Sazuna/UAT_keywords huggingface dataset:
Precise Measurement of the Cosmic-Ray Spectrum and &lt;ln A&gt; by LHAASO: Connecting the Galactic to the Extragalactic Components. Recently, the LHAASO Collaboration has provided precise measurements of the cosmic rays (CRs) all-particle energy spectrum and mean logarithmic mass   from 0.3 to 30 PeV. Combining the CR measurements by AMS-02 and DAMPE in space and those by LHAASO and Auger on the ground, we construct a model to recover all these measurements from tens of GeV to tens of EeV. We find that the LHAASO measurement is crucial in the model construction by connecting the Galactic component to the extragalactic component. The precise measurements of CR spectra for individual species by AMS-02 and DAMPE together with the newest LHAASO results clearly indicate three Galactic CR components, that is, a soft low-energy background, a hard high-energy component, and a local source contribution. However, the LHAASO data show that above ∼1016 eV, a nonnegligible extra component, possibly of extragalactic origin, must be included. Combining the Auger results and the LHAASO results, we figure out the extragalactic CRs that need at least two components at lower and higher energies. Thanks to the measurements by LHAASO, the constraints on the model parameters are quite stringent. The spectrum features and mass measurements in all energy ranges are all well reproduced in the model.

Keywords: Ultra-high-energy cosmic radiation, Galactic cosmic rays, Cosmic ray sources, Particle astrophysics, Cosmic rays
Quasi-parallel Antisunward-propagating Whistler Waves Associated with the Electron Deficit in the Near-Sun Solar Wind: Particle-in-cell Simulation. In situ observations of the solar wind have shown that the electron velocity distribution function (VDF) consists of a quasi-Maxwellian core, comprising most of the electron population, and two sparser components: the halo, which are suprathermal and quasi-isotropic electrons, and an escaping beam population, the strahl. Recent Parker Solar Probe (PSP) and Solar Orbiter (SO) observations have added one more ingredient to the known nonthermal features, the deficit—a depletion in the sunward region of the VDF, already predicted by exospheric models but never so extensively observed. By employing particle-in-cell simulations, we study electron VDFs that reproduce those typically observed in the inner heliosphere and investigate whether the electron deficit may contribute to the onset of kinetic instabilities. Previous studies and in situ observations show that strahl electrons drive oblique whistler waves unstable, which in turn scatters them. As a result, suprathermal electrons can occupy regions of phase space where they fulfill resonance conditions with the parallel-propagating whistler wave. The suprathermal electrons lose kinetic energy, resulting in the generation of unstable waves. The sunward side of the VDF, initially depleted of electrons, is gradually filled, as this wave‑particle interaction process, triggered by the depletion itself, takes place. Our findings are compared and validated against current PSP and SO observations: among others, our study provides a mechanism explaining the presence in the heliosphere of regularly observed parallel antisunward whistler waves, suggests why these waves are frequently observed concomitant with distributions presenting an electron deficit, and describes a noncollisional heat flux regulating process.

Keywords: Space plasmas, Solar wind, Plasma astrophysics
Unveiling the Emission Mechanisms of Blazar PKS 1510−089. II. Jet−BLR Connection and Black Hole Mass Estimation. The flat spectrum radio quasar PKS 1510−089 is one of the most active blazars across the entire electromagnetic spectrum, displaying periods of flaring activity. This study explores its spectral variability over a decade. By employing the nonthermal dominance parameter, we analyze the Hβ and λ5100 continuum light curves, as well as the FWHM of the Hβ emission line, to identify whether the primary source of the continuum emission is the accretion disk or the jet during activity periods. Our results show an anticorrelation between the FWHM and the luminosity of the Hβ emission line across all data sets. This indicates that variations in Hβ luminosity consistently reflect the canonical broad-line region (BLR), irrespective of whether the primary ionizing source is the accretion disk or the jet. The anticorrelation persisted when comparing the FWHM of Hβ against the luminosity at λ5100 in the disk dominance regime. These findings, along with the observation that flaring events in the λ5100 continuum, attributed to the jet, coincide with flares in the Hβ emission line, suggest that the base of the jet is located within the BLR. Based on the 219 spectra within the disk dominance regime, we estimated a mean black hole mass of MBH = 2.85 ± 0.37 × 108M⊙.

Keywords: Supermassive black holes, Flat-spectrum radio quasars, Galaxy jets, Emission line galaxies, Active galactic nuclei
The Arizona Molecular ISM Survey with the SMT: Variations in the CO(2–1)/CO(1–0) Line Ratio across the Galaxy Population. The J = 1 → 0 spectral line of carbon monoxide (CO(1–0)) is the canonical tracer of molecular gas. However, CO(2–1) is frequently used in its place, following the assumption that the higher-energy line can be used to infer the CO(1–0) luminosity and molecular gas mass. The use of CO(2–1) depends on a knowledge of the ratio between CO(2–1) and CO(1–0) luminosities, r21. Here, we present galaxy-integrated r21 measurements for 122 galaxies spanning stellar masses from 109 to 1011.5 M⊙ and star formation rates (SFRs) from 0.08 to 35 M⊙ yr‑1. We find strong trends between r21 and SFR, SFR surface density, star formation efficiency, and distance from the star formation main sequence (SFMS). We show that the assumption of a constant r21 can introduce biases into the molecular gas trends in galaxy population studies and demonstrate how this affects the recovery of important galaxy scaling relations, including the Kennicutt–Schmidt law and the relation between SFMS offset and star formation efficiency. We provide a prescription that accounts for variations in r21 as a function of SFR and can be used to convert between CO(2–1) and CO(1–0) when only one line is available. Our prescription matches variations in r21 for both AMISS and literature samples and can be used to derive more accurate gas masses from CO(2–1) observations.

Keywords: Molecular gas, Surveys, Millimeter astronomy, Molecular clouds, Interstellar medium, Redshift surveys
SCUBADive. I. JWST+ALMA Analysis of 289 Submillimeter Galaxies in COSMOS-web. JWST has enabled detecting and spatially resolving the heavily dust-attenuated stellar populations of submillimeter galaxies, revealing detail that was previously inaccessible. In this work, we construct a sample of 289 submillimeter galaxies with joint Atacama Large Millimeter/submillimeter Array (ALMA) and JWST constraints in the COSMOS field. Sources are originally selected using the SCUBA-2 instrument and have archival ALMA observations from various programs. Their JWST NIRCam imaging is from COSMOS-Web and PRIMER. We extract multiwavelength photometry in a manner that leverages the unprecedented near-infrared (NIR) spatial resolution of JWST, and we fit the data with spectral energy distribution models to derive photometric redshifts, stellar masses, star formation rates, and optical attenuation. The sample has an average  ,  ,  , and  . There are 81 (30%) galaxies that have no previous optical/NIR detections, including 75% of the z &gt; 4 subsample (n = 28). The faintest observed NIR sources have the highest redshifts and largest AV = 4 ± 1. In a preliminary morphology analysis we find that ∼10% of the members of our sample exhibit spiral arms and 5% host stellar bars, with one candidate bar found at z &gt; 3. Finally, we find that the clustering of JWST sources within 10″ of a submillimeter galaxy is a factor of 2 greater than what is expected based on either random clustering or the distribution of sources around any red galaxy irrespective of a submillimeter detection.

Keywords: Observational astronomy, Submillimeter astronomy, High-redshift galaxies, Galaxy evolution
Force Analysis of Venus's Induced Magnetosphere: A Multifluid Hall–Magnetohydrodynamics Study. Understanding which processes control atmospheric escape and the loss of water from planetary environments is crucial. The ESA's Venus Express spacecraft has observed a significant depletion in Venus's upper atmosphere, driven by the solar wind. In such scenarios, the electromagnetic force can accelerate planetary ions to energies that allow them to escape from the planet. However, it is extremely challenging to directly measure electromagnetic forces on planetary ions. Here we present a 3D multifluid Hall–magnetohydrodynamics simulation model to investigate electromagnetic force terms and the effects of each term on solar wind plasma and planetary ions. We find that the total electromagnetic force reaches its peak near the bow shock and the magnetic pileup boundary, with obvious asymmetric characteristics, which slows down the solar wind plasma and compresses the heavy ions toward Venus. In addition, the morphology of the convection electric field force shows obvious north–south asymmetry, which leads to the formation of asymmetric structures and plasma flows in the Venusian magnetotail. The electromagnetic force patterns obtained by simulation are consistent with the results and speculation from observations, suggesting that the multifluid model developed here has substantial capacity in further analysis regarding planetary ion escape.

Keywords: Planetary magnetospheres, Plasma physics, Venus, Magnetohydrodynamical simulations
Phase-resolved Hubble Space Telescope WFC3 Spectroscopy of the Weakly Irradiated Brown Dwarf GD 1400 and Energy Redistribution–Irradiation Trends in Six White Dwarf–Brown Dwarf Binaries. Irradiated brown dwarfs offer a unique opportunity to bridge the gap between stellar and planetary atmospheres. We present high-quality Hubble Space Telescope/Wide Field Camera 3/G141 phase-resolved spectra of the white dwarf–brown dwarf binary GD 1400, covering more than one full rotation of the brown dwarf. Accounting for brightness variations caused by ZZ Ceti pulsations, we revealed weak (∼1%) phase-curve amplitude modulations originating from the brown dwarf. Subband light-curve exploration in various bands showed no significant wavelength dependence on amplitude or phase shift. Extracted day- and nightside spectra indicated chemically similar hemispheres, with slightly higher dayside temperatures, suggesting efficient heat redistribution or the dominance of radiative escape over atmospheric circulation. A simple radiative and energy redistribution model reproduced the observed temperatures well. Cloud-inclusive models fit the day and night spectra better than cloudless models, indicating global cloud coverage. We also begin qualitatively exploring atmospheric trends across six irradiated brown dwarfs, from the now complete "Dancing with the Dwarfs" white dwarf–brown dwarf sample. The trend we find in the dayside/nightside temperature and irradiation levels is consistent with efficient heat redistribution for irradiation levels less than ∼109 erg s‑1 cm‑2 and decreasing efficiency above that level.

Keywords: Close binary stars, Brown dwarfs, Substellar companion stars, Exoplanet atmospheres
Tearing-mediated Alfvénic Turbulence in a Relativistic Plasma. In astrophysical relativistic plasmas, Alfvénic turbulence exists across a wide range of scales. Similar to a nonrelativistic case, this turbulence can be influenced by the tearing instability. We argue that in an ultrarelativistic pair plasma the tearing effects become significant at the critical scale given by  , where L⊥ represents the outer scale of the turbulence and drel the relativistic electron inertial scale. Here n = 1 corresponds to the Harris magnetic configurations, while n = 2 applies to localized (non-Harris) magnetic profiles of turbulence-generated current sheets. Below the critical scale, the energy spectrum of magnetic fluctuations steepens to W(k)dk ∝ k‑(7n+2)/3ndk. However, this happens only when  , where   is the magnetization parameter based on the magnetic fluctuations. If the opposite inequality holds, the Alfvénic cascade is instead affected by charge starvation at scales below  , and the energy spectrum becomes steeper than W(k)dk ∝ k‑3dk. When drel is replaced by its nonrelativistic equivalent, our results agree with the nonrelativistic analysis of N. F. Loureiro &amp; S. Boldyrev (2018). In the Harris case n = 1, they agree with the recent relativistic studies by I. Demidov &amp; Y. Lyubarsky.

Keywords: Plasma astrophysics, Magnetic fields
Global and Local Infall in the ASHES Sample (GLASHES). I. Pilot Study in G337.541. Recent high-angular-resolution observations indicate the need for core growth to form high-mass stars. To understand the gas dynamics at the core scale in the very early evolutionary stages before being severely affected by feedback, we have conducted Atacama Large Millimeter/submillimeter Array (ALMA) observations toward a 70 μm dark massive clump, G337.541-00.082 as part of the Global and Local infall in the ASHES sample (GLASHES) program. Using dense gas tracers such as N2H+ (J = 1─0) and HNC (J = 3─2), we find signs of infall from the position─velocity diagram and more directly from the blue asymmetry profile in addition to the clump-scale velocity gradient. We estimate infall velocities from intermediate and low-mass cores to be 0.28─1.45 km s−1, and infall rates to be on the order of 10−4─10−3 M⊙ yr−1, both are higher than those measured in low-mass star-forming regions by more than a factor of 5 and an order of magnitude, respectively. We find a strong correlation between the infall velocity with the nonthermal velocity dispersion, suggesting that infall may contribute significantly to the observed line width. Consistent with clump-fed scenarios, we show that the mass infall rate is larger for larger core masses and shorter distances to the clump center. Such high infall rates in cores embedded in IRDCs can be considered as strong signs of core growth, allowing high-mass star formation from intermediate-mass cores that would not initially form high-mass stars at their current mass.

Keywords: Star forming regions, Star formation, Infrared dark clouds
Obliquity Dependence of Ocean Productivity and Atmospheric CO<SUB>2</SUB> on Earth-like Worlds. Obliquity can shape the habitability of a planet by changing the seasonal availability of incident solar radiation. Changes in incident radiation can lead to changes in the availability of light, temperature, ocean circulation, stratification, and corresponding nutrient availability, all of which are important in determining ocean net primary productivity (NPP). Moreover, a fraction of the carbon assimilated by phytoplankton is sequestered in the deep ocean. Therefore, changes in productivity can alter the distribution of CO2 between the ocean and atmosphere. In this study, we investigate the effects of obliquity on ocean NPP and the atmospheric CO2 concentration using ROCKE-3D fully coupled to the NASA GISS Ocean Biogeochemistry Model. We find sea surface temperature primarily controls the NPP response, with both properties reaching a maximum at an obliquity of 45°. We find that the response of the seasonal amplitude of NPP to obliquity is controlled primarily by photosynthetically available radiation and secondarily by changes in nutrient availability. We also find that atmospheric CO2 increases in response to obliquity, with a minimum at 15° and a maximum at 60°. The obliquity-driven CO2 changes are controlled primarily by temperature-driven solubility changes, with circulation and biology either enhancing solubility-driven changes at low obliquities or acting against and partially offsetting solubility-driven changes at higher obliquities. The magnitude of obliquity-driven changes is likely too small to be detectable, though future studies are needed to determine whether changing obliquity simultaneously with other orbital parameters can lead to larger, potentially detectable changes in NPP and CO2.

Keywords: Ocean-atmosphere interactions, Biosignatures, Carbon dioxide, Habitable planets
Reverberation Evidence for Stream Collision and Delayed Disk Formation in Tidal Disruption Events. When a star passes through the tidal disruption radius of a massive black hole (BH), it can be torn apart by the tidal force of the BH, known as the tidal disruption event (TDE). Since the observed UV/optical luminosity significantly exceeds the predictions of the compact disk model in classical TDE theory, two competing models, stream collision and envelope reprocessing, have been proposed to address this discrepancy. To distinguish between these models, we investigated the continuum reverberation behaviors for ~30 TDEs with high-quality multiband light curves. We found that over half of them exhibit a positive lag by a few days in UV/optical bands, indicating that their inferred sizes are significantly larger than the envelope sizes in reprocessing. Moreover, X-ray emissions are not only significantly delayed relative to the primary UV/optical peak but also lag behind the rebrightening bump by up to several tens of days, completely different from the X-ray illumination reprocessing. Additionally, the anticorrelated UV‑optical continuum in ASASSN-15lh further disfavors the reprocessing scenario. In contrast, the model of stream collisions, combined with delayed accretion disk formation, can provide a unified explanation for the diverse TDE observations, e.g., the optical/X-ray population and the frequently observed rebrightening bump. This model describes a unification scheme wherein the UV/optical emission originates from stream collisions during the early stage of TDE evolution and gradually transitions to being dominated by a accretion disk with detectable X-ray emission in the late stage. After transitioning to a quiescent state, recurrent flares may be observed in some cases, possibly related to repeating partial TDEs.

Keywords: Tidal disruption
The Coronal Power Spectrum from MHD Mode Conversion above Sunspots. Sunspots are intense regions of magnetic flux that are rooted deep below the photosphere. It is well established that sunspots host magnetohydrodynamic waves, with numerous observations showing a connection to the internal acoustic (or p-)modes of the Sun. The p-modes are fast waves below the equipartition layer and are thought to undergo a double mode conversion as they propagate upward into the atmosphere of sunspots, which can generate Alfvénic modes in the upper atmosphere. We employ 2.5D magnetohydrodynamic numerical simulations to investigate the adiabatic wave propagation and examine the resulting power spectra of coronal Alfvénic waves. A broadband wave source is used, which has a 1D power spectrum mimicking aspects of the observed p-mode power spectrum. We examine magnetoacoustic wave propagation and mode conversion from the photosphere to the corona. Frequency filtering of the upwardly propagating acoustic waves is a natural consequence of a gravitationally stratified atmosphere and plays a key role in shaping the power spectra of mode-converted waves. We demonstrate that the slow and fast magnetoacoustic waves and Alfvén waves above the equipartition layer have similarly shaped power spectra, which are modified versions of the driver spectrum. Notably, the results reveal that the coronal wave power spectra have a peak at a higher frequency than that of the underlying p-mode driver. This matches observations of coronal Alfvénic waves and further supports the role of the mode conversion process as a mechanism for Alfvénic wave generation in the Sun's atmosphere.

Keywords: Alfven waves, Sunspots, Solar coronal waves, Magnetohydrodynamical simulations
Black Hole Accretion and Spin-up through Stellar Collisions in Dense Star Clusters. Dynamical interactions in dense star clusters could significantly influence the properties of black holes, leaving imprints on their gravitational-wave signatures. While previous studies have mostly focused on repeated black hole mergers for spin and mass growth, this work examines the impact of physical collisions and close encounters between black holes and (noncompact) stars. Using Monte Carlo N-body models of dense star clusters, we find that a large fraction of black holes retained upon formation undergo collisions with stars. Within our explored cluster models, the proportion of binary black hole mergers affected by stellar collisions ranges from 10%–60%. If all stellar-mass black holes are initially nonspinning, we find that up to 40% of merging binary black holes may have components with dimensionless spin parameter χ ≳ 0.2 because of prior stellar collisions, while typically about 10% have spins near χ = 0.7 from prior black hole mergers. We demonstrate that young star clusters are especially important environments, as they can produce collisions of black holes with very massive stars, allowing for significant spin-up of the black holes through accretion. Our predictions for black hole spin distributions from these stellar collisions highlight their sensitivity to accretion efficiency, underscoring the need for detailed hydrodynamic calculations to better understand the accretion physics following these interactions.

Keywords: Accretion, Tidal disruption, Stellar mass black holes, N-body simulations
Exploring the Evolution of a Dwarf Spheroidal Galaxy with SPH Simulations. II. AGN Feedback. We investigate active galactic nucleus (AGN) feedback from an intermediate-mass black hole at the center of a dwarf spheroidal galaxy, by performing isolated galaxy simulations using a modified version of the GADGET-3 code. We consider Leo II (PGC 34176) in the Local Group as our simulation reference model. Beginning with black hole seeds ranging from 103‑106 M⊙, our simulations focus on comparing stellar/SN-only feedback with AGN+stellar/SN feedback over 13.7 Gyr of galactic evolution. Our results indicate that a low-mass AGN in a dwarf galaxy influences the star formation history under specific physical conditions. While AGN feedback is generally negative on star formation, instances of positive feedback were also identified. Despite measurable effects on the evolution of the dwarf host galaxy, black hole seeds exhibited only marginal growth. We tested several physical scenarios as modified models in our simulations, primarily concerning the dynamics of the central black holes, which may wander within dwarf galaxies rather than being centrally located. However, none of these adjustments significantly impacted the growth of the black hole seeds. This suggests that intermediate-mass black holes may struggle to achieve higher masses in isolated environments, with mergers and interactions likely playing crucial roles in their growth. Nevertheless, AGN feedback exhibited nonnegligible effects in our simulated dwarf spheroidal galaxies, despite the assumed dominant role of stellar feedback in the low-mass regime.

Keywords: Hydrodynamical simulations, Active galactic nuclei, Stellar feedback, Dwarf spheroidal galaxies