Sazuna/UAT_keywords huggingface dataset:
Stellar Population Synthesis with Distinct Kinematics: Multiage Asymmetric Drift in SDSS-IV MaNGA Galaxies. We present the first asymmetric drift (AD) measurements for unresolved stellar populations of different characteristic ages above and below 1.5 Gyr. These measurements sample the age-velocity relation in galaxy disks. In this first paper, we develop two efficient algorithms to extract AD on a spaxel-by-spaxel basis from optical integral-field spectroscopic data cubes. The algorithms apply different spectral templates, one using simple stellar populations and the other a stellar library; their comparison allows us to assess systematic errors in derived multicomponent velocities, such as template mismatch. We test algorithm reliability using mock spectra and Monte Carlo Markov Chains on real data from the MaNGA survey in Sloan Digital Sky Survey IV. We quantify random and systematic errors in AD as a function of signal-to-noise and stellar population properties with the aim of applying this technique to large subsets of the MaNGA galaxy sample. As a demonstration of our methods, we apply them to an initial sample of seven galaxies with comparable stellar mass and color to the Milky Way. We find a wide range of distinct AD radial profiles for young and old stellar populations.

Keywords: Galaxy stellar disks, Galaxy kinematics, Galaxy stellar content, Spiral galaxies
A Solar Coronal Hole and Fast Solar Wind Turbulence Model and First-orbit Parker Solar Probe (PSP) Observations. We propose a turbulence-driven solar wind model for a fast solar wind flow in an open coronal hole where the solar wind flow and the magnetic field are highly aligned. We compare the numerical results of our model with Parker Solar Probe measurements of the fast solar wind flow and find good agreement between them. We find that (1) the majority quasi-2D turbulence is mainly responsible for coronal heating, raising the temperature to about $\sim {10}^{6}$ K within a few solar radii, which leads in turn to the acceleration of the solar wind; (2) the heating rate due to quasi-2D turbulence near the coronal base is larger than that due to nearly incompressible/slab turbulence; (3) the quasi-2D energy in forward-propagating modes decreases with increasing distance, while the nearly incompressible/slab energy in forward-propagating modes increases, reaching a peak value at ∼11.7 ${R}_{\odot }$ before decreasing with increasing heliocentric distance; (4) the correlation length increases with increasing distance from the coronal base; and (5) the variance of the density fluctuations decreases as a function of heliocentric distance.

Keywords: Interplanetary turbulence, The Sun, Solar wind
Far-ultraviolet Absorption and Photoluminescence of Monolayer Graphene and Its Implications for Extended Red Emission. A monolayer graphene (GR) film on a lithium fluoride substrate was prepared to measure the optical properties of graphene in the far-UV region. The photoabsorption of the GR/LiF sample was universal in the spectral region of 105-350 nm, with an excitonic band near 130 nm and the absorbance of the GR/LiF sample at 10 K was ∼10% larger than that at 300 K. Upon far-UV excitation, the photoluminescence (PL) spectra of the GR/LiF sample showed a broad band at 630 nm at 300 K and two adjacent bands at 560 and 634 nm at 10 K. GR had a PL similar to the extended red emission (ERE) band, fulfilling the known observational model constraints of the light-driven process dominated by far-UV excitations, carbonaceous nature of ERE carriers, and broad emission in the red and near-IR regions. The result implies that graphene materials are promising candidates for carriers for the ERE.

Keywords: Radiative processes, Interstellar emissions, Laboratory astrophysics, Astrochemistry
New Calculations of Stark-broadened Profiles for Neutral Helium Lines Using Computer Simulations. We present new calculations of Stark-broadened profiles for neutral helium lines using computer simulations that include some important aspects aimed at better representing the dynamical environment of the helium atom. These include the unification of ion and electron treatment, the correction for ion dynamics, the transition of the electron contribution to broadening from the core to the wings of the profile, the numerical integration of the time evolution operator of helium perturbed by a fluctuating electric field, the Debye correction for the correlation of the motion of charged perturbers, local density variations, and particle reinjection. We compare the results of our simulations for the He I λλ4471 and 4922 lines with other results published in the literature. We also test our simulation environment for narrow lines (He I $\lambda \lambda 5877$ and 6678) and broader lines (He I $\lambda \lambda 4026$ and 4144). We find that the narrow lines are more difficult to produce adequately than the broader ones.

Keywords: White dwarf stars, Astrophysical processes, Spectroscopy, Collisional broadening, N-body simulations
A Carbon-enhanced Lyman Limit System: Signature of the First Generation of Stars?. We present the study of a Lyman limit system (LLS) at zabs = 1.5441 toward quasar J134122.50+185213.9 observed with VLT X-shooter. This is a very peculiar system with strong C I absorption seen associated with a neutral hydrogen column density of log N(H I) (cm-2) = 18.10, too small to shield the gas from any external UV flux. The low-ionization absorption lines exhibit a simple kinematic structure consistent with a single component. Using CLOUDY models to correct for ionization, we find that the ionization parameter of the gas is in the range -4.5 &lt; log U &lt; -4.2 and the gas density -1.5 &lt; log n(H) (cm-3) &lt; -1.2. The models suggest that carbon is overabundant relative to iron, [C/Fe] &gt; +2.2 at [Fe/H] ∼-1.6. Such a metal abundance pattern is reminiscent of carbon-enhanced metal-poor stars detected in the Galaxy halo. Metal enrichment by the first generation of supernovae provide a plausible explanation for the inferred abundance pattern in this system.

Keywords: Quasar absorption line spectroscopy, Quasars, Lyman limit systems, CEMP stars, Chemically peculiar stars
Contribution of High-energy GRB Emissions to the Spectrum of the Isotropic Diffuse γ-Ray Background. High-precision measurement of the isotropic diffuse γ-ray background (IGRB) has been extrapolated to the TeV energy region using the Fermi-LAT experiment. Various kinds of astrophysical sources are candidates for its origin. However, a consensus on the dominant source has been difficult to reach. Recent observations of the γ-ray emission of γ-ray bursts (GRBs), denoted as the synchrotron self-Compton (SSC) component in the afterglow phase, in the sub-TeV energy region by MAGIC and HESS experiments shed new light on this topic. In this work, we revisit the contribution from the SSC component of GRBs to the IGRB. First, a sample set of GRB events is obtained and examined using observations from Fermi-LAT. Second, the SSC component, described by the energy ratio Rext and spectral index βext, is assigned to every GRB event. We can obtain the total spectrum contribution based on this GRB sample. We find that when Rext and βext reach ∼20% and -1.6, respectively, the contribution from GRB emission dominates in the energy region of hundreds of GeV. We hope that the LHAASO and CTA experiments under construction can observe a large number of GRBs to fix those parameters in coming years. A surviving tail is expected, which can serve to check our calculations based on future satellite experiments such as HERD and GAMMA400.

Keywords: Gamma-ray sources, Gamma-ray bursts
Large-amplitude, Wideband, Doppler-shifted, Ion Acoustic Waves Observed on the Parker Solar Probe. Electric field spectra measured on the Parker Solar Probe typically contain upwards of 1000 large-amplitude (∼15 mV m-1), wideband (∼100-15,000 Hz), few-second-duration, electric field waveforms per day. The satellite also collected about 85 three-second bursts of electric field waveforms per day at a data rate of ∼150,000 samples per second. Eight such bursts caught these waves, all of which were located in switchbacks of the magnetic field. A wave burst on 2019 September 7, when the spacecraft was at an altitude of 55 solar radii, is described. It contained Doppler-shifted ion acoustic waves that propagated in the direction opposite to the local magnetic field at all rest-frame frequencies from 60 Hz to nearly the proton plasma frequency of 2200 Hz, while no other wave modes were present. The eight bursts all contained ion acoustic waves whose individual net potentials were ≤1 V. A second burst, analyzed in conjunction with ion plasma measurements, showed that the ion acoustic waves were associated with broadened, plateaued, ion spectra containing unheated ions. Because the ion acoustic waves had phase velocities that varied from 140 to 90 km s-1, ions interacting with these waves via the Landau resonance had a chance to diffuse in parallel velocity space from 90 to 140 km s-1 in the plasma rest frame. The most likely generation mechanism of the ion acoustic waves is the ion-ion acoustic instability, while the electron-ion instability is a less likely candidate.

Keywords: Solar wind
Gravitational Waves from Neutrino Emission Asymmetries in Core-collapse Supernovae. We present a broadband spectrum of gravitational waves (GWs) from core-collapse supernovae (CCSNe) sourced by neutrino emission asymmetries for a series of full 3D simulations. The associated GW strain probes the long-term secular evolution of CCSNe and small-scale turbulent activity and provides insight into the geometry of the explosion. For nonexploding models, both the neutrino luminosity and the neutrino gravitational waveform will encode information about the spiral SASI. The neutrino memory will be detectable for a wide range of progenitor masses for a galactic event. Our results can be used to guide near-future decihertz and long-baseline GW detection programs, including aLIGO, the Einstein Telescope, and DECIGO.

Keywords: Supernova neutrinos, Gravitational waves, Core-collapse supernovae
Exploring the Stellar Age Distribution of the Milky Way Bulge Using APOGEE. We present stellar age distributions of the Milky Way bulge region using ages for ∼6000 high-luminosity ( $\mathrm{log}(g)\lt 2.0$ ), metal-rich ([Fe/H] ≥ -0.5) bulge stars observed by the Apache Point Observatory Galactic Evolution Experiment. Ages are derived using The Cannon label-transfer method, trained on a sample of nearby luminous giants with precise parallaxes for which we obtain ages using a Bayesian isochrone-matching technique. We find that the metal-rich bulge is predominantly composed of old stars (&gt;8 Gyr). We find evidence that the planar region of the bulge ( $| {Z}_{\mathrm{GC}}| \leqslant 0.25$ kpc) is enriched in metallicity, Z, at a faster rate (dZ/dt ∼ 0.0034 Gyr-1) than regions farther from the plane (dZ/dt ∼ 0.0013 Gyr-1 at $| {Z}_{\mathrm{GC}}| \gt 1.00$ kpc). We identify a nonnegligible fraction of younger stars (age ∼2-5 Gyr) at metallicities of +0.2 &lt; [Fe/H] &lt; +0.4. These stars are preferentially found in the plane ( $| {Z}_{\mathrm{GC}}| \leqslant 0.25$ kpc) and at Rcy ≈ 2-3 kpc, with kinematics that are more consistent with rotation than are the kinematics of older stars at the same metallicities. We do not measure a significant age difference between stars found inside and outside the bar. These findings show that the bulge experienced an initial starburst that was more intense close to the plane than far from the plane. Then, star formation continued at supersolar metallicities in a thin disk at 2 kpc ≲ Rcy ≲ 3 kpc until ∼2 Gyr ago.

Keywords: Stellar ages, Milky Way formation, Galaxy bulges, Galactic bulge, Milky Way evolution, Milky Way Galaxy
HCN Production in Titan's Atmosphere: Coupling Quantum Chemistry and Disequilibrium Atmospheric Modeling. Hydrogen cyanide (HCN) is a critical reactive source of nitrogen for building key biomolecules relevant for the origin of life. Still, many HCN reactions remain uncharacterized by experiments and theory, and the complete picture of HCN production in planetary atmospheres is not fully understood. To improve this situation, we develop a novel technique making use of computational quantum chemistry, experimental data, and atmospheric numerical simulations. First, we use quantum chemistry simulations to explore the entire field of possible reactions for a list of primary species in N2-, CH4-, and H2-dominated atmospheres. In this process, we discover 33 new reactions with no previously known rate coefficients. From here, we develop a consistent reduced atmospheric hybrid chemical network (CRAHCN) containing experimental values when available and our calculated rate coefficients otherwise. Next, we couple CRAHCN to a 1D chemical kinetic model (ChemKM) to compute the HCN abundance as a function of atmospheric depth on Titan. Our simulated atmospheric HCN profile agrees very well with the Cassini observations. CRAHCN contains 104 reactions; however, nearly all of the simulated atmospheric HCN profile can be obtained using a scaled-down network of only 19 dominant reactions. From here, we form a complete picture of HCN chemistry in Titan's atmosphere, from the dissociation of the main atmospheric species, down to the direct production of HCN along four major channels. One of these channels was first discovered and characterized in Pearce et al. and this work.

Keywords: Astrobiology, Reaction rates, Pre-biotic astrochemistry, Atmospheric science
NuSTAR Hard X-Ray Spectra of Radio Galaxies. The Nuclear Spectroscopic Telescope Array (NuSTAR) observatory, with its 3-78 keV broadband spectral coverage, enables the detection of the high-energy cutoff in a number of active galaxies, including several individual radio-loud ones. In this work, we present systematic and uniform analyses of 55 Nuclear Spectroscopic Telescope Array (NuSTAR) spectra for a large sample of 28 radio galaxies, 20 of which are FR II galaxies. We perform spectral fitting to measure the high-energy cutoff Ecut, photon index Γ, reflection factor R, and Fe Kα line equivalent width (EW). Measurements of Ecut are given for 13 sources, and lower limits are given for the rest. We find that those Ecut nondetections could primarily be attributed to the obviously smaller net photon counts in their spectra. This indicates that the NuSTAR spectra of the majority of our sample are dominated by the thermal coronal emission, and the Ecut distribution of the sample is indistinguishable from that of a radio-quiet one in the literature. The flatter NuSTAR spectra we observed, comparing with radio-quiet sources, are thus unlikely due to jet contamination. The radio galaxies also show weaker X-ray reflection (both in R and Fe Kα line EW) compared with radio-quiet ones. Combining with the radio-quiet sample, we see a correlation between R and EW but with considerably large scatter. Notably, the radio-loud and -quiet sources appear to follow a common Γ-R correlation trend, supporting the outflowing corona model for both populations in which higher bulk outflowing velocity yields weaker reflection and flatter X-ray slope.

Keywords: Radio loud quasars, Active galaxies, X-ray active galactic nuclei
The Isotropic Interplanetary Dust Cloud and Near-infrared Extragalactic Background Light Observed with COBE/DIRBE. We report observation of isotropic interplanetary dust (IPD) by analyzing the infrared (IR) maps of the Diffuse Infrared Background Experiment (DIRBE) on board the Cosmic Background Explorer (COBE) spacecraft. To search for the isotropic IPD, we perform new analysis in terms of the solar elongation angle (ɛ), because we expect the zodiacal light (ZL) intensity from the isotropic IPD to decrease as a function of ɛ. We use the DIRBE weekly averaged maps covering 64° ≲ ɛ ≲ 124° and inspect the ɛ dependence of residual intensity after subtracting conventional ZL components. We find the ɛ dependence of the residuals, indicating the presence of the isotropic IPD. However, the mid-IR ɛ dependence is different from that of the isotropic IPD model at ɛ ≳ 90°, where the residual intensity increases as a function of ɛ. To explain the observed ɛ dependence, we assume a spheroidal IPD cloud showing higher density farther away from the Sun. We estimate the intensity of the near-IR extragalactic background light (EBL) by subtracting the spheroidal component, assuming the spectral energy distribution from the residual brightness at 12 μm. The EBL intensity is derived as ${45}_{-8}^{+11}$ , ${21}_{-4}^{+3}$ , and $15\pm 3\,{\mathrm{nWm}}^{-2}\,{\mathrm{sr}}^{-1}$ at 1.25, 2.2, and 3.5 μm, respectively. The EBL is still a few times larger than the integrated light of normal galaxies, suggesting the existence of unaccounted-for extragalactic sources.

Keywords: Early universe, Population III stars, Diffuse radiation, Observational cosmology, Infrared astronomy, Infrared Astronomical Satellite, Galaxy evolution, Intergalactic medium, Zodiacal cloud, Interplanetary dust, Cosmic background radiation, Primordial black holes
Long-term Period Changes and Brightness Variations for the Deeply Eclipsing Cataclysmic Variable SW Sex. SW Sex is a deeply eclipsing cataclysmic variable with an orbital period of 0.1349 days. Based on the new photometric observations together with the data collected in the literature, we find that the orbital period shows a period wiggle from 1980 to 2015, and then decreases severely until 2020, when our observations end. If the oscillation with an amplitude of 0.000973 days and a period of 36.57 yr is due to the presence of a third body, the mass of this component can be determined as M3sini' = 0.014 M⊙. Supposing the companion and the central binary are coplanar, its mass would correspond to a giant planet. However, Applegate's mechanism can also provide enough energy to force such variation and more data will distinguish the reason. The rapid decline of the orbital period at a rate of -4.24 × 10-10 s s-1 in 2015-2020 cannot be attributed to magnetic braking. Also, Applegate's mechanism fails to produce such a fast decrease. It can be explained as the angular momentum loss caused by a strong disk wind, which declares its existence by synchronizing the period decrease with the brightness increase. In addition, the long-term brightness oscillation with an amplitude of 0.6 mag and a timescale of about 9.7 yr is discovered. This is the first it has been detected for nova-like cataclysmic variables (CVs). It will provide valuable information for understanding the disk activity and the evolution of the CVs.

Keywords: CCD photometry, Stellar winds, Stellar accretion disks, Nova-like variable stars, Stellar evolution
Precollapse Properties of Superluminous Supernovae and Long Gamma-Ray Burst Progenitor Models. We analyze the properties of 42 rapidly rotating, low-metallicity, quasi-chemically homogeneously evolving stellar models in the mass range between 4 and 45 $\,{M}_{\odot }$ at the time of core collapse. Such models were proposed as progenitors for both superluminous supernovae (SLSNe) and long-duration gamma-ray bursts (lGRBs) and the Type Ic-BL supernovae (SNe) that are associated with them. Our findings suggest that whether these models produce a magnetar-driven SLSN explosion or a near-critically rotating black hole is not a monotonic function of the initial mass. Rather, their explodability varies nonmonotonically depending on the late core evolution, once chemical homogeneity is broken. Using different explodability criteria, we find that our models have a clear preference to produce SLSNe at lower masses and lGRBs at higher masses, but we find several exceptions, expecting lGRBs to form from stars as low as 10 $\,{M}_{\odot }$ and SLSNe with progenitors as massive as 30 $\,{M}_{\odot }$ . In general, our models reproduce the predicted angular momenta, ejecta masses, and magnetic field strengths at core collapse inferred for SLSNe and lGRBs and suggest significant interaction with their circumstellar medium, particularly for explosions with low ejecta mass.

Keywords: Neutron stars, Gamma-ray bursts, Neutron star cores, Black holes, Late stellar evolution, Stellar evolutionary models, Circumstellar matter, Magnetars, Supernovae, Nonstandard evolution, Astrophysical black holes, Stellar evolution
Elimination of the Blue Loops in the Evolution of Intermediate-mass Stars by the Neutrino Magnetic Moment and Large Extra Dimensions. For searching beyond Standard Model physics, stars are laboratories that complement terrestrial experiments. Massless neutrinos in the Standard Model of particle physics cannot have a magnetic moment, but massive neutrinos have a finite magnetic moment in the minimal extension of the Standard Model. Large extra dimensions (LEDs) are a possible solution of the hierarchy problem. Both of these provide additional energy-loss channels in stellar interiors via the electromagnetic interaction and radiation into extra dimensions, respectively, and thus affect stellar evolution. We perform simulations of stellar evolution with such additional energy losses and find that they eliminate the blue loops in the evolution of intermediate-mass stars. The existence of Cepheid stars can be used to constrain the neutrino magnetic moment (NMM) and LEDs. In order for Cepheids to exist, the NMM should be smaller than the range ∼2 × 10-10μB-4 × 10-11μB, where μB is the Bohr magneton, and the fundamental scale in the (4+2)-spacetime should be larger than ∼2-5 TeV, depending on the rate of the 12C ${(\alpha ,\gamma )}^{16}{\rm{O}}$ reaction. The fundamental scale also has strong dependence on the metallicity. This value of the magnetic moment is in the range explored in the reactor experiments, but higher than the limit inferred from globular clusters. Similarly the fundamental scale value we constrain corresponds to a size of the compactified dimensions comparable to those explored in the torsion balance experiments, but it is smaller than the limits inferred from collider experiments and low-mass stars.

Keywords: Neutrino astronomy, Non-standard theories of gravity, Cepheid variable stars, Particle astrophysics, Stellar evolution
LB-1 Is Inconsistent with the X-Ray Source Population and Pulsar-Black Hole Binary Searches in the Milky Way. If confirmed, a wide binary system consisting of a 70 M⊙ black hole (BH) and an 8 M⊙ main-sequence star (LB-1) is observed to reside in the Milky Way (MW). While we remain agnostic about the nature of LB-1, we show that long-term evolution of an 8 M⊙ star around a BH with mass between 5 and 70 M⊙ makes them visible as ultraluminous X-ray (ULX) sources in the sky. Given the expected ULX phase lifetime (≈0.1 Myr) and their lack of detection in the MW, we conclude that the frequency of an 8-20 M⊙ star to be in binary around a stellar mass BH should be less (f &lt; 4 × 10-3). This is in tension with Liu et al., who claimed the detection frequency of an LB-1-like system to be around 8-20 M⊙ stars (f ≈ 3 × 10-2). Moreover, the 8 M⊙ star is likely to end as a neutron star (NS) born with a very small kick from an electron-capture supernova (ECSN), leaving behind a wide NS-BH binary. So far, less than 1% of all the detectable pulsars in the MW have been mapped and there has been no detection of any pulsars in binary systems around BHs, which sets an upper bound of about 100 possible pulsar-BH systems in the MW. We show whether the NS is born from ECSN, a frequency upper limit of (f ≈ 10-3) for stars with masses ≈8-20 M⊙ in the MW to have a BH companion. The rate discrepancy will further increase as more pulsars are mapped in the MW, yet these searches would not be able to rule out the Liu et al. detection frequency if NSs are instead born in core collapse SNe with the commonly inferred high kick velocities.

Keywords: Binary stars, Interstellar dust extinction, Pulsars, Astrophysical black holes, Common envelope binary stars