Sazuna/UAT_keywords huggingface dataset:
Confirmed Width-E<SUB>iso</SUB> and Width-L<SUB>iso</SUB> Relations in Gamma-Ray Bursts: Comparison with the Amati and Yonetoku Relations. The well-known Amati and Yonetoku relations in gamma-ray bursts show strong correlations between the rest-frame νfν spectrum peak energy, Ep,i, and the isotropic energy, Eiso, as well as isotropic peak luminosity, Liso. Recently, Peng et al. showed that the cosmological rest-frame spectral widths are also correlated with Eiso and with Liso. In this paper, we select a sample including 141 BEST time-integrated F spectra and 145 BEST peak flux P spectra observed by Konus-Wind with known redshift to recheck the connection between the spectral width and Eiso as well as Liso. We define six types of absolute spectral widths as the differences between the upper (E2) and lower energy bounds (E1) of the full width at 50%, 75%, 85%, 90%, 95%, and 99% of maximum of the EFE versus E spectra. It is found that all of the rest-frame absolute spectral widths are strongly positively correlated with Eiso as well as Liso for the long burst for both the F and P spectra. All of the short bursts are outliers for the width-Eiso relation, and most of the short bursts are consistent with the long bursts for the width-Liso relation for both F and P spectra. Moreover, all of the location energies, E2 and E1, corresponding to various spectral widths, are also positively correlated with Eiso as well as Liso. We compare all of the relations with the Amati and Yonetoku relations and find that the width-Eiso and width-Liso relations, when the widths are at about 90% maximum of the EFE spectra, almost overlap with the Amati relation and the Yonetoku relation, respectively. The correlations of E2 - Eiso, E1 - Eiso and E2 - Liso, E1 - Liso when the location energies are at 99% of maximum of the EFE spectra are very close to the Amati and Yonetoku relations, respectively. Therefore, we confirm the existence of tight width-Eiso and width-Liso relations for long bursts. We further show that the spectral shape is indeed related to Eiso and Liso. The Amati and Yonetoku relations are not necessarily the best relationships for relating the energy to the Eiso and Liso. They may be special cases of the width-Eiso and width-Liso relations or the energy-Eiso and energy-Liso relations.

Keywords: Gamma-ray bursts
On the Formation of Lyman β and the O I 1027 and 1028 Å Spectral Lines. We study the potential of Lyman β and the O I 1027 and 1028 Å spectral lines to help in understanding the properties of the chromosphere and transition region (TR). The oxygen transitions are located in the wing of Lyman β, which is a candidate spectral line for the solar missions Solar Orbiter/Spectral Imaging of the Coronal Environment and Solar-C (EUVST). We examine the general spectroscopic properties of the three transitions in the quiet Sun by synthesizing them assuming nonlocal thermal equilibrium and taking into account partial redistribution effects. We estimate the heights where the spectral lines are sensitive to the physical parameters, computing the response functions to temperature and velocity using a 1D semiempirical atmospheric model. We also synthesize the intensity spectrum using the 3D enhanced network simulation computed with the BIFROST code. The results indicate that Lyman β is sensitive to the temperature from the middle chromosphere to the TR, while it is mainly sensitive to the line-of-sight (LOS) velocity at the lower atmospheric layers, around 2000 km above the optical surface. The O I lines form lower in the middle chromosphere, being sensitive to the LOS velocities at heights lower than those covered by Lyman β. The spatial distribution of the intensity signals computed with the BIFROST atmosphere, as well as the inferred velocities from the line core Doppler shift, confirms the previous results. Therefore, these results indicate that the spectral window at 1025 Å contains several spectral lines that complement each other to seamlessly trace the thermal structure and gas dynamics from the middle chromosphere to the lower TR.

Keywords: Solar atmosphere, Solar chromosphere, Radiative transfer
Gamma-Ray Urgent Archiver for Novel Opportunities (GUANO): Swift/BAT Event Data Dumps on Demand to Enable Sensitive Subthreshold GRB Searches. We introduce a new capability of the Neil Gehrels Swift Observatory to provide event-level data from the Burst Alert Telescope (BAT) on demand in response to transients detected by other instruments. We show that the availability of these data can effectively increase the rate of detections and arcminute localizations of gamma-ray bursts (GRB) like GRB 170817 by &gt;400%. We describe an autonomous spacecraft-commanding pipeline purpose built to enable this science; to our knowledge, this is the first fully autonomous extremely low-latency commanding of a space telescope for scientific purposes. This pipeline has been successfully run in its complete form since 2020 January, and has resulted in the recovery of BAT event data for &gt;800 externally triggered events to date (gravitational waves, GWs; neutrinos; GRBs triggered by other facilities; fast radio bursts; and very high-energy detections), now running with a success rate of ∼90%. We exemplify the utility of this new capability by using the resultant data to (1) set the most sensitive upper limits on prompt 1 s duration short GRB-like emission within ±15 s around the unmodeled GW burst candidate S200114f, and (2) provide an arcminute localization for short GRB 200325A and other bursts. We also show that using data from GUANO to localize GRBs discovered by other instruments, we can increase the net rate of arcminute-localized GRBs by 10%-20% per year. Along with the scientific yield of more sensitive searches for subthreshold GRBs, the new capabilities designed for this project will serve as the foundation for further automation and rapid target of opportunity capabilities for the Swift mission, and have implications for the design of future rapid-response space telescopes.

Keywords: Space telescopes, Gamma-ray bursts, Gravitational wave sources, X-ray telescopes
High-resolution Spectroscopic Monitoring Observations of FU Orionis-type Object, V960 Mon. We present the results of high-resolution (R ≥ 30,000) optical and near-infrared (NIR) spectroscopic monitoring observations of an FU Orionis-type object (FUor), V960 Mon, which underwent an outburst in 2014 November. We have monitored this object with the Bohyunsan Optical Echelle Spectrograph and the Immersion GRating INfrared Spectrograph since 2014 December. Various features produced by a wind, disk, and outflow/jet were detected. The wind features varied over time and continually weakened after the outburst. We detected double-peaked line profiles in the optical and NIR, and the line widths tend to decrease with increasing wavelength, indicative of Keplerian disk rotation. The disk features in the optical and NIR spectra fit well with G-type and K-type stellar spectra convolved with a kernel to account for the maximum projected disk rotation velocities of about 40.3 ± 3.8 km s-1 and 36.3 ± 3.9 km s-1, respectively. We also report the detection of [S II] and H2 emission lines, which are jet/outflow tracers and rarely found in FUors.

Keywords: High resolution spectroscopy, FU Orionis stars
Detecting and Characterizing Young Quasars. I. Systemic Redshifts and Proximity Zone Measurements. In a multiwavelength survey of 13 quasars at 5.8 ≲ z ≲ 6.5, which were preselected to be potentially young, we find five objects with extremely small proximity zone sizes that may imply UV-luminous quasar lifetimes of ≲100,000 yr. Proximity zones are regions of enhanced transmitted flux in the vicinity of quasars that are sensitive to the quasars' lifetimes because the intergalactic gas has a finite response time to their radiation. We combine submillimeter observations from the Atacama Large Millimetre Array and the NOrthern Extended Millimeter Array, as well as deep optical and near-infrared spectra from the medium-resolution spectrograph on the Very Large Telescope and on the Keck telescopes, in order to identify and characterize these new young quasars, which provide valuable clues about the accretion behavior of supermassive black holes in the early universe and pose challenges on current black hole formation models to explain the rapid formation of billion-solar-mass black holes. We measure the quasars' systemic redshifts, black hole masses, Eddington ratios, emission-line luminosities, and star formation rates of their host galaxies. Combined with previous results, we estimate the fraction of young objects within the high-redshift quasar population at large to be 5% ≲ fyoung ≲ 10%. One of the young objects, PSO J158-14, shows a very bright dust continuum flux (Fcont = 3.46 ± 0.02 mJy), indicating a highly starbursting host galaxy with a star formation rate of approximately 1420 M☉ yr-1.

Keywords: Supermassive black holes, Quasar absorption line spectroscopy, Quasars, Intergalactic medium, Reionization
Electric Currents through J-shaped and Non-J-shaped Flare Ribbons. Increasing attention has recently been paid to solar flares exhibiting double-J-shaped ribbons in the lower solar atmosphere, in the context of extending the two-dimensional standard flare model to three dimensions, as motivated by the spatial correlation between photospheric current channels and flare ribbons. Here, we study the electric currents through the photospheric area swept by flare ribbons (termed the synthesized ribbon area (SRA)), with a sample of 71 two-ribbon flares, of which 36 are J-shaped. Electric currents flowing through one ribbon are highly correlated with those flowing through the other, and they therefore belong to the same current system. The nonneutrality factor of this current system is independent of the flare magnitude, implying that both direct and return currents participate in flares. J-shaped flares are distinct from non-J-shaped flares in the following ways: (1) electric-current densities within the J-shaped SRA are significantly smaller than those within the non-J-shaped SRA, but the J-shaped SRA and its associated magnetic flux is also significantly larger. (2) Electric currents through the SRA are positively correlated with the flare magnitude, but J-shaped flares show a stronger correlation than non-J-shaped flares. (3) The majority (75%) of J-shaped flares are eruptive, while the majority (86%) of non-J-shaped flares are confined; accordingly, hosting active regions of J-shaped flares are more likely to be sigmoidal than non-J-shaped flares. Thus, J-shaped flares constitute a distinct subset of two-ribbon flares, probably representative of eruptive ones. Further, we found that combining the SRA and its associated magnetic flux has the potential to differentiate eruptive from confined flares.

Keywords: Solar flares, Solar active regions, Solar coronal mass ejections, Solar storm, Magnetic fields
Plasma Diagnostics of the Supernova Remnant N132D using Deep XMM-Newton Observations with the Reflection Grating Spectrometer. We present XMM-Newton observations of N132D, the X-ray brightest supernova remnant in the Large Magellanic Cloud, using the Reflection Grating Spectrometer (RGS), which enables high-resolution spectroscopy in the soft X-ray band. A dozen emission lines from L-shell transitions of Si, S, Ar, Ca, and Fe at intermediate charge states are newly detected in the RGS data integrating the ∼200 ks on-axis observations. This enables accurate abundance measurements of these elements, whose K-shell emission is out of the RGS bandpass. The 0.3-2.0-keV spectra require at least three components of thermal plasmas with different electron temperatures and indicate clear evidence of non-equilibrium ionization (NEI). Our detailed spectral diagnostics further reveal that the forbidden-to-resonance line ratios of O VII and Ne IX are both higher than expected for typical NEI plasmas. This enhancement could be attributed to either resonance scattering or emission induced by charge exchange in addition to a possible contribution from the superposition of multiple-temperature components, although the lack of spatial information prevents us from concluding which is most likely.

Keywords: X-ray astronomy, High resolution spectroscopy, Supernova remnants
Molecular Distributions of the Protostellar Envelope and the Outflow of IRAS 15398-3359: Principal Component Analysis. Using the Atacama Large Millimeter/submillimeter Array, we have imaged 15 molecular-line emissions and the dust continuum emission around the Class 0 protostellar source IRAS 15398-3359. The outflow structure is mainly traced by the H2CO (Ka = 0 and 1), CCH, and CS emissions. These lines also trace the disk/envelope structure around the protostar. The H2CO (Ka = 2 and 3), CH3OH, and SO emissions are concentrated toward the protostar, while the DCN emission is more extended around the protostar. We have performed principal component analysis (PCA) for these distributions on two different scales, the outflow and the disk/envelope structure. For the latter case, the molecular-line distributions are classified into two groups, according to the contribution of the second principal component, one having a compact distribution around the protostar and the other showing a rather extended distribution over the envelope. Moreover, the second principal component value tends to increase as an increasing quantum number of H2CO (Ka = 0, 1, 2, and 3), reflecting the excitation condition: the distribution is more compact for higher excitation lines. These results indicate that PCA is effective at extracting the characteristic features of the molecular-line distributions around the protostar in an unbiased way. In addition, we identify four blobs in the outflow structure in the H2CO lines, some of which can also be seen in the CH3OH, CS, CCH, and SO emissions. The gas temperature derived from the H2CO lines ranges from 43-63 K, which suggests shocks due to the local impact of the outflow on clumps of the ambient gas.

Keywords: Interstellar molecules, Young stellar objects, Star formation, Interstellar medium, Protostars
A Peculiar Cyclotron Line near 16 keV Detected in the 2015 Outburst of 4U 0115+63?. In 2015 October, the Be/X-ray binary 4U 0115+63 underwent a type II outburst, reaching an X-ray luminosity of ∼1038 erg s-1. During the outburst, Nuclear Spectroscopic Telescope Array (NuSTAR) performed two Target of Opportunity observations. Using the broadband spectra from NuSTAR (3-79 keV), we have detected multiple cyclotron lines of the source, i.e., ∼12, 16, 22, and 33/35 keV. Obviously, the 16 keV line is not a harmonic component of the 12 keV line. As described by the phase-dependent equivalent widths of these cyclotron lines, the 16 keV and 12 keV lines are two different fundamental lines. In our work, we apply the two-poles cyclotron line model to the observation, i.e., the two line sets are formed at the same altitude (∼0.2 km over the NS surface) of different magnetic poles, with ∼1.1 × 1012 and 1.4 × 1012 G in two poles, respectively.

Keywords: Accretion, Neutron stars, High mass x-ray binary stars, Binary pulsars
Phase-dependent Study of Near-infrared Disk Emission Lines in LB-1. The mass, origin, and evolutionary stage of the binary system LB-1 have been intensely debated, following the claim that it hosts an ∼70M⊙ black hole, in stark contrast with the expectations for Galactic remnants. We conducted a high-resolution, phase-resolved spectroscopic study of its Paschen lines, using the Calar Alto 3.5 m telescope. We find that Paβ and Paγ (after subtraction of the stellar absorption component) are well fitted with a standard double-peaked disk profile. We measured the velocity shifts of the red and blue peaks at 28 orbital phases: the line center has an orbital motion in perfect antiphase with the secondary, and the radial velocity amplitude ranges from 8 to 13 km s-1, for different methods of profile modeling. We interpret this curve as proof that the disk traces the orbital motion of the primary, ruling out the circumbinary disk and the hierarchical triple scenarios. The phase-averaged peak-to-peak half-separation (a proxy for the projected rotational velocity of the outer part of the disk) is ∼70 km s-1, larger than the orbital velocity of the secondary and inconsistent with a circumbinary disk. From those results, we infer a primary mass 4-8 times higher than the secondary mass. Moreover, we show that the intensity ratio of the blue and red peaks has a sinusoidal behavior in phase with the secondary, which we attribute to external irradiation of the outer part of the disk. Finally, we discuss our findings in the context of competing scenarios proposed for LB-1. Further astrometric Gaia data will test between alternative solutions.

Keywords: Black hole physics, Be stars, Black holes, Stellar evolution
Gas-driven Inspiral of Binaries in Thin Accretion Disks. Numerical studies of gas accretion onto supermassive black hole binaries have generally been limited to conditions where the circumbinary disk (CBD) is 10-100 times thicker than expected for disks in active galactic nuclei. This discrepancy arises from technical limitations, and also from publication bias toward replicating fiducial numerical models. Here we present the first systematic study of how the binary's orbital evolution varies with disk scale height. We report three key results: (1) binary orbital evolution switches from outspiraling for warm disks (aspect ratio h/r ∼ 0.1), to inspiraling for more realistic cooler, thinner disks at a critical value of h/r ∼ 0.04, corresponding to orbital Mach number ${{ \mathcal M }}_{\mathrm{crit}}\approx 25$ . (2) The net torque on the binary arises from a competition between positive torque from gas orbiting close to the black holes, and negative torque from the inner edge of the CBD, which is denser for thinner disks. This leads to increasingly negative net torques on the binary for increasingly thin disks. (3) The accretion rate is modestly suppressed with increasing Mach number. We discuss how our results may influence modeling of the nano-Hz gravitational-wave background, as well as estimates of the Laser Interferometer Space Antenna merger event rate.

Keywords: Accretion, Supermassive black holes, Hydrodynamical simulations, Galaxy accretion disks, Gravitational waves, Compact objects
Retention of Long-period Gas Giant Planets: Type II Migration Revisited. During their formation, emerging protoplanets tidally interact with their natal disks. Proto-gas giant planets, with Hill radii larger than the disk thickness, open gaps and quench gas flow in the vicinity of their orbits. It is usually assumed that their type II migration is coupled to the viscous evolution of the disk. Although this hypothesis provides an explanation for the origin of close-in planets, it also encounters a predicament on the retention of long-period orbits for most gas giant planets. Moreover, numerical simulations indicate that the planets' migrations are not solely determined by the viscous diffusion of their natal disk. Here we carry out a series of hydrodynamic simulations combined with analytic studies to examine the transition between different paradigms of type II migration. We find a range of planetary mass for which gas continues to flow through a severely depleted gap so that the surface density distribution in the disk region beyond the gap is maintained in a quasi-steady state. The associated gap profile modifies the location of corotation and Lindblad resonances. In the proximity of the planet's orbit, high-order Lindblad and corotation torque are weakened by the gas depletion in the gap, while low-order Lindblad torques near the gap walls preserve their magnitude. Consequently, the intrinsic surface density distribution of the disk delicately determines both the pace and direction of the planets' type II migration. We show that this effect might stall the inward migration of giant planets and preserve them in disk regions where the surface density is steep.

Keywords: Exoplanet systems, Protoplanetary disks, Planet formation
Substructure in the Globular Cluster Populations of the Virgo Cluster Elliptical Galaxies M84 and M86. We have carried out a search for substructure within the globular cluster (GC) systems of M84 (NGC 4374) and M86 (NGC 4406), two giant elliptical galaxies in the Virgo Cluster. We use wide-field (36' × 36'), multicolor broadband imaging to identify GC candidates in these two galaxies, as well as several other nearby lower-mass galaxies. Our analysis of the spatial locations of the GC candidates reveals several substructures, including a peak in the projected number density of GCs in M86 that is offset from the system center and may be at least partly due to the presence of the dwarf elliptical galaxy NGC 4406B, a bridge that connects the M84 and M86 GC systems, and a boxy isodensity contour along the southeast side of the M86 GC system. We divide our sample into red (metal-rich) and blue (metal-poor) GC candidates to look for differences in the spatial distributions of the two populations and find that the blue cluster candidates are the dominant population in each of the substructures we identify. We also incorporate the measurements from two radial velocity surveys of the GCs in the region and find that the bridge substructure is populated by GCs with a mix of velocities that are consistent with either M86 and M84, possibly providing further evidence for interaction signatures between the two galaxies.

Keywords: Virgo Cluster, Giant elliptical galaxies, Star clusters
SN2019dge: A Helium-rich Ultra-stripped Envelope Supernova. We present observations of ZTF18abfcmjw (SN2019dge), a helium-rich supernova with a fast-evolving light curve indicating an extremely low ejecta mass (≈0.33 M⊙) and low kinetic energy (≈1.3 × 1050 erg). Early-time (&lt;4 days after explosion) photometry reveals evidence of shock cooling from an extended helium-rich envelope of ∼0.1 M⊙ located ∼1.2 × 1013 cm from the progenitor. Early-time He II line emission and subsequent spectra show signatures of interaction with helium-rich circumstellar material, which extends from ≳5 × 1013 cm to ≳2 × 1016 cm. We interpret SN2019dge as a helium-rich supernova from an ultra-stripped progenitor, which originates from a close binary system consisting of a mass-losing helium star and a low-mass main-sequence star or a compact object (i.e., a white dwarf, a neutron star, or a black hole). We infer that the local volumetric birth rate of 19dge-like ultra-stripped SNe is in the range of 1400-8200 $\,{\mathrm{Gpc}}^{-3}\,{\mathrm{yr}}^{-1}$ (i.e., 2%-12% of core-collapse supernova rate). This can be compared to the observed coalescence rate of compact neutron star binaries that are not formed by dynamical capture.

Keywords: Neutron stars, Surveys, Supernovae, Core-collapse supernovae