Sazuna/UAT_keywords huggingface dataset:
Measuring the Variability in K2 Optical Light Curves of 3C 273 and Other Fermi Active Galactic Nuclei in 2015-2017. We characterize the variability in nearly continuous optical observations of the bright radio-loud quasar 3C 273 and nine additional active galactic nuclei detected with the Fermi Gamma-ray Space Telescope Large Area Telescope (Fermi-LAT). Optical observations were obtained during the K2 mission with the Kepler spacecraft for periods of 49 to 83 days conducted with ≃1 minute (short) or ≃30 minutes (long) cadences in 2015-2017. 3C 273 was quiescent during the course of the observations, varying by only a factor of 1.02. Three objects, PKS 0047+023, PKS 1216-10, and PKS B2320-035, were active, varying by factors of 1.8-3.4. Six other objects were comparatively quiet, varying by factors of less than 1.4. Power spectral densities (PSDs) were calculated for each object. Overall, the slopes of most PSDs, as well as those we reported in an earlier paper, were in the range -2.0 to -2.7 and are consistent with those produced by turbulence in the relativistic jet, and not by "hot spots" in the disk emission. Mechanisms operating in the jet other than turbulence, such as "mini-jets" or "jet-in-jets", may also produce the observed range of PSD slopes. Both accretion disk and jet models are plausible origins for the 3C 273 optical variability during the K2 observations.

Keywords: Jets, Active galaxies, Active galactic nuclei
Formation of the Cosmic-Ray Halo: Galactic Spectrum of Primary Cosmic Rays. A self-consistent model of a one-dimensional cosmic-ray (CR) halo around the Galactic disk is formulated with the restriction of a minimum number of free parameters. It is demonstrated that the turbulent cascade of MHD waves does not necessarily play an essential role in the halo formation. Instead, an increase of the Alfvén velocity with distance to the disk leads to an efficient generic mechanism of the turbulent redshift, enhancing CR scattering by the self-generated MHD waves. As a result, the calculated size of the CR halo at lower energies is determined by the halo sheath, an energy-dependent region around the disk beyond which the CR escape becomes purely advective. At sufficiently high energies, the halo size is set by the characteristic thickness of the ionized gas distribution. The calculated Galactic spectrum of protons shows a remarkable agreement with observations, reproducing the position of the spectral break at $\approx 0.6$ TeV and the spectral shape up to ∼10 TeV.

Keywords: Galactic cosmic rays, Alfven waves, High energy astrophysics
Nonadiabatic Turbulence Driving during Gravitational Collapse. We investigate the generation of turbulence during the prestellar gravitational contraction of a turbulent spherical core. We define the ratio g of the one-dimensional turbulent velocity dispersion ${\sigma }_{1{\rm{D}}}$ to the gravitational velocity ${v}_{{\rm{g}}}$ to then analytically estimate g under the assumptions of (a) equipartition or virial equilibrium between the gravitational ( ${E}_{{\rm{g}}}$ ) and turbulent kinetic ( ${E}_{\mathrm{turb}}$ ) energies and (b) stationarity of transfer from gravitational to turbulent energy (implying ${E}_{\mathrm{turb}}/{E}_{{\rm{g}}}\,=$ cst). In the equipartition and virial cases, we find $g=\sqrt{1/3}\approx 0.58$ and $g=\sqrt{1/6}\approx 0.41$ , respectively; in the stationary case we find $g=\langle {v}_{\mathrm{rad}}\rangle {{ \mathcal L }}_{{\rm{d}}}/(4\pi \sqrt{3}\eta {{Rv}}_{{\rm{g}}})$ , where η is an efficiency factor, ${{ \mathcal L }}_{{\rm{d}}}$ is the energy injection scale of the turbulence, and R is the core's radius. Next, we perform AMR simulations of the prestellar collapse of an isothermal, transonic turbulent core at two different resolutions, and a nonturbulent control simulation. We find that the turbulent simulations collapse at the same rate as the nonturbulent one, so that the turbulence generation does not significantly slow down the collapse. We also find that (a) the simulations approach near balance between the rates of energy injection from the collapse and of turbulence dissipation; (b) $g\approx 0.395\pm 0.035$ , close to the "virial" value (turbulence is 30% ∼ 40% of nonthermal linewidth); (c) the injection scale is ${{ \mathcal L }}_{{\rm{d}}}\lesssim R$ , and (d) the "turbulent pressure" $\rho {\sigma }_{1{\rm{D}}}^{2}$ scales as $\sim {\rho }^{1.64}$ , an apparently nearly adiabatic scaling. We propose that this scaling and the nearly virial values of the turbulent velocity dispersion may be reconciled with the nondelayed collapse rate if the turbulence is dissipated as soon as it is generated.

Keywords: Collapsing clouds, Gravitational collapse, Molecular clouds
A Strong-lensing Model for the WMDF JWST/GTO Very Rich Cluster A1489. We present a first strong-lensing model for the galaxy cluster RM J121218.5+273255.1 (z = 0.35; hereafter RMJ1212; also known as A1489). This cluster is among the top 0.1% richest clusters in the redMaPPer catalog; it is significantly detected in X-ray and through the Sunyaev-Zel'dovich effect in ROSAT and Planck data, respectively, and its optical luminosity distribution implies a very large lens, following mass-to-light scaling relations. Based on these properties it was chosen for the Webb Medium Deep Fields (WMDF) James Webb Space Telescope/Guaranteed Time Observations program. In preparation for this program, RMJ1212 was recently imaged with Gemini Multi-Object Spectrograph (GMOS) on Gemini North and in seven optical and near-infrared bands with the Hubble Space Telescope (HST). We use these data to map the inner mass distribution of the cluster, uncovering various sets of multiple images. We also search for high-redshift candidates in the data, as well as for transient sources. We find over a dozen high-redshift (z ≳ 6) candidates based on both photometric redshift and the dropout technique. No prominent (≳5σ) transients were found in the data between the two HST visits. Our lensing analysis reveals a relatively large lens with an effective Einstein radius of θE ≃ 32 ± 3″ (zs = 2), in broad agreement with the scaling-relation expectations. RMJ1212 demonstrates that powerful lensing clusters can be selected in a robust and automated way following the light-traces-mass assumption.

Keywords: Galaxy clusters, Dark matter distribution, Strong gravitational lensing, Rich galaxy clusters, High-redshift galaxies
An ALMA Survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS Field: The Far-infrared/Radio Correlation for High-redshift Dusty Star-forming Galaxies. We study the radio properties of 706 submillimeter galaxies (SMGs) selected at 870 μm with the Atacama Large Millimeter Array from the SCUBA-2 Cosmology Legacy Survey map of the Ultra Deep Survey field. We detect 273 SMGs at &gt;4σ in deep Karl G. Jansky Very Large Array 1.4 GHz observations, of which a subset of 45 SMGs are additionally detected in 610 MHz Giant Metre-Wave Radio Telescope imaging. We quantify the far-infrared/radio correlation (FIRRC) through parameter qIR, defined as the logarithmic ratio of the far-infrared and radio luminosity, and include the radio-undetected SMGs through a stacking analysis. We determine a median qIR = 2.20 ± 0.03 for the full sample, independent of redshift, which places these z ∼ 2.5 dusty star-forming galaxies 0.44 ± 0.04 dex below the local correlation for both normal star-forming galaxies and local ultra-luminous infrared galaxies (ULIRGs). Both the lack of redshift evolution and the offset from the local correlation are likely the result of the different physical conditions in high-redshift starburst galaxies, compared to local star-forming sources. We explain the offset through a combination of strong magnetic fields (B ≳ 0.2 mG), high interstellar medium (ISM) densities and additional radio emission generated by secondary cosmic rays. While local ULIRGs are likely to have similar magnetic field strengths, we find that their compactness, in combination with a higher ISM density compared to SMGs, naturally explains why local and high-redshift dusty star-forming galaxies follow a different FIRRC. Overall, our findings paint SMGs as a homogeneous population of galaxies, as illustrated by their tight and nonevolving far-infrared/radio correlation.

Keywords: Starburst galaxies, High-redshift galaxies, Galaxy evolution
A Multiwavelength Analysis of the Faint Radio Sky (COSMOS-XS): the Nature of the Ultra-faint Radio Population. Ultra-deep radio surveys are an invaluable probe of dust-obscured star formation, but require a clear understanding of the relative contribution from radio active galactic nuclei (AGNs) to be used to their fullest potential. We study the composition of the μJy radio population detected in the Karl G. Jansky Very Large Array COSMOS-XS survey based on a sample of 1540 sources detected at 3 GHz over an area of ∼350 arcmin2. This ultra-deep survey consists of a single pointing in the well-studied COSMOS field at both 3 and 10 GHz and reaches rms sensitivities of 0.53 and 0.41 μJy beam-1, respectively. We find multiwavelength counterparts for 97% of radio sources, based on a combination of near-UV/optical to sub-millimeter data, and through a stacking analysis at optical/near-IR wavelengths we further show that the sources lacking such counterparts are likely to be high-redshift in nature (typical z ∼ 4-5). Utilizing the multiwavelength data over COSMOS, we identify AGNs through a variety of diagnostics and find these to make up 23.2 ± 1.3% of our sample, with the remainder constituting uncontaminated star-forming galaxies. However, more than half of the AGNs exhibit radio emission consistent with originating from star formation, with only 8.8 ± 0.8% of radio sources showing a clear excess in radio luminosity. At flux densities of ∼30 μJy at 3 GHz, the fraction of star formation-powered sources reaches ∼90%, and this fraction is consistent with unity at even lower flux densities. Overall, our findings imply that ultra-deep radio surveys such as COSMOS-XS constitute a highly effective means of obtaining clean samples of star formation-powered radio sources.

Keywords: Active galactic nuclei, Radio source counts, Galaxy evolution, Radio continuum emission, High-redshift galaxies, Catalogs
Depletion of Bright Red Giants in the Galactic Center during Its Active Phases. Observations in the near-infrared domain showed the presence of the flat core of bright late-type stars inside ∼0.5 pc from the Galactic center supermassive black hole (Sgr A*), while young massive OB/Wolf-Rayet stars form a cusp. Several dynamical processes were proposed to explain this apparent paradox of the distribution of the Galactic center stellar populations. Given the mounting evidence on the significantly increased activity of Sgr A* during the past million years, we propose a scenario based on the interaction between the late-type giants and a nuclear jet, whose past existence and energetics can be inferred from the presence of γ-ray Fermi bubbles and bipolar radio bubbles. Extended, loose envelopes of red giant stars can be ablated by the jet with kinetic luminosity in the range of Lj ≈ 1041- ${10}^{44}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ within the inner ∼0.04 pc of Sgr A* (S-cluster region), which would lead to their infrared luminosity decrease after several thousand jet-star interactions. The ablation of the atmospheres of red giants is complemented by the process of tidal stripping that operates at distances of ≲1 mpc, and by the direct mechanical interaction of stars with a clumpy disk at ≳0.04 pc, which can explain the flat density profile of bright late-type stars inside the inner half parsec from Sgr A*.

Keywords: Galactic center, Red supergiant stars, Relativistic jets, Stellar dynamics, Red giant stars
Statistical Properties of Habitable Zones in Stellar Binary Systems. Observations of exoplanets and protoplanetary disks show that binary stellar systems can host planets in stable orbits. Given the high binary fraction among stars, the contribution of binary systems to Galactic habitability should be quantified. Therefore, we have designed a suite of Monte Carlo experiments aimed at generating large (up to 106) samples of binary systems. For each system randomly extracted we calculate the intersection between the radiative habitable zones (HZs) and the regions of dynamical stability using published empirical formulations that account for the dynamical and radiative parameters of both stars of the system. We also consider constraints on planetary formation in binary systems. We find that the habitability properties of circumstellar and circumbinary regions are quite different and complementary with respect to the binary system parameters. Circumbinary HZs are, generally, rare (≃4%) in the global population of binary systems, even if they are common for stellar separations ≲0.2 au. Conversely, circumstellar HZs are frequent (≥80%) in the global population but are rare for stellar separations ≲1 au. These results are robust against variations of poorly constrained binary system parameters. We derive ranges of stellar separations and stellar masses for which HZs in binary systems can be wider than the HZs around single stars; the widening can be particularly strong (up to one order of magnitude) for circumstellar regions around M-type secondary stars. The comparison of our statistical predictions with observational surveys shows the impact of selection effects on the habitability properties of detected exoplanets in binary systems.

Keywords: Binary stars, Computational methods, Astrobiology, Habitable zone, Habitable planets
The Environmental Dependence of the X<SUB>CO</SUB> Conversion Factor. $\mathrm{CO}$ is the most widely used observational tracer of molecular gas. The observable $\mathrm{CO}$ luminosity is translated to ${{\rm{H}}}_{2}$ mass via a conversion factor, ${X}_{\mathrm{CO}}$ , which is a source of uncertainty and bias. Despite variations in ${X}_{\mathrm{CO}}$ , the empirically determined solar neighborhood value is often applied across different galactic environments. To improve understanding of ${X}_{\mathrm{CO}}$ , we employ 3D magnetohydrodynamics simulations of the interstellar medium (ISM) in galactic disks with a large range of gas surface densities, allowing for varying metallicity, far-ultraviolet (FUV) radiation, and cosmic-ray ionization rate (CRIR). With the TIGRESS simulation framework we model the three-phase ISM with self-consistent star formation and feedback, and post-process outputs with chemistry and radiation transfer to generate synthetic CO (1-0) and (2-1) maps. Our models reproduce the observed CO excitation temperatures, line widths, and line ratios in nearby disk galaxies. ${X}_{\mathrm{CO}}$ decreases with increasing metallicity, with a power-law slope of -0.8 for the (1-0) line and -0.5 for the (2-1) line. ${X}_{\mathrm{CO}}$ also decreases at higher CRIR and is insensitive to the FUV radiation. As density increases, ${X}_{\mathrm{CO}}$ first decreases owing to increasing excitation temperature and then increases when the emission is fully saturated. We provide fits between ${X}_{\mathrm{CO}}$ and observable quantities such as the line ratio, peak antenna temperature, and line brightness, which probe local gas conditions. These fits, which allow for varying beam size, may be used in observations to calibrate out systematic biases. We also provide estimates of the CO-dark ${{\rm{H}}}_{2}$ fraction at different gas surface densities, observational sensitivities, and beam sizes.

Keywords: Interstellar molecules, Molecular clouds, Chemical abundances, Galaxy disks, Interstellar medium, Magnetohydrodynamical simulations
The breakBRD Breakdown: Using IllustrisTNG to Track the Quenching of an Observationally Motivated Sample of Centrally Star-forming Galaxies. The observed breakBRD ("break bulges in red disks") galaxies are a nearby sample of face-on disk galaxies with particularly centrally concentrated star formation: they have red disks but recent star formation in their centers as measured by the Dn4000 spectral index. In this paper, we search for breakBRD analogs in the IllustrisTNG simulation and describe their history and future. We find that a small fraction (∼4% at z = 0; ∼1% at z = 0.5) of galaxies fulfill the breakBRD criteria, in agreement with observations. In comparison with the mass-weighted parent IllustrisTNG sample, these galaxies tend to consist of a higher fraction of satellite and splashback galaxies. However, the central, non-splashback breakBRD galaxies show similar environments, black hole masses, and merger rates, indicating that there is not a single formation trigger for inner star formation and outer quenching. We determine that breakBRD analog galaxies as a whole are in the process of quenching. The breakBRD state, with its highly centrally concentrated star formation, is uncommon in the history of either currently quiescent or star-forming galaxies; however, approximately 10% of 1010 &lt; M*/M⊙ &lt; 1011 quiescent galaxies at z = 0 have experienced SFR concentrations comparable to those of the breakBRDs in their past. Additionally, the breakBRD state is short lived, lasting a few hundred Myr up to ∼2 Gyr. The observed breakBRD galaxies may therefore be a unique sample of outside-in quenching galaxies.

Keywords: Galaxy environments, Astronomical simulations, Galaxy physics, Galaxy evolution, Galaxy quenching, Galaxy processes
The Significance of Low-frequency Interferometric Observations for the GPS Pulsar Flux Estimation: The Case of J1740+1000. In this paper we present recent Low Frequency Array observations of the pulsar J1740+1000. We confirm that its spectrum has a turnover at 260 MHz, which is unusual for a typical pulsar. We argue that in this case interferometric imaging provides more accurate pulsar flux estimates than other, more traditional, means such as beamformed observations. We conclude that existing calibration and imaging techniques can be used for a more comprehensive study of the influence of the interstellar medium on the point-like sources at very low frequencies in the near future.

Keywords: Interstellar medium, Radio pulsars
ALMaQUEST. IV. The ALMA-MaNGA QUEnching and STar Formation (ALMaQUEST) Survey. The ALMaQUEST (ALMA-MaNGA QUEnching and STar formation) survey is a program with spatially resolved 12CO(1-0) measurements obtained with the Atacama Large Millimeter Array (ALMA) for 46 galaxies selected from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) DR15 optical integral-field spectroscopic survey. The aim of the ALMaQUEST survey is to investigate the dependence of star formation activity on the cold molecular gas content at kiloparsec scales in nearby galaxies. The sample consists of galaxies spanning a wide range in specific star formation rate (sSFR), including starburst (SB), main-sequence (MS), and green valley (GV) galaxies. In this paper, we present the sample selection and characteristics of the ALMA observations and showcase some of the key results enabled by the combination of spatially matched stellar populations and gas measurements. Considering the global (aperture-matched) stellar mass, molecular gas mass, and star formation rate of the sample, we find that the sSFR depends on both the star formation efficiency (SFE) and the molecular gas fraction ( ${f}_{{{\rm{H}}}_{2}}$ ), although the correlation with the latter is slightly weaker. Furthermore, the dependence of sSFR on the molecular gas content (SFE or ${f}_{{{\rm{H}}}_{2}}$ ) is stronger than that on either the atomic gas fraction or the molecular-to-atomic gas fraction, albeit with the small HI sample size. On kiloparsec scales, the variations in both SFE and ${f}_{{{\rm{H}}}_{2}}$ within individual galaxies can be as large as 1-2 dex, thereby demonstrating that the availability of spatially resolved observations is essential to understand the details of both star formation and quenching processes.

Keywords: Molecular gas, Surveys, Star formation, Interstellar medium, Extragalactic astronomy, Galaxy quenching
Dust Attenuation Curves at z ∼ 0.8 from LEGA-C: Precise Constraints on the Slope and 2175ŠBump Strength. We present a novel approach to measure the attenuation curves of 485 individual star-forming galaxies with ${M}_{* }$ &gt; 1010 M☉ based on deep optical spectra from the VLT/VIMOS LEGA-C survey and multiband photometry in the COSMOS field. Most importantly, we find that the attenuation curves in the rest-frame 3000-4500 Å range are typically almost twice as steep as the Milky Way, LMC, SMC, and Calzetti attenuation curves, which is in agreement with recent studies of the integrated light of present-day galaxies. The attenuation at 4500 Å and the slope strongly correlate with the galaxy inclination: face-on galaxies show less attenuation and steeper curves compared to edge-on galaxies, suggesting that geometric effects dominate observed variations in attenuation. Our new method produces 2175 Å UV bump detections for 260 individual galaxies. Even though obvious correlations between UV bump strength and global galaxy properties are absent, strong UV bumps are most often seen in face-on, lower-mass galaxies (10 &lt; log10(M*/M☉) &lt; 10.5) with low overall attenuation. Finally, we produce a typical attenuation curve for star-forming galaxies at z ∼ 0.8; this prescription represents the effect of dust on the integrated spectral energy distributions of high-redshift galaxies more accurately than commonly used attenuation laws.

Keywords: Interstellar dust extinction
Theoretical versus Observational Uncertainties: Composition of Giant Exoplanets. In order to characterize giant exoplanets and better understand their origin, knowledge of how the planet's composition depends on its mass and stellar environment is required. In this work, we simulate the thermal evolution of gaseous planets and explore how various common model assumptions such as different equations of state, opacities, and heavy-element distributions affect the inferred radius and metallicity. We examine how the theoretical uncertainties translate into uncertainties in the inferred planetary radius and bulk metallicity. While we confirm the mass-metallicity trend previously reported in the literature, this correlation disappears when removing a 20 M⊕ heavy-element core from all the planets. We also show that using an updated hydrogen-helium equation of state leads to more compact planets. As a result, we present six planets that should be classified as inflated warm Jupiters. We next demonstrate that including the opacity enhancement due to metal-rich envelopes of irradiated planets changes the planetary radius significantly, which can have large effects on the inferred metallicity. Even though there are other model assumptions that have not been considered in this work, we could show that the calculated theoretical uncertainties can already be comparable or even larger than the observational ones. Therefore, theoretical uncertainties are likely to be even larger. We therefore conclude that progress in theoretical models of giant planets is essential in order to take full advantage of current and future exoplanetary data.

Keywords: Exoplanet evolution, Planetary interior, Extrasolar gaseous giant planets, Exoplanets