Sazuna/UAT_keywords huggingface dataset:
Reconciling the Tension between Light-curve Modeling of Type II Supernovae and Neutrino-driven Core-collapse Supernovae Models with Late-phase Spectroscopy. Type II supernovae (SNe II) are the most frequently observed outcome of core-collapse explosions and provide a valuable window into the physical mechanisms governing the deaths of massive stars. However, estimates of explosion properties based on optical light-curve modeling often show tension with the predictions of modern neutrino-driven explosion models. In particular, when based on light curves from the explosions of red supergiants (RSGs) tied to specific stellar wind models, many SNe II are found to originate from low-mass progenitors yet exhibit unusually high explosion energies (EK), far exceeding theoretical predictions. In this study, we incorporate late-phase (nebular) spectroscopy to estimate the helium core mass of the progenitor ( MHecore ), which serves as an additional constraint to break degeneracies in light-curve modeling. This approach is applied to a sample of 32 well-observed SNe II, using a light-curve model grid constructed from RSGs with arbitrarily stripped hydrogen-rich envelopes, rather than assuming a fixed wind model. Examining the resulting correlations among the physical parameters, we find that the tension between the observed  MHecore ─EK and EK─MNi relations and those predicted by neutrino-driven explosion models has significantly lessened by incorporating nebular spectroscopy in light-curve modeling. This study highlights the crucial role of nebular spectroscopy in interpreting SNe II observations and provides support to the neutrino-driven explosion mechanism as the dominant engine powering these events.

Keywords: Type II supernovae, Explosive nucleosynthesis, Core-collapse supernovae
Luminosity Distance Dispersion in Swiss-cheese Cosmology as a Function of the Hole Size Distribution. The luminosity distance─redshift (DL─z) relation derived from Type Ia supernovae (SNe Ia) yields evidence for a nonzero cosmological constant. SNe Ia analyses typically fit to the functional form DL(z) derived theoretically from the homogeneous and isotropic Friedmann─Lemaitre─Robertson─Walker (FLRW) metric. Yet, the metric in the epoch relevant to SNe Ia measurements deviates slightly from FLRW, due to gravitational clumping of mass into large-scale structures like filaments and voids, whose sizes span many orders of magnitude. The small deviation is modeled typically by scalar perturbations to the FLRW metric. Each line of sight to a SNe Ia passes through a random sequence of structures, so DL differs stochastically from one line of sight to the next. Here, we calculate the DL dispersion in an exact Lemaitre─Tolman─Bondi Swiss-cheese universe with a power-law hole size distribution, as a function of the lower cutoff  Rmin  and logarithmic slope γ. We find that the standard deviation of DL scales as  σDL∝z2.25±0.01(Rmin/24±1Mpc)(0.157±0.003)γ−(1.16±0.02)  for redshifts in the range 0.5 ≲ z ≲ 2.1. The scaling shows that the DL dispersion is dominated by a few large voids rather than the many small voids.

Keywords: Gravitation, Spacetime metric, Large-scale structure of the universe
Exploring the Signature of Assembly Bias and Modified Gravity Using Small-scale Clusterings of Galaxies. We apply a halo velocity bias model, γf, within the Aemulus simulation suite for General Relativity to investigate its efficacy in identifying the signature of assembly bias and Modified Gravity (MG). In the investigation of assembly bias, utilizing galaxy clustering data ranging from scales of 0.1 ∼ 60h−1 Mpc, we discover that our emulator model accurately recreates the cosmological parameters, Ωm and σ8, along with the velocity bias γf, staying well within the 1σ error margins, provided that assembly bias is considered. Ignoring assembly bias can considerably alter our model constraints on parameters Ωm and σ8 if the test sample includes assembly bias. Using our emulator for MG simulations, which encompasses two Dvali─Gabadadze─Porrati models (DGP; N1, N5) and two f(R) models (F4, F6), we can effectively identify a robust signature of modified gravity, for models such as DGP-N1 and f(R)-F4, as indicated by a noticeable deviation of γf from unity. Using the velocity of dark matter halos to effectively represent the underlying strength of the velocity field of these MG simulations, we find that the simple γf model can recover the truth with minimal bias. These evaluations indicate that our simple halo-velocity bias model is capable of detecting significant MG characteristics, although additional methodologies should be pursued to improve model constraints.

Keywords: Cosmology, Large-scale structure of the universe
Four Elements to Rule Them All: Abundances Are Rigidly Coupled in the Milky Way Disk. Chemical tagging is a central pursuit of galactic archaeology, but requires sufficiently discriminative abundances to uniquely identify sites of star formation. This task is complicated by intrinsic scatter among conatal stars, interelement correlations, imprecise abundance measurements, and systematics across stellar evolutionary states. In this work, we formalize the abundance correlation structure of the Milky Way disk by quantifying the information available in individual element abundances once a subset is known, and map interelement residual correlations to uncover hidden signatures of nucleosynthesis. We use two data sets of 79 (593) stars across −0.15 &lt; [Fe/H] &lt; 0.13 (−1 &lt; [Fe/H] &lt; 0.41) with measurements of 30 (19) element abundances of solar neighborhood stars, including 11 (7) light and α elements, 7 (3) Fe-peak elements, and 12 (9) neutron-capture elements. With a simple linear regression model, we predict most α and Fe-peak element abundances within 0.03 dex (∼7%), and neutron-capture elements within 0.05 dex (∼10%). Including first- and second-peak s-process elements as predictors improves most neutron-capture element predictions to within 0.02 dex (5%), although no predictive power is gained by including an r-process element. We uncover strong (anti-)correlations in small residual abundances between and within element families. Our finding that the disk abundance space is rigidly coupled, from light to heavy elements, implies chemical tagging is infeasible at &gt;2% precision for ∼30 elements. However, the residual structure encodes fingerprints of star formation history, inherited from nucleosynthesis and environmental variations, and provides critical constraints for chemical evolution models. Future disk surveys must achieve sub-2%─5% precision in 30+ elements to access this independent information.

Keywords: Stellar abundances, Solar neighborhood, Chemical abundances, Milky Way disk, S-process, Dimensionality reduction
On the Origin of Abundance Variations in the Milky Way's High-α Plateau. Using multielement abundances from the Sloan Digital Sky Survey APOGEE survey, we investigate the origin of abundance variations in Milky Way (MW) disk stars on the "high-α plateau," with −0.5 ≤ [Mg/H] ≤ −0.1 and 0.25 ≤ [Mg/Fe] ≤ 0.35. The elevated [α/Fe] ratios of these stars imply low enrichment contributions from Type Ia supernovae (SN Ia), but it is unclear whether their abundance patterns reflect pure core-collapse supernova (CCSN) enrichment. We find that plateau stars with higher [Fe/Mg] ratios also have higher [X/Mg] ratios for other iron-peak elements, suggesting that the [Fe/Mg] variations in the plateau population do reflect variations in the SN Ia/CCSN ratio. To quantify this finding, we fit the observed abundance patterns with a two-process model, calibrated on the full MW disk, which represents each star's abundances as the sum of a prompt CCSN process with amplitude Acc and a delayed SN Ia process with amplitude AIa. This model is generally successful at explaining the observed trends of [X/Mg] with AIa/Acc, which are steeper for elements with a large SN Ia contribution (e.g., Cr, Ni, Mn) and flatter for elements with low SN Ia contribution (e.g., O, Si, Ca). Our analysis does not determine the value of [Mg/Fe] corresponding to pure CCSN enrichment, but it should be at least as high as the upper edge of the plateau at [Mg/Fe] ≍ 0.35, and could be significantly higher. Compared to the two-process predictions, the observed trends of [X/Mg] with AIa/Acc are steeper for (C+N) but shallower for Ce, providing intriguing but contradictory clues about asymptotic giant branch enrichment in the early disk.

Keywords: Chemical enrichment, Milky Way disk, Chemical abundances, Galaxy chemical evolution
Establishing a Connection between the Jet and the Corona in Black Hole Low-mass X-Ray Binaries. Black hole low-mass X-ray binaries (LMXBs) undergo outbursts, during which their brightness increases greatly for timescales of months. The X-ray accretion and radio jet properties change dramatically throughout an outburst in a broadly consistent way between sources. Changes to the accretion flow and the corona are evident through X-ray spectral variations, while the jet's evolution produces changes in the radio. Typically, high-energy emission from the corona initially dominates the X-ray spectrum, and quasi-steady compact jets are observed in the radio. As the outburst progresses, emission from the corona fades and is superseded by lower-energy X-ray accretion disk emission. During this transition, the compact jets are quenched and discrete ejecta, called transient jets, are launched. The concurrence of the corona's weakening and the jet's transition from compact to transient implies a connection, but the precise relationship has not been established. Motivated by this, we aim to investigate the corona─jet connection. We perform spectral modeling in the hard and soft X-ray, utilizing NuSTAR, NICER, and Swift X-Ray Telescope observations to track the evolving X-ray corona for three LMXBs: MAXI J1348−630, MAXI J1535−571, and MAXI J1820+070. We use prior work to mark the presence of compact jets and the dates of discrete jet ejections. We find a clear connection between the evolution of the corona and the jet: across all three sources an increase in the distance of the corona from the black hole occurs near the time that the compact jet is quenched, and the transient jet is launched.

Keywords: X-ray transient sources, High energy astrophysics
Heavy Element Nucleosynthesis in Rotating Protomagnetar Winds. The astrophysical origin of elements synthesized through the rapid neutron capture process (r-process) is a long-standing mystery. The hot and dense environments of core-collapse supernovae have been suggested as potential r-process sites, particularly the neutrino-driven wind from the newly born protoneutron star (PNS). Wind models that neglect the potential effects of strong magnetic fields and/or rapid rotation of the PNS typically fail to achieve the necessary conditions for production of the third r-process peak, but robustly produce a limited or weak r-process for neutron-rich winds. Axisymmetric magnetohydrodynamic simulations of rotating and nonrotating PNS winds with magnetar-strength fields reveal that high entropy material is quasiperiodically ejected from the equatorial closed zone of the PNS magnetosphere. Here, we postprocess tracer particle trajectories from these simulations using a nuclear reaction network in order to explore the resulting nucleosynthesis across a range of PNS magnetic field strengths, rotation rates, and neutrino luminosities (cooling phase after core-bounce). We find that a robust r-process up to and beyond the third peak is generic to magnetar birth, even for magnetic fields as weak as ∼5 × 1014 G. Depending on the distribution of magnetic field strengths and rotation at birth, we estimate that magnetized PNS winds could account for ∼5%─100% of the Galactic r-process inventory, extending up to the third peak. The robust r-process in our calculations is accompanied by overproduction of elements with mass number A ≲ 120 compared to the solar abundances. We also find that 92Mo (a p-isotope) is produced in significant quantities in neutron-rich winds.

Keywords: Neutron stars, Nucleosynthesis, R-process, Magnetars, Supernovae
Imprints of Stellar Feedback on Magnetic Fields in the Iris Nebula NGC 7023. We present 850 μm polarized continuum observations carried out using SCUBA-2/POL-2 on the James Clerk Maxwell Telescope toward a reflection nebula, NGC 7023. The nebula is powered by the Herbig Ae Be star HD 200775 and also forms a hub in the hub-filament cloud, LDN 1172/1174. We detect submillimeter emission to the north and east of the location of the central star. The magnetic field (B-field) morphology is found to be curved and follows the clump morphology. The comparison of the B-field morphology at the clump scales (∼0.02 pc) derived using POL-2 data with that of the envelope scale (∼0.5 pc) derived using archival Planck/optical polarimetric observations suggests that the field lines are not preserved from envelope to clump scales. We suggest that this reordering of the magnetic field lines could be due to the interaction with the already evolved high-velocity outflow gas around the central star, which hints at the presence of outflow feedback. We estimated a B-field strength of 179 ± 50 μG in the starless core, and 121 ± 34 μG and 150 ± 42 μG in the protostellar cores, using the N2H+ (1─0) line observed with the 13.7 m single-dish telescope at the Taeduk Radio Astronomy Observatory (TRAO). The stability analysis gives magnetically subcritical values, while the magnetic, gravitational, and outflow kinetic energies are roughly balanced. Our study unveils the first possible evidence for magnetic field lines being shaped by outflow feedback in the vicinity of a photodissociation region driven by an intermediate-mass, pre-main-sequence star.

Keywords: Stellar feedback, Molecular clouds, Interstellar magnetic fields, Star formation, Polarimetry
Witnessing the Violent, Merger-driven Formation of an Extremely Massive Galaxy 1.7 Gyr after the Big Bang. We combine near-infrared imaging in two bands from the Hubble Space Telescope with archival observations of molecular gas to study SDSS J160705.16+533558.6 (J1607), an extremely luminous broad-line quasar at z = 3.65 that is also bright in the submillimeter. Via subtraction of the quasar point-spread function, we show that its host galaxy is massive, with a stellar mass of (5.8 ± 3.0) × 1011 M⊙, making it comparable to giant early-type galaxies (ETGs) at z ∼ 0. If the supermassive black hole in the quasar is accreting at the Eddington limit, then its mass is 3.5 × 109 M⊙, which is also consistent with local massive ETGs. The host has an extremely high star formation rate of 4300 ± 500 M⊙ yr−1 and a molecular gas mass of (2.4 ± 0.9) × 1010 M⊙. The quasar has two companions: one at a projected separation of 11 kpc with a stellar mass of (7.9 ± 5.0) × 1010 M⊙ but no detected molecular gas and one 6 kpc further away in the same direction with a molecular gas mass of (2.6 ± 1.3) × 1010 M⊙ but no detected stellar emission. Since neither companion shows evidence for active galactic nucleus activity, this may represent merger-driven quenching, in which the dynamics of the merger strip molecular gas from infalling galaxies. Overall, irrespective of whether the host is merging with the companions, these properties mark J1607 as forming what will become an extremely massive (∼1012 M⊙) galaxy by z = 0.

Keywords: Active galaxies, High-redshift galaxies, Quasars
Be Star Demographics: A Comprehensive Study of Thousands of Light Curves in the Magellanic Clouds. Multicolor OGLE survey light curves of about 20 yr duration are analyzed for about 3000 classical Be stars in the Large and Small Magellanic Clouds (LMC, SMC) in order to study their properties and variability. Each light curve was manually analyzed to distinguish between different scenarios, such as photospheric baseline levels and disk buildup and dissipation phases. This analysis was aided by dynamical disk models and photospheric models to coarsely determine the inclination angle and mass. Measured quantities such as the fraction of time spent actively ejecting mass (the duty cycle (DC)), the fraction of time spent with a detectable disk (the disk duty cycle (DDC)), the buildup and dissipation time of isolated disk events, and the number of mass outbursts per year allow us to characterize and compare the behavior of the two populations. There is a wide spread in the DC, with median values of 0.44 (LMC) and 0.60 (SMC). The DDC is high for both populations, with median values of 0.99 (LMC) and 1.0 (SMC), indicating that disks are almost always present for these stars. The occurrence rate of outbursts ranges from zero to about two per year, with median values of 0.31 (LMC) and 0.26 (SMC). There are strong statistical differences in the behavior of the LMC and SMC populations, with the lower metallicity stars being more active in terms of their DC and DDC, and with less frequent but longer-lasting outbursts.

Keywords: Emission line stars, Surveys, Stellar mass loss, Circumstellar matter, Photometry, Be stars, Magellanic Clouds
New Criterion for Fluid Model Applicability in Space Plasmas. Fluid models, in theory, should not be applied to describe space plasmas because there are insufficient particle─particle collisions in those thin media to transfer momentum between adjacent plasma parcels. However, in practice, fluid description often works well: countless studies successfully employ magnetohydrodynamics and other fluid models to describe space plasma phenomena. We resolve this controversy by demonstrating that in magnetized plasmas, particle─field interactions can effectively substitute for collisions in keeping the velocity distribution compatible with the fluid picture. Careful investigation of the specifics of the local momentum and energy transfer mechanism led to the introduction of a new criterion for determining when fluid models can be applied to magnetized collisionless plasma, moving beyond the traditional criteria based on collision frequency and the Knudsen number. According to the new criterion, fluid description can be applied to a significantly wider range of astrophysical plasmas than previously thought.

Keywords: Space plasmas, Magnetohydrodynamics, Solar wind
The b<SUP>3</SUP>Π─a<SUP>3</SUP>∆ and b<SUP>3</SUP>Π─X<SUP>1</SUP>Σ<SUP>+</SUP> Band Systems of ZrO. The zirconium oxide (ZrO) b3Π─a3∆ system is a prominent source of opacity in the atmospheres of S-type stars in the near-infrared region. The emission spectra of ZrO, obtained at the National Solar Observatory located at Kitt Peak in Arizona, have been utilized to analyze this band system. A reanalysis of the 0─0 vibrational band of the b3Π─a3∆ transition has been carried out. For the first time, the vibrational bands with  1≤v'≤3  and v″ ≤ 4 for the same electronic transition have been rotationally analyzed using PGOPHER. Additionally, the 0─0 and 1─1 bands of the spin-forbidden triplet─singlet transition (b3Π─X1Σ+) have also been identified and fitted. This new analysis revealed that the "e" parity levels are higher in energy than the "f" parity levels of the b3Π state, in contrast to previous reports. Furthermore, this study allowed for the precise determination of T0 for the a3∆ state, which is found to be 1383.49144(98) cm−1. The observed R-heads for the ∆v = 0, ±1 vibrational bands have been reported. Spectroscopic constants for the b3Π state for v '≤3  have been determined and utilized to derive equilibrium constants. These parameters, in conjunction with ab initio calculations of the transition dipole moment function, have been used to compute band strengths. Furthermore, a line list consisting of line positions, Einstein A values, and oscillator strengths has been generated, which can be used for the spectral modeling of S-type stars.

Keywords: Spectral line lists, Line positions, Rotational spectroscopy, Molecular spectroscopy, S stars, Line intensities
The End of the Road for Far-infrared Reddening Maps? Evidence for Reddening Errors Driven by Changes in Polycyclic Aromatic Hydrocarbon Abundance. Accurate correction for extinction by Galactic dust is essential for studying the extragalactic sky. In the low-extinction regions of the Ursa Major molecular cloud complex, we demonstrate that Galactic dust reddening maps constructed from observations of far-infrared emission are insensitive to variations in the abundance of polycyclic aromatic hydrocarbons (PAHs), and, as a result, to PAH-induced variations in reddening. Using galaxy counts to validate various reddening maps, we find evidence that maps based on far-infrared emission erroneously underpredict reddening at optical wavelengths compared to stellar reddening maps. This underestimation by far-infrared emission-based reddening maps—representing the largest discrepancy between maps of up to E(B − V) = 0.08 mag—is correlated with the relative brightness of PAH emission. Furthermore, we demonstrate theoretically that changes in PAH abundance via accretion from the gas phase is capable of altering extinction significantly with only minor changes to far-infrared emission. We show that modeling the extinction of Ursa Major using both far-infrared and mid-infrared emission more accurately traces dust extinction variations due to changes in PAH abundance. Finally, we discuss how SPHEREx observations of the 3.3 μm PAH feature are a promising way to overcome this limitation of far-infrared emission.

Keywords: Interstellar dust, Polycyclic aromatic hydrocarbons, Interstellar dust extinction
On the Sensitivity of Different Galaxy Properties to Warm Dark Matter. We study the impact of warm dark matter (WDM) particle mass on galaxy properties using 1024 state-of-the-art cosmological hydrodynamical simulations from the DREAMS project. We begin by using a multilayer perceptron (MLP) coupled with a normalizing flow to explore global statistical descriptors of galaxy populations, such as the mean, standard deviation, and histograms of 14 galaxy properties. We find that subhalo gas mass is the most informative feature for constraining the WDM mass, achieving a determination coefficient of R2 = 0.9. We employ symbolic regression to extract simple, interpretable relations with the WDM particle mass. Finally, we adopt a more localized approach by selecting individual dark matter halos and using a graph neural network (GNN) with a normalizing flow to infer the WDM mass, incorporating subhalo properties as node features and global simulation statistics as graph-level features. The GNN approach yields only a residual improvement over MLP models based solely on global features, indicating that most of the predictive power resides in the global descriptors, with only marginal gains from halo-level information.

Keywords: Warm dark matter, Hydrodynamical simulations, Galaxy dark matter halos