Sazuna/UAT_keywords huggingface dataset:
Kicking Time Back in Black Hole Mergers: Ancestral Masses, Spins, Birth Recoils, and Hierarchical-formation Viability of GW190521. A pair-instability supernova (PISN) prevents black hole (BH) formation from stellar collapse within the approximate mass range M ∈ [65, 130] M ⊙. However, such BHs may form hierarchically through merging ancestral BHs, whose properties determine those of the "child" one: mass, spin, and recoil velocity. Crucially, the child will leave its host environment if its birth recoil exceeds the corresponding escape velocity, preventing further mergers. We exploit relations between the final recoil and spin of quasi-circular BH mergers to obtain posterior probability distributions for the hypothetical ancestral masses, spins, and birth recoils of the component BHs of GW190521. To this, we present a Bayesian framework applicable to existing estimates for the components of BH merger observations. We consider both the quasi-circular (generically spinning) analysis performed by the LIGO–Virgo–KAGRA collaboration and the eccentric (aligned-spin) one performed by Romero-Shaw et al. We evaluate the probability p 2g  that the GW190521 components inferred by these analyses formed from the merger of stellar-origin BHs and were retained by their environment. For the primary component, which populates the PISN gap, such scenario is strongly suppressed if GW190521 happened in a globular cluster with p 2g  ∼ 10‑3 unless it was quasi circular and its ancestors had aligned spins, uncharacteristic of hierarchical formation channels, or small spins, which yields p 2g  ≃ 10‑2. If GW190521 was eccentric, we obtain p 2g  ≃ 0.1 for any host other than an active galactic nucleus, and zero for a globular cluster. If GW190521 was quasi circular, a nuclear star cluster origin is possible with p 2g  ∈ (∼0.4, ∼0.8).

Keywords: Gravitation, Gravitational waves, High energy astrophysics
Jet Interaction with Galaxy Cluster Mergers. Active galactic nucleus (AGN) bubbles in cool-core galaxy clusters are believed to facilitate the transport of cosmic-ray electrons (CRe) throughout the cluster. Recent radio observations reveal the complex morphologies of cluster diffuse emission, potentially linked to interactions between AGN bursts and the cluster environment. We perform 3D magnetohydrodynamical simulations of binary cluster mergers and inject a bidirectional jet at the center of the main cluster. Kinetic, thermal, magnetic, and cosmic ray (CR) energy are included in the jet and we use the two-fluid formalism to model the CR component. We explore a wide range of cluster merger and jet parameters. We discuss the formation of various wide-angle-tail and X-shaped sources in the early evolution of the jet and merger. During the last phase of the evolution, we find that the CR material efficiently permeates the central region of the cluster reaching radii of ∼1–2 Mpc within ∼5–6 Gyr, depending on the merger mass ratio. We find that solenoidal turbulence dominates during the binary merger and we explore the possibility for the CR jet material to be reaccelerated by super-Alfvènic turbulence and contribute to cluster scale radio emission. We find high volume fractions, ≳70%, at which the turbulent acceleration time is shorter than the electron cooling time. Finally, we study the merger shock interaction with the CRe material and show that it is unlikely that this material significantly contributes to the radio relic emission associated with the shocks. We suggest that multiple jet outbursts and/or off-center radio galaxies would increase the likelihood of detecting these merger shocks in the radio due to shock reacceleration.

Keywords: Galaxy clusters, Magnetohydrodynamics, High energy astrophysics, Plasma astrophysics, Intracluster medium
PyMerger: Detecting Binary Black Hole Mergers from the Einstein Telescope Using Deep Learning. We present PyMerger, a Python tool for detecting binary black hole (BBH) mergers from the Einstein Telescope (ET), based on a deep residual neural network (ResNet) model. ResNet was trained on data combined from all three proposed subdetectors of ET (TSDCD) to detect BBH mergers. Five different lower-frequency cutoffs (F low)—5 Hz, 10 Hz, 15 Hz, 20 Hz, and 30 Hz—with the match-filter signal-to-noise ratio (MSNR) ranges 4–5, 5–6, 6–7, 7–8, and &gt;8 were employed in the data simulation. Compared to previous work that utilized data from a single subdetector, the detection accuracy from TSDCD has shown substantial improvements, increasing from 60%, 60.5%, 84.5%, 94.5%, and 98.5% to 78.5%, 84%, 99.5%, 100%, and 100% for sources with MSNRs of 4–5, 5–6, 6–7, 7–8, and &gt;8, respectively. The ResNet model is evaluated on the first ET mock data challenge (ET-MDC1) data set, where the model demonstrates strong performance in detecting BBH mergers, identifying 5566 out of 6578 BBH events, with optimal SNRs starting from 1.2 and a minimum and maximum D  L  of 0.5 Gpc and 148.95 Gpc, respectively. Despite being trained only on BBH mergers without overlapping sources, the model achieves high BBH detection rates. Notably, even though the model was not trained on binary neutron star (BNS) and black hole-neutron star (BHNS) mergers, it successfully detected 11,477 BNS and 323BHNS mergers in ET-MDC1, with optimal SNRs starting from 0.2 and 1, respectively, indicating its potential for broader applicability.

Keywords: Convolutional neural networks, Gravitational wave detectors, Gravitational waves
Fast and Flexible Inference Framework for Continuum Reverberation Mapping Using Simulation-based Inference with Deep Learning. Continuum reverberation mapping (CRM) of active galactic nuclei (AGN) monitors multiwavelength variability signatures to constrain accretion disk structure and supermassive black hole (SMBH) properties. The upcoming Vera Rubin Observatory's Legacy Survey of Space and Time will survey tens of millions of AGN over the next decade, with thousands of AGN monitored with almost daily cadence in the deep drilling fields. However, existing CRM methodologies often require long computation time and are not designed to handle such large amounts of data. In this paper, we present a fast and flexible inference framework for CRM using simulation-based inference (SBI) with deep learning to estimate SMBH properties from AGN light curves. We use a long short-term memory summary network to reduce the high dimensionality of the light curve data and then use a neural density estimator to estimate the posterior of SMBH parameters. Using simulated light curves, we find SBI can produce more accurate SMBH parameter estimation with 103–105 times speed up in inference efficiency compared to traditional methods. The SBI framework is particularly suitable for wide-field CRM surveys as the light curves will have identical observing patterns, which can be incorporated into the SBI simulation. We explore the performance of our SBI model on light curves with irregular-sampled, realistic observing cadence and alternative variability characteristics to demonstrate the flexibility and limitation of the SBI framework.

Keywords: Supermassive black holes, Reverberation mapping, Neural networks
Large-scale Magnetic Field Model of GRB Afterglow Polarization: Effects of Field Anisotropy, Off-axis Viewing Angle, and Ordered Field. The afterglows of gamma-ray bursts are nonthermal electron synchrotron emissions from relativistic shocks. The origin of strong magnetic field in the emission region remains elusive, and two field amplification mechanisms via the plasma kinetic and magnetohydrodynamic instabilities have been discussed. The polarimetric observations are a powerful probe to distinguish these two mechanisms. So far, most theoretical works have focused on the former mechanism and constructed afterglow polarization models with microscopic-scale turbulence whose coherence length is much smaller than the thickness of the blast wave. In this work, focusing on the latter mechanism, we utilize our semianalytic model of the synchrotron polarization with large-scale turbulence whose coherence length is comparable to the thickness of the blast wave to investigate the effect of magnetic field anisotropy and the observer viewing angle. We find that the polarization in our large-scale turbulence model can exhibit both behaviors characteristic of the microscopic-scale turbulence model and those not seen in the microscopic-scale model. Then we find that the large-scale model could explain all the polarimetric observational data to date that seem to be forward shock emission. We also examine the effect of ordered-field components and find that polarization degree and polarization angle constant in time are realized only when the energy density ratio of the ordered and fluctuated components is ≳50. In this case, however, the polarization degree is much higher than the observed values.

Keywords: Non-thermal radiation sources, Jets, Gamma-ray bursts, Magnetic fields
DESI Emission-line Galaxies: Unveiling the Diversity of [O II] Profiles and Its Links to Star Formation and Morphology. We study the [O II] profiles of emission-line galaxies (ELGs) from the Early Data Release of the Dark Energy Spectroscopic Instrument (DESI). To this end, we decompose and classify the shape of [O II] profiles with the first two eigenspectra derived from principal component analysis. Our results show that DESI ELGs have diverse line profiles, which can be categorized into three main types: (1) narrow lines with a median width of ∼50 km s‑1, (2) broad lines with a median width of ∼80 km s‑1, and (3) two redshift systems with a median velocity separation of ∼150 km s‑1, i.e., double-peak galaxies. To investigate the connections between the line profiles and galaxy properties, we utilize the information from the COSMOS data set and compare the properties of ELGs, including star formation rate (SFR) and galaxy morphology, with the average properties of reference star-forming galaxies with similar stellar mass, sizes, and redshifts. Our findings show that, on average, DESI ELGs have a higher SFR and more asymmetrical/disturbed morphology than the reference galaxies. Moreover, we uncover a relationship between the line profiles, the excess SFR, and the excess asymmetry parameter, showing that DESI ELGs with broader [O II] line profiles have more disturbed morphology and higher SFR than the reference star-forming galaxies. Finally, we discuss possible physical mechanisms giving rise to the observed relationship and the implications of our findings on the galaxy clustering measurements, including the halo occupation distribution modeling of DESI ELGs and the observed excess velocity dispersion of the satellite ELGs.

Keywords: Principal component analysis, Galaxy spectroscopy, Galaxy mergers, Emission line galaxies
C<SUP>+</SUP> 133.5 nm Emission Mechanisms on Mars Revealed by the MAVEN Observations. C+ emission is generated by electron impact, dissociative ionization, photoionization, and resonant scattering with carbon-related atoms, molecules, and ions in the Martian ionosphere and thermosphere. The contribution of each mechanism to the emission, however, has not been elucidated due to the difficulty of observation and the fact that a part of the emission cross section is unclear. The current paper isolates the C+ emission mechanism using remote-sensing and in situ observations on board Mars Atmosphere and Volatile EvolutioN. Both electron impact and dissociative ionization/photoionization contribute to C+ emission below 150 km altitude when the CO density is high, but only dissociative ionization/photoionization contributes to the emission for the low CO density case, while only dissociative ionization/photoionization dominates the emission at altitudes between 150 and 165 km for both CO density cases. It is difficult to estimate the total flux of suprathermal electrons in the ionosphere from remote-sensing observations of C+ emission because the contribution of electron impact to C+ emission is small. In contrast, C-atom remote-sensing observations might provide a better understanding of the total flux of suprathermal electrons in the ionosphere than C+ emission, and global ultraviolet observations could be utilized as a tool for monitoring the ionosphere. The total flux of suprathermal electrons estimated from C-atom emission may be utilized to isolate the contribution of each C+ emission process to the brightness more accurately. This suggests that the C+ and C-atom emissions might be tracers of spatiotemporal variations in the Martian ionosphere and thermosphere.

Keywords: Mars, Solar system terrestrial planets, Ultraviolet spectroscopy, Extreme ultraviolet astronomy
Convective Mixing in Gas Giant Planets with Primordial Composition Gradients. Linking atmospheric measurements to the bulk planetary composition and ultimately the planetary origin is a key objective in planetary science. In this work, we identify the cases in which the atmospheric composition represents the bulk composition. We simulate the evolution of giant planets considering a wide range of planetary masses (0.3─2 M J), initial entropies ( 8-11kBmu−1 ), and primordial heavy-element profiles. We find that convective mixing is most efficient at early times (ages ≲107 yr) and that primordial composition gradients can be eroded. In several cases, however, the atmospheric composition can differ widely from the planetary bulk composition, with the exact outcome depending on the details. We show that the efficiency of convection is primarily controlled by the underlying entropy profile: For low primordial entropies of  8-9kBmu−1 , convective mixing can be inhibited and composition gradients can persist over billions of years. The scaling of mixing efficiency with mass is governed by the primordial entropy. For the same primordial entropy, low-mass planets mix more efficiently than high-mass planets. If the primordial internal entropy would increase with mass, however, this trend could reverse. We also present a new analytical model that predicts convective mixing under the existence of composition (and entropy) gradients. Our results emphasize the complexity in the interpretation of atmospheric abundance measurements and show the great need to better understand the planetary formation process as it plays a key role in determining the planetary evolution and final structure.

Keywords: Exoplanet atmospheric composition , Chemical abundances, Exoplanet evolution, Extrasolar gaseous planets, Exoplanet formation, Planetary interior, Astrophysical fluid dynamics
New Evidence for a Flux-independent Spectral Index of Sgr A* in the Near-infrared. In this work, we measure the spectral index of Sagittarius A* (Sgr A*) between the H (1.6 μm) and   (2.2 μm) broadband filters in the near-infrared (NIR), sampling over a factor ∼40 in brightness, the largest range probed to date by a factor ∼3. Sgr A*-NIR is highly variable, and studying the spectral index α (with F  ν  ∝ ν  α ) is essential to determine the underlying emission mechanism. For example, variations in α with flux may arise from shifts in the synchrotron cutoff frequency, changes in the distribution of electrons, or multiple concurrent emission mechanisms. We investigate potential variations of   with flux by analyzing seven epochs (2005–2022) of Keck Observatory imaging observations from the Galactic Center Orbits Initiative. We remove the flux contribution of known sources confused with SgrA*-NIR, which can significantly impact color at faint flux levels. We interpolate between the interleaved H and   observations using multi-output Gaussian processes. We introduce a flexible empirical model to quantify α variations and probe different scenarios. The observations are best fit by an   that is constant from ∼1 mJy to ∼40 mJy (dereddened 2 μm flux). We find no evidence for a flux dependence of Sgr A*'s intrinsic spectral index. In particular, we rule out a model explaining NIR variability purely by shifts in the synchrotron cutoff frequency. We also constrain the presence of redder, quiescent emission from the black hole, concluding that the dereddened 2 μm flux contribution must be ≤0.3 mJy at 95% confidence level.

Keywords: Supermassive black holes, Galactic center, Low-luminosity active galactic nuclei, Gaussian Processes regression, Spectral index, Infrared photometry
First Resolution of Microlensed Images of a Binary-lens Event. We resolve the multiple images of the binary-lens microlensing event ASASSN-22av using the GRAVITY instrument of the Very Large Telescope Interferometer (VLTI). The light curves show weak binary-lens perturbations, complicating the analysis, but the joint modeling with the VLTI data breaks several degeneracies, arriving at a strongly favored solution. Thanks to precise measurements of the angular Einstein radius θ E = 0.724 ± 0.002 mas and microlens parallax, we determine that the lens system consists of two M dwarfs with masses of M 1 = 0.258 ± 0.008 M ⊙ and M 2 = 0.130 ± 0.007 M ⊙, a projected separation of r ⊥ = 6.83 ± 0.31 au, and a distance of D L = 2.29 ± 0.08 kpc. The successful VLTI observations of ASASSN-22av open up a new path for studying intermediate-separation (i.e., a few astronomical units) stellar-mass binaries, including those containing dark compact objects such as neutron stars and stellar-mass black holes.

Keywords: Gravitational microlensing, Optical interferometry, Binary lens microlensing
Blue Luminescence from N-doped Graphene. Blue luminescence (BL) has been observed in various astrophysical environments, such as the inner region of the Red Rectangle Nebula. It has been previously linked to small polycyclic aromatic hydrocarbons. In this study, we explore the potential of N- and O-doped graphene material as carriers of BL. Using vacuum ultraviolet irradiation, pristine single-layer graphene films were exposed to solid N2 and O2 at low temperatures, resulting in the formation of N- or O-doped graphene. The photoluminescence (PL) spectrum of the synthesized N-doped graphene exhibits an asymmetrical peak at 378 nm, which is nearly identical to the BL observed in the Red Rectangle. In contrast, the synthesized O-doped graphene shows a symmetrical PL band at 414 nm. Further Raman and X-ray photoelectron spectroscopy analyses reveal that nitrogen atoms substitute carbon atoms in the graphene lattice, introducing structural defects and sp2 regions responsible for the observed luminescence. The simplicity of the bonding structures in the N-doped graphene, dominated by pyrrolic-N and pyridinic-N groups, further supports its potential as a model system for studying BL.

Keywords: Radiative processes, Interstellar emissions, Laboratory astrophysics, Astrochemistry
Evidence for Mass-dependent Evolution of Transitional Dwarf Galaxies in the Virgo Cluster. The presence of transitional dwarf galaxies in cluster environments supports the hypothesis that infalling star-forming galaxies are transformed into quiescent early-type dwarf galaxies (ETdGs) through environmental effects. We present a study on the evolution of transitional dwarf galaxies, specifically dwarf lenticulars (dS0s) and early-type dwarfs with blue cores (ETdG(bc)s), driven by environmental processes in the Virgo cluster utilizing the Extended Virgo Cluster Catalog. We investigated the morphological fraction and stellar mass of transitional dwarf galaxies in relation to the clustercentric distance, compared to dwarf elliptical galaxies (dEs) and dwarf irregular galaxies (dIrrs). We found that dS0s beyond 0.7Rvir exhibit a similar trend in the morphology-clustercentric distance relation to dEs, demonstrating a decreasing fraction with clustercentric distance, whereas ETdG(bc)s display an opposite trend to dS0s but a similar trend to dIrrs. The spatial distributions of transitional dwarf galaxies and dEs correlate with the mass, in which fractions of bright, massive galaxies increase toward the central region of the Virgo cluster. In the mass-clustercentric distance plane, dS0s exhibit a skewed distribution that favors more massive galaxies than dEs at a given clustercentric distance. In the projected phase-space diagram, dS0s are scarce in the stripped region, whereas ETdG(bc)s are absent in both the stripped and virialized regions. In addition, the dS0s in the virialized region are predominantly brighter and more massive than the dEs, indicating that the transformation of dS0s into dEs depends on the stellar mass. We propose that the majority of observed dS0s constitute a population that has settled into the Virgo cluster, whereas ETdG(bc)s represent a recently accreted population. We discuss the impact of ram pressure stripping effects on mass-dependent morphological evolution, as well as the time delay between star formation quenching and morphological transformation in dwarf galaxies.

Keywords: Galaxy clusters, Lenticular galaxies, Galaxy formation, Virgo Cluster, Dwarf galaxies, Galaxy evolution
Fast Radio Bursts and Interstellar Objects. Fast radio bursts (FRBs) are transient radio events with millisecond-scale durations and debated origins. Collisions between planetesimals and neutron stars (NSs) have been proposed as a mechanism to produce FRBs; the planetesimal strength, size, and density determine the time duration and energy of the resulting event. One source of planetesimals is the population of interstellar objects (ISOs), free-floating objects expected to be extremely abundant in galaxies across the Universe as products of planetary formation. We explore using the ISO population as a reservoir of planetesimals for FRB production, finding that the expected ISO–NS collision rate is comparable with the observed FRB event rate. Using a model linking the properties of planetesimals and the FRBs they produce, we further show that observed FRB durations are consistent with the sizes of known ISOs, and the FRB energy distribution is consistent with the observed size distributions of solar system planetesimal populations. Finally, we argue that the rate of ISO–NS collisions must increase with cosmic time, matching the observed evolution of the FRB rate. Thus, ISO–NS collisions are a feasible mechanism for producing FRBs.

Keywords: Neutron stars, Radio bursts, Asteroids, Interstellar objects
NIHAO-RiNG: A Comparison of Simulated Disk Galaxies from GASOLINE and GIZMO. We utilize the publicly available code GIZMO to re-simulate 12 galaxies selected from the Numerical Investigation of a Hundred Astronomical Object (NIHAO) simulation suite, which were run with the GASOLINE code, then compare their properties. We find that while both codes with the same initial conditions and large-scale environments can successfully produce similar galactic disks in Milky Way-mass systems, yet significant differences are still seen in many aspects, particularly the circumgalactic medium (CGM) environment they reside in. Specifically, the thermal feedback recipe used in GASOLINE results in ubiquitous, long-term, large-scale outflows, primarily driven by high-density hot interstellar medium from the galaxy center, preventing the intergalactic medium from falling efficiently. Recycled gas and inflows in the CGM appear at 104∼5 K, playing a crucial role in the formation of cold disks in the NIHAO simulations. In contrast, disk galaxies simulated by GIZMO do not exhibit prominent outflows at low redshifts, but instead display quasi-virialized hot gas halos that arise from the interaction between inflows and feedback-driven outflows. Therefore, the origins of mass and angular momentum of the cold disk in the two simulations are quite different, even though the final morphologies of the corresponding galaxies are both disky. The differences in the distribution of CGM gas are mainly due to different feedback models implemented in the two codes. Future observations of CGM could provide valuable insight into the physics governing the baryon cycle in galaxies.

Keywords: Hydrodynamical simulations, Galaxy formation, Cold dark matter, Circumgalactic medium