Sazuna/UAT_keywords huggingface dataset:
Double Tidal Disruption Events or Repeating Partial Tidal Disruption Events in AT 2020vdq. AT 2020vdq has been known as a candidate of repeating partial tidal disruption events (pTDEs) due to its two flares with a time interval of ∼1000 days. Here, a simplified method is proposed to test such repeating pTDEs scenario considering a main-sequence star tidally disrupted twice. For the two flares in AT 2020vdq if related to the repeating pTDEs scenario, a theoretical tidal disruption event (TDE)─model determined stellar mass of the original star disrupted for the first flare should be not very different from the mass of the star (to trace the reminder of the original star) disrupted for the second flare because a pTDE with impact parameter β smaller than 1 can lead to most of (probable higher than 90%) the stellar mass also bound to the reminder of the original star. After considering theoretical TDE model applied to describe the two flares in AT 2020vdq, the model determined stellar masses are about 2 and 0.36 M⊙ for the stars disrupted in the first flare and the second flare. The large mass difference cannot be reasonably expected by the repeating pTDEs with β around 0.6 in AT 2020vdq. The results in this manuscript indicate that the repeating pTDEs scenario is not preferred at current stage in AT 2020vdq, but the probable double TDEs for two individual stars tidally disrupted should be currently recommended.

Keywords: Tidal disruption, Active galaxies, Active galactic nuclei
Heavy Seeds and the First Black Holes: Insights from the BRAHMA Simulations. From the luminous quasars at z ∼ 6 to the recent z ∼ 9─11 active galactic nuclei (AGN) revealed by JWST, observations of the earliest black hole (BH) populations can provide unique constraints on BH evolution. We use the BRAHMA simulations with constrained initial conditions to investigate BH assembly in extreme overdense regions. The simulations implement heavy ∼104─105 M⊙ seeds forming in dense, metal-poor gas exposed to sufficient Lyman─Werner flux. With gas accretion modeled via the Bondi─Hoyle formalism and BH dynamics with a subgrid dynamical friction scheme, we isolate the impact of seeding, dynamics, accretion, and feedback on BH evolution. With fiducial stellar and AGN feedback inherited from IllustrisTNG, accretion is suppressed at z ≳ 9, leaving mergers as the dominant growth channel. Gas accretion dominates at z ≲ 9, where permissive models (super-Eddington or low radiative efficiency) build ∼109 M⊙ BHs powering quasars by z ∼ 6, while stricter IllustrisTNG-based prescriptions yield much smaller BHs (∼106─108 M⊙). Our seed models strongly affect mergers at z ≳ 9: only the most lenient models (with ∼105 M⊙ seeds) produce enough BH mergers to reach ≳106 M⊙ by z ∼ 10, consistent with current estimates for GN-z11. Our dynamical friction model gives low merger efficiencies. Therefore, even in such extreme regions, we are unable to produce ≳107 M⊙ BHs by z ∼ 9─10, as currently inferred for GHZ9, UHZ1, and CAPERS-LRD-z9. If the BH-to-stellar mass ratios of these sources are indeed so extreme, they would require either very short BH merger timescales or reduced AGN thermal feedback. Weaker stellar feedback boosts both star formation and BH accretion and cannot raise these ratios.

Keywords: Supermassive black holes, Galaxy formation, Active galactic nuclei, Hydrodynamical simulations
Inferring M<SUB>BH</SUB>─M<SUB>bulge</SUB> Evolution from the Gravitational-wave Background. We test the impact of an evolving supermassive black hole mass scaling relation (MBH─Mbulge) on the predictions for the gravitational-wave background (GWB). The observed GWB amplitude is 2─3 times higher than predicted by astrophysically informed models, which suggests the need to revise the assumptions in those models. We compare a semi-analytic model's ability to reproduce the observed GWB spectrum with a static versus evolving-amplitude MBH─Mbulge relation. We additionally consider the influence of the choice of galaxy stellar mass function (GSMF) on the modeled GWB spectra. Our models are able to reproduce the GWB amplitude with either a large number density of massive galaxies or a positively evolving MBH─Mbulge amplitude (i.e., the MBH/Mbulge ratio was higher in the past). If we assume that the MBH─Mbulge amplitude does not evolve, our models require a GSMF that implies an undetected population of massive galaxies (M⋆ ≥ 1011M⊙ at z &gt; 1). When the MBH─Mbulge amplitude is allowed to evolve, we can model the GWB spectrum with all fiducial values and an MBH─Mbulge amplitude that evolves as α(z) = α0(1 + z)1.04±0.5.

Keywords: Supermassive black holes, Black holes, Gravitational wave sources, Scaling relations, Gravitational waves, Galaxies
Feeding the Dead: Neutral Gas Inflow in a Long-quenched Ancient Massive Galaxy at z ∼ 2.7 Observed with JWST/NIRSpec. We report the spectroscopic detection of neutral gas inflow into a massive (M* ≃ 4 × 1010 M⊙) quiescent galaxy observed at zspec = 2.6576 with the James Webb Space Telescope (JWST). From the redshifted absorption of the Na I doublet at λλ5890, 5896, we estimate an inflow velocity  v=278−79+79  km s−1 and a column density  log(NNaI/cm2)=13.02−0.03+0.03 . We derive the inflowing mass of the gas  Min=1.6−0.1+0.1×108M⊙  and rate  Ṁin=19−7+6M⊙yr−1 . The presence of several surrounding galaxies suggests that the galaxy may be accreting gas from nearby companions. However, we cannot confirm this with current data, and the intergalactic medium or cosmic filaments are also viable sources of the inflowing gas. Despite the ongoing inflow, the galaxy remains quiescent, with an upper limit to the star formation rate of 0.2 M⊙ yr−1. Moreover, its star formation history suggests that the galaxy has remained quiescent during the past ∼1 Gyr, with half of its stars formed by redshift  z50=11−3+18 . We discuss that the inflow is not massive, dense, or long-lived enough to ignite significant star formation (SF), or it is fueling low-level active galactic nucleus activity instead. This is direct evidence that quiescent galaxies can accrete cold gas after their quenching while keeping their SF subdued. Follow-up observations with JWST and the Atacama Large Millimeter/submillimeter Array will be needed to constraint the nature of the inflowing gas.

Keywords: Galaxies, Quenched galaxies, Cold neutral medium, Star formation, Galaxy quenching, Galaxy spectroscopy, High-redshift galaxies, Post-starburst galaxies
Evolution of the Shock Properties of the 2023 March 13 Event from In Situ and Remote-sensing Data. Shocks driven by coronal mass ejections (CMEs) are the most powerful accelerators of gradual solar energetic particles (SEPs) in the inner heliosphere. On 2023 March 13, a halo CME, as seen from the Solar and Heliospheric Observatory (SOHO) and the Sun TErrestrial Relations Observatory (STEREO), gave rise to a strong SEP event. In this work, we aim to analyze this CME-driven shock from multiple spacecraft, using both remote-sensing observations from STEREO-A/COR2 and in situ data from the Parker Solar Probe (PSP), Solar Orbiter (SolO), and Wind. In order to determine its direction of propagation and kinematic properties, we model the shock geometry using STEREO-A/COR2 and SOHO Large Angle and Spectrometer Coronagraph (LASCO)/C3 observations as an expanding ellipsoid. The density compression ratio of the shock is determined by fitting the brightness profile from the coronagraphic images with that obtained from raytracing simulations of a double-Gaussian shock-density profile. We compare physical quantities such as compression ratio and Alfvénic Mach number derived from remote-sensing observations with in situ measurements by PSP, SolO, STEREO-A, and Wind. From STEREO-A/COR2, we determine the compression ratio around the entire shock front in the corona, finding significant inhomogeneities that can impact the values found during in situ crossings. Following the evolution of the parameters characterizing the CME from the source to space, we find that closer to the Sun both the gas compression ratio and the Alfvénic Mach number remain almost constant, while they increase at larger radial distances. This indicates a nontrivial evolution of the shock parameters during its journey through the interplanetary space.

Keywords: Solar energetic particles, Shocks, Solar coronal mass ejections, Solar corona
Distinct Source Regions for Slow Solar Wind Populations Differentiated by Residual Energy during Parker Solar Probe Encounter 7. The properties of solar wind are closely related to its source region in the solar atmosphere. Here, we investigate the variability of solar wind measured by Parker Solar Probe (PSP) during Encounter 7 (E7) and connect it to spatiotemporal changes in magnetic connectivity to multiple solar sources in the solar atmosphere. During E7, PSP sequentially detected fast solar wind (FSW), Alfvénic slow solar wind (ASSW), and magnetic-velocity alignment structures (MVAS; with high magnitude of the magnetic field and velocity correlation coefficient Cvb and moderately negative normalized residual energy σr). ASSW and MVAS both have ∣Cvb∣ ∼ 1 but differ in σr. We trace back to the solar atmosphere by applying potential field source surface modeling and ballistic backmapping, and find that FSW, ASSW, and MVAS belong to three distinct regions. Combining these results with EUV observations from SDO/AIA and Hinode/EUV Imaging Spectrometer, we find that magnetic footpoints in the first region oscillate between the center and boundary of a coronal hole, corresponding to variable solar wind containing FSW and MVAS. In the second region, footpoints lie on the western side of NOAA active region (AR) 12796, evidenced by open field lines, enhanced EUV intensity on the AIA map, and blueshifted Doppler velocity, indicating that ASSW may originate from the AR. Footpoints in the third region are primarily located in a quiet Sun region, a possible MVAS source region. These findings highlight the complex and dynamic linkage between solar wind variability and its diverse source regions.

Keywords: Solar wind, Solar active regions, Alfven waves, Solar magnetic fields, Solar coronal holes
On the Mass Budget Problem of Protoplanetary Disks: Streaming Instability and Optically Thick Emission. Statistical studies of protoplanetary disks and exoplanet populations often exhibit a "missing mass" problem, where the observed dust masses in (sub)millimeter surveys are significantly lower than expected when compared to the masses of exoplanetary systems. We investigate how the streaming instability and subsequent planetesimal formation in protoplanetary disks might solve this missing mass problem when (sub)millimeter observations are usually interpreted under the assumption of optically thin emission. We conduct hydrodynamical simulations of the streaming instability with self-gravity, after which radiative transfer calculations with dust scattering are performed to measure the (sub)millimeter intensity. The measured intensity is then used to estimate the disk mass under the assumption of optically thin emission and compared to the true mass in the simulation to calculate the observational bias via the mass excess. We find that the emission from overdense filaments that emerges due to the streaming instability is optically thick at (sub)millimeter wavelengths, leading to mass excess factors of ∼2─7.

Keywords: Dust continuum emission, Protoplanetary disks, Radiative transfer, Planetesimals
Hydro-radiative Simulations, Analytical Modeling, and Laboratory Scaling of Complex Shock Structures in Novae Ejecta. Radiative shocks are fundamental in astrophysical phenomena, particularly in novae ejecta, where interactions between fast and slow outflows lead to double-shock structures (DSSs). However, direct observations of these shocks remain challenging due to their deep embedding within the ejecta and their small cooling layer. Hydro-radiative simulations with the RAMSES code taking radiative cooling into account are used to model the evolution of DSSs. Additionally, an analytical framework is developed to validate simulation results and predict key shock parameters. Simulations reveal significant cooling effects behind the forward shock, leading to strong density and temperature gradients. The analytical model successfully reproduces these results and enables a detailed parametric study, highlighting the influence of main parameters. Finally, using scaling laws, we miniaturize the DSS to a laboratory scale, preserving key dimensionless parameters that govern the DSS dynamics. By combining simulations, theoretical modeling, and scaling laws, this study paves the way for direct investigation of radiative shocks. It offers a unique opportunity to refine our understanding of astrophysical shock dynamics and validate current models.

Keywords: Shocks, Laboratory astrophysics, Theoretical models, Scaling relations
Can Dwarf Spheroidal Galaxies Host a Central Black Hole?. We construct mass models of Milky Way dwarf spheroidal galaxies to place constraints on the central black hole masses they can host. We model the galaxies as a three-component system consisting of the stars, dark matter halo, and a central black hole, using the Osipkov─Merritt─Cuddeford class of the anisotropic distribution function. The posterior distribution of black hole mass remains flat toward the low-mass end, indicating that the kinematic data places an upper limit on the black hole mass. Our analysis yields a 95% credible upper limit of  log(M∙/M⊙)&lt;6 . We combine our results with black hole mass measurements and upper limits from the literature to construct a unified M∙─σ* relation spanning σ* ∼ 10─300 km s−1, described by  log(M∙)=8.32+4.08logσ*/200kms−1 , with an intrinsic scatter of σint = 0.55. We compare the inferred limits to models of black hole growth via momentum-driven accretion and stellar capture, which predict black hole masses in the range 103─104 M⊙ for the range σ* ∼ 6─12 km s−1, in close agreement with the M∙─σ* relation within the 95% credible upper limits on the black hole masses derived in this work.

Keywords: Galaxy dynamics
Chemical and Isotopic Homogeneity between the L Dwarf CD-35 2722 B and Its Early M Host Star. CD-35 2722 B is an L dwarf companion to the nearby, ∼50─200 Myr old M1 dwarf CD-35 2722 A. We present a detailed analysis of both objects using high-resolution (R ∼ 35,000) K-band spectroscopy from the Keck Planet Imager and Characterizer combined with archival photometry. With a mass of  30−4+5MJup  (planet-to-host mass ratio 0.05) and projected separation of 67 ± 4 au from its host, CD-35 2722 B likely formed via gravitational instability. We explore whether the chemical composition of the system tells a similar story. Accounting for systematic uncertainties, we find  [M/H]=−0.16−0.02+0.03(stat)±0.25(sys)  dex and  12C/13C=132−14+20  for the host, and  [M/H]=0.27-0.06+0.07(stat)±0.12(sys)  dex,  12CO/13CO=159−24+33(stat)−33+40(sys) , and C/O = 0.55 ± 0.01 (stat) ± 0.04 (sys) for the companion. The chemical compositions for the brown dwarf and host star agree within the 1.5σ level, supporting a scenario where CD-35 2722 B formed via gravitational instability. We do not find evidence for clouds on CD-35 2722 B despite it being a photometrically red mid-L dwarf and thus expected to be quite cloudy. We retrieve a temperature structure that is more isothermal than models and investigate its impact on our measurements, finding that constraining the temperature structure to self-consistent models does not significantly impact our retrieved chemical properties. Our observations highlight the need for data from complementary wavelength ranges to verify the presence of aerosols in likely cloudy L dwarfs.

Keywords: High resolution spectroscopy, Atmospheric composition, Brown dwarfs, L dwarfs
Multispecies Ion Acceleration in the Interaction of Multiple Reconnection Current Sheets. Magnetic reconnection is an important origin of high-energy multispecies ions in the heliosphere, and the interaction of multiple current sheets in reconnection around the kinetic scale is inevitable because of magnetic convection and braiding. Here, we perform hybrid particle-in-cell simulations with kinetic ions and fluid electrons to study the multispecies ion acceleration in this multiple current sheet interaction process. We show that the interaction between multiple current sheets can spontaneously drive turbulence, inducing a power law of −7/3 for the magnetic energy spectrum. We find that both the early reconnection stage and the subsequent turbulence stage can efficiently accelerate ions, with the maximum energy per nucleon species independently increasing as  ∊max∝tγ , and we have also reproduced the observed power-law  ∊max∝(Q/M)α , where Q and M are, respectively, the ion charge and mass. Comparing the two stages, we find that the acceleration efficiency in the turbulence stage is higher, with index γ being approximately twice that of the reconnection stage and index α being smaller, indicating that the turbulence can more efficiently accelerate heavier ions with smaller Q/M, and these characteristics are not sensitive to plasma β. We demonstrate that the underlying physics is that the magnetic structure in the turbulence stage has a statistically larger curvature, thereby enhancing the dominant Fermi acceleration. Our results highlight the crucial role of multiple current sheet interactions and the resulting turbulence in multispecies ion acceleration, and will have multiple potential implications on the origin of energetic ions observed in the heliosphere.

Keywords: Solar magnetic reconnection, Interplanetary turbulence, Solar energetic particles, Interplanetary particle acceleration, Magnetic fields
Can Instrumental Effects Obscure the True Photospheric Wave Spectrum?. Optical aberrations and instrument resolution can affect the observed morphological properties of features in the solar atmosphere. However, little work has been done to study the effects of spatial resolution on the dynamical processes occurring in the Sun's atmosphere. In this work, owing to the availability of high-resolution observations of a magnetic pore captured with the Interferometric BIdimensional Spectrometer mounted at the Dunn Solar Telescope, we studied the impact of the diffraction limit and the sampling of an instrument on line-of-sight Doppler velocity oscillations. We reported a noticeable shift in the dominant frequency band from 5 to 3 mHz, as both the angular and detector resolutions of the instruments were degraded. We argue that the observed behavior is a result of the increased contamination of straylight from neighboring quiet Sun regions, masking the true behavior of umbral oscillations. These results suggest that the wave energy contributions reported in the literature and based on low-resolution instrumentation may be fundamentally underestimated. As we move into the era of high-resolution instrumentation such as DKIST and MUSE, this paper will offer a critical baseline for interpreting new observations, especially in terms of distinguishing true dynamic behaviors from artifacts introduced by instrument-related limitations.

Keywords: Solar oscillations, Solar photosphere, Solar magnetic fields
Observations of Electrostatic Solitary Waves in the Martian Magnetic Reconnection Exhaust Region. This study reports for the first time the occurrence of electrostatic solitary waves during a reconnection exhaust event observed by NASA's Mars Atmosphere and Volatile Evolution mission on 2015 February 9 in the dayside Martian magnetosheath region. A total of seven burst events were analyzed, showing that the peak amplitudes of most solitary structures lie in the range of 1─4 mV m−1, with pulse durations between 0.3 and 0.7 ms. The generation mechanism of these nonlinear waves is modeled by treating the reconnection exhaust region as an unmagnetized, multicomponent plasma composed of fluid H+, O+,  O2+ , and  CO2+  ions along with background superthermal electrons. The Sagdeev pseudopotential technique is used to analyze solitary waves with arbitrary amplitude. The theoretical model predicts positive potential ion acoustic solitons having bipolar electric fields with amplitudes of (1.4─3.4) mV m−1 and having pulse durations of (0.3─0.5) ms, which are in good agreement with the observed values in the reconnection exhaust region.

Keywords: Planetary magnetospheres, Mars, Solar wind
Double to Tenfold M-shell Photoionization of Singly Charged Lanthanum Ions. Using the photon-ion merged-beams technique at the PETRA III synchrotron light source, we have measured cross sections for double and up to tenfold photoionization of La+ ions by a single photon in the energy range 820─1400 eV, where resonances and thresholds occur that are associated with the excitation or ionization of one M-shell electron. These cross sections represent experimental benchmark data for the further development of quantum theoretical methods, which will have to provide the bulk of the atomic data required for the modeling of nonequilibrium plasmas such as kilonovae. In the present work, we have upgraded the Jena Atomic Calculator and pushed the state-of-the-art of quantum calculations for heavy many-electron systems to new limits. In particular, we have performed large-scale calculations of the La+ photoabsorption cross section and of the deexcitation cascades, which set in after the initial creation of a 3d hole. Our theoretical results largely agree with our experimental findings. However, our theoretical product-ion charge-state distributions are somewhat narrower than the experimental ones, which is most probably due to the simplifications necessary to keep the cascade calculations tractable.

Keywords: Laboratory astrophysics
Physical Conditions for Synthesis of Sc, Ti, and V in Neutrino-driven Supernovae. We present the results of simulations of nucleosynthesis in a core-collapse supernova including the neutrino process. Using the Si layer of a 13M⊙ zero-metal progenitor as the initial composition, we calculate the nucleosynthesis by adopting the temperature, density, neutrino flux, and duration of nucleosynthesis as arbitrary parameters and compare the results with the observed abundance ratios of Sc, Ti, and V in very-metal-poor (VMP) stars taken from the Stellar Abundances for Galactic Archaeology database. As a result, for the first time, we identify the quantitative requirements on local physical conditions. To reproduce the abundance ratios in the VMP stars, the explosive nucleosynthesis should take place under the neutrino exposure, which is the time integration of the neutrino flux, of σν ∼ 1035 erg cm−2 and temperature of 2.0 GK ≤ T ≤ 3.2 GK. The dependence on the density and each value of the neutrino flux and the duration of nucleosynthesis is weak. We also discuss whether the quantitative requirements are realized during the explosion. Although the requirements are difficult to realize in the one-dimensional simulations, the nonmonotonic thermal evolution shown in recent three-dimensional simulations may satisfy them. Because the evolution is likely caused by turbulent motion stemming from the initial asphericity of the progenitor, it is important to calculate the long-term three-dimensional supernova explosion of multidimensional metal-free progenitor models and follow the nucleosynthesis self-consistently.

Keywords: Explosive nucleosynthesis, Core-collapse supernovae, Nucleosynthesis, Stellar abundances, Supernova dynamics