Sazuna/UAT_keywords huggingface dataset:
Disk Draining in LIGO Progenitor Black Hole Binaries and Its Significance to Electromagnetic Counterparts. The effect of tidal forces on transport within a relic accretion disk in binary black holes is studied here with a suite of two-dimensional hydrodynamic simulations. As the binary contracts owing to the emission of gravitational waves, the accretion disk is truncated, and a two-armed spiral wave is excited, which remains stationary in the rotating reference frame of the coalescing binary. Such spiral waves lead to increased transport of mass and angular momentum. Our findings suggest that even in the case of weakly ionized accretion disks spiral density waves will drain the disk long before the orbit of the two black holes decays enough for them to merge, thus dimming prospects for a detectable electromagnetic counterpart.

Keywords: Close binary stars, Hydrodynamical simulations, Accretion
The Critical Role of Dark Matter Halos in Driving Star Formation. Understanding the physical mechanisms that drive star formation is crucial for advancing our knowledge of galaxy evolution. We explore the interrelationships between key galaxy properties associated with star formation, with a particular focus on the impact of dark matter (DM) halos. Given the sensitivity of atomic hydrogen (H I) to external processes, we concentrate exclusively on central spiral galaxies. We find that the molecular-to-atomic gas mass ratio ( /MH I) strongly depends on stellar mass and specific star formation rate (sSFR). In the star formation efficiency (SFE)–sSFR plane, most galaxies fall below the H2 fundamental formation relation, with SFEH I being consistently lower than  . Using the improved halo masses derived by D. Zhao et al., for star-forming galaxies, both SFEH I and  /MH I increase rapidly and monotonically with halo mass, indicating a higher efficiency in converting H I to H2 in more massive halos. This trend ultimately leads to the unsustainable state where SFEH I exceeds   at halo mass around 1012M⊙. For halos with masses exceeding 1012M⊙, galaxies predominantly experience quenching. We propose a plausible evolutionary scenario in which the growth of halo mass regulates the conversion of H I to H2, star formation, and the eventual quenching of galaxies. The disk size, primarily regulated by the mass, spin and concentration of the DM halo, also significantly influences H I to H2 conversion and star formation. These findings underscore the critical role of DM halos as a global regulator of galaxy-wide star formation, a key factor that has been largely under-appreciated in previous studies. *This is the fifth paper in the "From Halos to Galaxies" series.

Keywords: Galaxy dark matter halos, Star formation, Galaxy evolution, Interstellar medium, Galaxy quenching
How to Escape from a Trap: Outcomes of Repeated Black Hole Mergers in Active Galactic Nuclei. Stellar-mass black holes (BHs) embedded in active galactic nuclei (AGN) may be major sources of astrophysical gravitational waves (GWs), contributing both to the observed LIGO–Virgo–KAGRA population of binary BH mergers and to future populations of LISA-band extreme mass ratio inspirals (EMRIs). The ability of these BHs to pair up into binaries, inspiral, and produce GWs will be shaped by the existence of migration traps, regions in the AGN where hydrodynamic torques vanish. Previous works have studied the existence and location of migration traps in AGN disks. Here, we investigate how individual BHs may escape such traps as an outcome of mergers, potentially suppressing hierarchical growth. We find that while GW recoil kicks are strong enough to kick merged BHs onto inclined orbits, gas drag quickly realigns them into the AGN disk. A more robust escape mechanism is gap opening: once a BH grows above a critical mass, its gravity disturbs the AGN gas sufficiently to eliminate the trap. In low-mass AGN relevant for LISA, gaps open easily, and the resulting "wet EMRI" masses are unlikely to reflect protracted hierarchical mergers. In combination with our previous work, we find that migration traps only exist in a relatively narrow range of AGN luminosities, L ∈ [1043.5, 1045.5] erg s‑1. We identify an even narrower AGN luminosity range for which stellar mass BHs can grow into the pair-instability mass gap and beyond. This characteristic luminosity scale may assist in indirect tests of the "AGN channel" for binary BH mergers.

Keywords: Accretion, Black hole physics, Black holes, Active galactic nuclei, Gravitational waves
The First Chemical Census of the Milky Way's Nuclear Star Cluster. An important step in understanding the formation and evolution of the nuclear star cluster (NSC) is to investigate its chemistry and chemical evolution. Additionally, exploring the NSC's relationship to the other structures in the Galactic center and the Milky Way disks is of great interest. Extreme optical extinction has previously prevented optical studies, but near-IR high-resolution spectroscopy is now possible. Here, we present a detailed chemical abundance analysis of 19 elements—more than 4 times as many as previously published—for nine stars in the NSC of the Milky Way, observed with the Immersion GRating INfrared Spectrometer on the Gemini South telescope. This study provides new, crucial observational evidence to shed light on the origin of the NSC. We demonstrate that it is possible to probe a variety of nucleosynthetic channels, reflecting different chemical evolution timescales. Our findings reveal that the NSC trends for the elements F, Mg, Al, Si, S, K, Ca, Ti, Cr, Mn, Co, Ni, Cu, and Zn, as well as for the s-process elements Ba, Ce, Nd, and Yb, generally follow the inner-bulge trends within uncertainties. This suggests a likely shared evolutionary history, and our results indicate that the NSC population is consistent with the chemical sequence observed in the inner Galaxy (the inner-disk sequence). However, we identify a significant and unexplained difference in the form of higher Na abundances in the NSC compared to the inner bulge. This is also observed in few Galactic globular clusters and may suggest a common enrichment process at work in all these systems.

Keywords: M giant stars, Chemical abundances
Formation of Ultra-short-period Planets in Hot Jupiter Systems: Application to WASP-47. The WASP-47 system is notable as the first known system hosting both inner and outer low-mass planetary companions around a hot Jupiter, with an ultra-short-period (USP) planet as the innermost planetary companion. The formation of such a unique configuration poses challenges to the lonely hot Jupiter formation model. Hot Jupiters in multiple planetary systems may have a similar formation process with warm Jupiter systems, which are more commonly found with companions. This implies that the WASP-47 system could bridge our understanding of both hot and warm Jupiter formation. In this work, we propose a possible formation scenario for the WASP-47 system based on its orbital configuration. The mean motion resonance trapping, giant planet perturbations, and tidal effects caused by the central star are key factors in the formation of USP planets in multiple planetary systems with hot Jupiters. Whether a planet can become a USP planet or a short-period super-Earth planet depends on the competition between eccentricity excitation by nearby giant planet perturbations and the eccentricity damping due to tidal effects. The   value of the innermost planet is essential for the final planetary configuration. Our results suggest that a   in the range of [1, 10] is favorable for the formation of the WASP-47 system. Based on the formation scenario, we estimate an occurrence rate of 8.4% ± 2.4% for USP planets in systems similar to WASP-47.

Keywords: Exoplanet dynamics, Exoplanet formation
Cascaded Gamma-Ray Emission Associated with the KM3NeT Ultrahigh-energy Event KM3-230213A. A neutrino-like event with an energy of ∼220 PeV was recently detected by the KM3NeT/ARCA telescope. If this neutrino comes from an astrophysical source or from the interaction of an ultrahigh-energy cosmic ray in the intergalactic medium, the ultrahigh-energy gamma rays that are coproduced with the neutrinos will scatter with the extragalactic background light, producing an electromagnetic cascade and resulting in emission at GeV-to-TeV energies. In this Letter, we compute the gamma-ray flux from this neutrino source considering various source distances and strengths of the intergalactic magnetic field (IGMF). We find that the associated gamma-ray emission could be observed by existing imaging air Cherenkov telescopes and air shower gamma-ray observatories, unless the strength of the IGMF is B ≳ 3 × 10‑13 G or the ultrahigh-energy gamma rays are attenuated inside of the source itself. In the latter case, this source is expected to be radio-loud.

Keywords: Ultra-high-energy cosmic radiation
A Large Molecular Gas Reservoir in the Protocluster SPT2349‑56 at z = 4.3. We present Atacama Compact Array (ACA) Band-3 observations of the protocluster SPT2349‑56, an extreme system hosting &gt;10 ultraluminous infrared galaxies (ULIRGs; LIR ≳ 1012L⊙) in a 200 kpc diameter region at z = 4.3, to study its integrated molecular gas content via CO(4–3) and the long-wavelength dust continuum. The ∼30 hr integration represents one of the longest exposures yet taken on a single pointing with the ACA 7 m. The low-resolution ACA data (21 0 × 12 2) reveal a 75% excess CO(4–3) flux compared to the sum of individual sources detected in higher-resolution Atacama Large Millimeter/submillimeter Array (ALMA) data (1 0 × 0 8). Our work also reveals a similar result by tapering the ALMA data to 10″. In contrast, the 3.2 mm dust continuum shows little discrepancy between ACA and ALMA. A single-dish [C II] spectrum obtained by APEX/FLASH supports the ACA CO(4–3) result, revealing a large excess in [C II] emission relative to ALMA. The missing flux is unlikely due to undetected faint sources but instead suggests that high-resolution ALMA observations might miss extended and low-surface-brightness gas. Such emission could originate from the circumgalactic medium or the preheated protointracluster medium (proto-ICM). If this molecular gas reservoir replenishes the star formation fuel, the overall depletion timescale will exceed 400 Myr, reducing the requirement for the simultaneous ULIRG activity in SPT2349‑56. Our results highlight the role of an extended gas reservoir in sustaining a high star formation rate in SPT2349‑56 and potentially establishing the ICM during the transition phase to a mature cluster.

Keywords: Submillimeter astronomy, High-redshift galaxies, Galaxy evolution
Detection of [C I] Emission in Nebular Spectra of a Peculiar Type Ia Supernova 2022pul. SN 2022pul gains special attention due to its possible origin as a super-Chandrasekhar-mass white dwarf (WD) explosion (also called a 03fg-like Type Ia supernova), which shows prominent [O I], [Ne I], and [Ca II] lines in its late-time spectra taken at ∼+300 days after the time of peak brightness. In this Letter, we present new optical observations of this peculiar object, extending up to over 500 days after peak brightness. In particular, in the t ∼ +515 days spectrum, we identified for the first time the presence of narrow emission from [C I] λλ9824, 9850, which appears asymmetric and quite similar to the accompanied [O I] λ6300 line in strength and profile. Based on the violent merger model that accounts well for previous observations but leaves little carbon in the center of the ejecta, this carbon line can be reproduced by increasing the degree of clumping in the ejecta and setting the carbon mass the same as that of oxygen (∼0.06 M⊙) in the innermost region (≲2000 km s−1). In principle, the central carbon could come from the secondary WD if it is ignited when hit by the shock wave of the explosion of the primary WD and explodes as a Ca-rich supernova, whereas pure deflagration of a super-Chandrasekhar-mass WD can account for such unburnt carbon more naturally.

Keywords: White dwarf stars, Type Ia supernovae, Supernovae
Constraining the Cosmic-Ray Energy Based on Observations of Nearby Galaxy Clusters by LHAASO. Galaxy clusters act as reservoirs of high-energy cosmic rays (CRs). As CRs propagate through the intracluster medium, they generate diffuse γ-rays detectable by arrays such as LHAASO. These γ-rays result from proton─proton (pp) collisions of very high-energy cosmic rays or inverse Compton (IC) scattering of positron-electron pairs created by pγ interactions of ultra-high-energy cosmic rays (UHECRs). We analyzed diffuse γ-ray emission from the Coma, Perseus, and Virgo clusters using LHAASO data. Diffuse emission was modeled as a disk of radius R500 for each cluster while accounting for point sources. No significant diffuse emission was detected, yielding 95% confidence level (C.L.) upper limits on the γ-ray flux: for WCDA (1─25 TeV) and KM2A (&gt;25 TeV), less than (49.4, 13.7, 54.0) and (1.34, 1.14, 0.40) × 10−14 ph cm−2 s−1 for Coma, Perseus, and Virgo, respectively. The γ-ray upper limits can be used to derive model-independent constraints on the integral energy of cosmic ray protons above 10 TeV (corresponding to the LHAASO observational range &gt;1 TeV under the pp scenario) to be less than (1.96, 0.59, 0.08) × 1061 erg. The absence of detectable annuli/ring-like structures, indicative of cluster accretion or merging shocks, imposes further constraints on models in which the UHECRs are accelerated in the merging shocks of galaxy clusters.

Keywords: Galaxy clusters, Gamma-ray sources, Virgo Cluster, Coma Cluster, Perseus Cluster, Ultra-high-energy cosmic radiation
3D MC. I. X-Ray Tomography Begins to Unravel the 3D Structure of a Molecular Cloud in our Galaxy's Center. Astronomers have used observations of the Galactic gas and dust via infrared, microwave, and radio to study molecular clouds in extreme environments such as the Galactic center. More recently, X-ray telescopes have opened up a new wavelength range in which to study these molecular clouds. Previous flaring events from Sgr A* propagate X-rays outwards in all directions, and these X-rays interact with the surrounding molecular gas, illuminating different parts of the clouds over time. We use a combination of X-ray observations from Chandra and molecular gas tracers (line data from Herschel and the Submillimeter Array) to analyze specific features in the Sticks cloud, one of three clouds in the Three Little Pigs system in the Central Molecular Zone (Galactic longitude and latitude of 0 106 and −0 082 respectively). We also present a novel X-ray tomography method we used to create 3D map of the Sticks cloud. By combining X-ray and molecular tracer observations, we are able to learn more about the environment inside the Sticks cloud.

Keywords: X-ray astronomy, Astronomy data modeling, Molecular data, Black holes, Molecular clouds, Interstellar medium, Radio astronomy
Emergence of cHz Quasiperiodic Oscillations from a Low-angular-momentum Flow onto a Supermassive Black Hole. Quasiperiodic oscillations (QPOs) are very common in black hole accretion systems that are seen from the modulations in luminosity. Many supermassive black hole sources (e.g., RE J1034+396, 1H 0707-495, MCG-6-30-15, 1ES 1927+654, Sgr A*) have been observed to exhibit QPO-like variability in the range of mHz in different energy bands (e.g., radio, near-IR, X-rays). Due to the shorter infalling time, low-angular-momentum accretion flows can have resonance close to the black hole, which will raise variability cHz or beyond QPOs for supermassive black holes. In this study, for the first time, we show that such resonance conditions can be achieved in simulations of low-angular-momentum accretion flows onto a black hole. The QPOs could have values beyond νQPO ≳ 0.1–1 × 107M⊙/MBH cHz and the harmonics have a ratio of 2:1. Hunting these cHz QPOs down will provide a smoking gun signature for the presence of low-angular-momentum accretion flows around black holes (e.g., Sgr A*, 1ES 1927+654).

Keywords: Accretion, Black hole physics, Magnetohydrodynamics, Supermassive black holes
The JCMT BISTRO Survey: Magnetic Fields Align with Orbital Structure in the Galactic Center. We present the magnetic field in the dense material of the Central Molecular Zone (CMZ) of the Milky Way, traced in 850 μm polarized dust emission as part of the James Clerk Maxwell Telescope B-fields in STar-forming Region Observations survey. We observe a highly ordered magnetic field across the CMZ between Sgr B2 and Sgr C that is strongly preferentially aligned with the orbital gas flows within the clouds of the CMZ. We find that the observed relative orientations are nonrandom at a &gt;99% confidence level and are consistent with models in which the magnetic field vectors are aligned within 30° to the gas flows in 3D. The deviations from aligned magnetic fields are most prominent at positive Galactic longitudes, where the CMZ clouds are more massive, denser, and more actively forming stars. Our observed strongly preferentially parallel magnetic field morphology leads us to hypothesize that in the absence of star formation, the magnetic field in the CMZ is entrained in the orbital gas flows around Sgr A*, while gravitational collapse and feedback in star-forming regions can locally reorder the field. This magnetic field behavior is similar to that observed in the CMZ of the nuclear starburst galaxy NGC 253. This suggests that despite its current low star formation rate, the CMZ of the Milky Way is analogous to those of more distant, actively star-forming, galaxies.

Keywords: Star formation, Galactic center, Magnetic fields, Molecular clouds
Discovery of a Low-mass Strong-lens System in SMACS J0723.3−7327. We report the discovery of an intriguing, low-mass galaxy-scale strong-lens system in the SMACS J0723.3−7327 galaxy cluster. By modeling James Webb Space Telescope imaging and Very Large Telescope Multi-Unit Spectroscopic Explorer spectroscopic data, we find that the lens is cluster member galaxy at z = 0.397 with an Einstein radius of 0 424 ± 0 012, stellar mass of M* = (3.3 ± 0.8) × 1010 M⊙, half-light radius of ∼1 kpc, and central stellar velocity dispersion of 140 ± 6 km s−1. This lens galaxy is one of the few strong lens galaxies known to date that have stellar mass as low as M* ∼ 1010.5 M⊙, offering an exceptional opportunity to peek into the population of low-mass galaxies that has largely remained unexplored in the context of strong-lensing studies. This strong lens system can also assist in assessing the systematic uncertainty in the lens modeling of cluster member galaxies.

Keywords: Galaxy formation, Strong gravitational lensing, Galaxy evolution
Decay of Turbulent Upper-hybrid Waves in Weakly Magnetized Solar Wind Plasmas. Large-scale and long-term two-dimensional particle-in-cell simulations of high resolution are performed for the first time to study the dynamics of electrostatic decay of upper-hybrid wave turbulence generated by electron beams into Langmuir/ -mode ( ) waves in weakly to moderately magnetized plasmas, in conditions relevant to type III solar radio bursts. Simulations use parameters characteristic of beam–plasma interactions between ∼0.1 and 1 au. The impact of plasma magnetic field on decay is shown, and magnetic properties of   waves are determined. During their energy transport through k wavevector scales, waves undergo several decay cascades, acquiring increasing magnetic energy until they reach electromagnetic  -mode dispersion below the plasma frequency. Whereas the impact of magnetic field on decaying waves of large k = ∣k∣ is weak, important differences with respect to the unmagnetized plasma case manifest at small k-scales, where a boundary layer delimiting a spectral domain free of   energy is revealed. It prevents decayed waves from reaching the  -mode cutoff frequency and a high level of left-handed polarization, and it modifies the conditions for the appearance of modulational instabilities and strong turbulence phenomena at k ∼ 0. Ordinary  -mode waves are generated jointly with  -mode waves at comparable energy levels, via electromagnetic decay, whereas  -mode emissions are much weaker in most cases. These results provide support for the interpretation of observations by satellites such as Parker Solar Probe and Solar Orbiter, and they supply a solid basis for tackling the more complex problem of dynamics of upper-hybrid wave turbulence in magnetized plasmas where random density fluctuations cannot be neglected.

Keywords: Radio bursts, Solar wind, Solar electromagnetic emission
Natural Generation of Alfvén Waves from Three-dimensional Bursty Interchange Magnetic Reconnection in the Solar Corona. Alfvén waves play a significant role in solar coronal heating, solar wind acceleration, and Alfvénic turbulence formation. As a fundamental process, magnetic reconnection has long been credited as a crucial source of Alfvén waves. However, how magnetic reconnection triggers Alfvén waves remains unclear. Here, employing high-resolution simulations of three-dimensional bursty interchange magnetic reconnection in the solar corona, we unveil that Alfvén waves are spontaneously excited in the reconnecting current sheet and propagate bidirectionally, mainly along unreconnected magnetic fields. Generated by the transient reconnection events, flux ropes with enhanced total pressure persistently displace the magnetic fields in their surrounding, launching the observed large-amplitude and quasi-linearly polarized Alfvén waves, which carry substantial energy for heating the quiet corona and accelerating the solar wind. Our findings underscore the natural association between Alfvén waves and intermittent magnetic reconnection, which can be generalized to various plasma systems in astrophysical and laboratorial environments.

Keywords: Solar corona, Alfven waves, Solar magnetic reconnection, Magnetohydrodynamical simulations
A Massive H I-absorption-selected Galaxy at z ≈ 2.356. We use the Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array to detect CO(1–0), CO(3–2), and rest-frame 349 GHz continuum emission from an H I-selected galaxy, DLA1020+2733g, at z ≈ 2.3568 in the field of the z = 2.3553 damped Lyα absorber (DLA) toward QSO J1020+2733. The VLA CO(1–0) detection yields a molecular gas mass of (2.84 ± 0.42) × 1011 × (αCO/4.36) M⊙, the largest ever measured in an H I-selected galaxy. The DLA metallicity is +0.28 ± 0.16, from the Zn IIλ2026 absorption line detected in a Keck Echellette Spectrograph and Imager spectrum. This continues the trend of high-metallicity DLAs being frequently associated with massive galaxies. We obtain a star formation rate (SFR) of ≲400 M⊙ yr‑1 from the rest-frame 349 GHz continuum emission and a relatively long molecular gas depletion timescale of ≳0.6 Gyr. The excitation of the J = 3 rotational level is subthermal, with  , suggesting that DLA1020+2733g has a low SFR surface density. The large velocity spread of the CO lines, ≈500 km s‑1, and the long molecular gas depletion timescale suggest that DLA1020+2733g is likely to be a cold rotating-disk galaxy.

Keywords: Radio interferometry, Damped Lyman-alpha systems, High-redshift galaxies