Sazuna/UAT_keywords huggingface dataset:
The Relationship between Age, Metallicity, and Abundances for Disk Stars in a Simulated Milky Way. Observations of the Milky Way's low-α disk show that several element abundances correlate with age at fixed metallicity, with unique slopes and small scatters around the age-[X/Fe] relations. In this study, we turn to simulations to explore the age-[X/Fe] relations for the elements C, N, O, Mg, Si, S, and Ca that are traced in a FIRE-2 cosmological zoom-in simulation of a Milky Way-like galaxy, m12i, and understand what physical conditions give rise to the observed age-[X/Fe] trends. We first explore the distributions of mono-age populations in their birth and current locations, [Fe/H], and [X/Fe], and find evidence for inside-out radial growth for stars with ages &lt;7 Gyr. We then examine the age-[X/Fe] relations across m12i's disk and find that the direction of the trends agrees with observations, apart from C, O, and Ca, with remarkably small intrinsic scatters, σ int (0.01 - 0.04 dex). This σ int measured in the simulations is also metallicity dependent, with σ int ≈ 0.025 dex at [Fe/H] = -0.25 dex versus σ int ≈ 0.015 dex at [Fe/H] = 0 dex, and a similar metallicity dependence is seen in the GALAH survey for the elements in common. Additionally, we find that σ int is higher in the inner galaxy, where stars are older and formed in less chemically homogeneous environments. The age-[X/Fe] relations and the small scatter around them indicate that simulations capture similar chemical enrichment variance as observed in the Milky Way, arising from stars sharing similar element abundances at a given birth place and time.

Keywords: Hydrodynamical simulations, Milky Way Galaxy, Chemical abundances
Optimized Photometric Redshifts for the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). We present the first comprehensive release of photometric redshifts (photo- z's) from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) team. We use statistics based upon the Quantile-Quantile (Q-Q) plot to identify biases and signatures of underestimated or overestimated errors in photo- z probability density functions (PDFs) produced by six groups in the collaboration; correcting for these effects makes the resulting PDFs better match the statistical definition of a PDF. After correcting each group's PDF, we explore three methods of combining the different groups' PDFs for a given object into a consensus curve. Two of these methods are based on identifying the minimum f-divergence curve, i.e., the PDF that is closest in aggregate to the other PDFs in a set (analogous to the median of an array of numbers). We demonstrate that these techniques yield improved results using sets of spectroscopic redshifts independent of those used to optimize PDF modifications. The best photo- z PDFs and point estimates are achieved with the minimum f-divergence using the best four PDFs for each object (mFDa4) and the hierarchical Bayesian (HB4) methods, respectively. The HB4 photo- z point estimates produced σ NMAD = 0.0227/0.0189 and ∣∆z/(1 + z)∣ &gt; 0.15 outlier fraction = 0.067/0.019 for spectroscopic and 3D Hubble Space Telescope redshifts, respectively. Finally, we describe the structure and provide guidance for the use of the CANDELS photo- z catalogs, which are available at https://archive.stsci.edu/prepds/candels/.

Keywords: Galaxy distances, Hierarchical models, Redshift surveys
High-energy Neutrino Emission from Espresso-reaccelerated Ions in Jets of Active Galactic Nuclei. We present a bottom-up calculation of the flux of ultrahigh-energy cosmic rays (UHECRs) and high-energy neutrinos produced by powerful jets of active galactic nuclei (AGNs). By propagating test particles in 3D relativistic magnetohydrodynamic jet simulations, including a Monte Carlo treatment of sub-grid pitch-angle scattering and attenuation losses due to realistic photon fields, we study the spectrum and composition of the accelerated UHECRs and estimate the amount of neutrinos produced in such sources. We find that UHECRs may not be significantly affected by photodisintegration in AGN jets where the espresso mechanism efficiently accelerates particles, consistent with Auger's results that favor a heavy composition at the highest energies. Moreover, we present estimates and upper bounds for the flux of high-energy neutrinos expected from AGN jets. In particular, we find that (i) source neutrinos may account for a sizable fraction, or even dominate, the expected flux of cosmogenic neutrinos; (ii) neutrinos from the β-decay of secondary neutrons produced in nucleus photodisintegration end up in the teraelectronvolt to petaelectronvolt band observed by IceCube, but can hardly account for the observed flux; (iii) UHECRs accelerated via the espresso mechanism lead to nearly isotropic neutrino emission, which suggests that nearby radio galaxies may be more promising as potential sources. We discuss our results in light of multimessenger astronomy and current/future neutrino experiments.

Keywords: Radio jets, Ultra-high-energy cosmic radiation, Neutrino astronomy, Relativistic jets, Cosmological neutrinos, Particle astrophysics
Locating Type II-P Supernovae Using the Expanding Photosphere Method. I. Comparing Distances from Different Line Velocities. W present the results of our work testing a version of the Expanding Photosphere Method (EPM) used by Hamuy et al. and Dessart &amp; Hillier to calculate distances to Type II-P supernovae, accounting for the deviations of their luminosities from those of true blackbodies. This method was applied to a sample of supernovae with data sets covering different postexplosion time periods. Different spectral lines in visible wavelengths-Hβ, He I, Fe II, Sc II, Na I, and Ba II-are used to measure the expansion velocity with the goal of determining the species that produces the most reliable distance determination when combined with the blackbody temperature of the effective photosphere. This research suggests that Hβ, Fe II, and Ba II lines are most likely to yield accurate distances when combined with blackbody temperature, and provides further evidence of EPM's effectiveness as an indicator of distance, provided we have a minimum of three data sets covering a broad range of postexplosion phases of the supernova.

Keywords: Galaxy distances, Baade-Wesselink method, Effective temperature, Type II supernovae, Spectral line identification, Radial velocity
Comprehensive Study of Mass Ejection and Nucleosynthesis in Binary Neutron Star Mergers Leaving Short-lived Massive Neutron Stars. By performing general relativistic hydrodynamics simulations with an approximate neutrino radiation transfer, the properties of ejecta in the dynamical and post-merger phases are investigated in the cases in which the remnant massive neutron star collapses into a black hole in ≲20 ms after the onset of the merger. The dynamical mass ejection is investigated in three-dimensional simulations. The post-merger mass ejection is investigated in two-dimensional axisymmetric simulations with viscosity using the three-dimensional post-merger systems as the initial conditions. We show that the typical neutron richness of the dynamical ejecta is higher for the merger of more asymmetric binaries; hence, heavier r-process nuclei are dominantly synthesized. The post-merger ejecta are shown to have only mild neutron richness, which results in the production of lighter r-process nuclei, irrespective of the binary mass ratios. Because of the larger disk mass, the post-merger ejecta mass is larger for more asymmetric binary mergers. Thus, the post-merger ejecta can compensate for the underproduced lighter r-process nuclei for asymmetric merger cases. As a result, by summing up both ejecta components, the solar residual r-process pattern is reproduced within the average deviation of a factor of three, irrespective of the binary mass ratio. Our result also indicates that the (about a factor of a few) light-to-heavy abundance scatter observed in r-process-enhanced stars can be attributed to variation in the binary mass ratio and total mass. Implications of our results associated with the mass distribution of compact neutron star binaries and the magnetar scenario of short gamma-ray bursts are discussed.

Keywords: Neutron stars, R-process
M Subdwarf Research. III. Spectroscopic Diagnostics for Breaking Parameter Degeneracy. To understand the parameter degeneracy of M subdwarf spectra at low resolution, we assemble a large number of spectral features in the wavelength range 0.6-2.5 μm with band strength quantified by narrowband indices. Based on the index trends of BT-Settl model sequences, we illustrate how the main atmospheric parameters (T eff, log g, [M/H], and [α/Fe]) affect each spectral feature differently. Furthermore, we propose a four-step process to determine the four parameters sequentially, which extends the basic idea proposed by Jao et al. Each step contains several spectral features that break the degeneracy effect when determining a specific stellar parameter. Finally, the feasibility of each spectroscopic diagnostic with different spectral quality is investigated. The result is resolution-independent down to R ~ 200.

Keywords: M subdwarf stars, Stellar abundances, Stellar effective temperatures, M stars, Stellar atmospheres
Two-point Correlation Function Studies for the Milky Way: Discovery of Spatial Clustering from Disk Excitations and Substructure. We introduce a two-particle correlation function (2PCF) for the Milky Way, constructed to probe spatial correlations in the orthogonal directions of the stellar disk in the Galactic cylindrical coordinates of R, ϕ, and z. We use this new tool to probe the structure and dynamics of the Galaxy using the carefully selected set of solar neighborhood stars (d ≲ 3 kpc) from Gaia Data Release 2 that we previously employed for studies of axial symmetry breaking in stellar number counts. We make additional, extensive tests, comparing to reference numerical simulations, to ensure our control over possibly confounding systematic effects. Supposing either axial or north-south symmetry, we divide this data set into two nominally symmetric sectors and construct the 2PCF, in the manner of the Landy-Szalay estimator, from the Gaia data. In so doing, working well away from the midplane region in which the spiral arms appear, we have discovered distinct symmetry-breaking patterns in the 2PCF in its orthogonal directions, thus establishing the existence of correlations in stellar number counts alone at subkiloparsec length scales for the very first time. In particular, we observe extensive wavelike structures of amplitude greatly in excess of what we would estimate if the system were in a steady state. We study the variations in these patterns across the Galactic disk, and with increasing ∣z∣, and we show how our results complement other observations of non-steady-state effects near the Sun, such as vertical asymmetries in stellar number counts and the Gaia snail.

Keywords: Galaxy structure, Milky Way Galaxy
Laboratory Simulation of the Positron-Dust Interaction and its Implication for Interstellar Dark Clouds. We report the first laboratory experiment dealing with the interaction of a cosmic dust simulant with positrons emitted from a 22Na radioisotope. Measurements of a charge of micrometer SiO2 dust grains with an accuracy of one elementary charge e revealed +1 e steps due to positron annihilation inside the grain. The observed average rate of these charging events agrees well with prediction of a model based on the continuous slowing down approximation of energetic of positrons inside the grain. Less frequent charge steps larger than +1 e were attributed to emission of secondary electrons during positron slowing down. The determined coefficient of secondary electron emission is approximately inversely proportional to the grain radius. The experimental results led us to the formulation of a possible scenario of interstellar dark clouds charging.

Keywords: Interstellar dust, Interdisciplinary astronomy, Laboratory astrophysics, Nuclear physics
Complex Reactive Acids from Methanol and Carbon Dioxide Ice: Glycolic Acid (HOCH<SUB>2</SUB>COOH) and Carbonic Acid Monomethyl Ester (CH<SUB>3</SUB>OCOOH). The formation of complex organic molecules by simulated secondary electrons generated in the track of galactic cosmic rays was investigated in interstellar ice analogs composed of methanol and carbon dioxide. The processed ices were subjected to temperature-programmed desorption to mimic the transition of a cold molecular cloud to a warmer star-forming region. Reaction products were detected as they sublime using photoionization reflectron time-of-flight mass spectrometry. By employing isotopic labeling, tunable photoionization and computed adiabatic ionization energies isomers of C2H4O3 were investigated. Product molecules carbonic acid monomethyl ester (CH3OCOOH) and glycolic acid (HOCH2COOH) were identified. The abundance of the reactants detected in analog interstellar ices and the low irradiation dose necessary to form these products indicates that these molecules are exemplary candidates for interstellar detection. Molecules sharing a tautomeric relationship with glycolic acid, dihydroxyacetaldehyde ((OH)2CCHO), and the enol ethenetriol (HOCHC(OH)2), were not found to form despite ices being subjected to conditions that have successfully produced tautomerization in other ice analog systems.

Keywords: Interstellar molecules, Radical-radical recombination, Laboratory astrophysics, Astrochemistry, Pre-biotic astrochemistry
Shock-induced Stripping of the Satellite Interstellar and Circumgalactic Medium in IllustrisTNG Clusters at Z   0. Using the IllustrisTNG simulation, we study the interaction of large-scale shocks with the circumgalactic medium (CGM) and interstellar medium (ISM) of star-forming (SF) satellite galaxies in galaxy clusters. These shocks are usually produced by mergers and massive accretion. Our visual inspection shows that approximately half of SF satellites have encountered shocks in their host clusters at z ≤ 0.11. After a satellite crosses a shock front and enters the post-shock region, the ram pressure on it is boosted significantly. Both the CGM and ISM can be severely impacted, either by stripping or compression. The stripping of the ISM is particularly important for low-mass galaxies with $\mathrm{log}({M}_{* }/\,{h}^{-1}{M}_{\odot })\lt 10$ and can occur even in the outskirts of galaxy clusters. In comparison, satellites that do not interact with shocks lose their ISM only in the inner regions of clusters. About half of the ISM is stripped within about 0.6 Gyr after it crosses the shock front. Our results show that shock-induced stripping plays an important role in quenching satellite galaxies in clusters.

Keywords: Galaxy clusters, Hydrodynamical simulations, Ram pressure stripped tails, Shocks, Galaxy evolution, Galaxy quenching, Intracluster medium
Are the Heliosphere, Very Local Interstellar Medium, and Local Cavity in Pressure Balance with Galactic Gravity?. The Voyager spacecraft are providing the first in situ measurements of physical properties in the outer heliosphere beyond the heliopause. These data, together with data from the IBEX and Hubble Space Telescope and physical models consistent with these data, now provide critical measurements of pressures in the heliosphere and surrounding interstellar medium. Using these data, we assemble the first comprehensive survey of total pressures inside and outside of the heliopause, in the interstellar gas surrounding the heliosphere, and in the surrounding Local Cavity to determine whether the total pressures in each region are in balance with each other and with the gravitational pressure exerted by the galaxy. We intercompare total pressures in each region that include thermal, nonthermal, plasma, ram, and magnetic pressure components. An important result is the role of dynamic (ram) pressure. Total pressure balance at the heliopause can only be maintained with a substantial contribution of dynamic pressure from the inside. Also, total pressure balance between the outer heliosphere and pristine very local interstellar medium (VLISM) and between the pristine VLISM and the Local Cavity requires large dynamic pressure contributions. *Based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS AR-09525.01A. These observations are associated with programs #12475, 12596.

Keywords: Heliopause, Ultraviolet sources, Stellar-interstellar interactions, Heliosphere, Interstellar clouds, Warm neutral medium, Interstellar medium wind
Discovery of the Tadpole Molecular Cloud near the Galactic Nucleus. In this paper, we report the discovery of an isolated, peculiar compact cloud with a steep velocity gradient at 2.'6 northwest of Sgr A*. This "Tadpole" molecular cloud is unique owing to its characteristic head-tail structure in the position-velocity space. By tracing the CO J = 3-2 intensity peak in each velocity channel, we noticed that the kinematics of the Tadpole can be well reproduced by a Keplerian motion around a point-like object with a mass of 1 × 105 M ⊙. Changes in line intensity ratios along the orbit are consistent with the Keplerian orbit model. The spatial compactness of the Tadpole and absence of bright counterparts in other wavelengths indicate that the object could be an intermediate-mass black hole.

Keywords: Galactic center, Molecular clouds, Interstellar medium
The Origin of Star-forming Rings in S0 Galaxies. Spatially resolved integral field spectroscopic maps in a sample of 532 S0 galaxies from the MaNGA survey have unveiled the existence of inner rings (&lt;R&gt; ~ 1 R e) betraying ongoing star formation in a number of these objects. Activity gradients averaged over bins of galactocentric radius up to ~1.5 R e have been measured in the subspace defined by the first two principal components of the optical spectra of these galaxies. We find that the sign of the gradients is closely related to the presence of such rings in the spectral maps, which are especially conspicuous in the equivalent width of the Hα emission line, EW(Hα), with a fractional abundance-21%-34%-notably larger than that inferred from optical images. While the numbers of S0s with positive, negative, and flat activity gradients are comparable, star-forming rings are largely found in objects for which quenching proceeds from the inside out, in good agreement with predictions from cosmological simulations studying S0 buildup. Assessment of these ringed structures indicates that their frequency increases with the mass of their hosts, that they have shorter lifetimes in galaxies with ongoing star formation, that they may feed on gas from the disks, and that the local environment does not play a relevant role in their formation. We conclude that the presence of inner rings in EW(Hα) is a common phenomenon in fully formed S0s, possibly associated with annular disk resonances driven by weakly disruptive mergers preferentially involving a relatively massive primary galaxy and a tiny satellite strongly bound to the former.

Keywords: Lenticular galaxies, Galaxy spectroscopy, Galaxy evolution, Galaxy structure
The Roles of Morphology and Environment on the Star Formation Rate-Stellar Mass Relation in COSMOS from 0 &lt; z &lt; 3.5. We investigate the relationship between environment, morphology, and the star formation rate (SFR)-stellar mass relation derived from a sample of star-forming (SF) galaxies (commonly referred to as the "star formation main sequence", SFMS) in the COSMOS field from 0 &lt; z &lt; 3.5. We constructed and fit the far-UV-far-IR spectral energy distributions of our stellar-mass-selected sample of 111,537 galaxies with stellar and dust emission models using the public packages MAGPHYS and SED3FIT. From the best-fit parameter estimates, we construct the SFR-stellar mass relation as a function of redshift, local environment, NUVrJ color diagnostics, and morphology. We find that the shape of the main sequence derived from our color-color and specific-star-formation-rate-selected SF galaxy population, including the turnover at high stellar mass, does not exhibit an environmental dependence at any redshift from 0 &lt; z &lt; 3.5. We investigate the role of morphology in the high-mass end of the SFMS to determine whether bulge growth is driving the high-mass turnover. We find that SF galaxies experience this turnover independent of bulge-to-total ratio, strengthening the case that the turnover is due to the disk component's specific SFR evolving with stellar mass rather than bulge growth.

Keywords: Galaxy environments, Galaxy classification systems, Star formation, Galaxy evolution, Galaxy quenching
Meteorites and the RNA World: Synthesis of Nucleobases in Carbonaceous Planetesimals and the Role of Initial Volatile Content. Prebiotic molecules, fundamental building blocks for the origin of life, have been found in carbonaceous chondrites. The exogenous delivery of these organic molecules onto the Hadean Earth could have sparked the polymerization of the first RNA molecules in Darwinian ponds during wet-dry cycles. Here, we investigate the formation of the RNA and DNA nucleobases adenine, uracil, cytosine, guanine, and thymine inside parent body planetesimals of carbonaceous chondrites. An up-to-date thermochemical equilibrium model coupled with a 1D thermodynamic planetesimal model is used to calculate the nucleobase concentrations. Different from previous studies, we assume the initial volatile concentrations more appropriate for the formation zone of carbonaceous chondrite parent bodies. This represents more accurately cosmochemical findings that these bodies have formed inside the inner, ~2-5 au, warm region of the solar system. Due to these improvements, our model represents the concentrations of adenine and guanine measured in carbonaceous chondrites. Our model did not reproduce per se the measurements of uracil, cytosine, and thymine in these meteorites. This can be explained by transformation reactions between nucleobases and the potential decomposition of thymine. The synthesis of prebiotic organic matter in carbonaceous asteroids could be well explained by a combination of (i) radiogenic heating, (ii) aqueous chemistry involving a few key processes at a specific range of radii inside planetesimals where water can exist in the liquid phase, and (iii) a reduced initial volatile content (H2, CO, $\mathrm{HCN}$ , and CH2O) of the protoplanetary disk material in the parent body region compared to the outer region of comets.

Keywords: Chemical thermodynamics, Computational astronomy, Meteorite composition, Carbonaceous chondrites, Chemical abundances, Astrochemistry, Astrobiology, Planetesimals, Meteorites, Interdisciplinary astronomy, Comet volatiles , Pre-biotic astrochemistry