Sazuna/UAT_keywords huggingface dataset:
Proxima Centauri b: A Strong Case for Including Cosmic-Ray-induced Chemistry in Atmospheric Biosignature Studies. Due to its Earth-like minimum mass of 1.27 ME and its close proximity to our solar system, Proxima Centauri b is one of the most interesting exoplanets for habitability studies. Its host star, Proxima Centauri, is however a strongly flaring star, which is expected to provide a very hostile environment for potentially habitable planets. We perform a habitability study of Proxima Centauri b assuming an Earth-like atmosphere under high stellar particle bombardment, with a focus on spectral transmission features. We employ our extensive model suite calculating energy spectra of stellar particles, their journey through the planetary magnetosphere, ionosphere, and atmosphere, ultimately providing planetary climate and spectral characteristics, as outlined in Herbst et al. Our results suggest that together with the incident stellar energy flux, high particle influxes can lead to efficient heating of the planet well into temperate climates, by limiting CH4 amounts, which would otherwise run into antigreenhouse for such planets around M stars. We identify some key spectral features relevant for future spectral observations: First, NO2 becomes the major absorber in the visible, which greatly impacts the Rayleigh slope. Second, H2O features can be masked by CH4 (near-infrared) and CO2 (mid- to far-infrared), making them nondetectable in transmission. Third, O3 is destroyed and instead HNO3 features become clearly visible in the mid- to far-infrared. Lastly, assuming a few percent of CO2 in the atmosphere, CO2 absorption at 5.3 μm becomes significant (for flare and nonflare cases), strongly overlapping with a flare related NO feature in Earth's atmosphere.

Keywords: Exoplanet atmospheric composition , Photoionization, Exoplanets, Atmospheric science, Biosignatures, Exoplanet atmospheres, Cosmic rays
Confirmation of Enhanced Long-wavelength Dust Emission in OMC 2/3. Previous continuum observations from the MUSTANG camera on the Green Bank Telescope (GBT) of the nearby star-forming filament OMC 2/3 found elevated emission at 3.3 mm relative to shorter-wavelength data. As a consequence, the inferred dust emissivity index obtained from modified blackbody dust spectra was considerably lower than what is typically measured on ∼0.1 pc scales in nearby molecular clouds. Here we present new observations of OMC 2/3 collected with the MUSTANG-2 camera on the GBT that confirm this elevated emission. We also present for the first time sensitive 1 cm observations made with the Ka-band receiver on the GBT, which also show higher than expected emission. We use these observations - along with Herschel, JCMT, Mambo, and GISMO data - to assemble spectral energy distributions (SEDs) of a variety of structures in OMC 2/3 spanning the range 160 μm to 1 cm. The data at 2 mm and shorter are generally consistent with a modified blackbody spectrum and a single value of β ∼ 1.6. The 3 mm and 1 cm data, however, lie well above such an SED. The spectrum of the long-wavelength excess is inconsistent with both free-free emission and standard "Spinning Dust" models for Anomalous Microwave Emission (AME). The 3 mm and 1 cm data could be explained by a flatter dust emissivity at wavelengths shorter than 2 mm, potentially in concert with AME in some regions.

Keywords: Interstellar dust, Interstellar filaments, Molecular clouds, Dense interstellar clouds, Dust continuum emission, Star formation, Protostars
Prescriptions for Correcting Ultraviolet-based Redshifts for Luminous Quasars at High Redshift. High-redshift quasars typically have their redshift determined from rest-frame ultraviolet (UV) emission lines. However, these lines, and more specifically the prominent C IV λ1549 emission line, are typically blueshifted yielding highly uncertain redshift estimates compared to redshifts determined from rest-frame optical emission lines. We present near-infrared spectroscopy of 18 luminous quasars at 2.15 &lt; z &lt; 3.70 that allows us to obtain reliable systemic redshifts for these sources. Together with near-infrared spectroscopy of an archival sample of 44 quasars with comparable luminosities and redshifts, we provide prescriptions for correcting UV-based redshifts. Our prescriptions reduce velocity offsets with respect to the systemic redshifts by ∼140 km s-1 and reduce the uncertainty on the UV-based redshift by ∼25% with respect to the best method currently used for determining such values. We also find that the redshifts determined from the Sloan Digital Sky Survey Pipeline for our sources suffer from significant uncertainties, which cannot be easily mitigated. We discuss the potential of our prescriptions to improve UV-based redshift corrections given a much larger sample of high-redshift quasars with near-infrared spectra.

Keywords: Galaxy distances, Active galactic nuclei, Quasars
Deep Learning the Morphology of Dark Matter Substructure. Strong gravitational lensing is a promising probe of the substructure of dark matter halos. Deep-learning methods have the potential to accurately identify images containing substructure, and differentiate weakly interacting massive particle dark matter from other well motivated models, including vortex substructure of dark matter condensates and superfluids. This is crucial in future efforts to identify the true nature of dark matter. We implement, for the first time, a classification approach to identifying dark matter based on simulated strong lensing images with different substructure. Utilizing convolutional neural networks trained on sets of simulated images, we demonstrate the feasibility of deep neural networks to reliably distinguish among different types of dark matter substructure. With thousands of strong lensing images anticipated with the coming launch of Vera C. Rubin Observatory, we expect that supervised and unsupervised deep-learning models will play a crucial role in determining the nature of dark matter.

Keywords: Strong gravitational lensing, Convolutional neural networks, Dark matter
Constraints on the Emission of Gamma-Rays from M31 with HAWC. Cosmic rays, along with stellar radiation and magnetic fields, are known to make up a significant fraction of the energy density of galaxies such as the Milky Way. When cosmic rays interact in the interstellar medium, they produce gamma-ray emission which provides an important indication of how the cosmic rays propagate. Gamma-rays from the Andromeda galaxy (M31), located 785 kpc away, provide a unique opportunity to study cosmic-ray acceleration and diffusion in a galaxy with a structure and evolution very similar to the Milky Way. Using 33 months of data from the High Altitude Water Cherenkov Observatory, we search for teraelectronvolt gamma-rays from the galactic plane of M31. We also investigate past and present evidence of galactic activity in M31 by searching for Fermi bubble-like structures above and below the galactic nucleus. No significant gamma-ray emission is observed, so we use the null result to compute upper limits on the energy density of cosmic rays &gt;10 TeV in M31.

Keywords: High energy astrophysics, Galactic cosmic rays, Gamma-ray astronomy, Andromeda Galaxy, Particle astrophysics
When Does the Onset of Multiple Stellar Populations in Star Clusters Occur? III. No Evidence of Significant Chemical Variations in Main-sequence Stars of NGC 419. Recent studies have revealed that the onset age for the presence of multiple stellar populations (MPs) in star clusters seems to correspond to the disappearance of the extended main-sequence turnoff in young clusters, a pattern associated with stellar rotations. A speculative suggestion is that MPs might be caused by the magnetic brake, a stellar evolutionary effect linked to rotation. In this work, we use the young massive cluster NGC 419 as a testbed. We examined if its magnetically baked MS stars would exhibit MPs. Using the deep ultraviolet and visible images observed through the Hubble Space Telescope, combined with a specific color index that is sensitive to the nitrogen (N) abundance, we examined if its late G- and K-type MS stars are affected by N variation. Our analysis reports that the morphology of its GK-type MS is most likely a simple stellar population, and only a negligible probability, which indicates a N variation up to 0.4 dex is present. We therefore conclude that there is no significant N variation among its GK-type MS stars. The absence of a significant chemical variation among the late-type MS stars indicates that MPs might not be a specific pattern of magnetically braked stars.

Keywords: Globular star clusters, G dwarf stars, Stellar populations, K dwarf stars, Hertzsprung Russell diagram
Measuring the Hubble Constant from the Cooling of the CMB Monopole. The cosmic microwave background (CMB) monopole temperature evolves with the inverse of the cosmological scale factor, independent of many cosmological assumptions. With sufficient sensitivity, real-time cosmological observations could thus be used to measure the local expansion rate of the universe using the cooling of the CMB. We forecast how well a CMB spectrometer could determine the Hubble constant via this method. The primary challenge of such a mission lies in the separation of Galactic and extra-Galactic foreground signals from the CMB at extremely high precision. However, overcoming these obstacles could potentially provide an independent, highly robust method to shed light on the current low-/high-z Hubble tension. An experiment with 3000 linearly spaced bins between 5 GHz and 3 THz with a sensitivity of 1 $\mathrm{mJy}\sqrt{\mathrm{yr}}\,{\mathrm{sr}}^{-1}$ per bin, could measure H0 to 3% over a 10 yr mission, given current foreground complexity. This sensitivity would also enable high-precision measurements of the expected ΛCDM spectral distortions, but remains futuristic at this stage.

Keywords: Cosmic microwave background radiation
Suppressed or Enhanced Central Star Formation Rates in Late-type Barred Galaxies. Bars in disk-dominated galaxies are able to drive gas inflow inside the corotation radius, thus enhancing the central star formation rate (SFR). Previous work, however, has found that disk-dominated galaxies with centrally suppressed SFRs frequently host a bar. Here we investigate possible causes for the suppression of central SFRs in such cases. We compare the physical properties of a sample of disk-dominated barred galaxies with high central SFRs (HC galaxies) with those of a sample of disk-dominated barred galaxies with low central SFRs (LC galaxies). We find that the two samples have, on average, similar H I content and bars of similar strength. But we also find that the HCs have bluer colors than the LCs, and that outside the bar region, they host stronger spiral arms than the LCs, where closed rings are more often seen. We discuss and evaluate the possible causes for the suppression of the central SFR in the LC galaxies as opposed to its enhancement in the HC galaxies.

Keywords: Disk galaxies, Interstellar atomic gas, Galaxy structure, Spiral arms, Star formation, Barred spiral galaxies
Efficiently Jet-powered Radiation in Intermediate-luminosity Optical Transients. I show that a flow structure where wide jets hit a slower expanding shell might be very efficient in channeling the kinetic energy of the jets to radiation, therefore accounting for, at least a fraction of, intermediate-luminosity optical transients (ILOTs) where the total radiation energy is much larger than what recombination energy of the outflow can supply. This type of flow might occur in the frame of the high-accretion-powered ILOT (HAPI) model, where there is a high mass accretion rate as a result of stellar merger or mass transfer in a binary system. I derive the condition on the jets half opening angle for the jets not to penetrate through the slow shell, as well as the ratio of the photon diffusion time to expansion time. This ratio cannot be too large if a large fraction of the thermal energy is channeled to radiation. I apply the jet-powered radiation model to the Great Eruption of Eta Carinae, to V838 Mon, and to V4332 Sgr, and find a plausible set of parameters for these ILOTs. I expect the jet-powered radiation model to be more efficient in converting kinetic energy to radiation than ILOT models that are based on equatorial mass concentration. In many cases, though, I expect both jets and equatorial mass concentration to occur in the same system.

Keywords: Eruptive variable stars, Close binary stars, Stellar jets, Luminous blue variable stars, Variable stars
Ultra-light Dark Matter Is Incompatible with the Milky Way's Dwarf Satellites. The density profiles of dwarf galaxies are a highly varied set. If the dark matter is an ultra-light particle such as axions, then simulations predict a distinctive and unique profile. If the axion mass is large enough to fit the ultra-faint dwarf (UFD) satellites ( $m\gtrapprox {10}^{-21}$ eV), then the models do not fit the density profile of Fornax and Sculptor and are ruled out by more than $3-\sigma $ confidence. If the axion mass is in the mass range that can fit mass profiles of Fornax and Sculptor dwarf spheroidals, then its extended profile implies enormous masses ( $\approx {10}^{11}\mbox{--}{10}^{12}\,{M}_{\odot }$ ) for the UFDs. These large masses for the UFDS are ruled out by more than $3-\sigma $ confidence by dynamical friction arguments. The tension would increase further considering star formation histories and stellar masses of the UFDs. Unless future ultra-light dark matter (ULDM) simulations with baryonic feedback show a significant change in the density structure of the halos, the current data is incompatible with the ULDM scenario. Relaxing the slope constraint from classical dwarf galaxies would lead to excluding ULDM with mass less than $6\times {10}^{-22}\,{\rm{eV}}$ .

Keywords: Dark matter distribution, Dwarf galaxies, Dark matter, Dwarf spheroidal galaxies
Electron Energy Partition across Interplanetary Shocks. III. Analysis. An analysis of model fit results of 15,210 electron velocity distribution functions (VDFs), observed within ±2 hr of 52 interplanetary (IP) shocks by the Wind spacecraft near 1 au, is presented as the third and final part on electron VDFs near IP shocks. The core electrons and protons dominate in the magnitude and change in the partial-to-total thermal pressure ratio, with the core electrons often gaining as much or more than the protons. Only a moderate positive correlation is observed between the electron temperature and the kinetic energy change across the shock, while weaker, if any, correlations were found with any other macroscopic shock parameter. No VDF parameter correlated with the shock normal angle. The electron VDF evolves from a narrowly peaked core with flaring suprathermal tails in the upstream to either a slightly hotter core with steeper tails or much hotter flattop core with even steeper tails downstream of the weaker and strongest shocks, respectively. Both quasi-static and fluctuating fields are examined as possible mechanisms modifying the VDF, but neither is sufficient alone. For instance, flattop VDFs can be generated by nonlinear ion acoustic wave stochastic acceleration (I.e., inelastic collisions), while other work suggested they result from the combination of quasi-static and fluctuating fields. This three-part study shows that not only are these systems not thermodynamic in nature; even kinetic models may require modification to include things like inelastic collision operators to properly model electron VDF evolution across shocks or in the solar wind.

Keywords: Space plasmas, Interplanetary shocks, Plasma physics, Solar wind, Plasma astrophysics, Solar coronal mass ejection shocks, Interplanetary particle acceleration, Solar coronal mass ejections
MOSEL Survey: Tracking the Growth of Massive Galaxies at 2 &lt; z &lt; 4 Using Kinematics and the IllustrisTNG Simulation. We use K-band spectroscopic data from the Multi-Object Spectroscopic Emission Line survey to analyze the kinematic properties of galaxies at z &gt; 3. Our sample consists of 34 galaxies at 3.0 &lt; zspec &lt; 3.8 between 9.0 &lt; $\mathrm{log}({M}_{* }/{M}_{\odot })$ &lt; 11.0. We find that galaxies with $\mathrm{log}({M}_{* }/{M}_{\odot })$ &gt; 10.2 at z &gt; 3 have 56 ± 21 km s-1 lower integrated velocity dispersion compared to galaxies at z ≃ 2 of similar stellar mass. Massive galaxies at z &gt; 3 have either a flat or declining star formation history (SFH), whereas similar stellar mass galaxies at z ∼ 2.0 exhibit a slight peak in the past 500 Myr. Comparing with the IllustrisTNG cosmological simulation, we find that (I) the dynamical mass of massive galaxies in simulations ( $\mathrm{log}({M}_{* }/{M}_{\odot })$ &gt; 10.0) increases by ∼0.1 dex at a fixed stellar mass between z = 2.0-3.0, and (II) dynamical mass growth is coupled with a rapid rise in the ex situ stellar mass fraction (stars accreted from other galaxies) for massive galaxies at z &lt; 3.5. We speculate that the rising contribution of ex situ stellar mass to the total stellar mass growth of massive galaxies is driving the higher integrated velocity dispersion and rising SFHs of massive galaxies at z ∼ 2.0 compared to galaxies of similar stellar masses at z &gt; 3.

Keywords: High-redshift galaxies, Galaxy evolution, Spectroscopy, Galaxy kinematics
Response of SDO/HMI Observables to Heating of the Solar Atmosphere by Precipitating High-energy Electrons. We perform an analysis of the line-of-sight (LOS) observables of the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) for models of the solar atmosphere heated by precipitating high-energy electrons during solar flares. The radiative hydrodynamic (RADYN) flare models are obtained from the F-CHROMA database. The Stokes profiles for the Fe 6173 Å line observed by SDO/HMI are calculated using the radiative transfer code RH1.5D, assuming statistical equilibrium for atomic level populations, and imposing uniform background vertical magnetic fields of various strengths. The SDO/HMI observing sequence and LOS data processing pipeline algorithm are applied to derive the observables (continuum intensity, line depth, Doppler velocity, LOS magnetic field). Our results reveal that the strongest deviations of the observables from the actual spectroscopic line parameters are found for the model with a total energy deposited of Etotal = 1.0 × 1012 erg cm-2, injected with a power-law spectral index of δ = 3 above a low-energy cutoff of Ec = 25 keV. The magnitudes of the velocity and magnetic field deviations depend on the imposed magnetic field, and can reach 0.35 km s-1 for LOS velocities, 90 G for LOS magnetic field, and 3% for continuum enhancement for the 1000 G imposed LOS magnetic field setup. For Etotal ≥ 3.0 × 1011 erg cm-2 models, the velocity and magnetic field deviations are most strongly correlated with the energy flux carried by ∼50 keV electrons, and the continuum enhancement is correlated with the synthesized ∼55-60 keV hard X-ray photon flux. The relatively low magnitudes of perturbations of the observables and absence of magnetic field sign reversals suggest that the considered RADYN beam heating models augmented with the uniform vertical magnetic field setups cannot explain the strong transient changes found in the SDO/HMI observations.

Keywords: Solar photosphere, Solar flares, Solar magnetic fields, Spectropolarimetry
The Reddening and [O II] Emissions of the Quasar Mg II Absorption-line Systems. Using quasar Mg II narrow absorption lines (NALs) with velocity offset ( $\beta \equiv \tfrac{{\upsilon }_{r}}{c}=\tfrac{{\left(1+{z}_{\mathrm{em}}\right)}^{2}-({1+{z}_{\mathrm{abs}})}^{2}}{{\left(1+{z}_{\mathrm{em}}\right)}^{2}+{\left(1+{z}_{\mathrm{abs}}\right)}^{2}}$ , where c is the speed of light) ${\upsilon }_{r}\lt {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ , this paper investigates the $[{\rm{O}}\,{\rm{II}}]$ emissions and reddening associated with Mg II NALs by constructing composite spectra. Dust extinctions of all the inflow ( ${\upsilon }_{r}\lt -750$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ ), environment (-750 ≤ $\upsilon $ r &lt; 600 $\mathrm{km}\,{{\rm{s}}}^{-1}$ ), outflow ( $600\leqslant {\upsilon }_{r}\lt 2000$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ ), and strong intervening-like (2000 ≤ $\upsilon $ r &lt; 6000 $\mathrm{km}\,{{\rm{s}}}^{-1}$ ) Mg II NALs can be described by the SMC extinction curve, which suggest that all four types of Mg II NALs have similar dust properties. The colors of quasars hosting intervening-like Mg II NALs with ${W}_{r}^{\lambda \leqslant 1.5}$ Å and intervening Mg II NALs ( ${\upsilon }_{r}\geqslant 6000$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ ) are similar to those of control quasars (without Mg II NALs with ${\upsilon }_{r}\lt {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ ), which suggests that these two types of Mg II NALs are mainly formed within media unconnected with background quasars. The other three types of Mg II NALs have much more obvious reddening to background quasars, and the stronger absorptions or the absorptions detected in radio detected quasars produce larger reddening than the weaker absorptions or the absorptions in radio undetected quasars. In addition, the dust-to-gas ratios within inflow Mg II NALs are possibly lower than those within environment ones. We find that flux ratios $[{\rm{O}}\,{\rm{II}}]$ / $[\mathrm{Ne}\,{\rm{V}}]$ of quasars hosting inflow, outflow, intervening-like, and intervening Mg II NALs are similar to those of control quasars. For quasars hosting environment Mg II NALs, (1) the flux ratio $[{\rm{O}}\,{\rm{II}}]$ / $[\mathrm{Ne}\,{\rm{V}}]$ is much higher than that of control quasars, which suggests that there is a high star formation rate within the host galaxies of environment Mg II NALs; (2) the flux ratio $[{\rm{O}}\,{\rm{II}}]$ / $[\mathrm{Ne}\,{\rm{V}}]$ is positively correlated with absorption strengths; and (3) radio detected quasars have a slightly higher flux ratio $[{\rm{O}}\,{\rm{II}}]$ / $[\mathrm{Ne}\,{\rm{V}}]$ when compared to radio undetected quasars, which suggests that the quasar feedback enhances the star formation rate within host galaxies of environment absorbers. For quasars hosting outflow Mg II NALs, we find that $[{\rm{O}}\,{\rm{II}}]$ emission lines display excesses at blue wings with respect to the line profiles of control quasars, and the excesses are positively correlated with absorption strengths.

Keywords: Quasar absorption line spectroscopy, Interstellar dust extinction, Emission nebulae, Active galactic nuclei, Interstellar medium
Spinning Bar and a Star-formation Inefficient Repertoire: Turbulence in Hickson Compact Group NGC 7674. The physics regulating star formation (SF) in Hickson Compact Groups (HCG) has thus far been difficult to describe, due to their unique kinematic properties. In this study, we expand upon previous works to devise a more physically meaningful SF relation able to better encompass the physics of these unique systems. We combine CO(1-0) data from the Combined Array from Research in Millimeter Astronomy to trace the column density of molecular gas ${{\rm{\Sigma }}}_{\mathrm{gas}}$ and deep Hα imaging taken on the Southern Astrophysical Research Telescope tracing ${{\rm{\Sigma }}}_{\mathrm{SFR}}$ to investigate SF efficiency across face-on HCG, NGC 7674. We find a lack of universality in SF, with two distinct sequences present in the ${{\rm{\Sigma }}}_{\mathrm{gas}}$ - ${{\rm{\Sigma }}}_{\mathrm{SFR}}$ plane; one for inside and one for outside the nucleus. We devise an SF relation based on the multi-freefall nature of gas and the critical density, which itself is dependent on the virial parameter ${\alpha }_{\mathrm{vir}}$ , the ratio of turbulent to gravitational energy. We find that our modified SF relation fits the data and describes the physics of this system well with the introduction of a virial parameter of about 5-10 across the galaxy. This ${\alpha }_{\mathrm{vir}}$ leads to an order-of-magnitude reduction in SFR compared to ${\alpha }_{\mathrm{vir}}\approx 1$ systems.

Keywords: AGN host galaxies, Hickson compact group, Star forming regions, Star formation, Galaxies