Sazuna/UAT_keywords huggingface dataset:
Saturation Level of Turbulence in Collapsing Gas Clouds. We investigate the physical mechanism that determines the saturation level of the turbulence in collapsing gas clouds. We perform a suite of high-resolution numerical simulations that follow the collapse of turbulent gas clouds, with various effective polytropic exponents γ eff, initial Mach numbers ${{ \mathcal M }}_{0}$ , and initial turbulent seeds. Equating the energy injection rate from gravitational contraction and the dissipation rate of the turbulence, we obtain an analytic expression for the saturation level of the turbulence, and compare it with the numerical results. Consequently, the numerical results are well described by the analytic model, given that the turbulent driving scale in collapsing gas clouds is one-third the Jeans length of the collapsing core. These results indicate that the strength of the turbulence at first-core formations in the early universe/the present-day star formation process can be estimated solely by γ eff.

Keywords: Early universe, Population III stars, Hydrodynamics, Gravitational collapse, Population I stars, Collapsing clouds
Molecular Gas Reservoirs in Massive Quiescent Galaxies at z   0.7 Linked to Late-time Star Formation. We explore how the presence of detectable molecular gas depends on the inferred star formation histories (SFHs) in eight massive, quiescent galaxies at z ~ 0.7. Half of the sample have clear detections of molecular gas, traced by CO(2-1). We find that the molecular gas content is unrelated to the rate of star formation decline prior to the most recent 1 Gyr, suggesting that the gas reservoirs are not left over from their primary star formation epoch. However, the recent SFHs of CO-detected galaxies demonstrate evidence for secondary bursts of star formation in their last Gyr. The fraction of stellar mass formed in these secondary bursts ranges from f burst ≍ 0.3%-6% and ended between t end-burst ≍ 0-330 Myr ago. The CO-detected galaxies form a higher fraction of mass in the last Gyr ( ${f}_{{M}_{1\,\mathrm{Gyr}}}=2.6 \% \pm 1.8 \% $ ) compared to the CO-undetected galaxies ( ${f}_{{M}_{1\,\mathrm{Gyr}}}=0.2 \% \pm 0.1 \% $ ). The galaxies with gas reservoirs have enhanced late-time star formation, highlighting this as a contributing factor to the observed heterogeneity in the gas reservoirs in high-redshift quiescent galaxies. We find that the amount of gas and star formation driven by these secondary bursts are inconsistent with that expected from dry minor mergers, and instead are likely driven by recently accreted gas, i.e., gas-rich minor mergers. This conclusion would not have been made based on SFRUV+IR measurements alone, highlighting the power of detailed SFH modeling in the interpretation of gas reservoirs. Larger samples are needed to understand the frequency of low-level rejuvenation among quiescent galaxies at intermediate redshifts, and to what extent this drives the diversity of molecular gas reservoirs.

Keywords: Molecular gas, Galaxy formation, Quenched galaxies, Galaxy stellar content, Galaxy evolution, Galaxy quenching, High-redshift galaxies, Early-type galaxies
The Active Galactic Nuclei in the Hobby-Eberly Telescope Dark Energy Experiment Survey (HETDEX). III. A Red Quasar with Extremely High Equivalent Widths Showing Powerful Outflows. We report an active galactic nucleus (AGN) with an extremely high equivalent width (EW), EWLyα+N V,rest ≳921 Å, in the rest frame, at z ~ 2.24 in the Hobby-Eberly Telescope Dark Energy Experiment Survey (HETDEX), as a representative case of the high-EW AGN population. The continuum level is a nondetection in the HETDEX spectrum; thus the measured EW is a lower limit. The source is detected with significant emission lines (&gt;7σ) at Lyα + N V λ1241, C IV λ1549, and a moderate emission line (~4σ) at He II λ1640 within the wavelength coverage of HETDEX (3500-5500 Å). The r-band magnitude is 24.57 from the Hyper Suprime-Cam-HETDEX joint survey with a detection limit of r = 25.12 at 5σ. The Lyα emission line spans a clearly resolved region of ~10″ (85 kpc) in diameter. The Lyα line profile is strongly double peaked. The spectral decomposed blue gas and red gas Lyα emission are separated by ~1.″2 (10.1 kpc) with a line-of-sight velocity offset of ~1100 km s-1. This source is probably an obscured AGN with powerful winds.

Keywords: AGN host galaxies, Active galaxies, Low-luminosity active galactic nuclei
Multiwavelength Observations of the Obscuring Wind in the Radio-quiet Quasar MR 2251-178. Obscuring winds driven away from active supermassive black holes are rarely seen due to their transient nature. They have been observed with multiwavelength observations in a few Seyfert 1 galaxies and one broad absorption line radio-quiet quasar so far. An X-ray obscuration event in MR 2251-178 was caught in late-2020, which triggered multiwavelength (near-IR (NIR) to X-ray) observations targeting this radio-quiet quasar. In the X-ray band, the obscurer leads to a flux drop in the soft X-ray band from late-2020 to early-2021. X-ray obscuration events might have a quasi-period of two decades considering earlier events in 1980 and 1996. In the UV band, a forest of weak blueshifted absorption features emerged in the blue wing of Lyα λ1216 in late-2020. Our XMM-Newton, NuSTAR, and Hubble Space Telescope/COS observations are obtained simultaneously; hence, the transient X-ray obscuration event is expected to account for the UV outflow, although they are not necessarily caused by the same part of the wind. Both blueshifted and redshifted absorption features were found for He I λ10830, but no previous NIR spectra are available for comparison. The X-ray observational features of MR 2251-178 shared similarities with some other type 1 active galactic nuclei (AGNs) with obscuring wind. However, observational features in the UV to NIR bands are distinctly different from those seen in other AGN with obscuring winds. A general understanding of the observational variety and the nature of obscuring wind is still lacking.

Keywords: High resolution spectroscopy, Quasar absorption line spectroscopy, Active galactic nuclei, X-ray quasars, Astrophysical black holes
COOL-LAMPS. II. Characterizing the Size and Star Formation History of a Bright Strongly Lensed Early-type Galaxy at Redshift 1.02. We present COOL J1323+0343, an early-type galaxy at z = 1.0153 ± 0.0006, strongly lensed by a cluster of galaxies at z = 0.353 ± 0.001. This object was originally imaged by DECaLS and noted as a gravitational lens by COOL-LAMPS, a collaboration initiated to find strong-lensing systems in recent public optical imaging data, and confirmed with follow-up data. With ground-based grzH imaging and optical spectroscopy from the Las Campanas Observatory and the Nordic Optical Telescope, we derive a stellar mass, metallicity, and star formation history from stellar-population synthesis modeling. The lens modeling implies a total magnification, summed over the three images in the arc, of μ ~ 113. The stellar mass in the source plane is M * ~ 10.64 M ⊙ and the 1σ upper limit on the star formation rate (SFR) in the source plane is SFR ~ 3.75 × 10-2 M ⊙ yr-1 (log sSFR = -12.1 yr-1) in the youngest two age bins (0-100 Myr), closest to the epoch of observation. Our measurements place COOL J1323+0343 below the characteristic mass of the stellar mass function, making it an especially compelling target that could help clarify how intermediate-mass quiescent galaxies evolve. We reconstruct COOL J1323+0343 in the source plane and fit its light profile. This object is below the expected size evolution of an early-type galaxy at this mass with an effective radius r e  ~ 0.5 kpc. This extraordinarily magnified and bright lensed early-type galaxy offers an exciting opportunity to study the morphology and star formation history of an intermediate-mass early-type galaxy in detail at z ~ 1.

Keywords: Quenched galaxies, Strong gravitational lensing, Galaxy quenching, Galaxy evolution, Spectral energy distribution, Elliptical galaxies, Galaxy spectroscopy, High-redshift galaxies, Early-type galaxies
Temporal Evolutions and Quasiperiodic Variations Present in the Sunspot Number and Group Sunspot Area Data Measured at Kodaikanal Observatory for Solar Cycles 14-24. The Kodaikanal Observatory has made synoptic observations of the Sun in white light since 1904, and these images are sketched on the Stonyhurst grids called Sun charts. These continuous hand-drawn data sets are used for long-term studies of the Sun. This article investigates temporal and periodic variations of the monthly hemispheric sunspot number and sunspot group area for 1905-2016, covering solar cycles 14-24. We find that the temporal variations of the sunspot number and group area are different in each hemisphere and peak at different times of the solar cycle in the opposite hemisphere. For both data sets, Cycle 19 shows maximum amplitude. For the sunspot number time series, Cycle 24 was the weakest, and Cycle 15 for the group area. The existence of double peaks and violation of the "odd-even rule" was found in both data sets. We have studied the periodic and quasiperiodic variations in both time series using the wavelet technique. We noticed that, along with the fundamental mode of the ~11 yr cycle and polarity reversal period of 22 yr, the sunspot activity data also exhibited several midterm periodicities in the opposite hemispheres, in particular the Rieger-group, and quasi-biennial periodicities. The temporal evolution of these detected quasi-periodicities also differs in the northern and southern hemispheres. We analyzed the data set statistically to understand the bulk properties and coupling between the opposite hemispheres. The study indicates that the two hemispheric data sets differ, but some dependency could be present.

Keywords: Sunspots, Sunspot cycle, Sunspot number
Self-ionizing Galactic Winds. We present hydrodynamical simulations of galactic winds from star-forming galaxies including nonequilibrium ionization and frequency-dependent radiative transfer, processes that have remained largely unaccounted for in galactic wind studies. We consider radiation from massive stars, the metagalactic UV/X-ray background, and the self-radiation of the supernovae heated gas. We compare our results to classical galactic wind solutions and show the importance of our newly included physical processes toward observations of ions such as O III, O VI, O VII, and O VIII plus the observable soft X-ray spectra. Nonequilibrium ionization is reflected in overionized gas compared to equilibrium solutions, leading to much enhanced column densities of highly ionized species. The wind produces excess soft X-ray (E ≳ 100 eV) radiation that is several orders of magnitude higher compared to the metagalactic background. This radiation ionizes the higher ions (such as O VII) somewhat, but affects the lower ions (such as O III) significantly. We predict that the observable X-ray spectra should contain the signatures of such nonequilibrium effects, especially in X-ray lines such as O VII and O VIII. Simple estimates suggest that both the temperature and density of the winds may be overestimated by factors of a few to almost 2 orders of magnitude using simple equilibrium models. We conclude that both the nonequilibrium ionization and the radiation from the wind itself need to be considered for proper modeling of the optical/UV/X-ray emitting plasma in galactic winds.

Keywords: Galactic winds, Hydrodynamical simulations, Starburst galaxies, X-ray sources, Radiative transfer simulations
Observations of Quiescent Solar Wind Regions with Near-f <SUB>ce</SUB> Wave Activity. In situ measurements in the near-Sun solar wind from the Parker Solar Probe have revealed the existence of quiescent solar wind regions: extended regions of solar wind with low-amplitude turbulent magnetic field fluctuations compared to adjacent regions. Identified through the study of harmonic waves near the electron cyclotron frequency (f ce), these quiescent regions are shown to host a variety of plasma waves. The near-f ce harmonic waves are observed exclusively in quiescent regions, and as such, they can be used as markers for quiescent regions. A blob-finding algorithm is applied to data from Encounters 1-6 in order to identify near-f ce harmonic wave intervals and thereby locate quiescent regions. We carry out a superposed epoch analysis on the identified quiescent regions, and compare their bulk solar wind properties with adjacent regions of solar wind. Quiescent regions are found to contain relatively weak magnetic field variation and are entirely devoid of magnetic switchbacks. In the quiescent solar wind, the magnetic field closely follows the Parker spiral, while adjacent regions prefer more radial orientations, providing a clear picture of the magnetic geometry of these regions. Quiescent regions show minimal differences in multiple particle plasma parameters relative to the non-quiescent solar wind. The quiescent solar wind regions, studied throughout this work, are thought to represent the underlying solar wind, through which Alfvénic fluctuations propagate. Quantifying the properties of these regions may help to understand the formation/origin of the solar wind, and furthermore, to constrain the role that low-frequency Alfvén waves play in the regulation of solar wind temperature.

Keywords: Space plasmas, Heliosphere, Interplanetary turbulence, Solar wind, Solar magnetic fields
Dwarf Galaxies with Central Cores in Modified Newtonian Dynamics Gravity. Some dwarf galaxies are within the Mondian regime at all radii, i.e., the gravitational acceleration provided by the observed baryons is always below the threshold of g † ≃ 1.2 × 10-10 m s-2. These dwarf galaxies often show cores, in the sense that, assuming Newton's gravity to explain their rotation curves, the total density profile ρ(r) presents a central plateau or core ( $d\mathrm{log}\rho /d\mathrm{log}r\to 0$ when r → 0). Here we show that under modified Newtonian dynamics (MOND) gravity, the existence of this core implies a baryon content whose density ρ bar must decrease toward the center of the gravitational potential (ρ bar → 0 when r → 0). Such a drop of baryons toward the central region is neither observed nor appears in numerical simulations of galaxy formation following MOND gravity. We analyze the problem posed for MOND as well as possible work-arounds.

Keywords: Gravitation, Galaxy dynamics, Dwarf galaxies, Galaxy structure, Baryonic dark matter, Modified Newtonian dynamics, Dark matter
Cosmological Simulation of Galaxy Groups and Clusters. II. Studying Different Modes of Feedback through X-Ray Observations. The impact of feedback from active galactic nuclei (AGNs) on the cosmological evolution of the large-scale structure is a long-studied problem. However, it is still not well understood how the feedback energy couples to the ambient medium to influence the properties of AGN host galaxies and dark matter halos. In this work we investigate different modes of AGN feedback and their effect on the surrounding medium by probing the diffuse X-ray emission from the hot gas inside galaxy groups and clusters. For this purpose, we use the cosmological hydrodynamic simulation SIMBA to theoretically calculate the X-ray emission from simulated galaxy clusters/groups with the help of the Astrophysical Plasma Emission Code. We also perform synthetic observations of these systems with the Chandra X-ray telescope using the ray-tracing simulator Model of AXAF Response to X-rays. Our results show that in addition to the radiative wind mode of feedback from the AGNs, jet and X-ray modes of feedback play significant roles in suppressing the X-ray emission from the diffuse gas in the vicinity of the black hole. Our mock observational maps suggest that the signatures of AGN feedback from high-redshift objects may not be detected with the instrumental resolution of current X-ray telescopes like Chandra, but provide promising prospects for detection of these features with potential X-ray missions such as Lynx.

Keywords: Galaxy clusters, Active galactic nuclei, X-ray telescopes
A Study of the Spectral Properties of Two Gamma-Ray Bursts with the Main Bursts and Postbursts. The jet composition in gamma-ray bursts (GRBs) is still an unsolved issue. We try to provide some clues to the issue by analyzing the spectral properties of GRB 160509A and GRB 130427A with a main burst and a postburst. We first perform Bayesian time-resolved spectral analysis and compare the spectral components and spectral properties of the main bursts and postbursts of the two bursts and find that both bursts have the thermal components, and the thermal components are mainly found in the main bursts, while the postbursts are mainly dominated by the nonthermal components. We also find that the low-energy spectral indices of some time bins in the main bursts of these two GRBs exceed the so-called synchronous dead line, and in the postburst, only GRB 160509A has four time bins exceeding the dead line, while none of GRB 130427A exceed the dead line. We then constrain the outflow properties of both bursts and find that the main bursts is consistent with the typical properties of photosphere radiation. Therefore, our results support the transition of the GRB jet component from the fireball to the Poynting-flux-dominated jet. Finally, after analyzing the correlation and parameter evolution of the spectral parameters of the two bursts, we find that the correlations of the spectral parameters have different behaviors in the main bursts and postbursts. The parameter evolution trends of the main bursts and postbursts also show consistent and inconsistent behavior; therefore, we currently cannot determine whether the main bursts and postbursts come from the same origin.

Keywords: Gamma-ray bursts
Internal Rotation and Inclinations of Slowly Pulsating B Stars: Evidence of Interior Angular Momentum Transport. One of the largest uncertainties in stellar structure and evolution theory is the transport of angular momentum in the stellar interiors. Asteroseismology offers a powerful tool for measuring the internal rotation frequencies of pulsating stars, but the number of such measurements has remained few for ≳3 M ⊙ main-sequence stars. In this work, we compile a list of 52 slowly pulsating B stars for which the interior rotation has been measured asteroseismically. The measurements of the spin parameters, which describe the relative importance of rotation, for the gravito-inertial mode oscillations show that for 40 of the stars the oscillations fall within the subinertial regime. We find that the core rotation frequencies of the stars decrease as a function of age and show evidence of angular momentum transport occurring on the main sequence. Finally, we derive the inclination angles of the stars, showing that they are generally consistent with the expectations from surface cancellation effects for the given oscillation modes.

Keywords: Stellar interiors, Stellar pulsations, Stellar cores, Stellar rotation, Stellar evolution
The σ<SUB>Hβ </SUB>-based Dimensionless Accretion Rate and Its Connection with the Corona for AGNs. With respect to the Hβ FWHM (FWHMHβ ), the broad Hβ line dispersion (σ Hβ ) was preferred as a velocity tracer to calculate the single-epoch supermassive black hole mass (M BH) suggested by Yu et al. For a compiled sample of 311 broad-line active galactic nuclei (AGNs) with measured hard X-ray photon index (z &lt; 0.7), σ Hβ  and the optical Fe II relative strength (R Fe) are measured from their optical spectra, which are used to calculate σ Hβ -based virial M BH and dimensionless accretion rate ( $\dot{M}$ ). With respect to FWHMHβ , it is found that the mean value of σ Hβ -based M BH is on average larger by 0.26 dex and the mean value of σ Hβ -based $\dot{M}$ is on average smaller by 0.51 dex. It is found that there exists a nonlinear relationship between the Eddington ratio (L Bol/L Edd) and $\dot{M}$ , i.e., ${L}_{\mathrm{Bol}}/{L}_{\mathrm{Edd}}\propto {\dot{M}}^{0.56\pm 0.01}$ . This nonlinear relationship comes from the accretion efficiency η, which is smaller for AGNs with higher $\dot{M}$ . We find a strong bivariate correlation of the fraction of energy released in the corona F X with $\dot{M}$ and M BH, ${F}_{{\rm{X}}}\propto {\dot{M}}^{-0.57\pm 0.05}{M}_{\mathrm{BH}}^{-0.54\pm 0.06}$ . The flat slope of -0.57 ± 0.05 favors the shear stress tensor of the accretion disk being proportional to the geometric mean of gas pressure and total pressure. We find a strong bivariate relation of Γ with $\dot{M}$ and F X, ${\rm{\Gamma }}\propto {\dot{M}}^{-0.21\pm 0.02}{F}_{{\rm{X}}}^{0.02\pm 0.04}$ . The hard X-ray spectrum becomes softer with increasing F X, although the scatter is large.

Keywords: Supermassive black holes, Active galactic nuclei, Emission line galaxies
Impact of Rastall Gravity on Mass, Radius, and Sound Speed of the Pulsar PSR J0740+6620. Millisecond pulsars are perfect laboratories to test possible matter-geometry coupling and its physical implications in light of recent Neutron Star Interior Composition Explorer (NICER) observations. We apply Rastall field equations of gravity, where matter and geometry are nonminimally coupled, to Krori-Barua interior spacetime whereas the matter source is assumed to be anisotropic fluid. We show that all physical quantities inside the star can be expressed in terms of Rastall, ϵ, and compactness, C = 2GM/Rc 2, parameters. Using NICER and X-ray Multi-Mirror Newton X-ray-observational constraints on the mass and radius of the pulsar PSR J0740+6620, we determine the Rastall parameter to be at most ϵ = 0.041 in the positive range. The obtained solution provides a stable compact object; in addition the squared sound speed does not violate the conjectured sound speed ${c}_{s}^{2}\leqslant {c}^{2}/3$ unlike the general relativistic treatment. We note that no equations of state are assumed; the model however fits well with linear patterns with bag constants. In general, for ϵ &gt; 0, the theory predicts a slightly larger-size star in comparison to general relativity for the same mass. This has been explained as an additional force, due to matter-geometry coupling, in the hydrodynamic equilibrium equation, which contributes to partially diminishing the gravitational force effect. Consequently, we calculate the maximal compactness as allowed by the strong energy condition to be C = 0.735, which is ~2% higher than general relativity prediction. Moreover, for the surface density at saturation nuclear density ρ nuc = 2.7 × 1014 g cm-3, we estimate the maximum mass M = 4M ☉ at radius R = 16 km.

Keywords: Stellar structures, Neutron star cores, Millisecond pulsars, Massive stars, Non-standard theories of gravity