Sazuna/UAT_keywords huggingface dataset:
Atacama Cosmology Telescope: Dusty Star-forming Galaxies and Active Galactic Nuclei in the Equatorial Survey. We present a catalog of 510 radio-loud active galactic nuclei (AGNs, primarily blazars) and 287 dusty star-forming galaxies (DSFGs) detected by the Atacama Cosmology Telescope at $\gt 5\sigma $ significance in frequency bands centered on 148 GHz (2 mm), 218 GHz (1.4 mm), and 277 GHz (1.1 mm), from a 480 deg2 strip centered at R.A. 00h on the celestial equator with additional 360 deg2 shallower auxiliary fields at other longitudes. The combination of the deepest available 218 GHz wide-field imaging, our 277 GHz data, and multiband filtering results in the most sensitive wide-field millimeter-wave DSFG selection to date, with rms noise level referenced to 218 GHz reaching below 2 mJy. We have developed new techniques to remove Galactic contamination (including evidence for CO (2-1) line emission) from the extragalactic catalog, yielding a catalog of 321 Galactic sources in addition to the extragalactic catalog. We employ a new flux debiasing method that accounts for the heterogeneous sample selection in the presence of Galactic cuts. We present the spectral properties and source counts of the AGNs and DSFGs. The DSFG spectra depart from the Rayleigh-Jeans regime of an optically thin modified blackbody between 218 and 277 GHz, consistent with optically thick emission or an additional cold dust component. For AGNs with 148 and 218 GHz flux density &gt;50 mJy, we estimate the interyear rms fractional deviation in flux density due to source variability to be 40% with a 0.98 interband correlation coefficient. We provide source counts for AGNs in the range of 8-2870 mJy and for DSFGs in the range of 8-90 mJy. Our DSFG counts probe both the brighter, lensed population and the fainter, unlensed population. At 277 GHz we report the first measurements of source counts at these flux densities, finding an excess above most model count predictions. Finally, we present 30 of the brightest DSFGs that were selected for multifrequency study as candidate high-z lensed systems.

Keywords: Radio source catalogs, Galactic radio sources, Extragalactic radio sources, Blazars, Cosmic microwave background radiation, Radio source counts, Submillimeter astronomy, Radio sources
Probing Axial Symmetry Breaking in the Galaxy with Gaia Data Release 2. We study a set of solar neighborhood (d &lt; 3 kpc) stars from Gaia Data Release 2 to determine azimuthal star count differences, I.e., left and right of the line from the Galactic Center (GC) through the Sun - and compare these differences north and south. In this companion paper to Gardner et al., we delineate our procedures to remove false asymmetries from sampling effects, incompleteness, and/or interloper populations, as this is crucial to tests of axisymmetry. Particularly, we have taken care to make appropriate selections of magnitude, color, in-plane Galactocentric radius, and Galactic $| b| $ and $| z| $ . We find that requiring parallax determinations of high precision induces sampling biases, so that we eschew such requirements and exclude, e.g., regions around the lines of sight to the Magellanic Clouds, along with their mirror-image lines of sight, to ensure well-matched data sets. After making conservative cuts, we demonstrate the existence of azimuthal asymmetries and find differences in those, north and south. These asymmetries give key insights into the nature and origins of the perturbations on Galactic matter, allowing us to assess the relative influence of the Magellanic Clouds (LMC and SMC), the Galactic bar, and other masses on the Galactic mass distribution, as described in Gardner et al. The asymmetry's radial dependence reveals variations that we attribute to the Galactic bar, and it changes sign at a radius of (0.95 ± 0.03)R0, with R0 the Sun-GC distance, to give us the first direct assessment of the outer Lindblad resonant radius.

Keywords: Milky Way dark matter halo, Galaxy structure, Milky Way dynamics, Milky Way Galaxy
Runaway Coalescence of Pre-common-envelope Stellar Binaries. We study the process of runaway, unstable Roche lobe overflow in coalescing binary systems and its dependence on the properties of the binary involved. We create three-dimensional hydrodynamic models of binary coalescences and follow them through a phase of increasing Roche lobe overflow until the accretor is engulfed by the donor at the onset of a common-envelope phase. In these models, we vary binary properties of mass ratio, donor structure and spin, and equation of state through the gas adiabatic index. We compare the numerical results to semianalytic models of binary orbit evolution based on mass and angular momentum exchange between two point masses. Using our hydrodynamic simulations, we measure the key parameters: the donor mass-loss rate and the angular momentum exchanged per unit mass loss from the donor. Using these calibrations, the semianalytic model closely reproduces the escalating mass loss and runaway orbital decay observed in the hydrodynamic models. The semianalytic model accurately reproduces the major differences in orbit evolution that arise with varying mass ratio and donor structure. We encapsulate the semianalytic model in a publicly released Python package, RLOF. We apply this model to the observed period decay and subsequent merger of the binary V1309 Sco and find that it can simultaneously reproduce the observed orbital decay and time of outburst. We further demonstrate that there is a relationship between the period derivative and second derivative that can be a useful metric for evaluating candidate merging binaries.

Keywords: Hydrodynamical simulations, Binary stars, Interacting binary stars
Probing the Influence of a Tachocline in Simulated M-dwarf Dynamos. M-type stars are among the best candidates in searches for habitable Earth-like exoplanets, and yet many M-dwarfs exhibit extraordinary flaring that would bombard otherwise habitable planets with ionizing radiation. Observers have found that the fraction of M-stars demonstrating significant activity transitions from roughly 10% for main-sequence stars more massive than 0.35 M☉ to nearly 90% for less massive stars. The latter are typically rotating quite rapidly, suggesting differing spin-down histories. It is also below 0.35 M☉ when main-sequence stars become fully convective and may no longer contain a tachocline. We turn here to the more massive M-stars to study the impact such a layer may have on their internal dynamics. Using the global MHD code Rayleigh, we compare the properties of convective dynamos generated within rapidly rotating 0.4 M☉ stars, with the computational domain either terminating at the base of the convection zone or permitting overshoot into the underlying stable region. We find that a tachocline is not necessary for the organization of strong toroidal wreaths of magnetism in these stars, though it can increase the coupling of mean field amplitudes to the stellar rotation rate. Additionally, we note that the presence of a tachocline tends to make magnetic cycles more regular than they would otherwise have been, and can permit alternative field configurations with much longer cycles. Finally, we find that the tachocline helps enhance the emergent fields and organize them into larger spatial scales, providing favorable conditions for more rapid spin-down via the stellar wind.

Keywords: M dwarf stars, Stellar convection envelopes, Magnetohydrodynamical simulations, Low mass stars, Magnetic fields, Stellar evolution
Multiwavelength Absolute Magnitudes and Colors of Red Clump Stars in the Gaia Era. This study presents the multiwavelength investigation of the absolute magnitudes and colors of the red clump (RC) stars selected from APOGEE and GALAH DR2 combined catalog which is complemented with Gaia DR2 astrometric data and multiwavelength photometric data of GALEX GR6/7, SDSS DR7, Gaia DR2, 2MASS, and WISE sky surveys. The analyses are centered on the different distance estimation methods using Gaia trigonometric parallaxes, (1/ϖ) and Bayes statistics, and chemically defined Galactic disk populations on [α/Fe] × [Fe/H] plane. This investigation questions the long-studied problem of the population effects on RC luminosity. Using two different distance estimation approaches, (I) chemical thin and chemical thick disk RC stars are shown to have different absolute magnitudes, while colors remain the same in all photometric bands. Absolute magnitudes vary between -0.12 and +0.13 mag for the 1/ϖ with the change of the Galactic population. This variation in absolute magnitudes is found to be larger for the other method, (II) the Besançon population synthesis model of Galaxy for 2MASS photometry, in which the absolute magnitude difference between chemical populations were found between -0.35 and -0.40 mag from thin disk to thick disk. When results compared with each other, differences of absolute magnitudes are about three times larger in the model than in the observations. We confirm that the RC absolute magnitudes depend on α-element abundances of Galactic populations.

Keywords: Red giant clump, Absolute magnitude, Stellar populations
Rotational Disruption of Nonspherical Cometary Dust Particles by Radiative Torques. Rigorous statistical numerical analysis of the response of a nonspherical dust particle ensemble composed of aggregates of astronomical silicate is presented. It is found that the rotational disruption mechanism is not only likely to occur but to be a key element in explaining many separate observations of cometary dust. Namely, radiative torques are shown to spin-up and align cometary dust within the timescales of cometary activity. Additionally, the radiative torque alignment and disruption mechanisms within certain conditions are shown to be consistent with observations of rapid polarization of dust and spectral bluing of dust. The results indicate that radiative torques should be taken into account nearly universally when considering the evolution of cometary dust.

Keywords: Astrophysical dust processes, Circumstellar dust, Coma dust
Radial Evolution of Magnetic Field Fluctuations in an Interplanetary Coronal Mass Ejection Sheath. The sheaths of compressed solar wind that precede interplanetary coronal mass ejections (ICMEs) commonly display large-amplitude magnetic field fluctuations. As ICMEs propagate radially from the Sun, the properties of these fluctuations may evolve significantly. We have analyzed magnetic field fluctuations in an ICME sheath observed by MESSENGER at 0.47 au and subsequently by STEREO-B at 1.08 au while the spacecraft were close to radial alignment. Radial changes in fluctuation amplitude, compressibility, inertial-range spectral slope, permutation entropy, Jensen-Shannon complexity, and planar structuring are characterized. These changes are discussed in relation to the evolving turbulent properties of the upstream solar wind, the shock bounding the front of the sheath changing from a quasi-parallel to quasi-perpendicular geometry, and the development of complex structures in the sheath plasma.

Keywords: Interplanetary turbulence, Solar wind, Interplanetary magnetic fields
A New Census of the 0.2 &lt; z &lt; 3.0 Universe. I. The Stellar Mass Function. There has been a long-standing factor-of-two tension between the observed star formation rate density and the observed stellar mass buildup after z ∼ 2. Recently, we have proposed that sophisticated panchromatic SED models can resolve this tension, as these methods infer systematically higher masses and lower star formation rates than standard approaches. In a series of papers, we now extend this analysis and present a complete, self-consistent census of galaxy formation over 0.2 &lt; z &lt; 3 inferred with the Prospector galaxy SED-fitting code. In this work, Paper I, we present the evolution of the galaxy stellar mass function using new mass measurements of ∼105 galaxies in the 3D-HST and COSMOS-2015 surveys. We employ a new methodology to infer the mass function from the observed stellar masses: instead of fitting independent mass functions in a series of fixed redshift intervals, we construct a continuity model that directly fits for the redshift evolution of the mass function. This approach ensures a smooth picture of galaxy assembly and makes use of the full, non-Gaussian uncertainty contours in our stellar mass inferences. The resulting mass function has higher number densities at a fixed stellar mass than almost any other measurement in the literature, largely owing to the older stellar ages inferred by Prospector. The stellar mass density is ∼50% higher than previous measurements, with the offset peaking at z ∼ 1. The next two papers in this series will present the new measurements of the star-forming main sequence and the cosmic star formation rate density, respectively.

Keywords: Galaxy formation, Galaxy abundances, High-redshift galaxies, Galaxy properties
Modeling the Uncertainties of Solar System Ephemerides for Robust Gravitational-wave Searches with Pulsar-timing Arrays. The regularity of pulsar emissions becomes apparent once we reference the pulses' times of arrivals to the inertial rest frame of the solar system. It follows that errors in the determination of Earth's position with respect to the solar system barycenter can appear as a time-correlated bias in pulsar-timing residual time series, affecting the searches for low-frequency gravitational waves performed with pulsar-timing arrays. Indeed, recent array data sets yield different gravitational-wave background upper limits and detection statistics when analyzed with different solar system ephemerides. Crucially, the ephemerides do not generally provide usable error representations. In this article, we describe the motivation, construction, and application of a physical model of solar system ephemeris uncertainties, which focuses on the degrees of freedom (Jupiter's orbital elements) most relevant to gravitational-wave searches with pulsar-timing arrays. This model, BayesEphem, was used to derive ephemeris-robust results in NANOGrav's 11 yr stochastic-background search, and it provides a foundation for future searches by NANOGrav and other consortia. The analysis and simulations reported here suggest that ephemeris modeling reduces the gravitational-wave sensitivity of the 11 yr data set and that this degeneracy will vanish with improved ephemerides and with pulsar-timing data sets that extend well beyond a single Jovian orbital period.

Keywords: Ephemerides, Pulsar timing method, Millisecond pulsars, Astronomy data analysis, Gravitational waves
3D Radiative MHD Simulations of Starspots. There are no direct spatially resolved observations of spots on stars other than the Sun, and starspot properties are inferred indirectly through lightcurves and spectropolarimetric data. We present the first self-consistent 3D radiative MHD computations of starspots on G2V, K0V, and M0V stars, which will help us to better understand observations of activity, variability, and magnetic fields in late-type main-sequence stars. We used the MURaM code, which has been extensively used to compute "realistic" sunspots, for our simulations. We aim to study how fundamental starspot properties such as intensity contrast, temperature, and magnetic field strength vary with spectral type. We first simulated in 2D multiple spots of each spectral type to find out appropriate initial conditions for our 3D runs. We find that with increasing stellar effective temperature, there is an increase in the temperature difference between the umbra of the spot and its surrounding photosphere, from 350 K on the M0V star to 1400 K on the G2V star. This trend in our simulated starspots is consistent with observations. The magnetic field strengths of all the starspot umbrae are in the 3-4.5 kG range. The G2V and K0V umbrae have comparable magnetic field strengths around 3.5 kG, while the M0V umbra has a relatively higher field strength around 4 kG. We discuss the physical reasons behind both these trends. All of the three starspots develop penumbral filament-like structures with Evershed flows. The average Evershed flow speed drops from 1.32 km s-1 in the G2V penumbra to 0.6 km s-1 in the M0V penumbra.

Keywords: Starspots, Radiative magnetohydrodynamics, Sunspots, Stellar magnetic fields, Stellar activity
Uncertainty Quantification in Planetary Thermal History Models: Implications for Hypotheses Discrimination and Habitability Modeling. Multiple hypotheses/models have been put forward regarding Earth's cooling history. Searching for life beyond Earth has brought these models into a new light as they connect to an energy source that life can tap. Discriminating between different cooling models and adapting them to aid in the assessment of planetary habitability has been hampered by a lack of uncertainty quantification. Here, we provide an uncertainty quantification that accounts for a range of interconnected model uncertainties. This involved calculating over a million individual model evolutions to determine uncertainty metrics. Accounting for uncertainties means that model results must be evaluated in a probabilistic sense, even though the underlying models are deterministic. The uncertainty analysis was used to quantify the degree to which different models can satisfy observational constraints on the Earth's cooling. For the Earth's cooling history, uncertainty leads to ambiguity - multiple models, based on different hypotheses, can match observations. This has implications for using such models to forecast conditions for exoplanets that share Earth characteristics but are older than the Earth, I.e., ambiguity has implications for modeling the long-term life potential of terrestrial planets. Even for the most earthlike planet we know of, the Earth itself, model uncertainty and ambiguity leads to large forecast spreads. Given that Earth has the best data constraints, we should expect larger spreads for models of terrestrial planets, in general. The uncertainty analysis provided here can be expanded by coupling planetary cooling models to climate models and propagating uncertainty between them to assess habitability from a probabilistic view.

Keywords: Uncertainty bounds, Planetary interior, Habitable planets
First Observation of a Type II Solar Radio Burst Transitioning between a Stationary and Drifting State. Standing shocks are believed to be responsible for stationary Type II solar radio bursts, whereas drifting Type II bursts are excited by moving shocks often related to coronal mass ejections (CMEs). Observations of either stationary or drifting Type II bursts are common, but a transition between the two states has not yet been reported. Here, we present a Type II burst which shows a clear, continuous transition from a stationary to a drifting state, the first observation of its kind. Moreover, band splitting is observed in the stationary parts of the burst, as well as intriguing negative and positive frequency-drift fine structures within the stationary emissions. The relation of the radio emissions to an observed jet and a narrow CME were investigated across multiple wavelengths, and the mechanisms leading to the transitioning Type II burst were determined. We find that a jet eruption generates a streamer-puff CME and that the interplay between the CME-driven shock and the streamer is likely to be responsible for the observed radio emissions.

Keywords: Solar coronal radio emission, Solar coronal mass ejection shocks, Solar physics, Radio bursts, Solar radiation, Solar activity, Shocks
Dynamical Simulations of the First Globular Clusters. A Milky Way-like halo is simulated with tidally limited star clusters inserted in the dark matter halos present at high redshift. An n-body code augmented with velocity relaxation in the star clusters evolves the system. The stripped stars and remnant clusters that began in the lower mass subhalos have a distribution somewhat more extended than the dark matter halo, with a mean galactic radius of about 60 kpc inside 150 kpc, whereas the distribution of all stripped stars and clusters is more centrally concentrated than the dark matter. The clusters from low mass subhalos, those with a peak circular velocity of 12-18 $\,\mathrm{km}\,{{\rm{s}}}^{-1}$ , also produce most of the population's thin stellar streams. Together these suggest a search strategy for extremely metal-poor cluster stars and their remnants. The dependence of the stellar population distribution on subhalo mass is not seen in simulations that start clusters at lower redshift. The half mass radii of the clusters are set by the tidal fields of the initial subhalo, "dwarf galaxy" location, which causes the average half mass-radius to decrease with increasing redshift of formation. Starting clusters at greater than redshift 4 leads to cluster half mass radii approximately as seen in the Milky Way.

Keywords: Globular star clusters, Milky Way stellar halo, Milky Way formation
Star Formation Enhancement in Barred Disk Galaxies in Interacting Galaxy Clusters. A recent study shows that bars can be induced via interaction of galaxy clusters, but it has been unclear if the bar formation by the interaction between clusters is related to the enhancement of star formation. We study galaxies in 105 galaxy clusters at 0.015 &lt; z &lt; 0.060 detected from Sloan Digital Sky Survey data, in order to examine whether the fraction of star-forming galaxies (fsf) in 16 interacting clusters is enhanced compared with that of the other non-interacting clusters and to investigate the possible connection between the fsf enhancement and the bar formation in interacting clusters. We find that fsf is moderately higher (∼20%) in interacting clusters than in non-interacting clusters and that the enhancement of star formation in interacting clusters occurs only in moderate-mass disk-dominated galaxies ( ${10}^{10.0}\leqslant {M}_{\mathrm{star}}/{M}_{\odot }\lt {10}^{10.4}$ and the bulge-to-total light ratio is ≤0.5). We also find that the enhancement of fsf in moderate-mass disk-dominated galaxies in interacting clusters is mostly due to the increase of the number of barred galaxies. Our result suggests that the cluster-cluster interaction can simultaneously induce bars and star formation in disk galaxies.

Keywords: Galaxy clusters, Cosmological evolution, Galaxy formation, Galaxy environments, Galaxy infall, Star formation, Galaxy evolution, Tidal interaction, Barred spiral galaxies