Sazuna/UAT_keywords huggingface dataset:
A Cosmic Ray Acceleration Mechanism Based on Background Flow Velocity Inhomogeneities Yielding Power-law Spectra. In astrophysics, one significant challenge lies in understanding the acceleration of cosmic rays, which leads to the occurrence of a power law. In this article, momentum transport generated by the combined effects of pitch-angle diffusion and background flow velocity inhomogeneities is proposed to obtain a cosmic rays acceleration mechanism, starting from the well-known focused transport equation describing particle diffusion and acceleration. The inhomogeneities of background flow velocity are ubiquitous in the astrophysical environment. The equation for the isotropic part of the distribution function of charged energetic particles is derived, and its solution is obtained, demonstrating the form of momentum power laws of cosmic rays. In addition, if it is assumed that cosmic rays penetrate compressive MHD waves or turbulence, for quasi-steady states, the spectral index δ of the momentum power law spectrum of cosmic rays is found to be in the range [‑5, ‑3], which includes the observed power law indices of galactic cosmic rays. The results obtained in this article demonstrate that the mechanism proposed in this article, along with shock acceleration, may also contribute to the acceleration of galactic cosmic rays. Furthermore, when momentum convection effect and higher-order momentum derivative terms are considered, the indices of power laws should be smaller than ‑5. This may explain the power laws of solar energetic particle events.

Keywords: Galactic cosmic rays, Magnetic fields, Solar energetic particles
Gravitational-wave Dark Siren Cosmology Systematics from Galaxy Weighting. The detection of GW170817 and the measurement of its redshift from the associated electromagnetic counterpart provided the first gravitational-wave (GW) determination of the Hubble constant (H 0), demonstrating the potential power of standard siren cosmology. In contrast to this "bright siren" approach, the "dark siren" approach can be utilized for GW sources in the absence of an electromagnetic counterpart: One considers all galaxies contained within the localization volume as potential hosts. When statistically averaging over the potential host galaxies, weighting them by physically motivated properties (e.g., tracing star formation or stellar mass) could improve convergence. Using mock galaxy catalogs, we explore the impact of these weightings on the measurement of H 0. We find that incorrect weighting schemes can lead to significant biases due to two effects: the assumption of an incorrect galaxy redshift distribution, and preferentially weighting incorrect host galaxies during the inference. The magnitudes of these biases are influenced by the number of galaxies along each line of sight, the measurement uncertainty in the GW luminosity distance, and correlations in the parameter space of galaxies. We show that the bias may be overcome from improved localization constraints in future GW detectors, a strategic choice of priors or weighting prescription, and by restricting the analysis to a subset of high-signal-to-noise ratio events. We propose the use of hierarchical inference as a diagnostic of incorrectly weighted prescriptions. Such approaches can simultaneously infer the correct weighting scheme and the values of the cosmological parameters, thereby mitigating the bias in dark siren cosmology due to incorrect host-galaxy weighting.

Keywords: Cosmology, Gravitational wave sources, Gravitational wave astronomy, Hubble constant, Gravitational waves
Quadrupole Moment of a Magnetically Confined Mountain on an Accreting Neutron Star in General Relativity. General relativistic corrections are calculated for the quadrupole moment of a magnetically confined mountain on an accreting neutron star. The hydromagnetic structure of the mountain satisfies the general relativistic Grad–Shafranov equation supplemented by the flux-freezing condition of ideal magnetohydrodynamics, as in previous calculations of the magnetic dipole moment. It is found that the ellipticity, and hence the gravitational wave strain, are up to 12% greater than in the analogous Newtonian system. The direct contribution of the magnetic field to the nonaxisymmetric component of the stress-energy tensor is shown to be negligible in accreting systems such as low-mass X-ray binaries.

Keywords: Accretion, Neutron stars, Magnetohydrodynamics, Relativistic stars, Gravitational wave sources, General relativity, Gravitational waves, Low-mass x-ray binary stars, Magnetic fields, Relativistic fluid dynamics
Constraining the Gamma-Ray Burst Jet Opening Angle Based on the Very Steep Decay Phase. Thanks to the rapid follow-up observations by the Swift X-Ray Telescope (XRT), a good part of gamma-ray bursts' (GRBs) high-latitude emission have been observed in the X-ray band. Some even show a dropdown decay after this period, which strongly indicates the edge of the jet is corresponding to the breaking time. This study constrains the jet opening angles of GRBs by analyzing the very steep decay phase in the early X-ray afterglow. Using data from Swift/XRT, we identified GRBs with significant breaks in their light curves and applied a broken power-law model to describe the decay phases. Assuming a spherical and isotropic emitting surface, we set constraints on the radiation radius (Rγ) to estimate jet opening angles (θjet) from the breaking time. Our results indicate that jet opening angles can be constrained, although they are sensitive to the assumed radiation radius. This approach provides yet another method for estimating GRB jet opening angles.

Keywords: Gamma-ray bursts, Relativistic jets
The Optical Extinction Law Depends on Magnetic Field Orientation: The R<SUB>V</SUB>–ψ Relation. For aspherical interstellar dust grains aligned with their short axes preferentially parallel to the local magnetic field, the amount of extinction per grain is larger when the magnetic field is along the line of sight and smaller when in the plane of the sky. To the extent that optical extinction arises from both aligned and unaligned grain populations with different extinction properties, changes in the magnetic field orientation induce changes in its wavelength dependence, parameterized by RV ≡ AV/E(B ‑ V). We demonstrate that the measured total and polarized extinction curves of the diffuse Galactic interstellar medium imply RV varies from 3.21 when the magnetic field is along the line of sight (ψ = 0) to RV = 3.05 when in the plane of the sky (ψ = 90°). This effect could therefore account for much of the large-scale RV variation observed across the sky (σ(RV) ≃ 0.2), particularly at high Galactic latitudes.

Keywords: Interstellar dust extinction
SN H0pe: The First Measurement of H<SUB>0</SUB> from a Multiply Imaged Type Ia Supernova, Discovered by JWST. The first James Webb Space Telescope (JWST) Near InfraRed Camera imaging in the field of the galaxy cluster PLCK G165.7+67.0 (z = 0.35) uncovered a Type Ia supernova (SN Ia) at z = 1.78, called "SN H0pe." Three different images of this one SN were detected as a result of strong gravitational lensing, each one traversing a different path in spacetime, thereby inducing a relative delay in the arrival of each image. Follow-up JWST observations of all three SN images enabled photometric and rare spectroscopic measurements of the two relative time delays. Following strict blinding protocols which oversaw a live unblinding and regulated postunblinding changes, these two measured time delays were compared to the predictions of seven independently constructed cluster lens models to measure a value for the Hubble constant, H0 = 71.8 + 9.2 ‑ 8.1 km s‑1 Mpc‑1. The range of admissible H0 values predicted across the lens models limits further precision, reflecting the well-known degeneracies between lens model constraints and time delays. It has long been theorized that a way forward is to leverage a standard candle, but this has not been realized until now. For the first time, the lens models are evaluated by their agreement with the SN absolute magnifications, breaking degeneracies and producing our best estimate, H0 =   km s‑1 Mpc‑1. This is the first precise measurement of H0 from a multiply imaged SN Ia and only the second from any multiply imaged SN.

Keywords: Cosmology, Galaxy clusters, Strong gravitational lensing, Hubble constant, Type Ia supernovae, Gravitational lensing
An Indication of Gas Inflow in Clumpy Star-forming Galaxies near z ∼ 1: Lower Gas-phase Metallicities in Clumpy Galaxies Compared to Nonclumpy Galaxies. Despite the ubiquity of clumpy star-forming galaxies at high-redshift, the origin of clumps are still largely unconstrained due to the limited observations that can validate the mechanisms for clump formation. We postulate that if clumps form due to the accretion of metal-poor gas that leads to violent disk instability, clumpy galaxies should have lower gas-phase metallicities compared to nonclumpy galaxies. In this work, we obtain the near-infrared spectrum for 42 clumpy and nonclumpy star-forming galaxies of similar masses, star formation rates, and colors at z ≍ 0.7 using the Gemini Near-Infrared Spectrograph (GNIRS) and infer their gas-phase metallicity from the [N II]λ6584 and Hα line ratio. We find that clumpy galaxies have lower metallicities compared to nonclumpy galaxies, with an offset in the weighted average metallicity of 0.07 ± 0.02 dex. We also find an offset of 0.06 ± 0.02 dex between clumpy and nonclumpy galaxies in a comparable sample of 23 star-forming galaxies at z ≍ 1.5 using existing data from the FMOS-COSMOS survey. Similarly, lower [N II]λ6584/Hα ratios are typically found in galaxies that have more of their UVrest luminosity originating from clumps, suggesting that clumpier galaxies are more metal-poor. We also derive the intrinsic velocity dispersion and line-of-sight rotational velocity for galaxies from the GNIRS sample. The majority of galaxies have σ0/vc ≍ 0.2, with no significant difference between clumpy and nonclumpy galaxies. Our result indicates that clump formation may be related to the inflow of metal-poor gas; however, the process that forms them does not necessarily require significant, long-term kinematic instability in the disk.

Keywords: Galaxy formation, Star forming regions, Galaxy kinematics, Galaxy evolution, Metallicity
Blowing Out the Candle: How to Quench Galaxies at High Redshift—An Ensemble of Rapid Starbursts, AGN Feedback, and Environment. Recent observations with JWST and the Atacama Large Millimeter/submillimeter Array have revealed extremely massive quiescent galaxies at redshifts of z = 3 and higher, indicating both rapid onset and quenching of star formation. Using the cosmological simulation suite Magneticum Pathfinder, we reproduce the observed number densities and stellar masses, with 36 quenched galaxies of stellar mass larger than 3 × 1010 M ⊙ at z = 3.42. We find that these galaxies are quenched through a rapid burst of star formation and subsequent active galactic nucleus (AGN) feedback caused by a particularly isotropic collapse of surrounding gas, occurring on timescales of around 200 Myr or shorter. The resulting quenched galaxies host stellar components that are kinematically fast rotating and alpha-enhanced, while exhibiting a steeper metallicity and flatter age gradient compared to galaxies of similar stellar mass. The gas of the galaxies has been metal enriched and ejected. We find that quenched galaxies do not inhabit the densest nodes, but rather sit in local underdensities. We analyze observable metrics to predict future quenching at high redshifts, finding that on shorter timescales &lt;500 Myr, the ratio M bh/M * is the best predictor, followed by the burstiness of the preceding star formation, t 50–t 90 (time to go from 50% to 90% stellar mass). On longer timescales, &gt;1 Gyr, the environment becomes the strongest predictor, followed by t 50–t 90, indicating that at high redshifts the consumption of old gas and lack of new gas are more relevant for long-term prevention of star formation than the presence of a massive AGN. We predict that relics of such high-z quenched galaxies should best be characterized by a strong alpha enhancement.

Keywords: Galaxy formation, Quenched galaxies, Computational methods, Galaxy evolution, High-redshift galaxies, Galaxies
PS1-11aop: Probing the Mass-loss History of a Luminous Interacting Supernova Prior to Its Final Eruption with Multiwavelength Observations. Luminous interacting supernovae (SNe) are a class of stellar explosions whose progenitors underwent vigorous mass loss in the years prior to core collapse. While the mechanism by which this material is ejected is still debated, obtaining the full density profile of the circumstellar medium (CSM) could reveal more about this process. Here, we present an extensive multiwavelength study of PS1-11aop, a luminous and slowly declining Type IIn SNe discovered by the Pan-STARRS Medium Deep Survey. PS1-11aop had a peak r-band magnitude of ‑20.5 mag, a total radiated energy &gt;8 × 1050 erg, and it exploded near the center of a star-forming galaxy with super-solar metallicity. We obtained multiple detections at the location of PS1-11aop in the radio and X-ray bands between 4 and 10 yr post-explosion, and if due to the supernova (SN), it is one of the most luminous radio SNe identified to date. Taken together, the multiwavelength properties of PS1-11aop are consistent with a CSM density profile with multiple zones. The early optical emission is consistent with the SN blastwave interacting with a dense and confined CSM shell, which contains multiple solar masses of material that was likely ejected in the final &lt;10–100 yr prior to the explosion, (∼0.05‑1.0 M ⊙ yr‑1 at radii of ≲1016 cm). The radio observations, on the other hand, are consistent with a sparser environment (≲2 × 10‑3 M ⊙ yr‑1 at radii of ∼0.5–1 × 1017 cm)—thus probing the history of the progenitor star prior to its final mass-loss episode.

Keywords: Radio transient sources, Core-collapse supernovae, Stellar mass loss
ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Nested Morphological and Kinematic Structures of Outflows Revealed in SiO and CO Emission. The Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP) reveals complex nested morphological and kinematic features of molecular outflows through the CO (J = 2‑1) and SiO (J = 5‑4) emission. We characterize the jet and outflow kinematics of the ALMASOP sample in four representative sources (HOPS 10, 315, 358, and G203.21-11.20W2) through channel maps and position–velocity diagrams (PVDs) parallel and transverse to the outflow axes. The combined CO and SiO emission exhibits the coexistence of the conventional extremely high-velocity jets and shell-like low-velocity cavity walls and new features. More complex, nested bubble-like and filamentary structures in the images and channel maps, triangle-shaped regions near the base of the parallel PVDs, and regions composed of rhombus/oval shapes in the transverse PVDs are also evident. Such features find natural explanations within the bubble structure of the unified model of jet, wind, and ambient medium. The reverse shock cavity is revealed on the PVD base regions, and other features naturally arise within the dynamic postshock region of magnetic interaction. The finer nested shells observed within the compressed wind region reveal previously unnoticed shocked emission between the jet and the conventional large cavity walls. These pseudopulse-produced filamentary features connect to the jetlike knotty blobs, creating an impression of episodicity in mass ejection. SiO emission is enhanced downstream of the reverse shock boundary, with jetlike excitation conditions. Combined, these observed features reveal the extended structures induced by the magnetic interplay between a jet-bearing magnetized wide-angle wind and its ambient magnetized surrounding medium.

Keywords: Stellar-interstellar interactions, Interstellar line emission, Jets, Termination shock, Stellar jets, Stellar bow shocks, Young stellar objects, Stellar winds, Interstellar medium, CO line emission, Protostars, Radio astronomy
The S<SUP>4</SUP>G-WISE View of Global Star Formation in the Nearby Universe. In this work, we present source-tailored Wide-field Infrared Survey Explorer (WISE) mid-infrared photometry (at 3.4, 4.6, 12, and 23 μm) of 2812 galaxies in the extended Spitzer Survey of Stellar Structure in Galaxies sample, and characterize the mid-infrared colors and dust properties of this legacy nearby galaxy data set. Informed by the relative emission between W3 (12 μm) and W4 (23 μm), we rederive star formation rate (SFR) scaling relations calibrated to L TIR, which results in improved agreement between the two tracers. By inverse–variance weighting the W3 and W4-derived SFRs, we generate a combined mid-infrared SFR that is a broadly robust measure of star formation activity in dusty, star-forming galaxies in the nearby Universe. In addition, we investigate the use of a W3-derived dust density metric, Σ12 μm (L ⊙/kpc2), to estimate the SFR deficit of low mass, low dust galaxies. This is achieved by combining WISE with existing Galaxy Evolution Explorer ultraviolet (UV) photometry, which we further use to explore the relationship between dust and UV emission as a function of morphology. Finally, we use our derived SFR prescriptions to examine the location of galaxies in the log SFR–log M stellar plane, as a function of morphological type, which underscores the complexity of dust-derived properties seen in galaxies of progressively earlier type.

Keywords: Galaxy photometry, Star formation, Infrared photometry
Line List for the A<SUP>2</SUP>Π‑X<SUP>2</SUP>Σ<SUP>+</SUP> and the B<SUP>2</SUP>Σ<SUP>+</SUP>‑X<SUP>2</SUP>Σ<SUP>+</SUP> Band Systems of CaF. The spectral analysis of molecule-rich asymptotic giant branch (AGB) stars is challenging. Although other calcium and fluorine bearing molecules are observed in the microwave and in the visible spectrum of AGB stars, CaF has never been detected, despite favorable chemical equilibrium predictions. Yet, measuring the CaF abundance could give more insight into the fluorine budget of AGB stars and allow better simulation of stellar spectra. In this work, we present an analysis of the visible spectrum of CaF obtained with a Fourier transform spectrometer. CaF A2Π‑X2Σ+ and B2Σ+‑X2Σ+ band systems were excited with a hollow cathode discharge. Using previous fluorescence spectroscopy measurements, highly accurate ground state constants, and reasonable extrapolation schemes, the strongest features of CaF in the visible spectrum can be accurately modeled for both band systems. Spectroscopic constants are determined for A2 Π with v ≤ 16 and for B2Σ+ with v ≤ 20. Ab initio transition dipole moment curves of both transitions were calculated and scaled, and we provide a line list with Einstein A coefficients and oscillator strengths. This line list can be used to simulate spectra of CaF at temperatures and pressures relevant to astrophysical environments.

Keywords: Spectral line lists, Laboratory astrophysics, Molecular spectroscopy, Molecular spectroscopic constants
Transients by Black Hole Formation from Red Supergiants: Impact of Dense Circumstellar Matter. Failed supernovae (SNe), which are likely the main channel for forming stellar-mass black holes, are predicted to accompany mass ejections much weaker than typical core-collapse SNe. We conduct a grid of one-dimensional radiation hydrodynamical simulations to explore the emission of failed SNe from red supergiant progenitors, leveraging recent understanding of the weak explosion and the dense circumstellar matter (CSM) surrounding these stars. We find from these simulations and semianalytical modeling that diffusion in the CSM prolongs the early emission powered by shock breakout/cooling. The early emission has peak luminosities of ~107–108 L⊙ in optical and UV and durations of days to weeks. The presence of dense CSM aids in the detection of the early bright peak from these events via near-future wide-field surveys such as Rubin Observatory, ULTRASAT, and UVEX.

Keywords: Circumstellar matter, Transient sources, Astrophysical black holes
Epsilon Canis Majoris: The Brightest Extreme-ultraviolet Source with Surprisingly Low Interstellar Absorption. The B2 star Epsilon Canis Majoris (ϵ CMa), at parallax distance d = 124 ± 2 pc, dominates the H I photoionization of the Local Interstellar Cloud. At its closer parallax distance compared to previous estimates, ϵ CMa has a 0.9 mag fainter absolute magnitude MV = ‑3.97 ± 0.04. We combine measurements of distance with the integrated flux f = (41.5 ± 3.3) × 10‑6 erg cm‑2 s‑1 and angular diameter θd = 0.80 ± 0.05 mas to produce a consistent set of stellar parameters: radius R = 10.7 ± 0.7 R⊙, mass M = 13.1 ± 2.3 M⊙, gravity  , effective temperature Teff ≈ 21,000 K, and luminosity L ≈ 20,000 L⊙. These parameters place ϵ CMa outside the β Cephei instability strip, consistent with its observed lack of pulsations. The observed extreme-ultraviolet spectrum yields a hydrogen photoionization rate ΓHI ≈ 10‑15 s‑1 (at Earth). The total flux decrement factor at the Lyman limit (ΔLL = 5000 ± 500) is a combination of attenuation in the stellar atmosphere (Δstar = 110 ± 10) and interstellar medium (ΔISM = 45 ± 5) with optical depth τLL = 3.8 ± 0.1. After correcting for interstellar H I column density NHI = (6 ± 1) × 1017cm‑2, we find a stellar LyC photon flux ΦLyC ≈ 3000 cm‑2 s‑1 and ionizing luminosity QLyC = 1045.7±0.3 photons s‑1. The photoionization rate ΓH ≈ (1–2) × 10‑14 s‑1 at the cloud surface produces an ionization fraction (30%–40%) for total hydrogen density nH = 0.2 cm‑3. With its 27.3 ± 0.4 km s‑1 heliocentric radial velocity and small proper motion, ϵ CMa passed within 9.3 ± 0.5 pc of the Sun 4.4 Myr ago, with a 180 times higher photoionization rate.

Keywords: Photoionization, Interstellar medium, B stars
Type IV-like Solar Radio Burst Consisting of a Series of Short-time Bursts Observed by PSP. Solar and interplanetary radio bursts can reflect the existence and motion of energetic electrons and are therefore a kind of vital phenomenon in solar activities. The present study reported a solar radio storm observed by the Parker Solar Probe (PSP) in its eighth orbital encounter phase, and it lasted about 20 hr in a frequency range of 0.5–15 MHz, called the type IV-like burst. It consists of a series of numerous short-time (ST) bursts with the central frequency drifting slowly from ~5 to ~1 MHz, and each individual ST burst appears at a much faster frequency drifting rate and has a typical frequency range of a few MHz and a short duration of about 1–4 minutes. Based on the empirical models of the solar atmosphere adopted commonly, combining the in situ measurement by PSP, we analyzed and compared some possible mechanisms for the generation of these small-scale ST bursts and proposed that they were generated probably by a group of solitary kinetic Alfvén waves (SKAWs) in a magnetic loop accompanying coronal mass ejection and slowly moving outward, in which the frequency drifting of individual ST burst is caused by the SKAW's propagation and the central frequency drifting may be attributed to the motion of the magnetic loop.

Keywords: Space plasmas, Radio bursts, Solar radio emission, Solar physics, Interplanetary physics