adsabs/SciX_UAT_keywords huggingface dataset:
Red Satellite Galaxies: The Best Tracers of Host-mass Distribution in the Illustris-TNG100 Simulation

We use the IllustrisTNG100-1 simulation to investigate the degree to which satellite galaxies trace the mass density of large, isolated host galaxies. As expected, the mass density profiles of the host galaxies are well fitted by Navarro, Frenk & White profiles. The degree to which the satellite number density profiles trace the hosts' mass density profiles is a strong function of host and satellite color. For red hosts, the number density profile of blue satellites is significantly less than the host mass density profile for all host-satellite separations r ≲ 0.8r200. For blue hosts, the number density profile of blue satellites agrees fairly well with the host mass density profile for all host-satellite separations r ≲ 0.8r200. For both red and blue hosts, we find that red satellites are the best tracers of the mass density profiles within the hosts' virial radii.

Keywords: dark matter; galaxy dark matter halos; dwarf galaxies; galaxies
New Fe I Level Energies and Line Identifications from Stellar Spectra. III. Initial Results from UV, Optical, and Infrared Spectra

The spectrum of neutral iron is critical to astrophysics, yet furnace laboratory experiments cannot reach high-lying Fe I levels. Instead, Peterson & Kurucz and Peterson et al. adopted ultraviolet (UV) and optical spectra of warm stars to identify and assign energies for 124 Fe I levels with 1900 detectable Fe I lines, and to derive astrophysical gf values for over 1000 of these. An energy value was assumed for each unknown Fe I level, and confirmed if the wavelengths predicted in updated Kurucz Fe I calculations matched the wavelengths of four or more unidentified lines in the observed spectra. Nearly all these identifications were for LS levels, those characterized by spin-orbit coupling, whose lines fall primarily at UV and optical wavelengths. This work contributes nearly 100 new Fe I level identifications. Thirty-nine LS levels are identified largely by incorporating published positions of unidentified laboratory Fe I lines with wavelengths <2000 Å. Adding infrared (IR) spectra provided 60 Fe I jK levels, where a single outer electron orbits a compact core. Their weak IR lines are searchable, because their mutual energies obey tight relationships. For each new Fe I level, this work again makes publicly available its identification, its energy, and a list of its potentially detectable lines with theoretical gf values, totalling >16,000 lines. For over 2000 of these, this work provides astrophysical gf values adjusted semiempirically to fit the stellar spectra. The potential impact of this work on modeling UV and IR stellar spectra is noted.

Keywords: atomic data benchmarking; spectral line identification; transition probabilities; experimental techniques; line positions; stellar abundances; stellar ages; stellar colors
Thermal Formation of Ammonium Carbamate on the Surface of Laboratory Analogs of Carbonaceous Grains in Protostellar Envelopes and Planet-forming Disks

The catalytic role of dust grain surfaces in the thermal reaction CO2 + 2NH3 → NH4+NH2COO- was recently demonstrated by our group. The rate coefficients for the reaction at 80 K on the surface of nanometer-sized carbon and silicate grains were measured to be up to three times higher compared to the reaction rate coefficients measured on KBr. In this study, the reaction was performed on carbon grains and on KBr in the extended temperature range of 50-80 K and with the addition of water ice. The reaction activation energy was found to be about three times lower on grains compared to the corresponding ice layer on KBr. Thus, the catalytic role of the dust grain surface in the studied reaction can be related to a reduction of the reaction barrier. Addition of water to NH3:CO2 ice on grains slowed the reaction down. At the H2O:CO2 ratio of 5:1, the reaction was not detected on the experimental timescale. This result calls into question the thermal formation of ammonium carbamate in dense molecular clouds and outer regions of protostellar and protoplanetary environments with dominating water ice mantle chemistry. However, it can still happen in inner regions of protostellar and protoplanetary environments in crystalline ices.

Keywords: interstellar dust; carbonaceous grains; astrochemistry; reaction catalysts; reaction rates; laboratory astrophysics; solid matter physics
The Velocity Map Asymmetry of Ionized Gas in MaNGA. I. The Catalog and General Properties

The SDSS-IV MaNGA survey has measured two-dimensional maps of emission-line velocities for a statistically powerful sample of nearby galaxies. The asymmetric features of these kinematics maps reflect the nonrotational component of a galaxy's internal motion of ionized gas. In this study, we present a catalog of kinematic asymmetry measurements of the Hα velocity map of a sample of 5353 MaNGA galaxies. Based on this catalog, we find that "special" galaxies (e.g., merging galaxies, barred galaxies, and active galactic nucleus host galaxies) contain more galaxies with highly asymmetric velocity maps. However, we notice that more than half of galaxies with high kinematic asymmetry in our sample are quite "regular." For those "regular" galaxies, kinematic asymmetry shows a significant anticorrelation with stellar mass at $\mathrm{log}{M}_{\star }\lt 9.7$ , while such a trend becomes very weak at $\mathrm{log}{M}_{\star }\gt 9.7$ . Moreover, at a given stellar mass, the kinematic asymmetry shows weak correlations with photometric morphology, star formation rate, and environment, while it is independent of H I gas content. We also have quantified the observational effects in the kinematic asymmetry measurement. We find that both the signal-to-noise ratio of Hα flux and disk inclination angle contribute to the measures of kinematic asymmetry, while the physical spatial resolution is an irrelevant factor inside the MaNGA redshift coverage.

Keywords: galaxies; galaxy kinematics; galaxy formation; galaxy structure
CI Tau: A Controlled Experiment in Disk-Planet Interaction

CI Tau is a young (~2 Myr) T Tauri system with a substantial near-infrared (NIR) excess in its spectral energy distribution (SED), indicating that the protoplanetary disk extends very close to its star. This is seemingly at odds with the radial-velocity discovery of CI Tau b, a ~12 MJ planet at ~0.1 au, which would be expected to carve a wide, deep cavity in the innermost disk. To investigate this apparent contradiction, we run 2D hydrodynamics simulations to study the effect of the planet on the disk, then post-process the results with radiative transfer to obtain an SED. We find that at ~0.1 au, even such a massive companion has little impact on the NIR excess, a result that holds regardless of planetary eccentricity and dust size distribution. Conversely, the observed full-disk signature in CI Tau's SED is consistent with the existence of the hot super-Jupiter CI Tau b. As our simulations uncover, clear transition-disk signatures in SEDs are more likely to be signposts of nascent "warm" Jupiters, located at around 1 au in the future habitable zones of their host stars.

Keywords: protoplanetary disks; exoplanet detection methods; radiative transfer; hydrodynamics
Lifting the Veil on Quark Matter in Compact Stars with Core g-mode Oscillations

Compact stars containing quark matter may masquerade as neutron stars in the range of measured mass and radius, making it difficult to draw firm conclusions on the phase of matter inside the star. The sensitivity of core g-mode oscillations to the presence of a mixed phase may alleviate this difficulty. In hybrid stars that admit quark matter in a mixed phase, the g-mode frequency rises sharply due to a marked decrease in the equilibrium sound speed. Resonant excitation of g-modes can leave an imprint in the waveform of coalescing binary compact stars. We present analytic and numeric results to assess the sensitivity displayed by g-mode oscillations to quark matter in a homogeneous or mixed phase and also compute relevant damping times in quark matter due to viscosity.

Keywords: neutron stars; gravitational waves; stellar oscillations
Nuclear Physics Multimessenger Astrophysics Constraints on the Neutron Star Equation of State: Adding NICER's PSR J0740+6620 Measurement

In the past few years, new observations of neutron stars (NSs) and NS mergers have provided a wealth of data that allow one to constrain the equation of state (EOS) of nuclear matter at densities above nuclear saturation density. However, most observations were based on NSs with masses of about 1.4 M⊙, probing densities up to ~three to four times the nuclear saturation density. Even higher densities are probed inside massive NSs such as PSR J0740+6620. Very recently, new radio observations provided an update to the mass estimate for PSR J0740+6620, and X-ray observations by the NICER and XMM telescopes constrained its radius. Based on these new measurements, we revisit our previous nuclear physics multimessenger astrophysics constraints and derive updated constraints on the EOS describing the NS interior. By combining astrophysical observations of two radio pulsars, two NICER measurements, the two gravitational-wave detections GW170817 and GW190425, detailed modeling of the kilonova AT 2017gfo, and the gamma-ray burst GRB 170817A, we are able to estimate the radius of a typical 1.4 M⊙ NS to be ${11.94}_{-0.87}^{+0.76}\,\mathrm{km}$ at 90% confidence. Our analysis allows us to revisit the upper bound on the maximum mass of NSs and disfavors the presence of a strong first-order phase transition from nuclear matter to exotic forms of matter, such as quark matter, inside NSs.

Keywords: nuclear physics; neutron stars; neutron star cores; gravitational waves
VERTICO and IllustrisTNG: The Spatially Resolved Effects of Environment on Galactic Gas

It has been shown in previous publications that the TNG100 simulation quantitatively reproduces the observed reduction in each of the total atomic and total molecular hydrogen gas for galaxies within massive halos, i.e., dense environments. In this Letter, we study how well TNG50 reproduces the resolved effects of a Virgo-like cluster environment on the gas surface densities of satellite galaxies with m * > 109 M ⊙ and star formation rate > 0.05 M ⊙ yr-1. We select galaxies in the simulation that are analogous to those in the HERACLES and VERTICO surveys and mock-observe them to the common specifications of the data. Although TNG50 does not quantitatively match the observed gas surface densities in the centers of galaxies, the simulation does qualitatively reproduce the trends of gas truncation and central density suppression seen in VERTICO in both H I and H2. This result promises that modern cosmological hydrodynamic simulations can be used to reliably model the post-infall histories of cluster satellite galaxies.

Keywords: galaxy environments; galaxy evolution; interstellar atomic gas; interstellar molecules
Tentative Evidence for Transit-timing Variations of WASP-161b

We report on the detection of transit-timing variations (TTV) of WASP-161b by using the combination of Transiting Exoplanet Survey Satellite (TESS) data and archival data. The midpoint of the transits in TESS data are offset by ~67 minutes in 2019 January, and ~203 minutes in 2021 January, based on the ephemeris published in previous work. We are able to reproduce the transit timings from the archival light curve (SSO-Europa; 2018 January) and find that the timing is consistent with the published ephemeris under a constant period assumption. Conversely, we find that the transit midpoint of the SSO-Europa light curve indicates a 6.97 minutes variation at 4.63σ compared to the prediction obtained from TESS timings, and a constant orbit period assumption. The TTVs could be modeled with a quadratic function, yielding a constant period change. The period derivative $\dot{P}$ is -1.16 × 10-7 ± 2.25 × 10-8 days per day (or -3.65 s yr-1), using timings obtained from SSO-Europa and TESS light curves. Different scenarios, including a decaying period and apsidal precession, can potentially explain these TTVs but they both introduce certain inconsistencies.

Keywords: exoplanet systems; exoplanet astronomy; transit timing variation method; transit photometry
Identification of Radio Frequency Interference Using Multi-scale TransUNet

Radio observation is a method for conducting astronomical observations using radio waves. A common challenge in radio observations is Radio Frequency Interference (RFI), which refers to the unintentional or intentional interference of radio signals from other wireless sources within the radio frequency band. Such interference contaminates the astronomical signals received by radio telescopes, significantly affecting time–frequency domain astronomical observations and research. Consequently, identifying RFI is crucial. In this paper, we employ a deep learning approach to detect RFI present in observation data and propose an improved network structure based on TransUNet. This network leverages the principles of a multi-scale convolutional attention mechanism. It introduces an auxiliary branch to extract high-dimensional image information and an enhanced coordinate attention mechanism for feature map extraction, enabling more comprehensive and accurate identification of RFI in time–frequency images. We introduce a novel architecture named the Multi-Scale TransUNet Network, abbreviated as MS-TransUNet. We utilized observation data from the 40 m radio telescope at the Yunnan Observatory as a data set for training, validating, and testing the network. Compared with previous deep learning networks (U-Net, RFI-Net, R-Net, DSC, EMSCA-UNet), the recall rate and f2 score have been significantly improved. Specifically, the recall rate is improved by at least 2.99%, and the f2 score is improved by at least 2.46%. Experiments demonstrate that this network is exceptional in identifying RFI more comprehensively while ensuring high precision.

Keywords: radio astronomy; convolutional neural networks; astronomy data visualization
Black Hole to Photosphere: 3D GRMHD Simulations of Collapsars Reveal Wobbling and Hybrid Composition Jets

Long-duration γ-ray bursts (GRBs) accompany the collapse of massive stars and carry information about the central engine. However, no 3D models have been able to follow these jets from their birth via black hole (BH) to the photosphere. We present the first such 3D general-relativity magnetohydrodynamic simulations, which span over six orders of magnitude in space and time. The collapsing stellar envelope forms an accretion disk, which drags inwardly the magnetic flux that accumulates around the BH, becomes dynamically important, and launches bipolar jets. The jets reach the photosphere at ~1012 cm with an opening angle θ j ~ 6° and a Lorentz factor Γ j ≲ 30, unbinding ≳90% of the star. We find that (i) the disk-jet system spontaneously develops misalignment relative to the BH rotational axis. As a result, the jet wobbles with an angle θ t ~ 12°, which can naturally explain quiescent times in GRB lightcurves. The effective opening angle for detection θ j + θ t suggests that the intrinsic GRB rate is lower by an order of magnitude than standard estimates. This suggests that successful GRBs are rarer than currently thought and emerge in only ~0.1% of supernovae Ib/c, implying that jets are either not launched or choked inside most supernova Ib/c progenitors. (ii) The magnetic energy in the jet decreases due to mixing with the star, resulting in jets with a hybrid composition of magnetic and thermal components at the photosphere, where ~10% of the gas maintains magnetization σ ≳ 0.1. This indicates that both a photospheric component and reconnection may play a role in the prompt emission.

Keywords: gamma-ray bursts; core-collapse supernovae; relativistic jets; stellar jets; polar jets; plasma jets; type ic supernovae; type ib supernovae; magnetohydrodynamical simulations
Spectroscopically Identified Cataclysmic Variables from the LAMOST Survey. I. The Sample

A sample of cataclysmic variables (CVs) is presented including spectroscopically identified 380 spectra of 245 objects, of which 58 CV candidates are new discoveries. The BaggingTopPush and the Random Forest algorithms are applied to the Fifth Data Release (DR5) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) to retrieve CVs with strong emission lines and with broad absorption lines respectively. Based on spectroscopic classification, 134 dwarf novae, 41 nova-like variables, and 19 magnetic CVs are identified from the sample. In addition, 89 high-inclination systems and 33 CVs showing companion stars are recognized and discussed for their distinct spectral characteristics. Comparisons between CVs from LAMOST and from published catalogs are made in spatial and magnitude distribution, and the difference of their locus in the Gaia color-absolute magnitude diagram (CaMD) are also investigated. More interestingly, for two dwarf novae observed through LAMOST and SDSS in different epochs, their spectra both in quiescence phase and during outburst are exhibited.

Keywords: cataclysmic variable stars; dwarf novae; nova-like variable stars; catalogs; astronomy data analysis
CO and CO2 Productions Rates of Comets Observed by NEOWISE within Year 1 of the Reactivated Mission

We report on the observed fluxes of the comets detected by NEOWISE during the first year of operations after the spacecraft's reactivation. The sample included 57 comets. Of the comets detected, 30 were short-period comets (27 Jupiter-family comets, 1 Centaur, 2 Halley-type comets), and 27 were long-period comets. From the measured fluxes in the two NEOWISE bands, proxies for the gas production and coma dust are derived. We find a relationship between heliocentric distance, perihelion distance, and the gas-to-dust proxy fractions.

Keywords: comets; short period comets; long period comets; infrared astronomy
Precession-induced Variability in AGN Jets and OJ 287

The combined study of the flaring of active galactic nuclei (AGNs) at radio wavelengths and parsec-scale jet kinematics with Very Long Baseline Interferometry has led to the view that (i) the observed flares are associated with ejections of synchrotron blobs from the core, and (ii) most of the flaring follows a one-to-one correlation with the ejection of the component. Recent results have added to the mounting evidence showing that the quasi-regular component injections into the relativistic jet may not be the only cause of the flux variability. We propose that AGN flux variability and changes in jet morphology can both be of deterministic nature, i.e., having a geometric/kinetic origin linked to the time-variable Doppler beaming of the jet emission as its direction changes due to precession (and nutation). The physics of the underlying jet leads to shocks, instabilities, or ejections of plasmoids. The appearance (morphology, flux, etc.) of the jet can, however, be strongly affected and modulated by precession. We demonstrate this modulating power of precession for OJ 287. For the first time, we show that the spectral state of the spectral energy distribution (SED) can be directly related to the jet's precession phase. We model the SED evolution and reproduce the precession parameters. Further, we apply our precession model to 11 prominent AGNs. We show that for OJ 287 precession seems to dominate the long-term variability (≳1 yr) of the AGN flux, SED spectral state, and jet morphology, while stochastic processes affect the variability on short timescales (≲0.2 yr).

Keywords: active galactic nuclei; blazars; relativistic jets; galaxy mergers; radio interferometry; gravitational waves
Hyperbolic Meteoroids Impacting the Moon

Since the discovery of the Moon's asymmetric ejecta cloud, the origin of its sunward-canted density enhancement has not been well understood. We propose impact ejecta from meteoroids on hyperbolic trajectories (β-meteoroids) that hit the Moon's sunward side could explain this unresolved asymmetry. β-meteoroids are submicron in size, comparable to or smaller than the regolith particles they hit, and can impact the Moon at very high speeds ∼100 km s-1. Therefore, their impact regime may differ from the significantly larger and slower sporadic meteoroids responsible for generating the bulk of the lunar impact ejecta cloud. We compare lunar impact ejecta production to β-meteoroid fluxes observed by multiple spacecraft. If β-meteoroids are able to liberate similar sized submicron particles, orbital dust detector measurements from the Lunar Dust Experiment on board the Lunar Atmosphere and Dust Environment Explorer spacecraft only need to detect one ejecta grain out of every 106 β-meteoroid impacts to the lunar surface to explain the sunward asymmetry with this additional population. This finding suggests β-meteoroids may also contribute to the evolution of other airless surfaces in the inner solar system, and by extension, at exozodiacal systems.

Keywords: circumstellar dust; interplanetary dust; meteoroid dust clouds; zodiacal cloud; lunar impacts; impact phenomena; ejecta
Special Supernova Signature from BH-NS/BH Progenitor Systems

The gravitational-wave detection by the LIGO-Virgo scientific collaboration shows that black hole and neutron star (BH-NS) or BH-BH systems with a BH mass of tens of solar masses widely exist in the universe. Two main types of scenarios have been invoked for the formation of BH-NS/BH systems, including isolated binary evolution in galactic fields and dynamical interactions in dense environments. Here we propose that if the BH-NS/BH systems are formed from isolated binary evolution, the supernova (SN) signal associated with the second core collapse would show some identifiable features, due to the accretion feedback from the companion BH. Depending on the binary properties, we show that the SN lightcurve could present a sharp peak around ∼10 days, with luminosity even at the level of the super luminous SNe (e.g., $\sim {10}^{44}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ ) or present a plateau feature lasting for several tens of days with regular luminosity of core collapse SNe. Comparing the event rate density of these special SN signals with the event rate density of LIGO-Virgo detected BH-NS/BH systems could help to distinguish the BH-NS/BH formation channel.

Keywords: supernovae; gravitational waves; black holes; neutron stars