Sazuna/UAT_keywords huggingface dataset:
The MAVERIC Survey: Dynamical Origin of Radio Sources in Galactic Globular Clusters. We investigate potential correlations between radio source counts (after background corrections) of 22 Galactic globular clusters (GCs) from the MAVERIC survey and the stellar encounter rates (Γ) and masses (M) of the GCs. Applying a radio luminosity limit of ${L}_{\mathrm{lim}}=5.0\times {10}^{27}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ , we take a census of radio sources in the core and those within the half-light radius of each cluster. By following a maximum likelihood method and adopting a simplified linear model, we find an unambiguous dependence of core radio source counts on Γ and/or M at 90% confidence, but no clear dependence of source counts within the half-light radius on either Γ or M. Five of the identified radio sources in GC cores above our adopted limit are millisecond pulsars or neutron star X-ray binaries, the dependence of which on Γ is well known, but another is a published black hole (BH) X-ray binary candidate, and 10 others are not identified. Accounting for these verified cluster members increases the significance of the correlation with M and/or Γ (to 99% confidence) for fits to core and half-light region source counts, while excluding a dependence on Γ alone at 90% (core) and 68% (half-light) confidence. This is consistent with published dynamical simulations of GC BH interactions that argue Γ will be a poor predictor of the distribution of accreting BHs in GCs. Future multiwavelength follow-up to verify cluster membership will enable stronger constraints on the dependence of radio source classes on cluster properties, promising a new view on the dynamics of BHs in GCs.

Keywords: Globular star clusters, Neutron stars, Black holes, Stellar dynamics, Compact objects, Low-mass x-ray binary stars
The Lopsided Distribution of Satellites of Isolated Central Galaxies. Satellites are not randomly distributed around their central galaxies but show polar and planar structures. In this paper, we investigate the axis asymmetry or lopsidedness of satellite galaxy distributions around isolated galaxies in a hydrodynamic cosmological simulation. We find a statistically significant lopsided signal by studying the angular distribution of the satellite galaxies' projected positions around isolated central galaxies in a two-dimensional plane. The signal is dependent on galaxy mass, color, and large-scale environment. Satellites that inhabit low-mass blue hosts, or located further from the hosts, show the most lopsided signal. Galaxy systems with massive neighbors exhibit stronger lopsidedness. This satellite axis-asymmetry signal also decreases as the universe evolves. Our findings are in agreement with recent observational results and they provide a useful perspective for studying galaxy evolution, especially on the satellite accretion, internal evolution, and interaction with the cosmic large-scale structure.

Keywords: Cold dark matter, Dwarf galaxies, Astrostatistics, Large-scale structure of the universe
The Evolution of the Ultraluminous Lyα Luminosity Function over z = 5.7-6.6. Ultraluminous Lyα emitting galaxies (ULLAEs) with $\mathrm{log}L(\mathrm{Ly}\alpha )\gt 43.5$ erg s-1 near the epoch of reionization (z &gt; 5) make up the bright end of the LAE luminosity function (LF) and may provide insight into the process of reionization, including the formation of ionized bubbles around these extreme systems. We present a spectroscopic LF for ULLAEs at z = 5.7. We used data from the HEROES ~45 deg2 Subaru Hyper Suprime-Cam survey, which is centered on the North Ecliptic Pole and has both broadband (grizY) and narrowband (NB816 and NB921) imaging, to select candidate ULLAEs based on a NB816 excess and a strong broadband Lyman break. We spectroscopically observed 17 ULLAE candidates with DEIMOS on Keck II. We confirmed 12 as LAEs at z = 5.7, 9 of which are ULLAEs. The remaining sources are an active galactic nuclei at z = 5.7, an [O III]λ5007 emitter at z = 0.63, a red star, and two spectroscopic nondetections. Using the nine confirmed ULLAEs, we construct a ULLAE LF at z = 5.7. After applying a comprehensive incompleteness correction, we compare our new z = 5.7 LF with our recent z = 6.6 LF and with other LFs from the literature to look for evolution at the ultraluminous end. We find the overall ratio of the z = 5.7 to z = 6.6 ULLAE comoving number densities to be ${1.92}_{-0.71}^{+1.12}$ , which corresponds to an LF offset of ${0.28}_{-0.20}^{+0.20}$ dex.

Keywords: Lyman-alpha galaxies, Observational cosmology, Emission line galaxies, Galaxies
Determining the Structure of Rotating Massive Stellar Cores with Gravitational Waves. The gravitational wave (GW) signal resulting from stellar core collapse encodes a wealth of information about the physical parameters of the progenitor star and the resulting core-collapse supernova (CCSN). We present a novel approach to constrain CCSN progenitor properties at collapse using two of the most detectable parts of the GW signal: the core-bounce signal and evolution of the dominant frequency mode from the protoneutron star. We focus on the period after core bounce but before explosion and investigate the predictive power of GWs from rotating CCSNe to constrain properties of the progenitor star. We analyze 34 2D and four 3D neutrino-radiation-hydrodynamic simulations of stellar core collapse in progenitors of varied initial mass and rotation rate. Extending previous work, we verify the compactness of the progenitor at collapse to correlate with the early ramp-up slope, and in rotating cases, also with the core angular momentum. Combining this information with the bounce signal, we present a new analysis method to constrain the pre-collapse core compactness of the progenitor. Because these GW features occur less than a second after core bounce, this analysis could allow astronomers to predict electromagnetic properties of a resulting CCSN even before shock breakout.

Keywords: Gravitational wave astronomy, Massive stars, Gravitational wave sources, Core-collapse supernovae
Compressive Oscillations in Hot Coronal Loops: Are Sloshing Oscillations and Standing Slow Waves Independent?. Employing high-resolution EUV imaging observations from SDO/AIA, we analyze a compressive plasma oscillation in a hot coronal loop triggered by a C-class flare near one of its footpoints, as first studied by Kumar et al. We investigate the oscillation properties in both the 131 Å and 94 Å channels and find that what appears as a pure sloshing oscillation in the 131 Å channel actually transforms into a standing wave in the 94 Å channel at a later time. This is the first clear evidence of such transformation and confirms the results of a recent numerical study that suggests that these two oscillations are not independent phenomena. We introduce a new analytical expression to properly fit the sloshing phase of an oscillation and extract the oscillation properties. For the AIA 131 Å channel, the obtained oscillation period and damping time are 608 ± 4 s and 431 ± 20 s, respectively, during the sloshing phase. The corresponding values for the AIA 94 Å channel are 617 ± 3 s and 828 ± 50 s. During the standing phase that is observed only in the AIA 94 Å channel, the oscillation period and damping time have increased to 791 ± 5 s and 1598 ± 138 s, respectively. The plasma temperature obtained from the differential emission measure analysis indicates substantial cooling of the plasma during the oscillation. Considering this, we show that the observed oscillation properties and the associated changes are compatible with damping due to thermal conduction. We further demonstrate that the absence of a standing phase in the 131 Å channel is a consequence of cooling plasma besides the faster decay of oscillation in this channel.

Keywords: Solar coronal loops, Magnetohydrodynamics, Solar coronal waves
Ion Acceleration Efficiency at the Earth's Bow Shock: Observations and Simulation Results. Collisionless shocks are some of the most efficient particle accelerators in heliospheric and astrophysical plasmas. Here we study and quantify ion acceleration at Earth's bow shock with observations from NASA's Magnetospheric Multiscale (MMS) satellites and in a global hybrid-Vlasov simulation. From the MMS observations, we find that quasiparallel shocks are more efficient at accelerating ions. There, up to 15% of the available energy goes into accelerating ions above 10 times their initial energy. Above a shock-normal angle of ~50°, essentially no energetic ions are observed downstream of the shock. We find that ion acceleration efficiency is significantly lower when the shock has a low Mach number (MA &lt; 6) while there is little Mach number dependence for higher values. We also find that ion acceleration is lower on the flanks of the bow shock than at the subsolar point regardless of the Mach number. The observations show that a higher connection time of an upstream field line leads to somewhat higher acceleration efficiency. To complement the observations, we perform a global hybrid-Vlasov simulation with realistic solar-wind parameters with the shape and size of the bow shock. We find that the ion acceleration efficiency in the simulation shows good quantitative agreement with the MMS observations. With the combined approach of direct spacecraft observations, we quantify ion acceleration in a wide range of shock angles and Mach numbers.

Keywords: Shocks, Interplanetary particle acceleration, Planetary bow shocks, Magnetic fields
Chandra Observations of Excess Fe Kα Line Emission in Galaxies with High Star Formation Rates: X-Ray Reflection on Galaxy Scales?. In active galactic nuclei (AGNs), fluorescent Fe Kα (iron) line emission is generally interpreted as originating from obscuring material around a supermassive black hole on the scale of a few parsecs. However, recent Chandra studies indicate the existence of iron line emission extending to kiloparsec scales in the host galaxy. The connection between iron line emission and large-scale material can be spatially resolved directly only in nearby galaxies, but could be inferred in more distant AGNs by a connection between line emission and star-forming gas and dust that is more extended than the parsec-scale torus. Here we present the results from a stacking analysis and X-ray spectral fitting performed on sources in the Chandra Deep Field South (CDFS) 7 Ms observations. From the deep stacked spectra, we select sources with stellar mass $\mathrm{log}({M}_{* }/{M}_{\odot })\gt 10$ at 0.5 &lt; z &lt; 2, obtaining 25 sources with high-infrared (IR) luminosity (star formation rate, SFRFIR ≥ 17 M⊙ yr-1) and 32 sources below this threshold. We find that the equivalent width (EW) of the iron line EW(Fe) is a factor of three higher with 3σ significance for high-IR luminosity measured from Herschel observations, indicating a connection between iron line emission and star-forming material on galaxy scales. We show that there is no significant dependence of the EW(Fe) on M* or X-ray luminosity, suggesting that the reflection of AGN X-ray emission over large scales in their host galaxies may be widespread.

Keywords: AGN host galaxies, X-ray astronomy, Far infrared astronomy, X-ray active galactic nuclei, Active galactic nuclei, Extragalactic astronomy
Mass-Radius Relationships for Irradiated Ocean Planets. Massive and water-rich planets should be ubiquitous in the universe. Many of these worlds are expected to be subject to important irradiation from their host star, and display supercritical water layers surrounded by extended steam atmospheres. Irradiated ocean planets with such inflated hydrospheres have been recently shown to be good candidates for matching the mass-radius distribution of sub-Neptunes. Here we describe a model that computes a realistic structure for water-rich planets by combining an interior model with an updated equation of state (EOS) for water, and an atmospheric model that takes into account radiative transfer. We find that the use of inappropriate EOSs can lead to the overestimation of the planetary radius by up to ~10%, depending on the planet size and composition. Our model has been applied to the GJ 9827 system as a test case and indicates Earth- or Venus-like interiors for planets b and c, respectively. Planet d could be an irradiated ocean planet with a water mass fraction (WMF) of ~20% ± 10%. We also provide fits for the mass-radius relationships, allowing one to directly retrieve a wide range of planetary compositions, without the requirement to run the model. Our calculations finally suggest that highly irradiated planets lost their H/He content through atmospheric loss processes, and that the leftover material led to either super-Earths or sub-Neptunes, depending on the WMF.

Keywords: Planetary theory, Hydrosphere, Exoplanets, Exoplanet astronomy, Computational methods, Exoplanet structure, Planetary interior
Chandra, NuSTAR, and Optical Observations of the Cataclysmic Variables IGR J17528-2022 and IGR J20063+3641. We report on Chandra, NuSTAR, and MDM observations of two International Gamma-ray Astrophysics Laboratory (INTEGRAL) sources, namely IGR J17528-2022 and IGR J20063+3641. IGR J17528-2022 is an unidentified INTEGRAL source, while IGR J20063+3641 was recently identified as a magnetic cataclysmic variable (mCV) by Halpern et al. The Chandra observation of IGR J17528-2022 has allowed us to locate the optical counterpart to the source and to obtain its optical spectrum, which shows a strong Hα emission line. The optical spectrum and flickering observed in the optical time-series photometry in combination with the X-ray spectrum, which is well fit by an absorbed partially covered thermal bremsstrahlung model, suggest that this source is a strong mCV candidate. The X-ray observations of IGR J20063+3641 reveal a clear modulation with a period of 172.46 ± 0.01 s, which we attribute to the white dwarf spin period. Additional MDM spectroscopy of the source has also allowed for a clear determination of the orbital period at 0.731 ± 0.015 days. The X-ray spectrum of this source is also well fit by an absorbed partially covered thermal bremsstrahlung model. The X-ray spectrum, spin periodicity, and orbital periodicity allow this source to be further classified as an intermediate polar.

Keywords: Cataclysmic variable stars, X-ray binary stars, X-ray sources
Living with Neighbors. IV. Dissecting the Spin-Orbit Alignment of Dark Matter Halos: Interacting Neighbors and the Local Large-scale Structure. Spin-orbit alignment (SOA; i.e., the vector alignment between the halo spin and the orbital angular momentum of neighboring halos) provides an important clue to how galactic angular momenta develop. For this study, we extract virial-radius-wise contact halo pairs with mass ratios between 1/10 and 10 from a set of cosmological N-body simulations. In the spin-orbit angle distribution, we find a significant SOA in that 52.7% ± 0.2% of neighbors are on the prograde orbit. The SOA of our sample is mainly driven by low-mass target halos (&lt;1011.5 h-1 M⊙) with close merging neighbors, corroborating the notion that tidal interaction is one of the physical origins of SOA. We also examine the correlation of SOA with the adjacent filament and find that halos closer to the filament show stronger SOA. Most interestingly, we discover for the first time that halos with the spin parallel to the filament experience most frequently prograde polar-interaction (i.e., fairly perpendicular but still prograde interaction; spin-orbit angle ~70°). This instantly invokes the spin-flip event and the prograde-polar interaction will soon flip the spin of the halo to align it with the neighbor's orbital angular momentum. We propose that SOA originates from the local cosmic flow along the anisotropic large-scale structure, especially that along the filament, and grows further by interactions with neighbors.

Keywords: Galaxy dark matter halos, Large-scale structure of the universe, Galaxy interactions, Galaxy kinematics, Cosmic web, N-body simulations, Dark matter, Galaxy encounters
The Drag Instability in a 2D Isothermal C-shock. We extend the linear analysis of the drag instability in a 1D perpendicular isothermal C-shock by Gu &amp; Chen to 2D perpendicular and oblique C-shocks in the typical environment of star-forming clouds. Simplified dispersion relations are derived for the unstable modes. We find that the mode property of the drag instability generally depends on the ratio of the transverse (normal to the shock flow) to longitudinal (along the shock flow) wavenumber. For the transversely large-scale mode, the growth rate and wave frequency of the drag instability in a 2D shock resemble those in a 1D shock. For the transversely small-scale mode, the drag instability is characterized by an unstable mode coupled with an acoustic mode primarily along the transverse direction. When the shock is perpendicular or less oblique, there exists a slowly propagating mode, which can potentially grow into a nonlinear regime and contribute to the maximum growth of the instability. In contrast, when the shock is more oblique, this slowly propagating unstable mode disappears, and the maximum growth of the drag instability is likely contributed from the transversely large-scale mode (i.e., almost 1D mode). In all cases that we consider, the magnitude of the density perturbations is significantly larger than that of the velocity and magnetic field perturbations, implying that the density enhancement governs the dynamics in the linear regime of the instability. A few issues in the linear analysis, as well as the possible astrophysical implications, are also briefly discussed.

Keywords: Star forming regions, Plasma astrophysics, Molecular clouds, Interstellar magnetic fields, Shocks
Spiral Arms and a Massive Dust Disk with Non-Keplerian Kinematics: Possible Evidence for Gravitational Instability in the Disk of Elias 2-27. To determine the origin of the spiral structure observed in the dust continuum emission of Elias 2-27 we analyze multiwavelength continuum ALMA data with a resolution of ~0"2 (~23 au) at 0.89, 1.3, and 3.3 mm. We also study the kinematics of the disk with 13CO and C18O ALMA observations in the J = 3-2 transition. The spiral arm morphology is recovered at all wavelengths in the dust continuum observations, where we measure contrast and spectral index variations along the spiral arms and detect subtle dust-trapping signatures. We determine that the emission from the midplane is cold and interpret the optical depth results as signatures of a disk mass higher than previous constraints. From the gas data, we search for deviations from Keplerian motion and trace the morphology of the emitting surfaces and the velocity profiles. We find an azimuthally varying emission layer height in the system, large-scale emission surrounding the disk, and strong perturbations in the channel maps, colocated with the spirals. Additionally, we develop multigrain dust and gas hydrodynamical simulations of a gravitationally unstable disk and compare them to the observations. Given the large-scale emission and highly perturbed gas structure, together with the comparison of continuum observations to theoretical predictions, we propose infall-triggered gravitational instabilities as the origin for the observed spiral structure.

Keywords: Hydrodynamical simulations, Gravitational instability, Planetary system formation, Protoplanetary disks, Planet formation
Efficiently Cooled Stellar Wind Bubbles in Turbulent Clouds. I. Fractal Theory and Application to Star-forming Clouds. Winds from massive stars have velocities of 1000 km s-1 or more and produce hot, high-pressure gas when they shock. We develop a theory for the evolution of bubbles driven by the collective winds from star clusters early in their lifetimes, which involves interaction with the turbulent, dense interstellar medium of the surrounding natal molecular cloud. A key feature is the fractal nature of the hot bubble's surface. The large area of this interface with surrounding denser gas strongly enhances energy losses from the hot interior, enabled by turbulent mixing and subsequent cooling at temperatures T ~ 104-105 K, where radiation is maximally efficient. Due to the extreme cooling, the bubble radius scales differently ( ${{ \mathcal R }}_{b}\propto {t}^{1/2}$ ) from the classical Weaver et al. solution and has expansion velocity and momentum lower by factors of 10-102 at given ${{ \mathcal R }}_{b}$ , with pressure lower by factors of 102-103. Our theory explains the weak X-ray emission and low shell expansion velocities of observed sources. We discuss further implications of our theory for observations of the hot bubbles and cooled expanding shells created by stellar winds and for predictions of feedback-regulated star formation in a range of environments. In a companion paper, we validate our theory with a suite of hydrodynamic simulations.

Keywords: Stellar wind bubbles, Young star clusters, Molecular clouds, Stellar winds, Star formation, Star clusters
Efficiently Cooled Stellar Wind Bubbles in Turbulent Clouds. II. Validation of Theory with Hydrodynamic Simulations. In a companion paper, we develop a theory for the evolution of stellar wind-driven bubbles in dense, turbulent clouds. This theory proposes that turbulent mixing at a fractal bubble/shell interface leads to highly efficient cooling, in which the vast majority of the input wind energy is radiated away. This energy loss renders the majority of the bubble evolution momentum driven rather than energy driven, with expansion velocities and pressures orders of magnitude lower than in the classical Weaver et al. solution. In this paper, we validate our theory with three-dimensional, hydrodynamic simulations. We show that extreme cooling is not only possible, but is generic to star formation in turbulent clouds over more than three orders of magnitude in density. We quantify the few free parameters in our theory, and show that the momentum exceeds the wind input rate by only a factor ${\alpha }_{p}\sim 1.2\mbox{--}4$ . We verify that the bubble/cloud interface is a fractal with dimension $\sim 2.5\mbox{--}2.7$ . The measured turbulent amplitude ( ${v}_{t}\sim 200\mbox{--}400\,\ \mathrm{km}\,\ {{\rm{s}}}^{-1}$ ) in the hot gas near the interface is shown to be consistent with theoretical requirements for turbulent diffusion to efficiently mix and radiate away most of the wind energy. The fraction of energy remaining after cooling is only $1-{\rm{\Theta }}\sim 0.1\mbox{--}0.01$ , decreasing with time, explaining observations that indicate low hot-gas content and weak dynamical effects of stellar winds.

Keywords: Stellar wind bubbles, Young star clusters, Molecular clouds, Stellar winds, Star formation, Star clusters
Contribution of Secondary Neutrinos from Line-of-sight Cosmic-Ray Interactions to the IceCube Diffuse Astrophysical Flux. In 10 years of observations, the IceCube neutrino observatory has revealed a neutrino sky in tension with previous expectations for neutrino point-source emissions. Astrophysical objects associated with hadronic processes might act as production sites for neutrinos, observed as point sources at Earth. Instead, a nearly isotropic flux of astrophysical neutrinos is observed up to PeV energies, prompting a reassessment of the assumed transport and production physics. This work applies a new physical explanation for neutrino production from populations of active galactic nuclei and starburst galaxies to three years of public IceCube point-source data. Specifically, cosmic rays produced at such sources might interact with extragalactic background light and gas along the line of sight, generating a secondary neutrino flux. This model is tested alongside a number of typical flux weighting schemes, in all cases the all-sky flux contribution being constrained to percent levels of the reported IceCube diffuse astrophysical flux.

Keywords: Starburst galaxies, Cosmic rays, Blazars, Neutrino astronomy, Active galactic nuclei, Intergalactic medium, Gamma-rays, Particle astrophysics, Extragalactic magnetic fields