adsabs/SciX_UAT_keywords huggingface dataset:
A Rich Satellite Population of the NGC 4437 Group and Implications of a Magnitude Gap for Galaxy Group Assembly History

Both observations and cosmological simulations have recently shown that there is a large scatter in the number of satellites of Milky Way (MW)-like galaxies. In this study, we investigate the relation between the satellite number and galaxy group assembly history using the r-band magnitude gap (Δm 12) between the brightest and second-brightest galaxies as an indicator. From 20 deg2 of the Hyper Suprime-Cam Subaru Strategic Program Wide layer, we identify 17 dwarf satellite candidates around NGC 4437, a spiral galaxy with about one-fourth of the MW stellar mass. We estimate their distances using the surface brightness fluctuation method. Then we confirm five candidates as members of the NGC 4437 group, resulting in a total of seven group members. Combining the NGC 4437 group (with Δm 12 = 2.5 mag) with other groups in the literature, we find a stratification of the satellite number by Δm 12 for a given host stellar mass. The satellite number for the given host stellar mass decreases as Δm 12 increases. The same trend is found in simulated galaxy groups in the TNG50 simulation of the IllustrisTNG project. We also find that the host galaxies in groups with a smaller Δm 12 (like NGC 4437) have assembled their halo mass more recently than those in larger gap groups, and that their stellar-to-halo mass ratios increase as Δm 12 increases. These results show that the large scatter in the satellite number is consistent with a large range of Δm 12, indicating diverse group assembly histories.

Keywords: galaxy groups; dwarf galaxies; galaxy dark matter halos; distance indicators; galaxy distances; luminosity function
A Machine Learning-based Source Property Inference for Compact Binary Mergers

The detection of the binary neutron star merger, GW170817, was the first success story of multi-messenger observations of compact binary mergers. The inferred merger rate, along with the increased sensitivity of the ground-based gravitational-wave (GW) network in the present LIGO/Virgo, and future LIGO/Virgo/KAGRA observing runs, strongly hints at detections of binaries that could potentially have an electromagnetic (EM) counterpart. A rapid assessment of properties that could lead to a counterpart is essential to aid time-sensitive follow-up operations, especially robotic telescopes. At minimum, the possibility of counterparts requires a neutron star (NS). Also, the tidal disruption physics is important to determine the remnant matter post-merger, the dynamics of which could result in the counterparts. The main challenge, however, is that the binary system parameters, such as masses and spins estimated from the real-time, GW template-based searches, are often dominated by statistical and systematic errors. Here, we present an approach that uses supervised machine learning to mitigate such selection effects to report the possibility of counterparts based on the presence of an NS component, and the presence of remnant matter post-merger in real time.

Keywords: compact objects; black holes; neutron stars
Resonant Chains and the Convergent Migration of Planets in Protoplanetary Disks

An increasing number of compact planetary systems with multiple planets in a resonant chain have been detected. The resonant chain must be maintained by convergent migration of the planets due to planet–disk interactions if it is formed before the dispersal of the protoplanetary gas disk. For type I migration in an adiabatic disk, we show that an analytic criterion for convergent migration can be developed by requiring that any part of the resonant chain should be convergently migrating toward the remaining part. The criterion depends primarily on the logarithmic gradients α and β of the surface density and temperature profiles of the disk, respectively, and it is independent of the absolute values of the surface density and temperature. The analytic criterion is applied to the Kepler-60, Kepler-80, Kepler-223, TOI-178, and TRAPPIST-1 systems. Due to the variation of planetary masses within the resonant chains, we find that convergent migration typically requires rather extreme values of (α, β) that have little or no overlap with common disk models. Finally, we show that there is an empirical relationship between the distance of the innermost planet from the central star and the stellar mass for the observed resonant chain systems, which supports the idea that the resonant chains are formed and maintained by stalling the migration of the innermost planet near the inner edge of the disk truncated by the magnetic fields of the protostar.

Keywords: celestial mechanics; protoplanetary disks; exoplanet systems; planetary system formation
Exploring the Mass and Redshift Dependencies of the Cluster Pressure Profile with Stacks on Thermal Sunyaev-Zel'dovich Maps

We provide novel constraints on the parameters defining the universal pressure profile (UPP) within clusters of galaxies, and explore their dependencies on cluster mass and redshift, from measurements of Sunyaev-Zel'dovich (SZ) Compton y-profiles. We employ both Planck 2015 MILCA and Atacama Cosmology Telescope (ACT) Data Release 4 y-maps over a common ~2100 deg2 footprint. We combine existing cluster catalogs, based on Kilo Degree Survey, Sloan Digital Sky Survey, and Dark Energy Spectroscopic Instrument Legacy Imaging Surveys observations, for a total of 23,820 clusters, spanning the mass range 1014.0 M ⊙ < M 500 < 1015.1 M ⊙ and the redshift range 0.02 < z < 0.98. We split the clusters into three independent bins in mass and redshift; for each combination, we detect the stacked SZ cluster signal and extract the mean y angular profile. The latter is predicted theoretically by adopting a halo model framework, and a Markov Chain Monte Carlo approach is employed to estimate the UPP parameters, the hydrostatic mass bias b h, and possible cluster miscentering effects. We constrain [P 0, c 500, α, β] to [5.9, 2.0, 1.8, 4.9] with Planck and to [3.8, 1.3, 1.0, 4.4] with ACT, using the full cluster sample, in agreement with previous findings. We do not find any compelling evidence for residual mass or redshift dependencies, thus expanding the validity of the cluster pressure profile over much larger M 500 and z ranges; this is the first time that the model has been tested on such a large (complete and representative) cluster sample. Finally, we obtain loose constraints on the hydrostatic mass bias in the range 0.2-0.3, again in broad agreement with previous works.

Keywords: galaxy clusters; intracluster medium; large-scale structure of the universe
A Grid of Core-collapse Supernova Remnant Models. I. The Effect of Wind-driven Mass Loss

Massive stars can shed material via steady, line-driven winds, eruptive outflows, or mass transfer onto a binary companion. In the case of single stars, the mass is deposited by the stellar wind into the nearby environment. After the massive star explodes, the stellar ejecta interact with this circumstellar material (CSM), oftentimes resulting in bright X-ray line emission from both the shock-heated CSM and ejecta. The amount of material lost by the progenitor, the mass of ejecta, and its energetics all impact the bulk spectral characteristics of this X-ray emission. Here we present a grid of core-collapse supernova remnant models derived from models for massive stars with zero-age main-sequence masses of ~10-30 M⊙ evolved from the pre-main-sequence stage with wind-driven mass loss. Evolution is handled by a multistage pipeline of software packages. First, we use mesa (Modules for Experiments in Stellar Astrophysics) to evolve the progenitors from pre-main-sequence to iron core collapse. We then use the Supernova Explosion Code (snec) to explode the mesa models, and we follow them for the first 100 days following core collapse. Finally, we couple the snec output, along with the CSM generated from mesa mass-loss rates, into the cosmic-ray hydrodynamics code to model the remnant phase to 7000 yr after core collapse. At the end of each stage, we compare our outputs with those found in the literature, and we examine any qualitative and quantitative differences in the bulk properties of the remnants and their spectra based on the initial progenitor mass, as well as mass-loss history.

Keywords: core-collapse supernovae; supernova remnants; computational methods; x-ray astronomy; stellar evolution; stellar mass loss; astronomical simulations; astronomy software
Extremely Energetic Supernova Explosions Embedded in a Massive Circumstellar Medium: The Case of SN 2016aps

We perform one-dimensional radiation-hydrodynamic simulations of energetic supernova (SN) ejecta colliding with a massive circumstellar medium (CSM) aimed at explaining SN 2016aps, likely the brightest SN observed to date. SN 2016aps was a superluminous Type IIn SN, which released as much as $\gtrsim 5\times {10}^{51}$ erg of thermal radiation. Our results suggest that the multiband light curve of SN 2016aps is well explained by the collision of a $30\,{M}_{\odot }$ SN ejecta with the explosion energy of 1052 erg and a $\simeq 8\,{M}_{\odot }$ wind-like CSM with the outer radius of 1016 cm, that is, a hypernova explosion embedded in a massive CSM. This finding indicates that very massive stars with initial masses larger than $40\,{M}_{\odot }$ , which supposedly produce highly energetic SNe, occasionally eject their hydrogen-rich envelopes shortly before the core collapse. We suggest that the pulsational pair-instability SNe may provide a natural explanation for the massive CSM and the energetic explosion. We also provide the relations among the peak luminosity, the radiated energy and the rise time for interacting SNe with the kinetic energy of 1052 erg, which can be used for interpreting SN 2016aps-like objects in future surveys.

Keywords: core-collapse supernovae; supernovae; type ii supernovae; circumstellar matter; stellar astronomy; radiative transfer; hydrodynamical simulations
Atmospheric Interactions of Ejecta on Earth and Mars Including the Effect of Vaporization

Atmospheres play an important role in ejecta deposition after an impact event. Many impact experiments and simulations neglect the effect of atmospheres. We simulate ejecta plumes created by craters with transient diameters of 2 and 20 km on Mars and Earth, to show the effect atmospheric density and crater size have on the strength of the interaction. The interaction of ejecta with an atmosphere is explored in this study using a two-fluid hydrocode that simultaneously simulates ejecta and atmospheres as coupled, continuum fields to correctly capture the transfer of mass, energy, and momentum between the two. Here, we study the effect of vaporization of plume material as well as the effect of the bow shock. We find that only the fastest ejecta is vaporized with a peak vaporized mass of 2.5 × 105 kg, 3.5 s after the impact in our 2 km diameter terrestrial crater. Terrestrial meteorites are preferentially formed from the fastest ejecta. However, that fastest ejecta is mostly vaporized in our simulations, so to form a terrestrial meteorite, there must be a sufficiently large impact for solid material to be ejected and not vaporize. Thus, we place a lower limit of 33 km on the size of crater needed to generate terrestrial meteorites, but the crater size needed could be substantially larger. The bow shocks in our simulations result in lofting of ejecta, especially vaporized material, in the wake of the impactor.

Keywords: atmospheric effects
Formation of Galactic Disks. I. Why Did the Milky Way's Disk Form Unusually Early?

Recent results from spectroscopic and astrometric surveys of nearby stars suggest that the stellar disk of our Milky Way (MW) was formed quite early, within the first few billion years of its evolution. Chemokinematic signatures of disk formation in cosmological zoom-in simulations appear to be in tension with these data, implying that MW-like disk formation is delayed in simulations. We investigate the formation of galactic disks using a representative sample of MW-like galaxies from the cosmological volume simulation TNG50. We find that on average MW-mass disks indeed form later than the local data suggest. However, their formation time and metallicity exhibit a substantial scatter, such that ∼10% of MW-mass galaxies form disks early, similar to the MW. Thus, although the MW is unusual, it is consistent with the overall population of MW-mass disk galaxies. The direct MW analogs assemble most of their mass early, ≳10 Gyr ago, and are not affected by destructive mergers after that. In addition, these galaxies form their disks during the early enrichment stage when the interstellar medium metallicity increases rapidly, with only ∼25% of early-forming disks being as metal-poor as the MW was at the onset of disk formation, [Fe/H] ≈ ‑1.0. In contrast, most MW-mass galaxies either form disks from already enriched material or experience late destructive mergers that reset the signatures of galactic disk formation to later times and higher metallicities. Finally, we also show that earlier disk formation leads to more dominant rotationally supported stellar disks at redshift zero.

Keywords: galaxy formation; galaxy disks; milky way disk; star formation; magnetohydrodynamical simulations
Galaxy Mergers up to z < 2.5. II. AGN Incidence in Merging Galaxies at Separations of 3-15 kpc

We present a study of the incidence of active galactic nucleus (AGN) in a sample of major merging systems at 0.3 < z < 2.5. Galaxies in this merger sample have projected separations between 3 and 15 kpc and are selected from the CANDELS/3D-Hubble Space Telescope catalogs using a peak-finding algorithm. AGNs in mergers and non-mergers are identified on the basis of their X-ray emission, optical lines, mid-infrared colors, and radio emission. Among galaxies with adequate measurements to find potential AGNs, we find a similar fraction of AGNs in mergers (16.4 ${\pm }_{3.1}^{5.0}$ %) compared to the fraction found in non-merging galaxies (15.4% ± 0.6%). In mergers, this fraction is obtained by assuming that, in unresolved observations, only one of the merging galaxies is the AGN source (16 merging systems have at least one AGN galaxy). The similarity between the fractions is possibly due to the higher availability of cold gas at high redshifts, where the excess of nuclear activity as a result of merging is less important than at lower redshifts. Star-forming galaxies have a higher incidence of AGNs than quiescent galaxies. In particular, starbursts in mergers are the most common sites of AGN activity, since they present higher AGN fractions and black hole accretion rates. We find no clear correlation between the black hole accretion rate and the galaxy properties (i.e., star formation rate, stellar mass) in mergers and non-mergers. However, mergers seem to have a higher correlation with star formation than non-mergers, which possibly indicates that the merging process is starting to influence the star formation and AGN activity even at this pre-coalescence stage.

Keywords: galaxy mergers; galaxy pairs; galaxy interactions; galaxy formation; galaxy evolution; high-redshift galaxies; active galactic nuclei; active galaxies
AGN X-Ray Irradiation of CO Gas in NGC 2110 Revealed by Chandra and ALMA

We report spatial distributions of the Fe-Kα line at 6.4 keV and the CO(J = 2-1) line at 230.538 GHz in NGC 2110, which are, respectively, revealed by Chandra and Atacama Large Millimeter/submillimeter Array (ALMA) at ≈0"5. A Chandra 6.2-6.5 keV to 3.0-6.0 keV image suggests that the Fe-Kα emission extends preferentially in a northwest to southeast direction out to ≈3″, or ∼500 pc, on each side. Spatially resolved spectral analyses support this by finding significant Fe-Kα emission lines only in the northwest and southeast regions. Moreover, their equivalent widths are found to be ∼1.5 keV, indicative for the fluorescence by nuclear X-ray irradiation as the physical origin. By contrast, CO(J = 2-1) emission is weak therein. For quantitative discussion, we derive ionization parameters by following an X-ray dominated region (XDR) model. We then find them high enough to interpret the weakness as the result of X-ray dissociation of CO and/or H2. Another possibility also remains that CO molecules follow a superthermal distribution, resulting in brighter emission in higher-J lines. Further follow-up observations are encouraged to draw a conclusion on what predominantly changes the interstellar matter properties and whether the X-ray irradiation eventually affects the surrounding star formation as active galactic nucleus (AGN) feedback.

Keywords: agn host galaxies; astrophysical black holes; molecular gas; star formation; x-ray active galactic nuclei; x-ray astronomy; submillimeter astronomy; radio astronomy; active galactic nuclei
Presumed Detection of C5 Molecule in the Interstellar Medium

The paper suggests the presence of the carbon chain C5 molecule in translucent, interstellar H I clouds. This species, the only five atom interstellar molecule, observable in dark, translucent clouds, seems to be observable in reasonably dense clouds, causing also rather high reddening. The paper shows two likely discovered spectral features of C5, ${{\rm{A}}}^{1}{{\rm{\Pi }}}_{u}-{{\rm{X}}}^{1}{{\rm{\Sigma }}}_{g}^{+}$ bands near 4975 and 5109 Å. The attempt to discover the 3789 Å C4 feature gave the negative result.

Keywords: interstellar medium; interstellar absorption; interstellar molecules
Formation of Halogen-bearing Species. II. Irradiation of Chloromethane in Carbon Monoxide Ice with VUV Light and Electrons

The synthesis of chlorine-bearing species in CO ice was studied by the irradiation of CH3Cl:CO ice at 10 K with vacuum-ultraviolet (VUV) light and energetic electrons. In contrast to the photochemical behavior of CH3F:CO ice, photolysis of CH3Cl:CO ice with Lyα or broadband VUV light afforded various products. This discrepancy was attributed to the abundant absorption bands of CH3Cl in the VUV region, particularly in the Lyα region. The Cl-bearing species including Cl2O, ClCO, C3Cl2, C3HCl, and HOOCl were characterized by observing their IR features. In contrast, electron bombardment of ice mixtures produced various carbon oxides and primary products, such as CH2Cl and HCO. In addition, the mechanism of energetic processes in electron bombardment was discussed.

Keywords: astrochemistry; molecular spectroscopy; line positions; molecule formation; galaxy chemical evolution; chemical abundances
Search for an Alien Message to a Nearby Star

If alien probes have colonized the whole galaxy, they could have formed an efficient galactic-scale communication network by establishing direct gravitationally lensed links between neighboring systems. Under this scenario, observing the positions opposite the nearest ecliptic stars represents a promising artifact SETI strategy that could make it possible to "eavesdrop" on the emission of local probes to one of these stars. In this context, we present here a first attempt to detect optical messages emitted from the solar system to the ecliptic star Wolf 359, the third-nearest stellar system, based on observations gathered by the TRAPPIST-South and SPECULOOS-South robotic telescopes. While sensitive enough to detect constant emission with emitting power as small as a few watts, this search led to a null result. We note that the putative alien probes could be emitting "off-axis" and be located much closer to the Sun than the start of the "solar gravitational line" at 550 au. We performed a search for such an off-axis emitter in our data, whose result turned out negative too.

Keywords: astrobiology; technosignatures; search for extraterrestrial intelligence
Analysis of the Unconcentrated Background of the EPIC pn Camera on Board XMM-Newton

Our understanding of the background of the EPIC/pn camera on board XMM-Newton is incomplete. This affects the study of extended sources and can influence the predictions of the expected background of future X-ray missions, such as the Advanced Telescope for High Energy Astrophysics (ATHENA). Here we provide new results based on the analysis of the largest data set ever used. We focus on the unconcentrated component of the EPIC/pn background, supposedly related to cosmic rays interacting with detector and telescope structures. We show that the so-called out field-of-view region of the pn detector is actually exposed to the sky. After carefully cleaning from the sky contamination, the unconcentrated background measured in the out field-of-view region does not show significant spatial variations, and its time behavior is anticorrelated with the solar cycle. We find a very tight linear correlation between unconcentrated backgrounds detected in the EPIC/pn and EPIC/MOS2 cameras. This relationship permits the correct evaluation of the pn unconcentrated background of each exposure on the basis of MOS2 data, avoiding the use of the contaminated out field-of-view region of the pn, as done in standard techniques. We find a tight linear correlation between the pn unconcentrated background and the proton flux in the 630-970 MeV energy band, as measured by the EPHIN instrument on board SOHO. Through this relationship, we quantify the contribution of cosmic-ray interaction to the pn unconcentrated background. This reveals a second source that contributes to the pn unconcentrated background for a significant fraction (30%-70%). This agent does not depend on the solar cycle or vary with time and is roughly isotropic. After having ruled out several candidates, we find that the hard X-ray photons of the cosmic X-ray background satisfy all known properties of the constant component. Our findings provide an important observational confirmation of simulation results on ATHENA and suggest that a high-energy particle monitor could contribute decisively to the reproducibility of the background for both experiments on ATHENA.

Keywords: particle astrophysics; astronomy data analysis; diffuse x-ray background; x-ray detectors; x-ray astronomy
Cosmological Model Insensitivity of Local H0 from the Cepheid Distance Ladder

The observed tension (∼9% difference) between the local distance ladder measurement of the Hubble constant, H0, and its value inferred from the cosmic microwave background could hint at new, exotic, cosmological physics. We test the impact of the assumption about the expansion history of the universe ( $0.01\lt z\lt 2.3$ ) on the local distance ladder estimate of H0. In the fiducial analysis, the Hubble flow Type Ia supernova (SN Ia) sample is truncated to z < 0.15, and the deceleration parameter (q0) is fixed to -0.55. We create realistic simulations of the calibrator and Pantheon samples, and account for a full systematics covariance between these two sets. We fit several physically motivated dark-energy models, and derive combined constraints from calibrator and Pantheon SNe Ia and simultaneously infer H0 and dark-energy properties. We find that the assumption on the dark-energy model does not significantly change the local distance ladder value of H0, with a maximum difference (ΔH0) between the inferred value for different models of 0.47 km ${{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$ , I.e., a 0.6% shift in H0, significantly smaller than the observed tension. Additional freedom in the dark-energy models does not increase the error in the inferred value of H0. Including systematics covariance between the calibrators, low-redshift SNe, and high-redshift SNe can induce small shifts in the inferred value for H0. The SN Ia systematics in this study contribute ≲0.8% to the total uncertainty of H0.

Keywords: hubble constant; dark energy; cosmological parameters; type ia supernovae