Sazuna/UAT_keywords huggingface dataset:
The Relative Contribution to Heavy Metals Production from Binary Neutron Star Mergers and Neutron Star-Black Hole Mergers. The origin of the heavy elements in the universe is not fully determined. Neutron star-black hole (NSBH) and binary neutron star (BNS) mergers may both produce heavy elements via rapid neutron-capture (r-process). We use the recent detection of gravitational waves from NSBHs, improved measurements of the neutron star equation of state (EoS), and the most modern numerical simulations of ejected material from binary collisions to measure the relative contribution of NSBHs and BNSs to the production of heavy elements. As the amount of r-process ejecta depends on the mass and spin distribution of the compact objects, as well as on the EoS of the neutron stars, we consider various models for these quantities, informed by gravitational-wave and pulsar data. We find that in most scenarios, BNSs have produced more r-process elements than NSBHs over the past 2.5 billion years. If black holes have preferentially small spins, BNSs can produce at least twice the amount of r-process elements than NSBHs. If black hole spins are small and there is a dearth of low-mass (&lt;5M⊙) black holes within NSBH binaries, BNSs can account for the near totality of the r-process elements from binaries. For NSBH to produce a large fraction of r-process elements, black holes in NSBHs must have small masses and large aligned spins, which is disfavored by current data.

Keywords: Gravitational wave astronomy, Gravitational waves, Heavy metal stars
A Month of Monitoring the New Magnetar Swift J1555.2-5402 during an X-Ray Outburst. The soft gamma-ray repeater Swift J1555.2-5402 was discovered by means of a short burst detected with Swift BAT on 2021 June 3. Then, 1.6 hr after the burst, the Neutron star Interior Composition Explorer (NICER) started daily monitoring of this target for a month. The absorbed 2-10 keV flux stayed nearly constant at around 4 × 10-11 erg s-1 cm-2 during the monitoring, showing only a slight gradual decline. An absorbed blackbody with a temperature of 1.1 keV approximates the soft X-ray spectrum. A 3.86 s periodicity is detected, and the period derivative is measured to be 3.05(7) × 10-11 s s-1. The soft X-ray pulse shows a single sinusoidal shape with an rms pulsed fraction that increases as a function of energy from 15% at 1.5 keV to 39% at 7 keV. The equatorial surface magnetic field, characteristic age, and spin-down luminosity are derived under the dipole field approximation to be 3.5 × 1014 G, 2.0 kyr, and 2.1 × 1034 erg s-1, respectively. We detect 5 and 45 bursts with Swift/BAT and NICER, respectively. Based on these properties, this new source is classified as a magnetar. A hard X-ray power-law component that extends up to at least 40 keV is detected with the Nuclear Spectroscopic Telescope Array (NuSTAR). The 10-60 keV flux is ~9 × 10-12 erg s-1 cm-2 with a photon index of ~1.2. The pulsed fraction has a sharp cutoff at around 10 keV with an upper limit (≲10%) in the hard-tail band. No radio pulsations are detected during the DSN or VERA observations. The 7σ upper limits of the flux density are 0.043 and 0.026 mJy at the S and X bands, respectively.

Keywords: Neutron stars, Pulsars, Soft gamma-ray repeaters, X-ray transient sources, Magnetars, Magnetic fields
Are Delayed Radio Flares Common in Tidal Disruption Events? The Case of the TDE iPTF 16fnl. Radio emission from tidal disruption events (TDEs) originates from an interaction of an outflow with the super-massive black hole (SMBH) circumnuclear material (CNM). In turn, this radio emission can be used to probe properties of both the outflow launched at the event and the CNM. Until recently, radio emission was detected only for a relatively small number of events. While the observed radio emission pointed to either relativistic or sub-relativistic outflows of different nature, it also indicated that the outflow has been launched shortly after stellar disruption. Recently, however, delayed radio flares, several months and years after stellar disruption, were reported in the case of the TDE ASASSN-15oi. These delayed flares suggest a delay in the launching of outflows and thus may provide new insights into SMBH accretion physics. Here, we present a new radio data set of another TDE, iPTF 16fnl, and discuss the possibility that a delayed radio flare also has been observed in this case, ~5 months after optical discovery, suggesting that this phenomenon may be common in TDEs. Unlike ASASSN-15oi, the data for iPTF 16fnl is sparse and the delayed radio flare can be explained by several alternative models: among them are a complex varying CNM density structure and a delayed outflow ejection.

Keywords: Black holes, High energy astrophysics, Tidal disruption, Transient sources, Time domain astronomy, Radio transient sources
Observational Kinematic Characteristics of Blobs in Solar Coronal Helmet and Pseudo Streamers. We examine two helmet and two pseudo streamers (HSs and PSs) observed on 2018 and 2019. The HSs (PSs) have dark coronal cavities and stretched loop structures (twin coronal cavities and narrow plasma sheet) at their bases, which are well observed in K-Coronagraph (K-Cor). Their outer-corona structures (top of core, cusp, and stalk) are also clearly identified in LASCO-C2. By investigating LASCO-C2 images, we find the following characteristics. (1) Blobs persistently move outward along the centers of HSs and PSs as well as their legs until the base of a stalk. We also detect outward-moving blobs along their outsides. (2) Blobs along the HS centers formed below tops of cores (~2.6 R⊙), while the other HS and PS blobs might be generated below 2.0 R⊙. (3) HS blob speeds are generally similar to or smaller than the solar wind speed based on Parker's model, while PS ones are larger. (4) HS (PS) blob speeds along the streamer centers are slightly smaller (larger) than those along the streamer legs, might be explained by the expansion-factor model. The blob speeds inside streamer structures (centers and legs) are larger than outside ones closer to solar equator, similar to typical solar wind speed distributions at solar minimum. (5) Several blobs along the HS centers only show sudden speed jumps at streamer cusps. These might be caused by sunward tension forces of overlying stretched closed fields and/or bidirectional outflows by magnetic reconnections in the cusps.

Keywords: Solar coronal streamers
Second-scale Submillimeter Variability of Sagittarius A* during Flaring Activity of 2019: On the Origin of Bright Near-infrared Flares. In 2019, Sgr A*-the supermassive black hole in the Galactic Center-underwent unprecedented flaring activity in the near-infrared (NIR), brightening by up to a factor of 100 compared to quiescent values. Here we report Atacama Large Millimeter/submillimeter Array (ALMA) observations of Sgr A*'s continuum variability at 1.3 mm (230 GHz)-a tracer of the accretion rate-conducted one month after the brightest detected NIR flare and in the middle of the flaring activity of 2019. We develop an innovative light-curve extraction technique which (together with ALMA's excellent sensitivity) allows us to obtain light curves that are simultaneously of high time resolution (2 s) and high signal-to-noise ratio (~500). We construct an accurate intrinsic structure function of the Sgr A* submm variability, improving on previous studies by about two orders of magnitude in timescale and one order of magnitude in sensitivity. We compare the 2019 June variability behavior with that of 2001-2017 and suggest that the most likely cause of the bright NIR flares is magnetic reconnection.

Keywords: Submillimeter astronomy, Supermassive black holes, Galactic center, Low-luminosity active galactic nuclei
Formation of Polar Terrestrial Circumbinary Planets. All circumbinary planets (CBPs) currently detected are in orbits that are almost coplanar to the binary orbit. While misaligned CBPs are more difficult to detect, observations of polar-aligned circumbinary gas and debris disks around eccentric binaries suggest that polar planet formation may be possible. A polar-aligned planet has a stable orbit that is inclined by 90° to the orbital plane of the binary with an angular momentum vector that is aligned to the binary eccentricity vector. With n-body simulations we model polar terrestrial planet formation using hydrodynamic gas disk simulations to motivate the initial particle distribution. Terrestrial planet formation around an eccentric binary is more likely in a polar alignment than in a coplanar alignment. Similar planetary systems form in a polar alignment around an eccentric binary and a coplanar alignment around a circular binary. The polar planetary systems are stable even with the effects of general relativity. Planetary orbits around an eccentric binary exhibit tilt and eccentricity oscillations at all inclinations; however, the oscillations are larger in the coplanar case than the polar case. We suggest that polar-aligned terrestrial planets will be found in the future.

Keywords: Extrasolar rocky planets, Exoplanet formation, Binary stars, Solar system terrestrial planets
Signatures of a Distant Planet on the Inclination Distribution of the Detached Kuiper Belt. A distant, massive planet in the outer solar system has recently been proposed to explain some observed features of extreme trans-Neptunian objects (TNOs). Here we use N-body simulations of the formation of the Kuiper Belt and Oort cloud as well as a survey simulator to compare models of the solar system with and without a ninth planet to one another as well as to observations. The main mechanism for TNOs to be deposited into the distant (a &gt; 50 au), detached (q &gt; 40 au) region of the Kuiper Belt in the eight-planet model is Kozai-Lidov oscillation of objects in mean motion resonances (MMR) with Neptune. This effect does not deposit low-inclination (i ≲ 20°) objects into this region. However, we find that the ninth planet generates a group of distant, detached TNOs at low inclinations that are not present in the eight-planet model. This disparity between the eight-planet and nine-planet models could provide a strong constraint on a possible planet nine with further detections of TNOs in the distant, detached region of the Kuiper Belt.

Keywords: Resonant Kuiper belt objects, Kuiper belt, Trans-Neptunian objects
Galaxy Rotation Curves Disfavor Traditional and Self-interacting Dark Matter Halos, Preferring a Disk Component or Einasto Function. We use the galaxy rotation curves in the SPARC database to compare nine different dark matter (DM) and modified gravity models on an equal footing, paying special attention to the stellar mass-to-light ratios. We compare three noninteracting DM models: a self-interacting DM model, two hadronically interacting DM models, and three modified Newtonian dynamics type models, modified Newtonian dynamics (MOND), a radial acceleration relation, and a maximal-disk model. The models with DM-gas interactions generate a disky component in the DM, which significantly improves the fits to the rotation curves compared to all other models except an Einasto halo; the MOND-type models give significantly worse fits.

Keywords: Galaxy dynamics, Galaxy physics, Baryonic dark matter, Galaxy rotation curves, Dark matter
The Effects of Dark Matter and Baryonic Physics on the Milky Way Subhalo Population in the Presence of the Large Magellanic Cloud. Given recent developments in our understanding of the Large Magellanic Cloud's (LMC) impact on the Milky Way's (MW) dark matter subhalo population, we compare the signatures of dark matter and baryonic physics on subhalos in MW systems with realistic LMC analogs. In particular, we study the effects of self-interacting dark matter (SIDM), warm dark matter (WDM), and the Galactic disk on the peak maximum circular velocity (Vpeak) function, radial distribution, and spatial distribution of MW and LMC-associated subhalos using cosmological dark matter-only zoom-in simulations of MW+LMC systems. For a fixed abundance of subhalos expected to host dwarf galaxies (Vpeak ≳ 20 km s-1), SIDM and WDM can produce a similar mass-dependent suppression of the subhalo Vpeak function, while disk disruption is mass independent. Subhalos in the inner regions of the MW are preferentially disrupted by both self-interactions and the disk, while suppression in WDM is radially independent. The relative abundance of LMC-associated subhalos is not strongly affected by disk disruption or WDM, but is significantly suppressed in SIDM due to self-interactions with the LMC at early times and with the MW during LMC infall at late times, erasing spatial anisotropy in the MW subhalo population. These results provide avenues to distinguish dark matter and baryonic physics by combining properties of the MW and LMC subhalo populations probed by upcoming observations of satellite galaxies and stellar streams.

Keywords: Milky Way dark matter halo, Galaxy abundances, Dark matter
Comparison of Anomalous and Galactic Cosmic-Ray Oxygen at 1 au during 1997-2020. Using quiet-time measurements of element oxygen within the energy range 7.3-237.9 MeV nuc-1 from the ACE spacecraft at 1 au, we compare the energy spectra and intensities of anomalous and Galactic cosmic rays (ACRs and GCRs, respectively) during 1997-2020. Our analysis shows that the transition from the ACR-dominated spectrum to the GCR-dominated spectrum occurs at energies ~15 to ~35 MeV nuc-1, and the transition energy Et is found to be well anticorrelated with varying solar activity. This is the first study of ACR-GCR transition energy dependence on the solar cycle variation. At energies below Et, the index of the power-law ACR-dominated spectrum (γ1) ranges from -2.0 to -0.5, whereas the GCR-dominated spectrum has a power-law index (γ2) changing from 0.3 to 0.8 at energies ranging from Et to 237.9 MeV nuc-1. Both γ1 and γ2 are positively correlated with solar activity. In addition, during the solar cycle 24/25 minimum period, the peak GCR intensity observed by ACE spacecraft is about 8% above its 2009 value, setting a new record since the space age, while the peak ACR intensity is almost similar to that of the previous two solar cycles with the same pattern of solar magnetic polarity, indicating a different modulation mechanism between ACRs and GCRs.

Keywords: Solar cycle, Heliosphere, Solar physics, Particle astrophysics, Cosmic rays
Formation of the First Two Black Hole-Neutron Star Mergers (GW200115 and GW200105) from Isolated Binary Evolution. In this work we study the formation of the first two black hole-neutron star (BHNS) mergers detected in gravitational waves (GW200115 and GW200105) from massive stars in wide isolated binary systems-the isolated binary evolution channel. We use 560 BHNS binary population synthesis model realizations and show that the system properties (chirp mass, component masses, and mass ratios) of both GW200115 and GW200105 match predictions from the isolated binary evolution channel. We also show that most model realizations can account for the local BHNS merger rate densities inferred by LIGO-Virgo. However, to simultaneously also match the inferred local merger rate densities for BHBH and NSNS systems we find we need models with moderate kick velocities (σ ≲ 102 km s-1) or high common-envelope efficiencies (αCE ≳ 2) within our model explorations. We conclude that the first two observed BHNS mergers can be explained from the isolated binary evolution channel for reasonable model realizations.

Keywords: Neutron stars, Compact binary stars, Gravitational waves, Astrophysical black holes, Stellar evolution
Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter-Parker Solar Probe Quadrature. This Letter addresses the first Solar Orbiter (SO)-Parker Solar Probe (PSP) quadrature, occurring on 2021 January 18 to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in the corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source region from where it originated. Thanks to the close approach of PSP to the Sun and the simultaneous Metis observation of the solar corona, the flow-aligned magnetic field and the bulk kinetic energy flux density can be empirically inferred along the coronal current sheet with an unprecedented accuracy, allowing in particular estimation of the Alfvén radius at 8.7 solar radii during the time of this event. This is thus the very first study of the same solar wind plasma as it expands from the sub-Alfvénic solar corona to just above the Alfvén surface.

Keywords: Space plasmas, Magnetohydrodynamics, Heliosphere, Interplanetary turbulence, Solar wind, Solar corona
When Hot Meets Cold: Post-flare Coronal Rain. Most solar flares demonstrate a prolonged, hour-long post-flare (or gradual) phase, characterized by arcade-like, post-flare loops (PFLs) visible in many extreme ultraviolet (EUV) passbands. These coronal loops are filled with hot (~30 MK) and dense plasma that evaporated from the chromosphere during the impulsive phase of the flare, and they very gradually recover to normal coronal density and temperature conditions. During this gradual cooling down to ~1 MK regimes, much cooler (~0.01 MK) and denser coronal rain is frequently observed inside PFLs. Understanding PFL dynamics in this long-duration, gradual phase is crucial to the entire corona-chromosphere mass and energy cycle. Here we report a simulation in which a solar flare evolves from pre-flare, over the impulsive phase all the way into its gradual phase, which successfully reproduces post-flare coronal rain. This rain results from catastrophic cooling caused by thermal instability, and we analyze the entire mass and energy budget evolution driving this sudden condensation phenomenon. We find that the runaway cooling and rain formation also induces the appearance of dark post-flare loop systems, as observed in EUV channels. We confirm and augment earlier observational findings, suggesting that thermal conduction and radiative losses alternately dominate the cooling of PFLs.

Keywords: Solar physics, Solar flares, Magnetohydrodynamical simulations
TOI-3362b: A Proto Hot Jupiter Undergoing High-eccentricity Tidal Migration. High-eccentricity tidal migration is a possible way for giant planets to be placed in short-period orbits. If this happens often, one would expect to catch proto hot Jupiters on highly elliptical orbits undergoing high-eccentricity tidal migration. As of yet, few such systems have been discovered. Here, we introduce TOI-3362b (TIC-464300749b), an 18.1 day, 5 MJup planet orbiting a main-sequence F-type star that is likely undergoing high-eccentricity tidal migration. The orbital eccentricity is 0.815 {}_{-0.032}^{+0.023}$ . With a semimajor axis of 0.153 {}_{-0.003}^{+0.002}$ au, the planet's orbit is expected to shrink to a final orbital radius of 0.051 {}_{-0.006}^{+0.008}$ au after complete tidal circularization. Several mechanisms could explain the extreme value of the planet's eccentricity, such as planet-planet scattering and secular interactions. Such hypotheses can be tested with follow-up observations of the system, e.g., measuring the stellar obliquity and searching for companions in the system with precise, long-term radial-velocity observations. The variation in the planet's equilibrium temperature as it orbits the host star and the tidal heating at periapse make this planet an intriguing target for atmospheric modeling and observation. Because the planet's orbital period of 18.1 days is near the limit of TESS's period sensitivity, even a few such discoveries suggest that proto hot Jupiters may be quite common.

Keywords: Exoplanet migration, Hot Jupiters, Exoplanet astronomy, Radial velocity, Transit photometry
Fallback Supernova Assembly of Heavy Binary Neutron Stars and Light Black Hole-Neutron Star Pairs and the Common Stellar Ancestry of GW190425 and GW200115. The detection of the unusually heavy binary neutron star merger GW190425 marked a stark contrast to the mass distribution from known Galactic pulsars in double neutron star binaries and gravitational-wave source GW170817. We suggest here a formation channel for heavy binary neutron stars and light black hole-neutron star binaries in which massive helium stars, which had their hydrogen envelope removed during a common-envelope phase, remain compact and avoid mass transfer onto the neutron star companion, possibly avoiding pulsar recycling. We present three-dimensional simulations of the supernova explosion of the massive stripped helium star and follow the mass fallback evolution and the subsequent accretion onto the neutron star companion. We find that fallback leads to significant mass growth in the newly formed neutron star. This can explain the formation of heavy binary neutron star systems such as GW190425, as well as predict the assembly of light black hole-neutron star systems such as GW200115. This formation avenue is consistent with the observed mass-eccentricity correlation of binary neutron stars in the Milky Way. Finally, avoiding mass transfer suggests an unusually long spin-period population of pulsar binaries in our Galaxy.

Keywords: Neutron stars, Black holes, Massive stars, Gravitational wave sources, Gravitational wave astronomy, Gravitational waves, Compact objects, Stellar remnants, Supernovae
Observational Effects of Banded Repeating FRBs. Recent observations have shown that repeating fast radio bursts (FRBs) exhibit band-limited emission, whose frequency-dependent amplitude can be modeled using a Gaussian function. In this analysis, we show that banded emission of FRBs can lead to incompleteness across the observing band. This biases the detected sample of bursts and can explain the various shapes of cumulative energy distributions seen for repeating FRBs. We assume a Gaussian shape of the burst spectra and use simulations to demonstrate the above bias using an FRB 121102-like example. We recovered energy distributions that showed a break in power law and flattening of power law at low energies, based on the fluence threshold of the observations. We provide recommendations for single-pulse searches and analysis of repeating FRBs to account for this incompleteness. Primarily, we recommend that burst spectra should be modeled to estimate the intrinsic fluence and bandwidth of the burst robustly. Also, bursts that lie mainly within the observing band should be used for analyses of energy distributions. We show that the bimodality reported in the distribution of energies of FRB 121102 by Li et al. disappears when burst bandwidth, instead of the center frequency of the observation, is used to estimate energy. Subbanded searches will also aid in detecting band-limited bursts. All the analysis scripts used in this work are available in a Github repository (https://github.com/KshitijAggarwal/banded_repeater_analysis).

Keywords: Extragalactic radio sources, Radio bursts, Astronomy data analysis, Radio transient sources