Sazuna/UAT_keywords huggingface dataset:
A Sharp Rise in the Detection Rate of Broad Absorption Line Variations in a Quasar SDSS J141955.26+522741.1. We present an analysis of the variability of broad absorption lines (BALs) in a quasar SDSS J141955.26+522741.1 at z = 2.145 with 72 observations from the Sloan Digital Sky Survey Data Release 16 (SDSS DR16). The strong correlation between the equivalent widths of BALs and the continuum luminosity, reveals that the variation of BAL troughs is dominated by the photoionization. The photoionization model predicts that when the time interval ΔT between two observations is longer than the recombination timescale trec, the BAL variations can be detected. This can be characterized as a "sharp rise" in the detection rate of BAL variation at ΔT = trec. For the first time, we detect such a "sharp rise" signature in the detection rate of BAL variations. As a result, we propose that the trec can be obtained from the "sharp rise" of the detection rate of BAL variation. It is worth mentioning that the BAL variations are detected at the time intervals less than the trec for half an order of magnitude in two individual troughs. This result indicates that there may be multiple components with different trec but the same velocity in an individual trough.

Keywords: Galaxy winds, Quasar absorption line spectroscopy, Broad-absorption line quasar
Spiral Arm Pattern Motion in the SAO 206462 Protoplanetary Disk. Spiral arms have been observed in more than a dozen protoplanetary disks, yet the origin of nearly all systems is under debate. Multi-epoch monitoring of spiral arm morphology offers a dynamical way to distinguish two leading arm formation mechanisms: companion-driven and gravitational instability induction, since these mechanisms predict distinct motion patterns. By analyzing multi-epoch J-band observations of the SAO 206462 system using the SPHERE instrument on the Very Large Telescope in 2015 and 2016, we measure the pattern motion for its two prominent spiral arms in polarized light. On one hand, if both arms are comoving, they can be driven by a planet at ${86}_{-13}^{+18}$ au on a circular orbit, with gravitational instability motion ruled out. On the other hand, they can be driven by two planets at ${120}_{-30}^{+30}$ au and ${49}_{-5}^{+6}$ au, offering tentative evidence (3.0σ) that the two spirals are moving independently. The independent arm motion is possibly supported by our analysis of a re-reduction of archival observations using the NICMOS instrument on board the Hubble Space Telescope (HST) in 1998 and 2005, yet artifacts including shadows can manifest spurious arm motion in HST observations. We expect future re-observations to better constrain the motion mechanism for the SAO 206462 spiral arms.

Keywords: Planetary system formation, Coronagraphic imaging, Protoplanetary disks, Orbital motion
Evidence of a Clear Atmosphere for WASP-62b: The Only Known Transiting Gas Giant in the JWST Continuous Viewing Zone. Exoplanets with cloud-free, haze-free atmospheres at the pressures probed by transmission spectroscopy represent a valuable opportunity for detailed atmospheric characterization and precise chemical abundance constraints. We present the first optical to infrared (0.3-5 μm) transmission spectrum of the hot Jupiter WASP-62b, measured with Hubble/STIS and Spitzer/IRAC. The spectrum is characterized by a 5.1σ detection of Na I absorption at 0.59 μm, in which the pressure-broadened wings of the Na D-lines are observed from space for the first time. A spectral feature at 0.4 μm is tentatively attributed to SiH at 2.1σ confidence. Our retrieval analyses are consistent with a cloud-free atmosphere without significant contamination from stellar heterogeneities. We simulate James Webb Space Telescope (JWST) observations, for a combination of instrument modes, to assess the atmospheric characterization potential of WASP-62b. We demonstrate that JWST can conclusively detect Na, H2O, FeH, NH3, CO, CO2, CH4, and SiH within the scope of its Early Release Science (ERS) program. As the only transiting giant planet currently known in the JWST Continuous Viewing Zone, WASP-62b could prove a benchmark giant exoplanet for detailed atmospheric characterization in the James Webb era.

Keywords: Exoplanet atmospheric composition , Planetary atmospheres, Exoplanet atmospheres
Neutron Star Mergers in Active Galactic Nucleus Accretion Disks: Cocoon and Ejecta Shock Breakouts. Neutron star mergers are believed to occur in accretion disks around supermassive black holes. Here we show that a putative jet launched from the merger of a binary neutron star (BNS) or a neutron star-black hole (NSBH) merger occurring at the migration trap in an active galactic nucleus (AGN) disk would be choked. The jet energy is deposited within the disk materials to power a hot cocoon. The cocoon is energetic enough to break out from the AGN disk and produce a bright X-ray shock breakout transient peaking at ∼0.15 days after the merger. The peak luminosity is estimated as $\sim {10}^{46}\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ , which can be discovered by the Einstein Probe from $z\lesssim 0.5$ . Later on, the nonrelativistic ejecta launched from the merger would break out the disk, powering an X-ray/UV flare peaking at ∼0.5 days after the merger. This second shock breakout signal may be detected by UV transient searches. The cocoon cooling emission and kilonova emission are outshone by the disk emission and are difficult to detect. Future joint observations of gravitational waves from BNS/NSBH mergers and associated two shock breakout signatures can provide strong support for the compact binary coalescence formation channel in AGN disks.

Keywords: Neutron stars, Gamma-ray bursts, Black holes, Active galactic nuclei, Gravitational waves
Bursts before Burst: A Comparative Study on FRB 200428-associated and FRB-absent X-Ray Bursts from SGR J1935+2154. Accompanied by an X-ray burst, the fast radio burst (FRB) FRB 200428 was recently confirmed as originating from the Galactic magnetar soft gamma repeater (SGR) SGR J1935+2154. Just before and after FRB 200428 was detected, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) had been monitoring SGR J1935+2154 for eight hours. From UTC 2020 April 27 23:55:00 to 2020 April 28 00:50:37, FAST detected no pulsed radio emission from SGR J1935+2154, while Fermi/Gamma-ray Burst Monitor registered 34 bursts in the X/soft γ-ray band, forming a unique sample of X-ray bursts in the absence of FRBs. After a comprehensive analysis on light curves, time-integrated, and time-resolved spectral properties of these FRB-absent X-ray bursts, we compare this sample with the FRB-associated X-ray burst detected by Insight-HXMT, INTEGRAL, and Konus-Wind. The FRB-associated burst distinguishes itself from other X-ray bursts by its nonthermal spectrum and a higher spectral peak energy, but otherwise is not atypical. We also compare the cumulative energy distribution of our X-ray burst sample with that of first repeating FRB source, FRB 121102, with the calibration of FRB 200428-X-ray burst association. We find a similarity between the two, offering indirect support of the magnetar origin of cosmological FRBs. The event rate density of magnetar bursts is about ∼150 times higher than the FRB event rate density at the energy of FRB 200428. This again suggests that, if all FRBs originate from magnetars, only a small fraction of X-ray bursts are associated with FRBs.

Keywords: Magnetars, Soft gamma-ray repeaters, Radio transient sources
Nonlinear Alfvén Wave Model of Stellar Coronae and Winds from the Sun to M Dwarfs. An M dwarf's atmosphere and wind are expected to be highly magnetized. The nonlinear propagation of Alfvén waves could play a key role in both heating the stellar atmosphere and driving the stellar wind. Using this Alfvén wave scenario, we carried out a one-dimensional compressive magnetohydrodynamic simulation to examine the nonlinear propagation of Alfvén waves from the M dwarf's photosphere, chromosphere to the corona, and interplanetary space. Based on the simulation results, we developed a semi-empirical method describing the solar and M dwarf's coronal temperature, stellar wind velocity, and wind's mass-loss rate. We find that M dwarfs' coronae tend to be cooler than the solar corona, and that M dwarfs' stellar winds can be characterized as having a faster velocity and much smaller mass-loss rate compared to those of the solar wind.

Keywords: M dwarf stars, Magnetohydrodynamics, Stellar chromospheres, Stellar winds, Alfven waves, Stellar coronae
Search for Continuous Gravitational Waves from Scorpius X-1 in LIGO O2 Data. We present the results of a search in LIGO O2 public data for continuous gravitational waves from the neutron star in the low-mass X-ray binary Scorpius X-1. We search for signals with ≈ constant frequency in the range 40-180 Hz. Thanks to the efficiency of our search pipeline we can use a long coherence time and achieve unprecedented sensitivity, significantly improving on existing results. This is the first search that has been able to probe gravitational wave amplitudes that could balance the accretion torque at the neutron star radius. Our search excludes emission at this level between 67.5 and 131.5 Hz, for an inclination angle 44° ± 6° derived from radio observations, and assuming that the spin axis is perpendicular to the orbital plane. If the torque arm is ≈26 km—a conservative estimate of the Alfvén radius—our results are more constraining than the indirect limit across the band. This allows us to exclude certain mass-radius combinations and to place upper limits on the strength of the star's magnetic field with a different probe than ever used before. We also correct a mistake that appears in the literature in the equation that gives the gravitational wave amplitude at the torque balance and we re-interpret the associated latest LIGO/Virgo results in light of this.

Keywords: Neutron stars, Low-mass x-ray binary stars, Gravitational waves
Plumelets: Dynamic Filamentary Structures in Solar Coronal Plumes. Solar coronal plumes long seemed to possess a simple geometry supporting spatially coherent, stable outflow without significant fine structure. Recent high-resolution observations have challenged this picture by revealing numerous transient, small-scale, collimated outflows ("jetlets") at the base of plumes. The dynamic filamentary structure of solar plumes above these outflows, and its relationship with the overall plume structure, have remained largely unexplored. We analyzed the statistics of continuously observed fine structure inside a single representative bright plume within a mid-latitude coronal hole during 2016 July 2-3. By applying advanced edge-enhancement and spatiotemporal analysis techniques to extended series of high-resolution images from the Solar Dynamics Observatory's Atmospheric Imaging Assembly, we determined that the plume was composed of numerous time-evolving filamentary substructures, referred to as "plumelets" in this paper, that accounted for most of the plume emission. The number of simultaneously identifiable plumelets was positively correlated with plume brightness, peaked in the fully formed plume, and remained saturated thereafter. The plumelets had transverse widths of 10 Mm and intermittently supported upwardly propagating periodic disturbances with phase speeds of 190-260 km s-1 and longitudinal wavelengths of 55-65 Mm. The characteristic frequency (≈ 3.3 mHz) is commensurate with that of solar p-modes. Oscillations in neighboring plumelets are uncorrelated, indicating that the waves could be driven by p-mode flows at spatial scales smaller than the plumelet separation. Multiple independent sources of outflow within a single coronal plume should impart significant fine structure to the solar wind that may be detectable by Parker Solar Probe and Solar Orbiter.

Keywords: Solar coronal transients, Solar magnetic reconnection, Solar extreme ultraviolet emission, Plasma jets, Solar wind, Astronomy data analysis, Solar coronal waves, Direct imaging, Solar oscillations, Solar activity, Solar coronal holes, Solar coronal plumes
Magnetic Fields in Elliptical Galaxies: An Observational Probe of the Fluctuation Dynamo Action. Fluctuation dynamos are thought to play an essential role in the evolution of magnetized galaxies, saturating within ∼0.01 Gyr and thus potentially acting as seeds for large-scale mean-field dynamos. However, unambiguous observational confirmation of the fluctuation dynamo action in a galactic environment is still missing. This is because, in spiral galaxies, it is difficult to differentiate between small-scale magnetic fields generated by a fluctuation dynamo and those due to the tangling of the large-scale field. We propose that observations of magnetic fields in elliptical galaxies would directly probe the fluctuation dynamo action. This is motivated by the fact that in ellipticals, due to their lack of significant rotation, the conventional large-scale dynamo is absent and the fluctuation dynamo is responsible for controlling the strength and structure of the magnetic field. By considering turbulence injected by Type Ia supernova explosions and possible magnetic field amplification by cooling flows, we estimate expected magnetic field strengths of $0.2\mbox{--}1\,\mu {\rm{G}}$ in the centers of quiescent elliptical galaxies. We use a semianalytic model of galaxy formation to estimate the distribution and redshift evolution of field strengths, tentatively finding a decrease in magnetic field strength with decreasing redshift. We analyze a historical sample of radio sources that exhibit the Laing-Garrington effect (radio polarization asymmetry in jets) and infer magnetic field strengths between $0.14\,\mathrm{and}\,1.33\,\mu {\rm{G}}$ for a uniform thermal electron density and between $1.36\,\mathrm{and}\,6.21\,\mu {\rm{G}}$ for the thermal electron density following the King profile. We examine observational techniques for measuring the magnetic field saturation state in elliptical galaxies, focusing on Faraday rotation measure grids, the Laing-Garrington effect, synchrotron emission, and gravitational lensing, and finding appealing prospects for future empirical analysis.

Keywords: Galaxy magnetic fields, Polarimetry, Interstellar magnetic fields, Elliptical galaxies, Magnetic fields
Statistical Correlation between the Distribution of Lyα Emitters and Intergalactic Medium H I at z ∼ 2.2 Mapped by the Subaru/Hyper Suprime-Cam. The correlation between neutral hydrogen (H I) in the intergalactic medium (IGM) and galaxies attracts great interest. We select four fields that include several coherently strong Lyα absorption systems at z ∼ 2.2 detected using background quasars from the whole SDSS/(e) Baryon Oscillation Spectroscopic Survey (BOSS) database. Deep narrowband and g-band imaging are performed using the Hyper Suprime-Cam on the Subaru Telescope. We select 2642 Lyα emitter (LAE) candidates at z = 2.177 ± 0.023 down to the Lyα luminosity of LLyα ≈ 2 × 1042 erg s-1 to construct the galaxy overdensity maps, covering an effective area of 5.39 deg2. Combining the sample with the Lyα absorption estimated from 64 (e) BOSS quasar spectra, we find a moderate to strong correlation between the LAE overdensity δLAE and the effective optical depth τLoS in lines of sight, with P value = 0.09% or &lt;0.01% when the field containing a significant quasar overdensity is included or excluded. Cross-correlation analysis also clearly suggests that up to 4 ± 1 pMpc, LAEs tend to cluster in regions rich in H I gas, as indicated by the high τLoS, and avoid the low τLoS regions where the H I gas is deficient. By averaging the τLoS as a function of the projected distance (d) to LAEs, we find a 30% excess signal at 2σ level at d &lt; 200 pkpc, indicating the dense H I in the circumgalactic medium, and a tentative excess at 400 &lt; d &lt; 600 pkpc in the IGM regime, corroborating the cross-correlation signal detected at about 0.5 pMpc. These statistical analyses suggest that galaxy-IGM H I correlations exist on scales ranging from several hundred pkpc to several pMpc at z ∼ 2.2.

Keywords: Galaxy formation, Large-scale structure of the universe, Intergalactic medium, Lyman-alpha galaxies, Two-point correlation function
The Breakdown Scale of H I Bias Linearity. The 21 cm intensity mapping experiments promise to obtain the large-scale distribution of H I gas at the post-reionization epoch. In order to reveal the underlying matter density fluctuations from the H I mapping, it is important to understand how H I gas traces the matter density distribution. Both nonlinear halo clustering and nonlinear effects modulating H I gas in halos may determine the scale below which the H I bias deviates from linearity. We employ three approaches to generate the mock H I density from a large-scale N-body simulation at low redshifts, and demonstrate that the assumption of H I linearity is valid at the scale corresponding to the first peak of baryon acoustic oscillations, but breaks down at k ≳ 0.1 h Mpc-1. The nonlinear effects of halo clustering and H I content modulation counteract each other at small scales, and their competition results in a model-dependent "sweet-spot" redshift near z = 1, where the H I bias is scale-independent down to small scales. We also find that the linear H I bias scales approximately linearly with redshift for z ≤ 3.

Keywords: Large-scale structure of the universe, Galaxy dark matter halos, Line intensities, H I line emission
An Ultradeep Multiband VLA Survey of the Faint Radio Sky (COSMOS-XS): Source Catalog and Number Counts. We present ultradeep, matched-resolution Karl G. Jansky Very Large Array observations at 10 and 3 GHz in the COSMOS field: the COSMOS-XS survey. The final 10 and 3 GHz images cover ∼16 and $\sim 180\,{\mathrm{arcmin}}^{2}$ and reach median rms values at the phase center of 0.41 and 0.53 μJy beam-1, respectively. Both images have an angular resolution of ∼2"0. To account for the spectral shape and resolution variations across the broad bands, we image all data with a multiscale, multifrequency synthesis algorithm. We present source catalogs for the 10 and 3 GHz image with 91 and 1498 sources, respectively, above a peak brightness threshold of 5σ. We present source counts with completeness corrections included that are computed via Monte Carlo simulations. Our corrected counts at 3 GHz are consistent within the uncertainties with other results at 3 and 1.4 GHz but extend to fainter flux densities than previous direct detections. The 3 GHz number counts exceed the counts predicted by the semiempirical simulations developed in the framework of the SKA Simulated Skies project, consistent with previous P(D) analyses. Our source counts suggest a steeper luminosity function evolution for faint star-forming sources. The semiempirical Tiered Radio Extragalactic Continuum Simulation predicts this steeper evolution and is in better agreement with our results at 10 and 3 GHz within the expected variations from cosmic variance. In summary, the multiband, matched-resolution COSMOS-XS survey in the COSMOS field provides a high-resolution view of the ultrafaint radio sky that can help guide next-generation radio facilities.

Keywords: Radio continuum emission, Radio source counts, Radio source catalogs
The Correlation between Black Hole Mass and Stellar Mass for Classical Bulges and the Cores of Ellipticals. The correlation between black hole mass and the stellar mass of the bulge of the host galaxy has attracted much attention ever since its discovery. While traditional investigations of this correlation have treated elliptical galaxies as single, monolithic spheroids, the recent realization that massive elliptical galaxies have undergone significant late-time ( $z\lesssim 2$ ) dissipationless assembly since their initially dense "red nugget" phase strongly suggests that black holes in present-day ellipticals should be associated only with their cores and not with their extended envelopes. We perform two-dimensional image decomposition of Two Micron All Sky Survey Ks-band images to derive the stellar mass of the cores of 35 nearby ellipticals with reliably measured black hole masses. We revisit the relation between black hole mass and bulge stellar mass by combining classical bulges with the cores of ellipticals. The new relation exhibits nearly identical slope ( ${M}_{\bullet }\propto {M}_{\mathrm{core}}^{1.2}$ ) as the conventional relation but a factor of ∼2 higher normalization and moderately larger intrinsic scatter (0.4 dex). At a core mass of ${10}^{11}\,{M}_{\odot }$ , ${M}_{\bullet }/{M}_{\mathrm{core}}=0.9 \% $ , but it rises to ${M}_{\bullet }/{M}_{\mathrm{core}}=1.5 \% $ for the most massive cores with mass ${10}^{12}\,{M}_{\odot }$ . Fast and slow rotator ellipticals follow the same correlation. The ${M}_{\bullet }\mbox{--}{M}_{\mathrm{core}}$ relation provides a revised benchmark for studies of black hole-galaxy coevolution in the high-redshift universe.

Keywords: Supermassive black holes, Galaxy structure, Active galaxies, Galaxy bulges, Scaling relations, Galaxy photometry, Galaxy evolution, Elliptical galaxies
X-Ray and Radio Bursts from the Magnetar 1E 1547.0-5408. We report on simultaneous radio and X-ray observations of the radio-emitting magnetar 1E 1547.0-5408 on 2009 January 25 and February 3, with the 64 m Parkes radio telescope and the Chandra and XMM-Newton X-ray observatories. The magnetar was observed in a period of intense X-ray bursting activity and enhanced X-ray emission. We report here on the detection of two radio bursts from 1E 1547.0-5408 reminiscent of fast radio bursts (FRBs). One of the radio bursts was anticipated by ∼1 s (about half a rotation period of the pulsar) by a bright SGR-like X-ray burst, resulting in a Fradio/FX ∼ 10-9. Radio pulsations were not detected during the observation showing the FRB-like radio bursts, while they were detected in the previous radio observation. We also found that the two radio bursts are neither aligned with the latter radio pulsations nor with the peak of the X-ray pulse profile (phase shift of ∼0.2). Comparing the luminosity of these FRB-like bursts and those reported from SGR 1935+2154, we find that the wide range in radio efficiency and/or luminosity of magnetar bursts in the Galaxy may bridge the gap between "ordinary" pulsar radio bursts and the extragalactic FRB phenomenon.

Keywords: Neutron stars, Pulsars, Radio bursts, Magnetars, X-ray bursts, Radio transient sources