Sazuna/UAT_keywords huggingface dataset:
Evidence for Gas-phase Metal Deficiency in Massive Protocluster Galaxies at z ∼2.2. We study the mass-metallicity relation for 19 members of a spectroscopically confirmed protocluster in the COSMOS field at z = 2.2 (CC2.2), and compare it with that of 24 similarly selected field galaxies at the same redshift. Both samples are Hα emitting sources, chosen from the HiZELS narrowband survey, with metallicities derived from the ${\rm{N}}2\ \left(\tfrac{[\mathrm{NII}]\lambda 6584}{{\rm{H}}\alpha }\right)$ line ratio. For the mass-matched samples of protocluster and field galaxies, we find that protocluster galaxies with 109.9 M⊙ ≤ M* ≤ 1010.9 M⊙ are metal deficient by 0.10 ± 0.04 dex (2.5σ significance) compared to their coeval field galaxies. This metal deficiency is absent for low-mass galaxies, M* &lt; 109.9 M⊙. Moreover, relying on both spectral energy distribution derived and Hα (corrected for dust extinction based on M*) star formation rates (SFRs), we find no strong environmental dependence of the SFR-M* relation; however, we are not able to rule out the existence of small dependence due to inherent uncertainties in both SFR estimators. The existence of 2.5σ significant metal deficiency for massive protocluster galaxies favors a model in which funneling of the primordial cold gas through filaments dilutes the metal content of protoclusters at high redshifts (z ≳ 2). At these redshifts, gas reservoirs in filaments are dense enough to cool down rapidly and fall into the potential well of the protocluster to lower the gas-phase metallicity of galaxies. Moreover, part of this metal deficiency could be originated from galaxy interactions that are more prevalent in dense environments. * Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Keywords: Large-scale structure of the universe, High-redshift galaxy clusters, Protoclusters, Galaxy evolution, Metallicity
Nonlinear Damping of Standing Kink Waves Computed With Elsässer Variables. In a previous paper, we computed the energy density and the nonlinear energy cascade rate for transverse kink waves using Elsässer variables. In this paper, we focus on the standing kink waves, which are impulsively excited in coronal loops by external perturbations. We present an analytical calculation to compute the damping time due to the nonlinear development of the Kelvin-Helmholtz instability. The main result is that the damping time is inversely proportional to the oscillation amplitude. We compare the damping times from our formula with the results of numerical simulations and observations. In both cases we find a reasonably good match. The comparison with the simulations shows that the nonlinear damping dominates in the high amplitude regime, while the low amplitude regime shows damping by resonant absorption. In the comparison with the observations, we find a power law inversely proportional to the amplitude η-1 as an outer envelope for our Monte Carlo data points.

Keywords: Magnetohydrodynamics, Solar coronal loops, Solar coronal heating, Solar physics, Solar active regions, Solar coronal waves, Solar corona
Sagittarius B1: A Patchwork of H II Regions and Photodissociation Regions. Sgr B1 is a luminous H II region in the Galactic center immediately next to the massive star-forming giant molecular cloud Sgr B2 and apparently connected to it from their similar radial velocities. In 2018 we showed from SOFIA FIFI-LS observations of the [O III] 52 and 88 μm lines that there is no central exciting star cluster and that the ionizing stars must be widely spread throughout the region. Here we present SOFIA FIFI-LS observations of the [O I] 146 and [C II] 158 μm lines formed in the surrounding photodissociation regions (PDRs). We find that these lines correlate neither with each other nor with the [O III] lines although together they correlate better with the 70 μm Herschel PACS images from Hi-GAL. We infer from this that Sgr B1 consists of a number of smaller H II regions plus their associated PDRs, some seen face-on and the others seen more or less edge-on. We used the PDR Toolbox to estimate densities and the far-ultraviolet intensities exciting the PDRs. Using models computed with Cloudy, we demonstrate possible appearances of edge-on PDRs and show that the density difference between the PDR densities and the electron densities estimated from the [O III] line ratios is incompatible with pressure equilibrium unless there is a substantial pressure contribution from either turbulence or magnetic field or both. We also conclude that the hot stars exciting Sgr B1 are widely spaced throughout the region at substantial distances from the gas with no evidence of current massive star formation.

Keywords: Galactic center, Interstellar line emission, H II regions, Photodissociation regions
The Clusters Hiding in Plain Sight (CHiPS) Survey: Complete Sample of Extreme BCG Clusters. We present optical follow-up observations for candidate clusters in the Clusters Hiding in Plain Sight survey, which is designed to find new galaxy clusters with extreme central galaxies that were misidentified as bright isolated sources in the ROSAT All-Sky Survey catalog. We identify 11 cluster candidates around X-ray, radio, and mid-IR-bright sources, including six well-known clusters, two false associations of foreground and background clusters, and three new candidates, which are observed further with Chandra. Of the three new candidates, we confirm two newly discovered galaxy clusters: CHIPS 1356-3421 and CHIPS 1911+4455. Both clusters are luminous enough to be detected in the ROSAT All-Sky Survey data if not because of their bright central cores. CHIPS 1911+4455 is similar in many ways to the Phoenix cluster, but with a highly disturbed X-ray morphology on large scales. We find the occurrence rate for clusters that would appear to be X-ray-bright point sources in the ROSAT All-Sky Survey (and any surveys with similar angular resolution) to be 2% ± 1%, and the occurrence rate of clusters with runaway cooling in their cores to be &lt;1%, consistent with predictions of chaotic cold accretion. With the number of new groups and clusters predicted to be found with eROSITA, the population of clusters that appear to be point sources (due to a central QSO or a dense cool core) could be around 2000. Finally, this survey demonstrates that the Phoenix cluster is likely the strongest cool core at z &lt; 0.7—anything more extreme would have been found in this survey.

Keywords: Galaxy clusters
New Look at the Molecular Superbubble Candidate in the Galactic Center. The l = +1°3 region in the Galactic center is characterized by multiple shell-like structures and their extremely broad velocity widths. We revisit the molecular superbubble hypothesis for this region, based on high-resolution maps of CO J = 1-0, 13CO J = 1-0, H13CN J = 1-0, H13CO+ J = 1-0, SiO J = 2-1, and CS J = 2-1 lines obtained from the Nobeyama Radio Observatory 45 m telescope, as well as CO J = 3-2 maps obtained from the James Clerk Maxwell telescope. We identified 11 expanding shells with total kinetic energy and typical expansion time Ekin ∼ 1051.9 erg and texp ∼ 104.9 yr, respectively. In addition, the l = +1°3 region exhibited high SiO J = 2-1/H13CN J = 1-0 and SiO J = 2-1/H13CO+ J = 1-0 intensity ratios, indicating that the region has experienced dissociative shocks in the past. These new findings confirm the molecular superbubble hypothesis for the l = +1°3 region. The nature of the embedded star cluster, which may have supplied 20-70 supernova explosions within 105 yr, is discussed. This work also shows the importance of compact broad-velocity-width features in searching for localized energy sources hidden behind severe interstellar extinction and stellar contamination.

Keywords: Milky Way Galaxy, Molecular clouds, Interstellar medium
R-mode Stability of GW190814's Secondary Component as a Supermassive and Superfast Pulsar. The nature of GW190814's secondary component m2 of mass 2.50-2.67 M⊙ in the mass gap between the currently known maximum mass of neutron stars and the minimum mass of black holes is currently under hot debate. Among the many possibilities proposed in the literature, m2 was suggested to be a superfast pulsar, while its r-mode stability against runaway gravitational radiation through the Chandrasekhar-Friedman-Schutz mechanism is still unknown. Previously, Fortin et al. constructed a sample of 33 unified equations of state using the same nuclear interactions from the crust to the core consistently; from that sample we use those equations that fulfill all currently known astrophysical and nuclear physics constraints to compare the minimum frequency required for m2 to rotationally sustain a mass greater than 2.50 M⊙ with the critical frequency above which the r-mode instability occurs. We use two extreme damping models assuming that the crust is either perfectly rigid or elastic. Using the stability of 19 observed low-mass X-ray binaries as an indication that the rigid crust damping of the r-mode dominates within the models studied, we find that m2 is r-mode-stable while rotating with a frequency higher than 870.2 Hz (0.744 times its Kepler frequency of 1169.6 Hz) as long as its temperature is lower than about 3.9 × 107 K, further supporting the proposal that GW190814's secondary component is a supermassive and superfast pulsar.

Keywords: Neutron stars, Pulsars
Source-dependent Properties of Two Slow Solar Wind States. Two states of the slow solar wind are identified from in situ measurements by the Parker Solar Probe (PSP) inside 50 solar radii from the Sun. At such distances the wind measured by PSP has not yet undergone significant transformation related to the expansion and propagation of the wind. We focus in this study on the properties of the quiet solar wind with no magnetic switchbacks. The two states differ by their plasma beta, flux, and magnetic pressure. PSP's magnetic connectivity established with potential field source surface reconstructions, tested against extreme ultraviolet and white-light imaging, reveals the two states correspond to a transition from a streamer to an equatorial coronal hole. The expansion factors of magnetic field lines in the streamer are 20 times greater than those rooted near the center of the coronal hole. The very different expansion rates of the magnetic field result in different magnetic pressures measured by PSP in the two plasma states. Solar wind simulations run along these differing flux tubes reproduce the slower and denser wind measured in the streamer and the more tenuous wind measured in the coronal hole. Plasma heating is more intense at the base of the streamer field lines rooted near the boundary of the equatorial hole than those rooted closer to the center of the hole. This results in a higher wind flux driven inside the streamer than deeper inside the equatorial hole.

Keywords: Slow solar wind, Solar coronal holes, Solar wind, Solar coronal streamers
Identifying Radio-active Galactic Nuclei among Radio-emitting Galaxies. Basing our analysis on ROGUE I, a catalog of over 32,000 radio sources associated with optical galaxies, we provide two diagnostics to select the galaxies where the radio emission is dominated by an active galactic nucleus (AGN), referred to in the paper as radio-AGNs. Each of these diagnostics can be applied independently. The first one, dubbed MIRAD, compares the flux FW3 in the W3 mid-infrared band of the Wide-field Infrared Survey Explorer telescope, with the radio flux at 1.4 GHz, F1.4. MIRAD requires no optical spectra. The second diagnostic, dubbed DLM, compares the 4000 Å break strength, Dn(4000), with the radio luminosity per unit stellar mass. The DLM diagram has already been used in the past, but not as stand-alone. For these two diagrams, we propose simple, empirical dividing lines that result in the same classification for the objects in common. These lines correctly classify as radio-AGN 99.5% of the extended radio sources in the ROGUE I catalog, and as star-forming galaxies 98%-99% of the galaxies identified as such by their emission-line ratios. Both diagrams clearly show that radio-AGNs are preferentially found among elliptical galaxies and among galaxies hosting the most massive black holes. Most of the radio sources classified as radio-AGNs in the MIRAD or DLM diagrams are either optically weak AGNs or retired galaxies.

Keywords: Surveys, Radio galaxies, Radio active galactic nuclei, Astronomical methods, Catalogs
Be It Unresolved: Measuring Time Delays from Lensed Supernovae. Gravitationally lensed Type Ia supernovae (SNe Ia) may be the next frontier in cosmic probes, able to deliver independent constraints on dark energy, spatial curvature, and the Hubble constant. Measurements of time delays between the multiple images become more incisive due to the standardized candle nature of the source, monitoring for months rather than years, and partial immunity to microlensing. While currently extremely rare, hundreds of such systems should be detected by upcoming time domain surveys. Others will have the images spatially unresolved, with the observed lightcurve a superposition of time-delayed image fluxes. We investigate whether unresolved images can be recognized as lensed sources given only lightcurve information, and whether time delays can be extracted robustly. We develop a method that we show can identify these systems for the case of lensed SNe Ia with two images and time delays exceeding ten days. When tested on such an ensemble, without microlensing, the method achieves a false-positive rate of ≲5%, and measures the time delays with a completeness of ≳93% and with a bias of ≲0.5% for Δtfit ≳ 10 days. Since the method does not assume a template of any particular type of SN, the method has the (untested) potential to work on other types of lensed SNe systems and possibly on other transients as well.

Keywords: Cosmology, Sky surveys, Strong gravitational lensing, Astrostatistics techniques, Type Ia supernovae, Supernovae
A Perspective on the Scaling of Magnetosheath Turbulence and Effects of Bow Shock Properties. We analyze magnetic field data from two magnetosheath crossings, representative of a larger collection of similar cases in the database of the Cluster spacecraft. We apply a novel data analysis method to identify the power-law behavior of the structure functions and to find the validity range of the power-law scaling. We validate the technique with solar wind magnetic field data and a synthetic magnetic field signal. This approach grants a rigorous determination of the scale range for a linear fit of the structure function in the log-log representation, which most often is chosen arbitrarily. The fitting allows an estimation of the power spectral index from the scale variation of the second-order structure function exponent. Data recorded during the first Cluster magnetosheath crossing, called Event 1, indicate three different power-law scaling regimes (injection, inertial, and kinetic) separated by two spectral breaks, consistent with the scenario of fully developed turbulence. However, data from the second Cluster magnetosheath crossing, called Event 2, depict a different scenario with only two power-law scaling regimes determined from the fit. A spectral slope shallower than the Kolmogorovian solar wind power-law index is determined at magnetohydrodynamic scales, spanning more than three frequency decades, which is separated by a spectral break from the kinetic regime. An analysis of simultaneous solar wind data from the Advanced Composition Explorer suggests that the scale behavior of the magnetosheath fluctuations might be controlled by the structure of the bow shock; solar wind turbulent fluctuations are only partially destroyed while they are carried across the bow shock. Both events are recorded in a quasi-perpendicular magnetosheath.

Keywords: Space plasmas, Interplanetary turbulence, Planetary bow shocks, Interplanetary magnetic fields, Solar-terrestrial interactions
A Physical Model for a Radiative, Convective Dusty Disk in AGN. An accretion disk in an Active Galactic Nucleus harbors and shields dust from external illumination. Our model shows that, at the midplane of the disk around an MBH = 107M⊙ black hole, dust can exist at 0.1 pc from the black hole, compared to 0.5 pc outside of the disk where such self-shielding is constrained. We construct a physical model of a disk region approximately located between the radius of dust sublimation at the disk midplane and the radius at which dust sublimes at the disk surface. Our main conclusion is that, for a wide range of model parameters such as local accretion rate and/or opacity, the accretion disk's own radiation pressure on dust significantly influences its vertical structure. In this region, convection plays important role in the vertical transport of energy. When the local accretion rate exceeds 2.5M⊙ yr, the 10-2 pc scale disk is supercritical with respect to dust opacity. Such a disk puffs up and transforms from geometrically thin to slim. Our model fits into the narrative of a "failed wind" scenario of Czerny &amp; Hryniewicz and the "compact torus" model of Baskin &amp; Laor, incorporating them as variations of the radiative dusty disk model.

Keywords: Astrophysical dust processes, Galaxy accretion disks, Active galactic nuclei
The Effect of Circumstellar Matter on the Double-peaked Type Ic Supernovae and Implications for LSQ14efd, iPTF15dtg, and SN 2020bvc. Double-peaked light curves are observed for some Type Ic supernovae (SNe Ic), including LSQ14efd, iPTF15dtg, and SN 2020bvc. One possible explanation of the first peak would be shock-cooling emission from massive extended material around the progenitor, which is produced by mass eruption or rapid expansion of the outermost layers of the progenitor shortly before the supernova explosion. We investigate the effects of such circumstellar matter (CSM) on the multiband optical light curves of SNe Ic using the radiation hydrodynamics code STELLA. Two different SNe Ic progenitor masses at the pre-SN stage (3.93 M⊙ and 8.26 M⊙) are considered in the SN models. The adopted parameter space consists of the CSM mass of MCSM = 0.05-0.3M⊙, the CSM radius of RCSM = 1013-1015 cm, and the explosion energy of Eburst = (1.0-12.0) × 1051 erg. We also investigate the effects of the radioactive nickel distribution on the overall shape of the light curve and the color evolution. Comparison of our SN models with the double-peaked SNe Ic LSQ14efd, iPTF15dtg, and SN 2020bvc indicates that these three SNe Ic had a similar CSM structure (i.e., MCSM ≈ 0.1-0.2M⊙ and RCSM = 1013-1014 cm), which might imply a common mechanism for their CSM formation. The implied mass-loss rate of $\dot{M}\gtrsim 1.0\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$ is too high to be explained by the previously suggested scenarios for pre-SN eruption, which calls for a novel mechanism.

Keywords: Type Ic supernovae, Supernovae
A Census of the Extended Neutral Hydrogen around 18 MHONGOOSE Galaxies. We present the analysis of the diffuse, low column density H I environment of 18 MHONGOOSE galaxies. We obtained deep observations with the Robert C. Byrd Green Bank Telescope and reached down to a 3σ column density detection limit of NHI = 6.3 × 1017 cm-2 over a 20 km s-1 line width. We analyze the environment around these galaxies, with a focus on H I gas that reaches column densities below NHI = 1019 cm-2. We calculate the total amount of H I gas in and around the galaxies, revealing that nearly all of these galaxies contained excess H I outside of their disks. We quantify the amount of diffuse gas in the maps of each galaxy, defined by H I gas with column densities below 1019 cm-2, and find a large spread in percentages of diffuse gas. However, by binning the percentage of diffuse H I into quarters, we find that the bin with the largest number of galaxies is the lowest quartile (0%-25% diffuse H I). We identified several galaxies that may be undergoing gas accretion onto the galaxy disk using multiple methods of analysis, including azimuthally averaging column densities beyond the disk, and identifying structure within our integrated intensity (moment 0) maps. We measured H I mass outside the disks of most of our galaxies, with rising cumulative flux even at large radii. We also find a strong correlation between the fraction of diffuse gas in a galaxy and its baryonic mass, and we test this correlation using both Spearman and Pearson correlation coefficients. We see evidence of a dark matter halo mass threshold of Mhalo ∼ 1011.1 M⊙ in which galaxies with high fractions of diffuse H I all reside below. It is in this regime that cold-mode accretion should dominate. Finally, we suggest a rotation velocity of vrot ∼ 80 km s-1 as an upper threshold to find diffuse-gas-dominated galaxies.

Keywords: Galaxy structure, Galaxy evolution, Galaxy accretion, Circumgalactic medium, Extragalactic astronomy
Hybrid Accretion of Carbonaceous Chondrites by Radial Transport across the Jupiter Barrier. Understanding the origin of chondritic components and their accretion pathways is critical to unraveling the magnitude of mass transport in the protoplanetary disk, as well as the accretionary history of the terrestrial planet region and, by extension, its prebiotic inventory. Here we trace the heritage of pristine components from the relatively unaltered CV chondrite Leoville through their mass-independent Cr and mass-dependent Zn isotope compositions. Investigating these chondritic fractions in such detail reveals an onion-shell structure of chondrules, which is characterized by 54Cr- and 66Zn-poor cores surrounded by increasingly 54Cr- and 66Zn-rich igneous rims and an outer coating of fine-grained dust. This is interpreted as a progressive addition of 54Cr- and 66Zn-rich, CI-like material to the accretion region of these carbonaceous chondrites. Our findings show that the observed Cr isotopic range in chondrules from more altered CV chondrites is the result of chemical equilibration between the chondrules and matrix during secondary alteration. The 54Cr-poor nature of the cores of Leoville chondrules implies formation in the inner solar system and subsequent massive outward chondrule transport past the Jupiter barrier. At the same time, CI-like dust is transferred inward. We propose that the accreting Earth acquired CI-like dust through this mechanism within the lifetime of the disk. This radial mixing of the chondrules and matrix shows the limited capacity of Jupiter to act as an efficient barrier and maintain the proposed noncarbonaceous and carbonaceous chondrite dichotomy over time. Finally, also considering current astrophysical models, we explore both inner and outer solar system origins for the CV chondrite parent body.

Keywords: Protoplanetary disks