Sazuna/UAT_keywords huggingface dataset:
On Strong Correlation between Shifted Velocity and Line Width of Broad Blueshifted [O III] Components in Quasars. We report strong linear correlation between shifted velocity and line width of the broad blueshifted [O III] components in Sloan Digital Sky Survey (SDSS) quasars. Broad blueshifted [O III] components are commonly treated as indicators of outflows related to a central engine; however, it is still an open question whether the outflows are related to central accretion properties or related to local physical properties of narrow emission-line regions (NLRs). Here, the reported strong linear correlation with Spearman rank correlation coefficient 0.75 can be expected under the assumption of active galactic nuclei (AGNs) feedback-driven outflows, through a large sample of 535 SDSS quasars with reliable blueshifted broad [O III] components. Moreover, there are very different detection rates for broad blueshifted and broad redshifted [O III] components in quasars, and no positive correlation can be found between shifted velocity and line width of the broad redshifted [O III] components, which provides further and strong evidence to reject the possibility of local outflows in NLRs leading to the broad blueshifted [O III] components in quasars. Thus, the strong linear correlation can be treated as strong evidence for the broad blueshifted [O III] components being better indicators of outflows related to central engine in AGNs. Furthermore, rather than central black hole masses, Eddington ratios and continuum luminosities have key roles in the properties of the broad blueshifted [O III] components in quasars.

Keywords: Supermassive black holes, Active galactic nuclei, Emission line galaxies, Quasars
The FIP and Inverse-FIP Effects in Solar Flares. The inverse first ionization potential (FIP) effect, the depletion in the coronal abundance of elements like Fe, Mg, and Si that are ionized in the solar chromosphere relative to those that are neutral, has been identified in several solar flares. We give a more detailed discussion of the mechanism of fractionation by the ponderomotive force associated with magnetohydrodynamic waves, paying special attention to the conditions in which inverse-FIP fractionation arises in order to better understand its relation to the usual FIP effect, i.e., the enhancement of the coronal abundance of Fe, Mg, Si, etc. The FIP effect is generated by parallel propagating Alfvén waves, with either photospheric, or more likely coronal, origins. The inverse-FIP effect arises as upward-propagating fast-mode waves with an origin in the photosphere or below refract back downwards in the chromosphere where the Alfvén speed is increasing with altitude. We give a more physically motivated picture of the FIP fractionation, based on the wave refraction around inhomogeneities in the solar atmosphere, and inspired by previous discussions of analogous phenomena in the optical trapping of particles by laser beams. We apply these insights to modeling the fractionation and find good agreement with the observations of Katsuda et al. and Dennis et al.

Keywords: Solar abundances, Alfven waves, Solar flares, Active solar corona
Reverberation Mapping of Changing-look Active Galactic Nucleus NGC 3516. The changes of broad emission lines should be a crucial issue in understanding the physical properties of changing-look active galactic nuclei (CL-AGNs). Here we present the results of an intensive and homogeneous 6 month long reverberation mapping (RM) monitoring campaign during a low-activity state of the CL-AGN Seyfert galaxy NGC 3516. Photometric and spectroscopic monitoring was carried out during 2018-2019 with the Lijiang 2.4 m telescope. The sampling is 2 days in most nights, and the average sampling is ∼3 days. The rest-frame time lags of Hα and Hβ are ${\tau }_{{\rm{H}}\alpha }={7.56}_{-2.10}^{+4.42}$ and ${\tau }_{{\rm{H}}\beta }={7.50}_{-0.77}^{+2.05}$ days, respectively. From an rms Hβ line dispersion of σline = 1713.3 ± 46.7 km s-1 and a virial factor of fσ = 5.5, the central black hole mass of NGC 3516 is estimated to be ${M}_{\mathrm{BH}}={2.4}_{-0.3}^{+0.7}\times {10}^{7}{M}_{\odot }$ , which is in agreement with previous estimates. The velocity-resolved delays show that the time lags increase toward negative velocity for both Hα and Hβ. The velocity-resolved RM of Hα is done for the first time. These RM results are consistent with other observations before the spectral-type change, indicating a basically constant broad-line region structure during the CL process. The CL model of changes of accretion rate seems to be favored by long-term Hβ variability and RM observations of NGC 3516.

Keywords: Supermassive black holes, Reverberation mapping, Active galaxies, Seyfert galaxies, Photometry, Spectroscopy
VLA Imaging of H I-bearing Ultra-diffuse Galaxies from the ALFALFA Survey. Ultra-diffuse galaxies have generated significant interest due to their large optical extents and low optical surface brightnesses, which challenge galaxy formation models. Here we present resolved synthesis observations of 12 H I-bearing ultra-diffuse galaxies (HUDs) from the Karl G. Jansky Very Large Array, as well as deep optical imaging from the WIYN 3.5 m telescope at Kitt Peak National Observatory. We present the data processing and images, including total intensity H I maps and H I velocity fields. The HUDs show ordered gas distributions and evidence of rotation, important prerequisites for the detailed kinematic models of Mancera Piña et al. We compare the H I and stellar alignment and extent, and find that H I extends beyond the already extended stellar component and the H I disk is often misaligned with respect to the stellar one, emphasizing the importance of caution when approaching inclination measurements for these extreme sources. We explore the H I mass-diameter scaling relation, and find that, although the HUDs have diffuse stellar populations, they fall along the relation with typical global H I surface densities. This resolved sample forms an important basis for more detailed study of the H I distribution in this extreme extragalactic population.

Keywords: Radio spectroscopy, Radio astronomy, Galaxy evolution, Galaxies
A Cuspy Dark Matter Halo. The cusp-core problem is one of the main challenges of the cold dark matter paradigm on small scales; the density of a dark matter halo is predicted to rise rapidly toward the center as ρ(r) ∝ rα with α between -1 and -1.5, while such a cuspy profile has not been clearly observed. We have carried out the spatially resolved mapping of gas dynamics toward a nearby ultradiffuse galaxy (UDG), AGC 242019. The derived rotation curve of dark matter is well fitted by the cuspy profile as described by the Navarro-Frenk-White model, while the cored profiles including both the pseudo-isothermal and Burkert models are excluded. The halo has α = -(0.90 ± 0.08) at the innermost radius of 0.67 kpc, Mhalo = (3.5 ± 1.2) × 1010 M⊙, and a small concentration of 2.0 ± 0.36. The UDG AGC 242019 challenges alternatives of cold dark matter by constraining the particle mass of fuzzy dark matter to be &lt;0.11 × 10-22 or &gt;3.3 × 10-22 eV, the cross section of self-interacting dark matter to be &lt;1.63 cm2 g-1, and the particle mass of warm dark matter to be &gt;0.23 keV, all of which are in tension with other constraints. The modified Newtonian dynamics is also inconsistent with a shallow radial acceleration relationship of AGC 242019. For the feedback scenario that transforms a cusp to a core, AGC 242019 disagrees with the stellar-to-halo mass ratio dependent model but agrees with the star formation threshold dependent model. As a UDG, AGC 242019 is in a dwarf-sized halo with weak stellar feedback, late formation time, normal baryonic spin, and low star formation efficiency (SFR/gas).

Keywords: Galaxy dark matter halos, Interstellar atomic gas, Galaxy dynamics, Dwarf galaxies, Dark matter density
Reconstructing Masses of Merging Neutron Stars from Stellar r-process Abundance Signatures. Neutron star mergers (NSMs) are promising astrophysical sites for the rapid neutron-capture ("r") process, but can their integrated yields explain the majority of heavy-element material in the Galaxy? One method to address this question implements a forward approach that propagates NSM rates and yields along with stellar formation rates and compares those results with observed chemical abundances of r-process-rich, metal-poor stars. In this work, we take the inverse approach by utilizing r-process-element abundance ratios of metal-poor stars as input to reconstruct the properties—especially the masses—of their neutron star (NS) binary progenitors. This novel analysis provides an independent avenue for studying the population of the original NS binary systems that merged and produced the r-process material now incorporated in Galactic metal-poor halo stars. We use ratios of elements typically associated with the limited-r-process and the actinide region to those in the lanthanide region (i.e., Zr/Dy and Th/Dy) to probe the NS masses of the progenitor merger. We find that NSMs can account for all r-process material in metal-poor stars that display r-process signatures, while simultaneously reproducing the present-day distribution of double-NS systems. Notably, with our model assumptions and the studied stellar sample, we postulate that the most r-process enhanced stars (the r-II stars) on their own would require progenitor NSMs of asymmetric systems that are distinctly different from present ones in the Galaxy. We also explore variations to the model and find that the predicted degree of asymmetry is most sensitive to the electron fraction of the remnant disk wind.

Keywords: Neutron stars, Nucleosynthesis, R-process, Compact binary stars, Nuclear astrophysics, Population II stars, Chemically peculiar stars
Construction of Explicit Symplectic Integrators in General Relativity. II. Reissner-Nordström Black Holes. In a previous paper, second- and fourth-order explicit symplectic integrators were designed for a Hamiltonian of the Schwarzschild black hole. Following this work, we continue to trace the possibility of construction of explicit symplectic integrators for a Hamiltonian of charged particles moving around a Reissner-Nordström black hole with an external magnetic field. Such explicit symplectic methods are still available when the Hamiltonian is separated into five independently integrable parts with analytical solutions as explicit functions of proper time. Numerical tests show that the proposed algorithms share desirable properties in their long-term stability, precision, and efficiency for appropriate choices of step size. For the applicability of one of the new algorithms, the effects of black hole's charge, the Coulomb part of the electromagnetic potential and the magnetic parameter on the dynamical behavior are surveyed. Under some circumstances, the extent of chaos becomes strong with an increase of the magnetic parameter from a global phase-space structure. No variation of the black hole's charge other than the Coulomb part affects the regular and chaotic dynamics of the particles' orbits. A positive Coulomb part more easily induces chaos than a negative one.

Keywords: Celestial mechanics, Black hole physics, Computational astronomy, Computational methods
Illuminating the Dark Side of Cosmic Star Formation Two Billion Years after the Big Bang. How and when did galaxies form and assemble their stars and stellar mass? The answer to these questions, so crucial to astrophysics and cosmology, requires the full reconstruction of the so-called cosmic star formation rate density (SFRD), i.e., the evolution of the average star formation rate per unit volume of the universe. While the SFRD has been reliably traced back to 10-11 billion years ago, its evolution is still poorly constrained at earlier cosmic epochs, and its estimate is mainly based on galaxies luminous in the ultraviolet and with low obscuration by dust. This limited knowledge is largely due to the lack of an unbiased census of all types of star-forming galaxies in the early universe. We present a new approach to finding dust-obscured star-forming galaxies based on their emission at radio wavelengths coupled with the lack of optical counterparts. Here, we present a sample of 197 galaxies selected with this method. These systems were missed by previous surveys at optical and near-infrared wavelengths, and 22 of them are at very high redshift (i.e., z &gt; 4.5). The contribution of these elusive systems to the SFRD is substantial and can be as high as 40% of the previously known SFRD based on UV-luminous galaxies. The mere existence of such heavily obscured galaxies in the first two billion years after the Big Bang opens new avenues to investigate the early phases of galaxy formation and evolution, and to understand the links between these systems and the massive galaxies that ceased their star formation at later cosmic times.

Keywords: Star formation, Galaxy formation, High-redshift galaxies, Galaxy evolution
Photospheric Velocity Gradients and Ejecta Masses of Hydrogen-poor Superluminous Supernovae: Proxies for Distinguishing between Fast and Slow Events. We present a study of 28 Type I superluminous supernovae (SLSNe) in the context of the ejecta mass and photospheric velocity. We combine photometry and spectroscopy to infer ejecta masses via the formalism of radiation diffusion equations. We present an improved method to determine the photospheric velocity by combining spectrum modeling and cross-correlation techniques. We find that Type I SLSNe can be divided into two groups according to their pre-maximum spectra. Members of the first group have a W-shaped absorption trough in their pre-maximum spectrum, usually identified as due to O II. This feature is absent in the spectra of supernovae in the second group, whose spectra are similar to that of SN 2015bn. We confirm that the pre- or near-maximum photospheric velocities correlate with the velocity gradients: faster evolving SLSNe have larger photospheric velocities around maximum. We classify the studied SLSNe into the Fast or the Slow evolving group according to their estimated photospheric velocities, and find that all those objects that resemble SN 2015bn belong to the Slow evolving class, while SLSNe showing the W-like absorption are represented in both Fast and Slow evolving groups. We estimate the ejecta masses of all objects in our sample, and obtain values in the range 2.9 (±0.8)-208 (±61) M⊙, with a mean of 43 (±12) M⊙. We conclude that Slow evolving SLSNe tend to have higher ejecta masses compared to the Fast SLSNe. Our ejecta mass calculations suggests that SLSNe are caused by energetic explosions of very massive stars, irrespective of the powering mechanism of the light curve.

Keywords: Ejecta, Supernovae, Radiative transfer
Possible Evidence of Hydrogen Emission in the First-overtone and Multimode RR Lyrae Variables. The nature of shock waves in nonfundamental mode RR Lyrae stars remains a mystery because of limited spectroscopic observations. We apply a pattern recognition algorithm on spectroscopic data from SDSS and LAMOST and report the first evidence of hydrogen emission in first-overtone (RRc) and multimode (RRd) RR Lyrae stars showing the "first apparition," which is the most prominent observational characteristic of shock in RR Lyrae variables. We find 10 RRc stars in SDSS, 10 RRc stars in LAMOST, and 3 RRd stars in LAMOST that show blueshifted Balmer emissions. The emission features possibly indicate the existence of shock waves. We calculate the radial velocities of the emission lines, which are related to the physical conditions occurring in the radiative zone of shock waves. Using photometric observations from ZTF, we present a detailed light-curve analysis for the frequency components in one of our RRd stars with hydrogen emission, RRdl3, for possible modulations. With the enormous volume of upcoming spectral observations of variable stars, our study raises the possibility of connecting the unexplained Blazhko effect to shock waves in nonfundamental mode RR Lyrae stars.

Keywords: Astronomy databases, Stellar pulsations, Stellar atmospheric opacity, Astronomy data analysis, Blazhko effect, RRd variable stars, RRc variable stars, RR Lyrae variable stars, Pulsation modes, Spectroscopy, Shocks, Stellar atmospheres
It's Dust: Solving the Mysteries of the Intrinsic Scatter and Host-galaxy Dependence of Standardized Type Ia Supernova Brightnesses. The use of Type Ia supernovae (SNe Ia) as cosmological tools has motivated significant effort to understand what drives the intrinsic scatter of SN Ia distance modulus residuals after standardization, characterize the distribution of SN Ia colors, and explain why properties of the host galaxies of the SNe correlate with SN Ia distance modulus residuals. We use a compiled sample of ∼1450 spectroscopically confirmed photometric light curves of SNe Ia and propose a solution to these three problems simultaneously that also explains an empirical 11σ detection of the dependence of Hubble residual scatter on SN Ia color. We introduce a physical model of color where intrinsic SN Ia colors with a relatively weak correlation with luminosity are combined with extrinsic dust-like colors (E(B - V)) with a wide range of extinction parameter values (RV). This model captures the observed trends of Hubble residual scatter and indicates that the dominant component of SN Ia intrinsic scatter is variation in RV. We also find that the recovered E(B - V) and RV distributions differ based on global host-galaxy stellar mass, and this explains the observed correlation (γ) between mass and Hubble residuals seen in past analyses, as well as an observed 4.5σ dependence of γ on SN Ia color. This finding removes any need to ascribe different intrinsic luminosities to different progenitor systems. Finally, we measure biases in the equation of state of dark energy (w) up to ∣Δw∣ = 0.04 by replacing previous models of SN color with our dust-based model; this bias is larger than any systematic uncertainty in previous SN Ia cosmological analyses.

Keywords: Cosmology, Interstellar dust, Type Ia supernovae, Circumstellar dust, Supernovae, Accelerating universe, Dark energy
Discovering New Strong Gravitational Lenses in the DESI Legacy Imaging Surveys. We have conducted a search for new strong gravitational lensing systems in the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys' Data Release 8. We use deep residual neural networks, building on previous work presented by Huang et al. These surveys together cover approximately one-third of the sky visible from the Northern Hemisphere, reaching a z-band AB magnitude of ∼22.5. We compile a training sample that consists of known lensing systems as well as non-lenses in the Legacy Surveys and the Dark Energy Survey. After applying our trained neural networks to the survey data, we visually inspect and rank images with probabilities above a threshold. Here we present 1210 new strong lens candidates.

Keywords: AGN host galaxies, Galaxy clusters, Quasars, Strong gravitational lensing, Galaxy groups, High-redshift galaxies, Galaxies
Host Galaxy Mass Combined with Local Stellar Age Improve Type Ia Supernovae Distances. Type Ia supernovae (SNe Ia) are standardizable candles, but for over a decade there has been a debate on how to properly account for their correlations with host galaxy properties. Using the Bayesian hierarchical model UNITY, we simultaneously fit for the SN Ia light curve and host galaxy standardization parameters on a set of 103 Sloan Digital Sky Survey II SNe Ia. We investigate the influences of host stellar mass, along with both localized (r &lt;3 kpc) and host-integrated average stellar ages, derived from stellar population synthesis modeling. We find that the standardization for the light-curve shape (α) is correlated with host galaxy standardization terms (γi) requiring simultaneous fitting. In addition, we find that these correlations themselves are dependent on host galaxy stellar mass that includes a shift in the color term (β) of 0.8 mag, only significant at 1.2σ due to the small sample. We find a linear host mass standardization term at the 3.7σ level, that by itself does not significantly improve the precision of an individual SN Ia distance. However, a standardization that uses both stellar mass and average local stellar age is found to be significant at &gt;3σ in the two-dimensional posterior space. In addition, the unexplained scatter of SNe Ia absolute magnitude post standardization, is reduced from ${0.122}_{-0.018}^{+0.019}$ to 0.109 ± 0.017 mag, or ∼10%. We do not see similar improvements when using global ages. This combination is consistent with either metallicity or line-of-sight dust affecting the observed luminosity of SNe Ia.

Keywords: Cosmological parameters, Observational cosmology, Type Ia supernovae, Distance indicators
Candidate Auroral Observations Indicating a Major Solar-Terrestrial Storm in 1680: Implication for Space Weather Events during the Maunder Minimum. The Maunder Minimum (MM; 1645-1715) is currently considered the only grand minimum within telescopic sunspot observations since 1610. During this epoch, the Sun was extremely quiet and unusually free from sunspots. However, despite a reduced frequency, candidate aurorae were reported in the mid-European sector during this period and have been associated with occurrences of interplanetary coronal mass ejections (ICMEs), although some of them have been identified as misinterpretations. Here, we have analyzed reports of candidate aurorae on 1680 June 1 with simultaneous observations in central Europe, and compared their descriptions with visual accounts of early modern aurorae. Contemporary sunspot drawings on 1680 May 22, 24, and 27 have shown a sunspot. This sunspot may have been a source of ICMEs, which caused the reported candidate aurorae. On the other hand, its intensity estimate shows that the geomagnetic storm during this candidate aurora was probably within the capability of the storms derived from the corotating interaction region (CIR). Therefore, we accommodate both ICMEs and CIRs as its possible origin. This interpretation is probably applicable to a number of candidate aurorae in the oft-cited Hungarian catalog, on the basis of the reconstructed margin of their equatorward auroral boundary. Moreover, this catalog itself has clarified that the considerable candidates during the MM were probably misinterpretations. Therefore, the frequency of the auroral visibility in Hungary was probably lower than previously considered and agrees more with the generally slow solar wind in the existing reconstructions, whereas sporadic occurrences of sunspots and coronal holes still caused occasional geomagnetic storms.

Keywords: Geomagnetic fields, Solar wind, Solar coronal mass ejections, Solar-terrestrial interactions, Maunder minimum, Solar coronal holes
StrayCats: A Catalog of NuSTAR Stray Light Observations. We present StrayCats, a catalog of NuSTAR stray light observations of X-ray sources. Stray light observations arise for sources 1°-4° away from the telescope pointing direction. At this off-axis angle, X-rays pass through a gap between the optics and aperture stop and so do not interact with the X-ray optics; instead, they directly illuminate the NuSTAR focal plane. We have systematically identified and examined over 1400 potential observations resulting in a catalog of 436 telescope fields and 78 stray light sources that have been identified. The sources identified include historically known persistently bright X-ray sources, X-ray binaries in outburst, pulsars, and type I X-ray bursters. In this paper, we present an overview of the catalog, how we identified the StrayCats sources, and the analysis techniques required to produce high-level science products. Finally, we present a few brief examples of the science quality of these unique data.

Keywords: Neutron stars, High mass x-ray binary stars, Pulsars, X-ray surveys, Low-mass x-ray binary stars, Astrophysical black holes