Sazuna/UAT_keywords huggingface dataset:
Wideband Monitoring Observations of PSR J1803-3002A in the Globular Cluster NGC 6522. We report the first wideband monitoring observations of PSR J1803-3002A, a relatively bright millisecond pulsar (MSP) in the globular cluster NGC 6522 with a spin period of 7.1 ms and no known binary companion. These observations were performed using the Parkes 64 m radio telescope with the Ultra-Wideband Low receiver system, which covers 704-4032 MHz. We confirm that PSR J1803-3002A is an isolated MSP located near the cluster center and probe the emission properties of the pulsar over the wide observed band. The mean pulse profile consists of three components, with the outer components becoming more prominent at higher frequencies, and a mean spectral index for the pulsed emission of -1.66 ± 0.07 over the observed band. The fractional linear and circular polarization increase with increasing frequency, which is unusual for pulsars. We determine a Faraday rotation measure of -107 ± 6 rad m-2 for the pulsar. PSR J1803-3002A is a distant pulsar in the Galactic plane, but our observations show no evidence of pulse broadening due to interstellar scattering. These results demonstrate the power of ultra-wideband receivers and signal processing systems.

Keywords: Globular star clusters, Astronomy data analysis, Pulsars
Fast Parameter Estimation of Binary Mergers for Multimessenger Follow-up. Significant human and observational resources have been dedicated to electromagnetic follow-up of gravitational-wave events detected by Advanced LIGO and Virgo. As the sensitivity of LIGO and Virgo improves, the rate of sources detected will increase. Margalit &amp; Metzger (2019) have suggested that it may be necessary to prioritize observations of future events. Optimal prioritization requires a rapid measurement of a gravitational-wave event's masses and spins, as these can determine the nature of any electromagnetic emission. We extend the relative binning method of Cornish (2013) and Zackay et al. (2018) to a coherent detector-network statistic. We show that the method can be seeded from the output of a matched-filter search and used in a Bayesian parameter measurement framework to produce marginalized posterior probability densities for the source's parameters within 20 minutes of detection on 32 CPU cores. We demonstrate that this algorithm produces unbiased estimates of the parameters with the same accuracy as running parameter estimation using the standard gravitational-wave likelihood. We encourage the adoption of this method in future LIGO-Virgo observing runs to allow fast dissemination of the parameters of detected events so that the observing community can make best use of its resources.

Keywords: Neutron stars, Close binary stars, Compact binary stars, Astronomy data analysis, Gravitational wave astronomy, Gravitational waves, Astronomical methods
The Formation of Saturn's and Jupiter's Electron Radiation Belts by Magnetospheric Electric Fields. The existence of planetary radiation belts with relativistic electron components means that powerful acceleration mechanisms are operating within their volume. Mechanisms that bring charged particles planetward toward stronger magnetic fields can cause their heating. On the basis that electron fluxes in Saturn's radiation belts are enhanced over discrete energy intervals, previous studies have suggested that rapid inward plasma flows may be controlling the production of their most energetic electrons. However, rapid plasma inflows languish in the planet's inner magnetosphere, and they are not spatially appealing as a mechanism to form the belts. Here we show that slow, global-scale flows resulting from transient noon-to-midnight electric fields successfully explain the discretized flux spectra at quasi- and fully relativistic energies, and that they are ultimately responsible for the bulk of the highest energy electrons trapped at Saturn. This finding is surprising, given that plasma flows at Saturn are dominated by the planetary rotation; these weak electric field perturbations were previously considered impactful only over a very narrow electron energy range where the magnetic drifts of electrons cancel out with corotation. We also find quantitative evidence that ultrarelativistic electrons in Jupiter's radiation belts are accelerated by the same mechanism. Given that similar processes at Earth drive a less efficient electron transport compared to Saturn and Jupiter, the conclusion is emerging that global-scale electric fields can provide powerful relativistic electron acceleration, especially at strongly magnetized and fast-rotating astrophysical objects.

Keywords: Saturn, Van Allen radiation belts, Solar system gas giant planets, Jupiter, Planetary magnetospheres
Differential Rotation of the Chromosphere in the He I Absorption Line. Differential rotation is the basis of the solar dynamo theory. Synoptic maps of He I intensity from Carrington rotations 2032-2135 are utilized to investigate the differential rotation of the solar chromosphere in the He I absorption line. The chromosphere is surprisingly found to rotate faster than the photosphere below it. The anomalous heating of the chromosphere and corona has been a big problem in modern astronomy. It is speculated that the small-scale magnetic elements with magnetic flux in the range of (2.9-32.0) × 1018 Mx, which are anchored in the leptocline, heat the quiet chromosphere to present the anomalous temperature increase, causing it to rotate at the same rate as the leptocline. The differential of rotation rate in the chromosphere is found to be strengthened by strong magnetic fields, but in stark contrast, at the photosphere strong magnetic fields repress the differential of rotation rate. A plausible explanation is given for these findings.

Keywords: Solar activity, Solar rotation, Solar chromosphere
Magnetohydrodynamic Turbulent Evolution of a Magnetic Cloud in the Outer Heliosphere. This Letter exploits joint observations of the same interplanetary coronal mass ejection by widely separated spacecraft to study, for the first time, the turbulent evolution of the magnetohydrodynamic (MHD) properties of the embedded magnetic cloud, during its propagation throughout interplanetary space. Specifically, the event was observed by Wind at 1 au on 1998 March 4-6 and tracked to the location of Ulysses at 5.4 au 18 days later, when the two spacecraft were radially aligned with the Sun. The analysis of the MHD invariants within the magnetic cloud, along with its energy budget, provides compelling evidence of magnetic erosion of the structure thanks to its interaction with a trailing magnetic cloud. The helical configuration is thus largely deformed and degraded, and the initial dominance of magnetic over kinetic energy is observed to evolve toward a less imbalanced condition. This is consistent with the expected conversion of magnetic energy into kinetic energy due to magnetic reconnection processes. Local interaction of the magnetic cloud's (MC) outer layers with the solar wind acts to generate larger amplitude Alfvénic fluctuations in the downstream region, leading the MC to turbulently evolve toward a more complex cross-helicity configuration in the outer heliosphere. Finally, evidence of a flux rope locally generated by magnetic reconnection events at 1 au that likely decays by the time it reaches Ulysses is also reported.

Keywords: Magnetohydrodynamics, Solar magnetic reconnection, Heliosphere, Interplanetary turbulence, Solar wind, Interplanetary magnetic fields, Solar coronal mass ejections
Recurrent Neutrino Emission from Supermassive Black Hole Mergers. The recent detection of possible neutrino emission from the blazar TXS 0506+056 was the first high-energy neutrino associated with an astrophysical source, making this special type of active galaxies a promising neutrino emitter. The fact that two distinct episodes of neutrino emission were detected with a separation of around 3 yr raises the possibility that emission could be periodic. Periodic emission is expected from supermassive binary black hole systems due to jet precession close to the binary's merger. Here, we show that, if TXS 0506+056 is a binary source, then the next neutrino flare could already have occurred, possibly still hidden in IceCube's not-yet-analyzed data. We derive the binary properties that would lead to the detection of gravitational waves from this system by the Laser Interferometer Space Antenna (LISA) over the next decade. Our results for the first time quantify the timescale of these correlations for the example of TXS 0506+056, connecting the possible neutrino and gravitational-wave signatures of such sources.

Keywords: Supermassive black holes, High energy astrophysics, Astrophysical black holes, Blazars, Active galactic nuclei, Cosmological neutrinos, Gravitational waves, Particle astrophysics
A Wide Planetary-mass Companion to a Young Low-mass Brown Dwarf in Ophiuchus. We present the discovery of a planetary-mass companion to CFHTWIR-Oph 98, a low-mass brown dwarf member of the young Ophiuchus star-forming region, with a wide 200 au separation (1"46). The companion was identified using Hubble Space Telescope images, and confirmed to share common proper motion with the primary using archival and new ground-based observations. Based on the very low probability of the components being unrelated Ophiuchus members, we conclude that Oph 98 AB forms a binary system. From our multiband photometry, we constrain the primary to be an M9-L1 dwarf, and the faint companion to have an L2-L6 spectral type. For a median age of 3 Myr for Ophiuchus, fits of evolutionary models to measured luminosities yield masses of 15.4 ± 0.8 MJup for Oph 98 A and 7.8 ± 0.8 MJup for Oph 98 B, with respective effective temperatures of 2320 ± 40 K and 1800 ± 40 K. For possible system ages of 1-7 Myr, masses could range from 9.6-18.4 MJup for the primary, and from 4.1-11.6 MJup for the secondary. The low component masses and very large separation make this binary the lowest binding energy system imaged to date, indicating that the outcome of low-mass star formation can result in such extreme, weakly bound systems. With such a young age, Oph 98 AB extends the growing population of young free-floating planetary-mass objects, offering a new benchmark to refine formation theories at the lowest masses.

Keywords: Brown dwarfs, Binary stars
The Most Ordinary Formation of the Most Unusual Double Black Hole Merger. The Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration reported the detection of the most massive black hole-black hole (BH-BH) merger to date with component masses of 85M⊙ and 66M⊙ (GW190521). Motivated by recent observations of massive stars in the 30 Doradus cluster in the Large Magellanic Cloud (M⋆ ≳ 200M⊙; e.g., R136a) and employing newly estimated uncertainties on pulsational pair-instability mass loss (that allow for the possibility of forming BHs with mass up to MBH ∼ 90M⊙), we show that it is trivial to form such massive BH-BH mergers through the classical isolated binary evolution (with no assistance from either dynamical interactions or exotica). A binary consisting of two massive (180M⊙ + 150M⊙) Population II stars (metallicity: Z ≈ 0.0001) evolves through a stable Roche lobe overflow and common envelope episode. Both exposed stellar cores undergo direct core collapse and form massive BHs while avoiding pair-instability pulsation mass loss or total disruption. LIGO/Virgo observations show that the merger rate density of light BH-BH mergers (both components: MBH &lt; 50M⊙) is of the order of 10-100Gpc-3yr-1, while GW190521 indicates that the rate of heavier mergers is 0.02-0.43Gpc-3yr-1. Our model (with standard assumptions about input physics), but extended to include 200M⊙ stars and allowing for the possibility of stellar cores collapsing to 90M⊙ BHs, produces the following rates: 63Gpc-3yr-1 for light BH-BH mergers and 0.04Gpc-3yr-1 for heavy BH-BH mergers. We do not claim that GW190521 was formed by an isolated binary, but it appears that such a possibility cannot be excluded.

Keywords: Black hole physics, Stellar remnants, Stellar evolution
Dynamical Modulation of Solar Flare Electron Acceleration due to Plasmoid-shock Interactions in the Looptop Region. A fast-mode shock can form in the front of reconnection outflows and has been suggested as a promising site for particle acceleration in solar flares. Recent developments in the study of magnetic reconnection have shown that numerous plasmoids can be produced in a large-scale current layer. Here we investigate the dynamical modulation of electron acceleration in the looptop region when plasmoids intermittently arrive at the shock by combining magnetohydrodynamics simulations with a particle kinetic model. As plasmoids interact with the shock, the looptop region exhibits various compressible structures that modulate the production of energetic electrons. The energetic electron population varies rapidly in both time and space. The number of 5-10 keV electrons correlates well with the compression area, while that of &gt;50 keV electrons shows good correlation with the strong compression area but only moderate correlation with shock parameters. We further examine the impacts of the first plasmoid, which marks the transition from a quasi-steady shock front to a distorted and dynamical shock. The number of energetic electrons is reduced by ∼20% at 15-25 keV and nearly 40% for 25-50 keV, while the number of 5-10 keV electrons increases. In addition, the electron energy spectrum above 10 keV evolves softer with time. We also find that double or even multiple distinct sources can develop in the looptop region when the plasmoids move across the shock. Our simulations have strong implications to the interpretation of nonthermal looptop sources, as well as the commonly observed fast temporal variations in flare emissions, including the quasi-periodic pulsations.

Keywords: Solar flares, Solar magnetic reconnection, Non-thermal radiation sources, Shocks, Solar particle emission
Identification of Hot Plasma Anomalies in Solar Wind Using Fe Ion Charge Distributions. A presence of high Fe charge states in the ionic charge state distributions of the solar wind (SW) plasma, commonly characterized by the mean charge QFe, provides valuable information on heating processes in the SW sources. We study the relationship between the parameter QFe and the charge state distributions of Fe ions using the Solar TErrestrial RElations Observatory/PLAsma and SupraThermal Ion Composition data on the beginning of the 24th Cycle (2010 January-2011 July). We find that the Fe charge state distributions related to SW with QFe ≈ 8-10 have an uni-modal shape peaked around Fe8+-Fe9+. When the QFe value increases, the distributions change: at first, the profile extends to higher charge states and then transforms into a bi-modal shape with a second maximum around Fe16+ and a minimum around Fe12+. We discuss possible reasons for such bi-modality through the example of the interplanetary coronal mass ejection (ICME) event on 2011 February 24-26, where it was related to the heating of an eruptive prominence. For such an analysis, it is informative to have a special measure of the fraction of highly charged ions for the Fe ion charge distribution in SW. In addition to QFe, we introduce a parameter q12 equal to a fraction of Fe ions with charges Q ≥ 12 and show that this parameter can be applied for identifying both the large-scale hot plasma enhancements associated with ICMEs and small hot fragments of SW plasma, which may be associated with small-scale solar activity in various coronal structures.

Keywords: Atomic physics, Solar wind, Solar physics, Solar coronal mass ejections, Solar corona
Bridging the Planet Radius Valley: Stellar Clustering as a Key Driver for Turning Sub-Neptunes into Super-Earths. Extrasolar planets with sizes between that of the Earth and Neptune (Rp = 1-4 R⊕) have a bimodal radius distribution. This "planet radius valley" separates compact, rocky super-Earths (Rp = 1.0-1.8 R⊕) from larger sub-Neptunes (Rp = 1.8-3.5 R⊕) hosting a gaseous hydrogen-helium envelope around their rocky core. Various hypotheses for this radius valley have been put forward, which all rely on physics internal to the planetary system: photoevaporation by the host star, long-term mass loss driven by the cooling planetary core, or the transition between two fundamentally different planet formation modes as gas is lost from the protoplanetary disk. Here we report the discovery that the planet radius distribution exhibits a strong dependence on ambient stellar clustering, characterized by measuring the position-velocity phase space density with Gaia. When dividing the planet sample into "field" and "overdensity" subsamples, we find that planetary systems in the field exhibit a statistically significant (p = 5.5 × 10-3) dearth of planets below the radius valley compared to systems in phase space overdensities. This implies that the large-scale stellar environment of a planetary system is a key factor setting the planet radius distribution. We discuss how models for the radius valley might be revised following our findings and conclude that a multiscale, multiphysics scenario is needed, connecting planet formation and evolution, star and stellar cluster formation, and galaxy evolution.

Keywords: Solar-planetary interactions, Exoplanet systems, Stellar dynamics, Star formation, Exoplanet formation, Planet formation
Expansion and Age of the Supernova Remnant G350.1-0.3: High-velocity Iron Ejecta from a Core-collapse Event. We report Chandra observations of the highly asymmetric core-collapse supernova remnant G350.1-0.3. We document expansion over 9 yr away from the roughly stationary central compact object, with sky-plane velocities up to 5000 d4.5 km s-1 (d4.5 is the distance in units of 4.5 kpc), redshifts ranging from 900 to 2600 km s-1, and three-dimensional space velocities approaching 6000 km s-1. Most of the bright emission comes from heavy-element ejecta particularly strong in iron. Iron-enhanced ejecta are seen at 4000-6000 km s-1, strongly suggesting that the supernova was not a common Type IIP event. While some fainter regions have roughly solar abundances, we cannot identify clear blast-wave features. Our expansion proper motions indicate that G350.1-0.3 is no more than about 600 yr old, independent of distance: the third youngest known core-collapse supernova in the Galaxy, and one of the most asymmetric.

Keywords: Supernova remnants, Ejecta, X-ray astronomy, Core-collapse supernovae
Detections of Dust in the Outskirts of M31 and M33. M31 and M33 serve as ideal places to study distributions of dust in the outskirts of spiral galaxies. In this Letter, using about 0.2 million stars selected from the LAMOST data and combining precise photometry and parallaxes from the Gaia DR2, we have constructed a two-dimensional foreground dust reddening map toward the M31 and M33 region (111°2 ≤ gl ≤ 136°2, -36°5 ≤ gb ≤ -16°5). The map has a typical spatial resolution of about 12' and precision of 0.01 mag. The complex structure of dust clouds toward M31 is revealed. By carefully removing the foreground extinction from the dust reddening map of Schlegel et al., we thus have obtained a residual map to study dust distributions in the outskirts of M31 and M33. A large amount of dust is detected in the M31 halo out to a distance of over 100 kpc. Dust in the M31 disk is found to extend out to about 2.5 times its optical radius, with a distribution that is consistent with either an exponential disk with a scale length of 7.2 kpc or two disks with a scale length of 11.1 kpc within its optical radius and 18.3 kpc beyond its optical radius. Dust in the disk of M33 is also found to extend out to about 2.5 times its optical radius, its distribution beyond one optical radius is consistent with an exponential disk with a scale length of 5.6 kpc. Our results provide new clues to the distributions and cycling of dust in galaxies.

Keywords: Interstellar dust, Andromeda Galaxy, Circumgalactic medium
Pulsational Pair-instability and the Mass Gap of Population III Black Holes: Effects of Overshooting. Since the discovery of GW190521, several proposals have been put forward to explain the formation of a black hole (BH) in the mass gap caused by (pulsational) pair-instability (PPI), M = 65-130 M⊙. We calculate the mass ejection of Population III stars by the PPI process using a stellar evolution and hydrodynamical code. If a relatively small, but reasonable, value is adopted for the overshooting parameter, the stars do not become red supergiants during the PPI phase. We show that in this case most of the hydrogen envelope remains after the mass ejection by PPI. We find that the BH mass could be at most around 110 M⊙ below the mass range of pair-instability supernovae.

Keywords: Population III stars, Black holes, Massive stars, Stellar mass loss, Stellar evolution
The First Integral Field Unit Spectroscopic View of Shocked Cluster Galaxies. Galaxy clusters grow by merging with other clusters, giving rise to Mpc-wide shock waves that travel at 1000-2500 km s-1 through the intracluster medium. To study the effects of merger shocks on the properties of cluster galaxies, we present the first spatially resolved spectroscopic view of five Hα-emitting galaxies located in the wake of shock fronts in the low redshift (z ∼ 0.2), massive (∼2 × 1015M☉), post-core passage merging cluster, CIZA J2242.8+5301 (nicknamed the "Sausage"). Our Gemini/Gemini Multi-Object Spectrograph-North integral field unit (IFU) observations, designed to capture Hα and [N II] emission, reveal the nebular gas distribution, kinematics, and metallicities in the galaxies over &gt;16 kpc scales. While the galaxies show evidence for rotational support, the flux and velocity maps have complex features like tails and gas outflows aligned with the merger axis of the cluster. With gradients that are incompatible with inside-out disk growth, the metallicity maps are consistent with sustained star formation (SF) throughout and outside of the galactic disks. In combination with previous results, these pilot observations provide further evidence of a likely connection between cluster mergers and SF triggering in cluster galaxies, a potentially fundamental discovery revealing the interaction of galaxies with their environment.

Keywords: Galaxy clusters, Emission line galaxies, Star formation, Galaxy evolution, Shocks, Metallicity