adsabs/SciX_UAT_keywords huggingface dataset:
Revealing the Dynamic Magnetoionic Environments of Repeating Fast Radio Burst Sources through Multiyear Polarimetric Monitoring with CHIME/FRB

Fast radio bursts (FRBs) display a confounding variety of burst properties and host-galaxy associations. Repeating FRBs offer insight into the FRB population by enabling spectral, temporal, and polarimetric properties to be tracked over time. Here, we report on the polarized observations of 12 repeating sources using multiyear monitoring with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) over 400-800 MHz. We observe significant rotation measure (RM) variations from many sources in our sample, including RM changes of several hundred radians per square meter over month timescales from FRBs 20181119A, 20190303A, and 20190417A, and more modest RM variability (ΔRM ≲ few tens of radians per square meter) from FRBs 20181030A, 20190208A, 20190213B, and 20190117A over equivalent timescales. Several repeaters display a frequency-dependent degree of linear polarization that is consistent with depolarization via scattering. Combining our measurements of RM variations with equivalent constraints on DM variability, we estimate the average line-of-sight magnetic field strength in the local environment of each repeater. In general, repeating FRBs display RM variations that are more prevalent and/or extreme than those seen from radio pulsars in the Milky Way and the Magellanic Clouds, suggesting repeating FRBs and pulsars occupy distinct magnetoionic environments.

Keywords: radio transient sources; polarimetry; radio bursts
Constraining the Nuclear Equation of State via Gravitational-wave Radiation of Short Gamma-Ray Burst Remnants

The observed internal plateau of X-ray emission in some short gamma-ray bursts (GRBs) suggests the formation of a remnant supramassive magnetar following a double neutron star (NS) merger. In this paper, we assume that the rotational energy is lost mainly via gravitational-wave radiation instead of magnetic dipole (MD) radiation, and present further constraints on the NS nuclear equation of state (EoS) via mass quadrupole deformation and r-mode fluid oscillations of the magnetar. We present two short GRBs with measured redshifts, 101219A and 160821B, whose X-ray light curves exhibit an internal plateau. This suggests that a supramassive NS may survive as the central engine. By considering 12 NS EoSs, within the mass quadrupole deformation scenario we find that the GM1, DD2, and DDME2 models give an Mp band falling within the 2σ region of the proto-magnetar mass distribution for ɛ = 0.01. This is consistent with the constraints from the MD radiation dominated model of rotational energy loss. However, for an r-mode fluid oscillation model with α = 0.1 the data suggest that the NS EOS is close to the Shen and APR models, which is obviously different from the MD radiation dominated and mass quadrupole deformation cases.

Keywords: gamma-ray bursts; gravitational waves
Evidence of Photosphere Emission Origin for Gamma-Ray Burst Prompt Emission

The physical origins of gamma-ray burst (GRB) prompt emission (photosphere or synchrotron) are still subject to debate, after more than five decades. Here, we find that many of the observed characteristics of 15 long GRBs, which have the highest prompt emission efficiency ϵ γ (ϵ γ ≳ 80%), strongly support photosphere (thermal) emission origin, in the following ways: (1) the relation between E p and E iso is almost ${E}_{{\rm{p}}}\propto {({E}_{\mathrm{iso}})}^{1/4}$ and the dispersion is quite small; (2) the simple power-law shape of the X-ray afterglow light curves and the presence of significant reverse shock signals in the optical afterglow light curves; (3) the best fits using the cutoff power-law model for time-integrated spectra; and (4) the consistent efficiency from observations (with E iso/E k ) and the predictions from the photosphere emission model (with η/Γ). We then further investigate the characteristics of the long GRBs for two distinguished samples (ϵ γ ≳ 50% and ϵ γ ≲ 50%). It is found that the different distributions for E p and E iso, and the similar observed efficiency (from the X-ray afterglow) and theoretically predicted efficiency (from the prompt emission or the optical afterglow), follow the predictions of the photosphere emission model well. Also, based on the same efficiency, we derive an excellent correlation of ${\rm{\Gamma }}\propto {E}_{\mathrm{iso}}^{1/8}{E}_{{\rm{p}}}^{1/2}/{\left({T}_{90}\right)}^{1/4}$ to estimate Γ. Finally, we show that different distributions for E p and E iso, and the consistent efficiency, exist for short GRBs. We also give a natural explanation of the extended emission (ϵ γ ≲ 50%) and the main pulse (ϵ γ ≳ 50%).

Keywords: gamma-ray bursts
Activity Discovered on Mars-Crossing Jupiter Family Comet 2018 OR by Citizen Scientists

We present the discovery of cometary activity on 2018 OR as part of our Active Asteroids project, a NASA Partner Program fueled by Zooniverse Citizen Scientists. Volunteers found 2018 OR with a long, diffuse tail in archival images from the Dark Energy Camera on the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory in Chile. Our team identified additional Canada-France-Hawaii-Telescope MegaCam and Zwicky Transient Facility archival data after classification by Citizen Scientists. Activity originating from 2018 OR and directed in the anti-solar and anti-velocity directions was visible in archival images between UT 2018 September 5-18. Our dynamical simulations indicate 2018 OR experiences close encounters with Jupiter over hundred-year timescales. The orbital period and dynamics suggest 2018 OR is a Jupiter Family Comet, and we recommend further observations from the community to reduce observational uncertainties and investigate activity patterns.

Keywords: comet tails; comet dynamics; short period comets
The Correlations of Stellar Tidal Disruption Rates with Properties of Massive Black Holes and Their Host Galaxies

Stars can be either disrupted as tidal disruption events (TDEs) or swallowed whole by massive black holes (MBHs) at galactic centers when they approach sufficiently close to these MBHs. In this work, we investigate the correlations of such stellar consumption rates with both the MBH mass M BH and the inner slope of the host-galaxy mass density distribution α. We introduce a simplified analytical power-law model with a power-law stellar-mass density distribution surrounding MBHs and separate the contributions of two-body relaxation and stellar orbital precession for the stellar orbital angular momentum evolution in nonspherical galaxy potentials. The stellar consumption rates derived from this simplified model can be well consistent with the numerical results obtained with a more realistic treatment of stellar distributions and dynamics around MBHs, providing an efficient way to estimate TDE rates. The origin of the correlations of stellar consumption rates with M BH and α is explained by the dependence of this analytical model on those MBH/host-galaxy properties and by the separation of the stellar angular momentum evolution mechanisms. We propose that the strong positive correlation between the rates of stellar consumption due to two-body relaxation and α provides one interpretation for the overrepresentation of TDEs found in some rare E+A/poststarburst galaxies. We find high TDE rates for giant stars, up to those for solar-type stars. Understanding the origin of the correlations of the stellar consumption rates will be necessary for obtaining the demographics of MBHs and their host galaxies via TDEs.

Keywords: galaxy dynamics; high energy astrophysics; supermassive black holes; tidal disruption; transient sources; time domain astronomy; gravitational wave astronomy
The FAST Discovery of an Eclipsing Binary Millisecond Pulsar in the Globular Cluster M92 (NGC 6341)

We report the discovery of an eclipsing binary millisecond pulsar in the globular cluster M92 (NGC 6341) with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). PSR J1717+4308A, or M92A, has a pulse frequency of 316.5 Hz (3.16 ms) and a dispersion measure of 35.45 pc cm-3. The pulsar is a member of a binary system with an orbital period of 0.20 days around a low-mass companion that has a median mass of ∼0.18 M⊙. From observations so far, at least two eclipsing events have been observed in each orbit. The longer one lasted for ∼5000 s in the orbital phase range 0.1-0.5. The other lasted for ∼500 s and occurred between 1000 and 2000 s before or after the longer eclipsing event. The lengths of these two eclipsing events also change. These properties suggest that J1717+4308A is a "red-back" system with a low-mass main-sequence or sub-giant companion. Timing observations of the pulsar and further searches of the data for additional pulsars are ongoing.

Keywords: globular star clusters; binary pulsars; eclipsing binary stars; millisecond pulsars; pulsar timing method
On the Accuracy of Time-delay Cosmography in the Frontier Fields Cluster MACS J1149.5+2223 with Supernova Refsdal

We study possible systematic effects on the values of the cosmological parameters measured through strong lensing analyses of the Hubble Frontier Field galaxy cluster MACS J1149.5+2223. We use the observed positions of a large set of spectroscopically selected multiple images, including those of supernova "Refsdal" with their published time delays. Starting from our reference model in a flat ΛCDM cosmology, published in Grillo et al. (2018), we confirm the relevance of the longest measurable time delay, between SX and S1, and an approximately linear relation between its value and that of H0. We perform true blind tests by considering a range of time delays around its original estimate of 345 ± 10 days, as an accurate measurement of this time delay is still not known at the time of analysis and writing. We investigate separately the impact of a constant sheet of mass at the cluster redshift, of a power-law profile for the mass density of the cluster main halo and of some scatter in the cluster member scaling relations. Remarkably, we find that these systematic effects do not introduce a significant bias on the inferred values of H0 and Ωm and that the statistical uncertainties dominate the total error budget: a 3% uncertainty on the time delay of image SX translates into approximately 6% and 40% (including both statistical and systematic 1σ) uncertainties for H0 and Ωm, respectively. Furthermore, our model accurately reproduces the extended surface brightness distribution of the supernova host. We also present the interesting possibility of measuring the value of the equation-of-state parameter w of the dark energy density, currently with a 30% uncertainty.

Keywords: strong gravitational lensing; cosmological parameters; dark matter; dark energy; galaxy clusters; hubble constant
Comparing Be Star Inclination Angles Determined from Hα Fitting and Gravitational Darkening

Using a sample of 92 Galactic Be stars, we compare inclination angles (the angle between a star's rotation axis and the line of sight) determined from Hα emission-line profile fitting to those determined by the spectroscopic signature of gravitational darkening. We find good agreement: 70% of the sample (64 out of 92 stars) is consistent with zero difference between the two methods using 1σ errors, and there is a strong linear correlation coefficient between the two methods of r = +0.63 ± 0.05. There is some evidence that the Hα profile fitting method overestimates the inclination angle for i ≲ 25°, perhaps due to the neglect of incoherent electron scattering on the Hα line widths, while the gravitational darkening method underestimates the inclination angle for i ≳ 70°, perhaps due to the neglect of disk radiative transfer effects on the optical spectrum. Overall, it is demonstrated that a single Hα spectrum of modest resolution and SNR can be used to extract a useful estimate for the inclination angle of an individual Be star. This allows equatorial rotation velocities for individual Be stars to be derived from $v\sin i$ measurements and will allow Be stars to be used to search for correlated spin axes in young, open clusters if unbiased (with respect to inclination) samples of Be stars are used.

Keywords: open star clusters; stellar rotation; be stars; star formation; early-type stars; fundamental parameters of stars; circumstellar disks
H2, He, and CO2 Pressure-induced Parameters for the HITRAN Database. II. Line Lists of CO2, N2O, CO, SO2, OH, OCS, H2CO, HCN, PH3, H2S, and GeH4

In recent years, extended efforts have been made to increase the potential for modeling and interpreting the spectra of planetary atmospheres using the HITRAN database. A significant objective is to provide broadening parameters due to the ambient pressure of He, H2, and CO2 gases. Since hydrogen and helium are the main constituents in the atmospheres of gas giants, and carbon dioxide dominates the atmospheres of many rocky planets, these spectroscopic data are essential for radiative transfer models dedicated to planetary atmospheres. In HITRAN2016, the He-, H2- and CO2-broadening parameters and their temperature dependencies, and in some cases pressure-induced shifts, were added to the line lists of CO, SO2, NH3, HF, HCl, OCS, and C2H2. This work describes a further expansion introduced in the HITRAN2020 edition. In particular, relevant data for the line lists of CO2, N2O, OH, H2CO, HCN, PH3, H2S, and GeH4 were added, while those for CO, SO2, and OCS were revised. The new data are based on the semiempirical models constructed on available and validated experimental measurements and theoretical predictions. These models strongly depend on the extent and quality of the available data. The paper explains how to use the online interface or the HITRAN Application Programming Interface (HAPI) to retrieve these data from the database. Examples of calculating a molecule's spectra in a mixture of buffer-gases using HAPI are also provided. We also provide a set of Python codes allowing one to populate any line list of corresponding molecules with relevant broadening parameters.

Keywords: molecular spectroscopy
The Behavior of HgMn Stars in the Far UV -2: μ Leporis

The analysis of 8 high resolution SWP spectra of the HgMn star μ Leporis obtained through the large aperture recorded by the International Ultraviolet Explorer reveals that the far ultraviolet flux of μ Leporis remained probably constant over a timescale of about 29 hr, ie. about 40% of the recently determined rotational period. One spectrum taken 10 yr before also has the same level than the average spectrum of the run. Whereas seven spectra of the 29 hr run have levels consistent with the average spectrum, one spectrum shows a lower flux by about 7% probably caused by a loss of the flux. The spectra taken with the LWP camera consistently show that the mid-UV flux remained stable over the 29 hr run. Hence the available IUE data do not show evidence of real flux variations in the ultraviolet range for μ Leporis.

Keywords: chemically peculiar stars
The Effects of Dust Optical Properties on the Scattering-induced Disk Polarization by Millimeter-sized Grains

Spatially resolved (sub)millimeter polarization has been detected by Atacama Large Millimeter/submillimeter Array in an increasing number of disks. The majority of the observations show polarization patterns consistent with self scattering, especially at Band 7. The inferred sizes of the grains are typically of order 100 μm, which is very different from the millimeter size commonly inferred from the dust opacity index β. In an effort to resolve this discrepancy, we first introduce the so-called "Coplanar Isotropic Radiation Field" approximation, which enables the computation of the (signed) polarization fraction semianalytically. With an oft-adopted dust composition, we find that models with big dust grains produce very small polarization with reversed orientation, which has not been observed. The semianalytic results are validated through Monte Carlo radiative transfer simulations. In these models, the "correct" polarization orientation and the small β index are mutually exclusive. To resolve this tension, we explore a wide range of dust models, parameterized by their complex refractive indices m = n + ik. We find that both the fraction and the orientation of the polarization depend on the refractive index in a complex way, and this dependence is mapped out on an n-k plane for a representative 3 mm size distribution and wavelength of 870 μm. In particular, 3 mm-sized refractory organics grains produce reversed polarization, whereas grains made of absorptive carbonaceous materials produce a percent-level, nonreversed polarization; the latter may alleviate the aforementioned tension in grain size estimates. We conclude that scattering-induced polarization has the potential to also probe the grain compositions.

Keywords: protoplanetary disks; dust continuum emission; circumstellar dust
On the Detection Potential of Blazar Flares for Current Neutrino Telescopes

Blazar jets are extreme environments, in which relativistic proton interactions with an ultraviolet photon field could give rise to photopion production. High-confidence associations of individual high-energy neutrinos with blazar flares could be achieved via spatially and temporally coincident detections. In 2017, the track-like, extremely high-energy neutrino event IC 170922A was found to coincide with increased γ-ray emission from the blazar TXS 0506+056, leading to the identification of the most promising neutrino point-source candidate so far. We calculate the expected number of neutrino events that can be detected with IceCube, based on a broadband parameterization of bright short-term blazar flares that were observed in the first 6.5 yr of Fermi/Large Area Telescope observations. We find that the integrated keV-to-GeV fluence of most individual blazar flares is far too small to yield a substantial Poisson probability for the detection of one or more neutrinos with IceCube. We show that the sample of potentially detectable high-energy neutrinos from individual blazar flares is rather small. We further show that the blazars 3C 279 and PKS 1510-089 dominate the all-sky neutrino prediction from bright and short-term blazar flares. In the end, we discuss strategies to search for more significant associations in future data unblindings of IceCube and KM3NeT.

Keywords: active galactic nuclei; blazars; neutrino astronomy; gamma-ray astronomy
Jet-powered Turbulence in Common Envelope Evolution

We conduct a three-dimensional hydrodynamical simulation of common envelope evolution (CEE) where a neutron star (NS) spirals in inside the envelope of a red supergiant star in a predetermined orbit. We find that the jets shed pairs of vortices in an expanding spiral pattern, inflate two expanding spirally shaped low-density bubbles, one above and one below the equatorial plane, and deposit angular momentum to the envelope. In the simulation we do not include the gravity of the NS such that all effects we find are solely due to the jets that the spiraling-in NS launches. The angular momentum that the jets deposit into the envelope is of the same order of magnitude as the orbital angular momentum and has the same direction. The turbulence that the jets induce in the common envelope might play a role in transporting energy and angular momentum. The jet-deposited energy that is radiated away (a process not studied here) leads to a transient event that is termed a common envelope jets supernova (CEJSN) and might mimic an energetic core collapse supernova. The turbulence and the spiral pattern that we explore here might lead to bumps in the late light curve of the CEJSN when different segments of the ejected envelope collide with each other. This study emphasizes the roles that jets can play in CEE (including jets launched by black hole companions) and adds to the rich variety of processes in CEJSN events.

Keywords: stellar jets; common envelope evolution
Ten-micron Emission in a Color-magnitude Diagram of M Giant Variables

Infrared color-magnitude diagrams are presented for variable M giants within the Two-Micron Sky Survey for which 10 μm dust emission was detected in IRAS low-resolution spectra. Dust emission is mostly limited to a definable region in absolute M Ks magnitude and (J - K s ) color, and to pulsation periods greater than 50 days.

Keywords: infrared photometry; stellar mass loss
Does GW190425 Require an Alternative Formation Pathway than a Fast-merging Channel?

The LIGO/Virgo Scientific Collaboration (LVC) recently announced the detection of a compact object binary merger, GW190425, with a total mass of ${3.4}_{-0.1}^{+0.3}$ M⊙ and individual component masses in the range of about 1.1-2.5 M⊙. If the constituent compact objects are neutron stars, then the total mass is five standard deviations higher than the mean of 2.66 ± 0.12 M⊙ for Galactic binary neutron stars. LVC suggests that the nondetection of such massive binary neutron star (BNS) systems in the Galaxy is due to a selection effect. However, we are unable to reconcile the inferred formation efficiency from the reported merger rate, ${{ \mathcal R }}_{\mathrm{GW}190425}={460}_{-390}^{+1050}$ yr-1 Gpc-3, with predictions from our own study for fast-merging BNS systems. Moreover, the comparable merger rates of GW190425 and GW170817 are possibly in tension with our results for two reasons: (i) more massive systems are expected to have lower formation rates, and (ii) fast-merging channels should constitute ≲10% of the total BNS systems if case BB unstable mass transfer is permitted to take place as a formation pathway. We argue that, to account for the high merger rate of GW190425 as a BNS system, (i) our understanding of NS formation in supernova explosions must be revisited, or (ii) more massive NSs must be preferentially born with either very weak or very high magnetic fields so that they would be undetectable in the radio surveys. Perhaps the detected massive NSs in NS-white dwarf binaries are our clues to the formation path of GW190425 systems.

Keywords: binary stars; ligo; neutron stars; common envelope binary stars
The SSA22 H I Tomography Survey (SSA22-HIT). I. Data Set and Compiled Redshift Catalog

We conducted a deep spectroscopic survey, named SSA22-HIT, in the SSA22 field with the DEep Imaging MultiObject Spectrograph (DEIMOS) on the Keck telescope, designed to tomographically map high-z H I gas through analysis of Lyα absorption in background galaxies' spectra. In total, 198 galaxies were spectroscopically confirmed at 2.5 < z < 6 with a few low-z exceptions in the 26 × 15 arcmin2 area, of which 148 were newly determined in this study. Our redshift measurements were merged with previously confirmed redshifts available in the 34 × 27 arcmin2 area of the SSA22 field. This compiled catalog containing 730 galaxies of various types at z > 2 is useful for various applications, and it is made publicly available. Our SSA22-HIT survey has increased by approximately twice the number of spectroscopic redshifts of sources at z > 3.2 in the observed field. From a comparison with publicly available redshift catalogs, we show that our compiled redshift catalog in the SSA22 field is comparable to those among major extragalactic survey fields in terms of a combination of wide area and high surface number density of objects at z > 2. About 40% of the spectroscopically confirmed objects in SSA22-HIT show reasonable quality of spectra in the wavelengths shorter than Lyα when a sufficient amount of smoothing is adopted. Our data set enables us to make the H I tomographic map at z ≳ 3, which we present in a parallel study.

Keywords: redshift surveys; high-redshift galaxies; catalogs; intergalactic medium