), 19 figures, and two tables

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We study the statistical properties of 320 bulges of disk galaxies in the Carnegie-Irvine Galaxy Survey, using robust structural parameters of galaxies derived from image fitting. We apply the Kormendy relation to classify classical and pseudo bulges and characterize bulge dichotomy with respect to bulge structural properties and physical properties of host galaxies. We confirm previous findings that pseudo bulges on average have smaller S\'{e}rsic indices, smaller bulge-to-total ratios, and fainter surface brightnesses when compared with classical bulges. Our sizable sample statistically shows that pseudo bulges are more intrinsically flattened than classical bulges. Pseudo bulges are most frequent (incidence $\gtrsim 80\%$) in late-type spirals (later than Sc). Our measurements support the picture in which pseudo bulges arose from star formation induced by inflowing gas, while classical bulges were born out of violent processes such as mergers and coalescence of clumps. We reveal differences with the literature that warrant attention: (1) the bimodal distribution of S\'{e}rsic indices presented by previous studies is not reproduced in our study; (2) classical and pseudo bulges have similar relative bulge sizes; and (3) the pseudo bulge fraction is considerably smaller in early-type disks compared with previous studies based on one-dimensional surface brightness profile fitting. We attribute the above differences to our improved image quality, more robust bulge-to-disk decomposition technique, and different classification criteria applied. Moreover, we find that barred galaxies do not host more pseudo bulges or more prominent pseudo bulges than unbarred galaxies. Various implications of these findings are discussed.

[23]  arXiv:2001.00369 [pdf, other]

Title: Mirror, mirror on the outflow cavity wall. Near-infrared CO overtone disc emission of the high-mass YSO IRAS 11101-5829

Authors: R. Fedriani, A. Caratti o Garatti, M. Koutoulaki, R. Garcia-Lopez, A. Natta, R. Cesaroni, R. Oudmaijer, D. Coffey, T. Ray, B. Stecklum

Comments: 11 pages, 10 figures

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

Aims: The inner regions of high-mass protostars are often invisible in the near-infrared. We aim to investigate the inner gaseous disc of IRAS11101-5829 through scattered light from the outflow cavity walls.
Methods: We observed the environment of the high-mass young stellar object IRAS11101-5829 and the closest knots of its jet, HH135-136, with the VLT/SINFONI. We also retrieved archival data from the high-resolution long-slit spectrograph VLT/X-shooter.
Results: We detect the first three bandheads of the $\upsilon=2-0$ CO vibrational emission for the first time in this object. It is coincident with continuum and Br$\gamma$ emission and extends up to $\sim10000$ au to the north-east and $\sim10 000$ au to the south-west. The line profiles have been modelled as a Keplerian rotating disc assuming a single ring in LTE. The model output gives a temperature of $\sim3000$ K, a CO column density of $\sim1\times10^{22}\mathrm{ cm^{-2}}$, and a projected Keplerian velocity $v_\mathrm{K}\sin i_\mathrm{disc} \sim 25\mathrm{ km s^{-1}}$, which is consistent with previous modelling in other high-mass protostars. In particular, the low value of $v_\mathrm{K}\sin i_\mathrm{disc}$ suggests that the disc is observed almost face-on, whereas the well-constrained geometry of the jet imposes that the disc must be close to edge-on. This apparent discrepancy is interpreted as the CO seen reflected in the mirror of the outflow cavity wall.
Conclusions: From both jet geometry and disc modelling, we conclude that all the CO emission is seen through reflection by the cavity walls and not directly. This result implies that in the case of highly embedded objects, as for many high-mass protostars, line profile modelling alone might be deceptive and the observed emission could affect the derived physical and geometrical properties; in particular the inclination of the system can be incorrectly interpreted.

[24]  arXiv:2001.00402 [pdf, other]

Title: An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: Dust attenuation in high-redshift Lyman break Galaxies

Authors: M. P. Koprowski, K. E. K. Coppin, J. E. Geach, U. Dudzeviciute, Ian Smail, O. Almaini, Fangxia An, A. W. Blain, S. C. Chapman, Chian-Chou Chen, C. J. Conselice, J. S. Dunlop, D. Farrah, B. Gullberg, W. Hartley, R. J. Ivison, A. Karska, D. Maltby, M. J. Michałowski, A. Pope, S. Salim, D. Scott, C. J. Simpson, J. M. Simpson, A. M. Swinbank, A. P. Thomson, J. L. Wardlow, P. P. van der Werf, K. E. Whitaker

Comments: 17 pages, 12 figures. Resubmitted to MNRAS after referee report

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We analyse 870um Atacama Large Millimetre Array (ALMA) dust continuum detections of 41 canonically-selected z~3 Lyman-break galaxies (LBGs), as well as 209 ALMA-undetected LBGs, in follow-up of SCUBA-2 mapping of the UKIDSS Ultra Deep Survey (UDS) field. We find that our ALMA-bright LBGs lie significantly off the locally calibrated IRX-beta relation and tend to have relatively bluer rest-frame UV slopes (as parametrised by beta), given their high values of the 'infrared excess' (IRX=L_IR/L_UV), relative to the average 'local' IRX-beta relation. We attribute this finding in part to the young ages of the underlying stellar populations but we find that the main reason behind the unusually blue UV slopes are the relatively shallow slopes of the corresponding dust attenuation curves. We show that, when stellar masses are being established via SED fitting, it is absolutely crucial to allow the attenuation curves to vary (rather than fixing it on Calzetti-like law), where we find that the inappropriate curves may underestimate the resulting stellar masses by a factor of ~2-3x on average. In addition, we find these LBGs to have relatively high specific star-formation rates (sSFRs), dominated by the dust component, as quantified via the fraction of obscured star formation ( f_obs = SFR_IR/SFR_(UV+IR)). We conclude that the ALMA-bright LBGs are, by selection, massive galaxies undergoing a burst of a star formation (large sSFRs, driven, for example, by secular or merger processes), with a likely geometrical disconnection of the dust and stars, responsible for producing shallow dust attenuation curves.

[25]  arXiv:2001.00409 [pdf, other]

Title: Induced superhorizon tensor perturbations from anisotropic non-Gaussianity

Authors: Atsuhisa Ota

Comments: 17 pages, 5 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)

We study cosmological tensor perturbations induced by second-order scalar perturbations in the presence of anisotropic non-Gaussianity. This class of induced tensor modes arises on superhorizon scales through the intrinsic quadrupole coupling between long modes and short modes. Scalar perturbations on all scales from the inflationary Hubble radius to the Silk damping scale at recombination contribute to the induced tensor powerspectrum at the cosmic microwave background (CMB) scale. In addition, the induced tensor spectrum becomes almost scale-invariant. The former property suggests that measurements of the CMB offer a test of tiny scale physics. However, the latter implies the secondary effect may contaminate the primordial tensor spectrum, which tells us the energy scale of inflation. We derive the induced tensor modes originated from two concrete examples of anisotropic non-Gaussianity; statistically anisotropic scalar non-Gaussianity and scalar-scalar-tensor non-Gaussianity, and discuss observational consequences of extremely short scale physics. Also, we comment on various possibilities of enhancing the induced spectrum with nonstandard early Universe physics.

[26]  arXiv:2001.00421 [pdf, other]

Title: Interpretation of ALMA velocity map for the obscuring torus in NGC1068

Authors: Bannikova E.Yu., Akerman N.A., Sergeyev A.V

Comments: 10 pages, 3 figures

Journal-ref: Astronomical and Astrophysical Transactions, vol.31, issue 4, 2020

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Recent ALMA observations have resolved the obscuring torus in the nearest Sy2 galaxy, NGC1068, in the millimeter band. These observations have confirmed the presence of a geometrically thick torus with an orbital motion of its matter and the velocity distribution which can reflect the clumpy structure. In the framework of N-body simulations we consider a dynamical model of an obscuring torus which accounts for the gravitational interaction between the clouds moving in the field of the central mass. In considered model, clouds are orbiting around the central mass exhibiting a spread in inclination and eccentricity. The self-gravity of the torus induces the velocity distribution of clouds with a global orbital motion which mimics the ALMA data for NGC1068.

[27]  arXiv:2001.00431 [pdf, other]

Title: Wolf-Rayet galaxies in SDSS-IV MaNGA. I. Catalog construction and sample properties

Authors: Fu-Heng Liang (1), Cheng Li (1), Niu Li (1), Renbin Yan (2), Houjun Mo (1 and 3), Wei Zhang (4), Camilo Machuca (5), Alexandre Roman-Lopes (6) ((1) Tsinghua Univ., (2) Univ. of Kentucky, (3) Univ. of Massachusetts Amherst, (4) NAOC, (5) Univ. of Wisconsin Madison, (6) Univ. de La Serena)

Comments: 18 pages, 11 figures, 2 tables; submitted to ApJ

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Wolf-Rayet (WR) galaxies are a rare population of galaxies that host living high-mass stars during their WR phase (i.e. WR stars), and are thus expected to provide interesting constraints on the stellar Initial Mass Function, massive star formation, stellar evolution models, etc. Spatially resolved spectroscopy should in principle provide a more efficient way of identifying WR galaxies than single-fiber surveys of galactic centers such as SDSS, as WR stars should be more preferentially found in discs. Using Integral Field Unit data from the ongoing SDSS-IV MaNGA survey, we have performed a thorough search for WR galaxies in a two-step method. We first identify HII regions in each datacube and carry out full spectral fitting to the stacked spectra. We then visually inspect the residual spectrum of each HII region and identify WR regions that present a significant ``blue bump'' at 4600-4750 \r{A}. The resulting WR catalog includes 267 WR regions of $\sim$500 pc (radius) sizes, distributed in 90 galaxies from the current sample of MaNGA (MaNGA Product Launch 7). We find WR regions are exclusively found in galaxies that show bluest colors and highest star formation rates for their mass, as well as late-type dominated morphologies and lower-than-average S\'ersic indices. We estimate the stellar mass function of WR galaxies and the mass-dependent detection rate. The detection rate of WR galaxies is typically $\sim$2%, with weak dependence on stellar mass. This detection rate is about 40 times higher than previous studies with SDSS single fiber data, and a factor of 2 lower than the CALIFA-based WR catalog. We make comparisons with SDSS and CALIFA studies, and conclude that different detection rates of different studies can be explained mainly by three factors: spatial coverage, spectral signal-to-noise ratio, and redshift ranges of the parent sample.

[28]  arXiv:2001.00506 [pdf, other]

Title: AGN feedback in the FR II galaxy 3C 220.1

Authors: Wenhao Liu, Ming Sun, Paul E. J. Nulsen, Diana M. Worrall, Mark Birkinshaw, Craig Sarazin, William R. Forman, Christine Jones, Chong Ge

Comments: 14 pages, 13 figures, MNRAS accepted

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)

We present results from a deep (174 ks) Chandra observation of the FR-II radio galaxy 3C 220.1, the central brightest cluster galaxy (BCG) of a $kT \sim$ 4 keV cluster at $z=0.61$. The temperature of the hot cluster medium drops from $\sim5.9$ keV to $\sim3.9$ keV at $\sim$ 35 kpc radius, while the temperature at smaller radii may be substantially lower. The central active galactic nucleus (AGN) outshines the whole cluster in X-rays, with a bolometric luminosity of $2.0\times10^{46}$ erg s$^{-1}$ ($\sim10$% of the Eddington rate). The system shows a pair of potential X-ray cavities $\sim35$ kpc east and west of the nucleus. The cavity power is estimated within the range of $1.0\times10^{44}$ erg s$^{-1}$ and $1.7\times10^{45}$ erg s$^{-1}$, from different methods. The X-ray enhancements in the radio lobes could be due to inverse Compton emission, with a total 2-10 keV luminosity of $\sim8.0\times10^{42}$ erg s$^{-1}$. We compare 3C 220.1 with other cluster BCGs, including Cygnus A, as there are few BCGs in rich clusters hosting an FR-II galaxy. We also summarize the jet power of FR-II galaxies from different methods. The comparison suggests that the cavity power of FR-II galaxies likely under-estimates the jet power. The properties of 3C 220.1 suggest that it is at the transition stage from quasar-mode feedback to radio-mode feedback.

[29]  arXiv:2001.00508 [pdf, other]

Title: Capabilities of bisector analysis of the Si I 10827 A line for estimating line-of-sight velocities in the quiet Sun

Authors: S.J. González Manrique (1), C. Quintero Noda (2,3), C. Kuckein (4), B. Ruiz Cobo (5,6), M. Carlsson (2,3) ((1) Astronomical Institute, Slovak Academy of Sciences, (2) Rosseland Centre for Solar Physics, University of Oslo, (3) Institute of Theoretical Astrophysics, University of Oslo, (4) Leibniz-Institut für Astrophysik Potsdam, (5) Instituto de Astrofísica de Canarias, (6) Departamento de Astrofísica, Universidad de La Laguna)

Comments: Accepted for publication in Astronomy & Astrophysics, 7 pages, 7 figures

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We examine the capabilities of a fast and simple method to infer line-of-sight (LOS) velocities from observations of the photospheric Si I 10827 A line. This spectral line is routinely observed together with the chromospheric He I 10830 A triplet as it helps to constrain the atmospheric parameters. We study the accuracy of bisector analysis and a line core fit of Si I 10827 A. We employ synthetic profiles starting from the Bifrost enhanced network simulation. The profiles are computed solving the radiative transfer equation, including non-local thermodynamic equilibrium effects on the determination of the atomic level populations of Si I. We found a good correlation between the inferred velocities from bisectors taken at different line profile intensities and the original simulation velocity at given optical depths. This good correlation means that we can associate bisectors taken at different line-profile percentages with atmospheric layers that linearly increase as we scan lower spectral line intensities. We also determined that a fit to the line-core intensity is robust and reliable, providing information about atmospheric layers that are above those accessible through bisectors. Therefore, by combining both methods on the Si I 10827 A line, we can seamlessly trace the quiet-Sun LOS velocity stratification from the deep photosphere to higher layers until around $\log \tau = -3.5$ in a fast and straightforward way. This method is ideal for generating quick-look reference images for future missions like the Daniel K. Inoue Solar Telescope and the European Solar Telescope, for example.

[30]  arXiv:2001.00517 [pdf, other]

Title: Production Method of Millimeter-Wave Absorber with 3D-Printed Mold

Authors: S. Adachi, M. Hattori, F. Kanno, K. Kiuchi, T. Okada, O. Tajima

Comments: 3 pages, 8 figures

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Applied Physics (physics.app-ph)

We established a production method of a good millimeter-wave absorber by using a 3D-printed mold. The mold has a periodic pyramid shape, and an absorptive material is filled into the mold. This shape reduces the surface reflection. The 3D-printed mold is made from a transparent material in the millimeter-wave range. Therefore, unmolding is not necessary. A significant benefit of this production method is easy prototyping with various shapes and various absorptive materials. We produced a test model and used a two-component epoxy encapsulant as the absorptive material. The test model achieved a low reflectance: $\sim 1\%$ at 100 GHz. The absorber is sometimes maintained at a low temperature condition for cases in which superconducting detectors are used. Therefore, cryogenic performance is required in terms of a mechanical strength for the thermal cycles, an adhesive strength, and a sufficient thermal conductivity. We confirmed the test-model strength by immersing the model into a liquid-nitrogen bath.

[31]  arXiv:2001.00541 [pdf, other]

Title: Detailed Iron-Peak Element Abundances in Three Very Metal-Poor Stars

Authors: John J. Cowan, Christopher Sneden, Ian U. Roederer, James E. Lawler, Elizabeth A. Den Hartog, Jennifer S. Sobeck, Ann Merchant Boesgaard

Comments: 30 pages, 11 figures. To appear in the Astrophysical Journal

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

We have obtained new detailed abundances of the Fe-group elements Sc through Zn (Z=21-30) in three very metal-poor ([Fe/H] $\approx -3$) stars: BD 03 740, BD -13 3442 and CD -33 1173. High-resolution ultraviolet HST/STIS spectra in the wavelength range 2300-3050\AA\ were gathered, and complemented by an assortment of optical echelle spectra. The analysis featured recent laboratory atomic data for number of neutral and ionized species for all Fe-group elements except Cu and Zn. A detailed examination of scandium, titanium, and vanadium abundances in large-sample spectroscopic surveys indicates that they are positively correlated in stars with [Fe/H]<-$2. The abundances of these elements in BD 03 740, BD -13 3442 and CD -33 1173 and HD 84937. (studied in a previous paper of this series) are in accord with these trends and lie at the high end of the correlations. Six elements have detectable neutral and ionized features, and generally their abundances are in reasonable agreement. For Cr we find only minimal abundance disagreement between the neutral (mean of [Cri/Fe]=+0.01) and ionized species (mean of [Crii/Fe]=+0.08), unlike most studies in the past. The prominent exception is Co, for which the neutral species indicates a significant overabundance (mean of [Co/H]=-2.53), while no such enhancement is seen for the ionized species (mean of [Coii/H]=-2.93). These new stellar abundances, especially the correlations among Sc, Ti, and V, suggest that models of element production in early high-mass metal-poor stars should be revisited.

[32]  arXiv:2001.00549 [pdf]

Title: Spectroscopic confirmation of a mature galaxy cluster at redshift two

Authors: J.P. Willis, R.E.A. Canning, E.S. Noordeh, S.W. Allen, A.L. King, A. Mantz, R.G. Morris, S.A. Stanford, G. Brammer

Comments: To appear in Nature, January 1st 2020. Authors formatted version, 20 pages, 7 figures

Journal-ref: Nature: volume 577, pages 39-41 (2020)

Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Galaxy clusters are the most massive virialized structures in the Universe and are formed through the gravitational accretion of matter over cosmic time. The discovery of an evolved galaxy cluster at redshift z=2, corresponding to a look-back time of 10.4 billion years, provides an opportunity to study its properties. The galaxy cluster XLSSC 122 was originally detected as a faint, extended X-ray source in the XMM Large Scale Structure survey and was revealed to be coincident with a compact over-density of galaxies with photometric redshifts of 1.9 +/- 0.2. Subsequent observations at millimetre wavelengths detected a Sunyaev-Zel'dovich decrement along the line of sight to XLSSC 122, thus confirming the existence of hot intracluster gas, while deep imaging spectroscopy from the European Space Agency's X-ray Multi-Mirror Mission (XMM-Newton) revealed an extended, X-ray bright gaseous atmosphere with a virial temperature of 60 million Kelvin, enriched with metals to the same extent as are local clusters. Here we report rest frame optical spectroscopic observations of XLSSC 122 and identify 37 member galaxies at a mean redshift of 1.98, corresponding to a look-back time of 10.4 billion years. We use photometry to determine a mean, dust-free stellar age of 2.98 billion years, indicating that star formation commenced in these galaxies at a mean redshift of 12, when the Universe was only 370 million years old. The full range of inferred formation redshifts, including the effects of dust, covers the interval from 7 to 13. These observations confirm that XLSSC 122 is a remarkably mature galaxy cluster with both evolved stellar populations in the member galaxies and a hot, metal-rich gas composing the intracluster medium.

[33]  arXiv:2001.00563 [pdf, other]

Title: Using Data Imputation for Signal Separation in High Contrast Imaging

Authors: Bin Ren, Laurent Pueyo, Christine Chen, Élodie Choquet, John H. Debes, Gaspard Duchêne, François Ménard, Marshall D. Perrin

Comments: 18 pages, 9 figures, ApJ under review after addressing the second referee report

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); Machine Learning (stat.ML)

To characterize circumstellar systems in high contrast imaging, the fundamental step is to construct a best point spread function (PSF) template for the non-circumstellar signals (i.e., star light and speckles) and separate it from the observation. With existing PSF construction methods, the circumstellar signals (e.g., planets, circumstellar disks) are unavoidably altered by over-fitting and/or self-subtraction, making forward modeling a necessity to recover these signals. We present a forward modeling--free solution to these problems with data imputation using sequential non-negative matrix factorization (DI-sNMF). DI-sNMF first converts this signal separation problem to a "missing data" problem in statistics by flagging the regions which host circumstellar signals as missing data, then attributes PSF signals to these regions. We mathematically prove it to have negligible alteration to circumstellar signals when the imputation region is relatively small, which thus enables precise measurement for these circumstellar objects. We apply it to simulated point source and circumstellar disk observations to demonstrate its proper recovery of them. We apply it to Gemini Planet Imager (GPI) K1-band observations of the debris disk surrounding HR 4796A, finding a tentative trend that the dust is more forward scattering as the wavelength increases. We expect DI-sNMF to be applicable to other general scenarios where the separation of signals is needed.

[34]  arXiv:2001.00566 [pdf, other]

Title: Neutrino emission upper limits with maximum likelihood estimators for joint astrophysical neutrino searches with large sky localizations

Authors: Doğa Veske, Zsuzsa Márka, Imre Bartos, Szabolcs Márka

Comments: 11 pages, 2 figures

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Since the start of the gravitational wave observation era, no joint high energy neutrino and gravitational wave event has been found. These non-detections could be used for setting an upper bound on the neutrino emission properties for gravitational wave events individually or for a set of them. Although in the previous joint high energy neutrino and gravitational wave event searches upper limits have been found, there is a lack of consistent method for the calculation. The problem addressed in this paper is finding those limits for astrophysical events which are localized poorly in the sky where the sensitivities of the neutrino detectors change significantly and can also emit neutrinos, for example the gravitational wave detections. Here we describe methods for assigning limits for expected neutrino count, emission fluence and isotropically equivalent emission based on maximum likelihood estimators. Then we apply described methods on the three GW detections from aLIGO's first observing run (O1) and find upper limits for them.

Cross-lists for Fri, 3 Jan 20

[35]  arXiv:1912.10690 (cross-list from gr-qc) [pdf, other]

Title: Threshold of primordial black hole formation in modified theories of gravity

Authors: Che-Yu Chen

Comments: 7 pages, 1 figure, typos corrected, references added

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

It is believed that primordial black holes (PBHs), if they exist, can serve as a powerful tool to probe the early stage of the cosmic history. Essentially, in the radiation dominated universe, PBHs could form by the gravitational collapse of overdense primordial perturbations produced during inflation. In this picture, one important ingredient is the threshold of density contrast, which defines the onset of PBH formation. In the literature, most of the estimations of threshold, no matter numerically or analytically, are implemented in the framework of general relativity. In this paper, by performing analytic estimations, we point out that the threshold for PBH formation depends on the gravitational theory under consideration. In GR, the analytic estimations adopted in this paper give a constant value of the formation threshold, assuming a fixed equation of state. If the theory is characterized by additional mass scales other than the Planck mass, the estimated threshold of density contrast may depend on the energy scale of the universe at the time of PBH formation. In this paper, we consider the Eddington-inspired-Born-Infeld gravity as an example. However, this conclusion is expected to be valid for any gravitational theory characterized by additional mass scales, suggesting the possibility of testing gravitational theories with PBHs.

[36]  arXiv:1912.13220 (cross-list from hep-th) [pdf, ps, other]

Title: Stringy Newton Gravity with $H$-flux

Authors: Kyoungho Cho, Kevin Morand, Jeong-Hyuck Park

Comments: 6 pages, No figure

Subjects: High Energy Physics - Theory (hep-th); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)

A Symmetry Principle has been shown to augment unambiguously the Einstein Field Equations, promoting the whole closed-string massless NS-NS sector to stringy graviton fields. Here we consider its weak field approximation, take a non-relativistic limit, and derive the stringy augmentation of Newton Gravity: \[ \begin{array}{lll} {\bf{\nabla}^{2}\Phi}=4\pi G \rho+\bf{H}{\bf{\cdot}}\bf{H}\,, \quad&\qquad\bf{\nabla}\bf{\cdot}\bf{H}=0\,, \quad&\qquad {\bf{\nabla}\bf{\times}\bf{H}}=4\pi G\, \bf{K}\,. \end{array} \] Not only the mass density $\rho$ but also the current density $\mathbf{K}$ is intrinsic to matter. Sourcing $\mathbf{H}$ which is of NS-NS $H$-flux origin, $\mathbf{K}$ is nontrivial if the matter is `stringy'. $\mathbf{H}$ contributes quadratically to the Newton potential, but otherwise is decoupled from the point particle dynamics, i.e. $\bf{\ddot{x}}=-\bf{\nabla}\Phi$. We define `stringization' analogous to magnetization and discuss regular as well as monopole-like singular solutions.

[37]  arXiv:2001.00040 (cross-list from hep-th) [pdf, other]

Title: Relaxing the TCC Bound on Inflationary Cosmology?

Authors: Vahid Kamali, Robert Brandenberger

Comments: 5 pages, no figures

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)

We demonstrate that the strict upper bounds on the energy scale of inflation and on the tensor-to-scalar ratio can be somewhat relaxed if we assume that - after an initial period of slow rolling when scales probed today in CMB experiments exit the Hubble radius - the equation of state of the background changes to correspond to an almost marginally accelerating universe. Constructing an actual model in which this happens appears, however, to be unnatural.

[38]  arXiv:2001.00043 (cross-list from hep-th) [pdf, other]

Title: Strengthening the TCC Bound on Inflationary Cosmology

Authors: Robert Brandenberger, Edward Wilson-Ewing

Comments: 5 pages, 1 figure

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)

We show that the constraints which follow from the {\it Trans-Planckian Censorship Conjecture} for inflationary cosmology can be strengthened if the pre-inflationary universe was dominated by radiation. The resulting upper bound on the energy scale of inflation is $\eta \sim 10^4 {\rm GeV}$, close to the scale accessible to accelerator experiments.

[39]  arXiv:2001.00242 (cross-list from gr-qc) [pdf, other]

Title: Bilinear noise subtraction at the GEO 600 observatory

Authors: Nikhil Mukund, James Lough, Christoph Affeldt, Fabio Bergamin, Aparna Bisht, Marc Brinkmann, Volker Kringel, Harald Lück, Séverin Landry Nadji, Michael Weinert

Comments: 8 pages, 8 figures

Subjects: General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det)

We develop a scheme to subtract off bilinear noise from the gravitational wave strain data and demonstrate it at the GEO 600 observatory. Modulations caused by test mass misalignments on longitudinal control signals are observed to have a broadband effect on the mid-frequency detector sensitivity ranging from 50 Hz to 500 Hz. We estimate this bilinear coupling by making use of narrow-band signal injections that are already in place for noise projection purposes. A coherent bilinear signal is constructed by a two-stage system identification process where the involved couplings are approximated in terms of stable rational functions. The time-domain filtering efficiency is observed to depend upon the system identification process especially when the involved transfer functions cover a large dynamic range and have multiple resonant features. We improve upon the existing filter design techniques by employing a Bayesian adaptive directed search strategy that optimizes across the several key parameters that affect the accuracy of the estimated model. The resulting post-offline subtraction leads to a suppression of modulation side-bands around the calibration lines along with a broadband reduction of the mid-frequency noise floor. The filter coefficients are updated periodically to account for any non-stationarities that can arise within the coupling. The observed increase in the astrophysical range and a reduction in the occurrence of non-astrophysical transients suggest that the above method is a viable data cleaning technique for current and future gravitational wave observatories.

[40]  arXiv:2001.00275 (cross-list from gr-qc) [pdf, ps, other]

Title: Reduction of the canonical Hamiltonian of the metric GR to its natural form

Authors: Alexei M. Frolov

Subjects: General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Methods for Astrophysics (astro-ph.IM)

The canonical Hamiltonian $H_C$ of the metric General Relativity is reduced to its natural form. The natural form of canonical Hamiltonian provides numerous advantages in actual applications to the metric GR, since the general theory of dynamical systems with such Hamiltonians is well developed. Furthermore, many analytical and numerically exact solutions for dynamical systems with natural Hamiltonians have been found and described in detail. In particular, based on this theory we can discuss an obvious analogy between free gravitational field(s) and few-particle systems where particles are connected to each other by the Coulomb, or harmonic potentials. We also developed an effective method which can be used to determine various Poisson brackets between analytical functions of dynamical variables. Furthermore, such variables can be chosen either from the straight, or dual sets of symplectic dynamical variables which always arise in any Hamiltonian formulation developed for the metric gravity.

[41]  arXiv:2001.00279 (cross-list from gr-qc) [pdf, other]

Title: Core-Collapse Supernova Gravitational-Wave Search and Deep Learning Classification

Authors: Alberto Iess, Elena Cuoco, Filip Morawski, Jade Powell

Comments: 19 pages, 8 figures

Subjects: General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG)

We describe a search and classification procedure for gravitational waves emitted by core-collapse supernova (CCSN) explosions, using a convolutional neural network (CNN) combined with an event trigger generator known as Wavelet Detection Filter (WDF). We employ both a 1-D CNN search using time series gravitational-wave data as input, and a 2-D CNN search with time-frequency representation of the data as input. To test the accuracies of our 1-D and 2-D CNN classification, we add CCSN waveforms from the most recent hydrodynamical simulations of neutrino-driven core-collapse to simulated Gaussian colored noise with the Virgo interferometer and the planned Einstein Telescope sensitivity curve. We find classification accuracies, for a single detector, of over 95% for both 1-D and 2-D CNN pipelines. For the first time in machine learning CCSN studies, we add short duration detector noise transients to our data to test the robustness of our method against false alarms created by detector noise artifacts. Further to this, we show that the CNN can distinguish between different types of CCSN waveform models.

[42]  arXiv:2001.00388 (cross-list from gr-qc) [pdf, other]

Title: Stability of polytropic stars in Palatini gravity

Authors: Aneta Wojnar

Comments: 4 pages, a contribution to the proceedings of The 6th Conference of the Polish Society on Relativity

Subjects: General Relativity and Quantum Cosmology (gr-qc); Solar and Stellar Astrophysics (astro-ph.SR)

We will briefly discuss the necessary conditions for stability of polytropies in $f(\hat R)$ Palatini gravity and the differences with the General Relativity ones.

[43]  arXiv:2001.00394 (cross-list from gr-qc) [pdf, other]

Title: Viable Gauge Choices in Cosmologies with Non-Linear Structures

Authors: Timothy Clifton, Christopher S. Gallagher, Sophia Goldberg, Karim A. Malik

Comments: 16 pages, 2 figures

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

A variety of gauges are used in cosmological perturbation theory. These are often chosen in order to attribute physical properties to a particular choice of coordinates, or otherwise to simplify the form of the resultant equations. Calculations are then performed with the understanding that they could have been done in any gauge, and that transformations between different gauges can be made at will. We show that this logic can be extended to the domain of large density contrasts, where different types of perturbative expansion are required, but that the way in which gauges can be chosen in the presence of such structures is severely constrained. In particular, most gauges that are commonly considered in the cosmology literature are found to be unviable in the presence of non-linear structures. This includes spatially flat gauge, synchronous gauge, comoving orthogonal gauge, total matter gauge, N-body gauge, and the uniform density gauge. In contrast, we find that the longitudinal gauge and the Newtonian motion gauge are both viable choices in both standard cosmological perturbation theory, and in the post-Newtonian perturbative expansions that are required in order to model non-linear structures.

[44]  arXiv:2001.00403 (cross-list from gr-qc) [pdf, other]

Title: On Tidal Love Numbers of Braneworld Black Holes and Wormholes

Authors: H. S. Tan

Comments: 32 pages, 7 figures

Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)

We study the tidal deformations of various known black hole and wormhole solutions in a simple context of warped compactification --- Randall-Sundrum theory in which the four-dimensional spacetime geometry is that of a brane embedded in five-dimensional Anti-de Sitter spacetime. The linearized gravitational perturbation theory generically reduces to either an inhomogeneous second-order ODE or a homogeneous third-order ODE of which indicial roots associated with an expansion about asymptotic infinity can be related to Tidal Love Numbers. We describe various tidal-deformed metrics, classify their indicial roots, and find that in particular the quadrupolar TLN is generically non-vanishing. Thus it could be a signature of a braneworld by virtue of its potential appearance in gravitational waveforms emitted in binary merger events.

[45]  arXiv:2001.00456 (cross-list from physics.pop-ph) [pdf]

Title: The Inspiring Universe

Authors: George Miley, Carolina Odman, Pedro Russo

Comments: 15 pages, published version available on Visser, J., & Visser, M. (Eds.). (2020). Seeking Understanding, Brill | Sense, Pages: 119--135

Subjects: Popular Physics (physics.pop-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM); Physics Education (physics.ed-ph)

Humans like to find things out. They naturally ask questions and explore the world around them. One observes such behavior already in neonatal infants. Inspiration to further develop such exploratory behavior, the quest to understand and do so deeply, is stimulated by different things, depending on the environment in which one is born and grows up. We thus do not all have the same chances to be inspired. However, there is one exception. Throughout human history humans around the world have stood in awe of the wonders of the sky, the universe. This is a source of inspiration that unites us all. The above considerations and possibly other ones have led to the Universe Awareness (UNAWE) project, which focuses specifically on underprivileged children between the ages of four and ten. Universe Awareness (UNAWE) uses the beauty and grandeur of the Universe to encourage young children, particularly those from an underprivileged background, to have an interest in science and technology and foster their sense of global citizenship from the earliest age.

Replacements for Fri, 3 Jan 20

[46]  arXiv:1208.5102 (replaced) [pdf, other]

Title: Gravitational Waves from Quasi-Circular Black Hole Binaries in Dynamical Chern-Simons Gravity

Authors: Kent Yagi, Nicolas Yunes, Takahiro Tanaka

Comments: 6 pages, 1 figure; errors corrected in Eqs. (8) and (9)

Journal-ref: Phys. Rev. Lett. 109, 251105 (2012)

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

[47]  arXiv:1711.03099 (replaced) [pdf, ps, other]

Title: On a Possible Giant Impact Origin for the Colorado Plateau

Authors: Xiaolei Zhang

Comments: 74 pages, 23 figures, revised and expanded version of the paper previously submitted to Earth and Planetary Science Letters

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)

[48]  arXiv:1907.04125 (replaced) [pdf, other]

Title: Primordial black holes dark matter from inflection point models of inflation and the effects of reheating

Authors: Nilanjandev Bhaumik, Rajeev Kumar Jain

Comments: v1: 36 pages, 8 figures; v2: 33 pages, 7 figures, version accepted in JCAP

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

[49]  arXiv:1907.04234 (replaced) [pdf, ps, other]

Title: Weak field limit of higher dimensional massive Brans-Dicke gravity: Observational constraints

Authors: Ozgur Akarsu, Alexey Chopovsky, Valerii Shulga, Ezgi Yalcinkaya, Alexander Zhuk

Comments: 8 pages, no figures and tables; matches the version published in Physical Review D

Journal-ref: Phys. Rev. D 101, 024004 (2020)

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)

[50]  arXiv:1907.10083 (replaced) [pdf, other]

Title: Spherical collapse in coupled quintessence with a $Λ$CDM background

Authors: Bruno J. Barros, Tiago Barreiro, Nelson J. Nunes

Comments: 11 pages, 9 figures. V2: Matches published version

Journal-ref: Phys. Rev. D 101, 023502 (2020)

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

[51]  arXiv:1907.12292 (replaced) [pdf, ps, other]

Title: Role of matter in gravitation: going beyond the Einstein-Maxwell theory

Authors: A. Emir Gumrukcuoglu, Ryo Namba

Comments: 5 pages; v2 update to match the published version

Journal-ref: Phys. Rev. D 100, 124064 (2019)

Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

[52]  arXiv:1908.02742 (replaced) [pdf, other]

Title: How planets grow by pebble accretion II: Analytical calculations on the evolution of polluted envelopes

Authors: M.G. Brouwers, C.W. Ormel

Comments: 18 pages, 11 figures. Published in A&A

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

[53]  arXiv:1908.04589 (replaced) [pdf, other]

Title: Study of Particle Multiplicity of Cosmic Ray Events using 2m$\times$2m Resistive Plate Chamber Stack at IICHEP-Madurai

Authors: Suryanarayan Mondal, V. M. Datar, Gobinda Majumder, N. K. Mondal, S. Pethuraj, K. C. Ravindran, B. Satyanarayana

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

[54]  arXiv:1909.04053 (replaced) [pdf, other]

Title: Clustering of primordial black holes formed in a matter-dominated epoch

Authors: Takahiko Matsubara, Takahiro Terada, Kazunori Kohri, Shuichiro Yokoyama

Comments: 17 pages, 16 figures, updated to match published version

Journal-ref: Phys. Rev. D 100, 123544 (2019)

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)

[55]  arXiv:1910.08117 (replaced) [pdf, other]

Title: An accurate strong lensing model of the Abell 2163 core

Authors: U. Rescigno (Università degli Studi di Milano, Italy), C. Grillo (Università degli Studi di Milano, Italy and Dark Cosmology Centre, University of Copenhagen, Denmark), M. Lombardi (Università degli Studi di Milano, Italy), P. Rosati (Università degli Studi di Ferrara, Italy and INAF - Osservatorio di Astrofisica e Scienza dello Spazio, Bologna, Italy), G. B. Caminha (Kapteyn Astronomical Institute, University of Groningen, The Netherlands), M. Meneghetti (INAF - Osservatorio di Astrofisica e Scienza dello Spazio, Bologna, Italy and INFN - Sezione di Bologna, Italy), A. Mercurio (INAF - Osservatorio Astronomico di Capodimonte, Napoli, Italy), P. Bergamini (Università degli Studi di Padova, Italy), D. Coe (Space Telescope Science Institute, Baltimore, USA)

Comments: Minor changes in v2. Accepted for publication in A&A; 13 pages, 11 figures

Subjects: Astrophysics of Galaxies (astro-ph.GA)

[56]  arXiv:1910.12953 (replaced) [pdf, other]

Title: Cold Clouds as Cosmic-Ray Detectors

Authors: Shmuel Bialy

Comments: Accepted for publication in Nature Communications Physics. (accepted version that includes, predictions for additional ortho-H2 lines, and a discussion of temperature dependence)

Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

[57]  arXiv:1911.06218 (replaced) [pdf, other]

Title: A Microlensing Accretion Disk Size Measurement in the Lensed Quasar WFI 2026-4536

Authors: Matthew A. Cornachione, Christopher W. Morgan, Martin Millon, Misty C. Bentz, Frederic Courbin, Vivien Bonvin, Emilio E. Falco

Comments: 26 pages, 8 figures, Appendix with data table, pg 12-25

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)

[58]  arXiv:1912.07386 (replaced) [pdf, other]

Title: The Evolving Coma Morphology of Interstellar Comet 2I/Borisov with Deep HST Imaging

Authors: Bryce T. Bolin

Comments: 5 pages, 3 figures and 1 table, submitted to MNRAS Letters. arXiv admin note: substantial text overlap with arXiv:1910.14004

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

[59]  arXiv:1912.10342 (replaced) [pdf, other]

Title: Lower AGN Abundance in Galaxy Clusters at z < 0.5

Authors: H. D. Mishra, X. Dai

Comments: 17 pages, 6 figures, accepted in AJ

Subjects: Astrophysics of Galaxies (astro-ph.GA)

[60]  arXiv:1912.10766 (replaced) [pdf, ps, other]

Title: Investigation of Chemical Differentiation among the NGC2264 Cluster-Forming Clumps

Authors: Kotomi Taniguchi, Adele Plunkett, Eric Herbst, Kazuhito Dobashi, Tomomi Shimoikura, Fumitaka Nakamura, Masao Saito

Comments: 5 figures, 9 tables, and 3 figures in appendix, 19 pages, Accepted by the Monthly Notices of the Royal Astronomical Society

Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

[61]  arXiv:1912.11142 (replaced) [pdf, other]

Title: Mapping the Northern Galactic Disk Warp with Classical Cepheids

Authors: D. M. Skowron, J. Skowron, P. Mróz, A. Udalski, P. Pietrukowicz, I. Soszyński, M. K. Szymański, R. Poleski, S. Kozłowski, K. Ulaczyk, K. Rybicki, P. Iwanek, M. Wrona, M. Gromadzki

Comments: This version is updated with a kinematical analysis of the Galactic warp using Gaia astrometric data

Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

[62]  arXiv:1912.12730 (replaced) [pdf, ps, other]

Title: Is Interstellar Object 2I/Borisov a Stardust Comet? Predictions for the Post Perihelion Period

Authors: T. Marshall Eubanks

Comments: Submitted to Astrophysical Journal Letters. Six pages, comments are welcomed. Minor typo in bibliography corrected

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

[63]  arXiv:1912.13026 (replaced) [pdf, ps, other]

Title: The skewness of z=0.5 redshift-space galaxy distribution in Modified Gravity

Authors: Wojciech A. Hellwing

Comments: 8 pages, 4 figures, proceedings from the XXXIX-th general assembly of the Polish Astronomical Society, September 2019, Olsztyn, Poland

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

• New submissions
• Cross-lists
• Replacements