Sazuna/UAT_keywords huggingface dataset:
The Impact of the Mass Spectrum of Lenses in Quasar Microlensing Studies. Constraints on a Mixed Population of Primordial Black Holes and Stars. We show that quasar microlensing magnification statistics induced by a population of point microlenses distributed according to a mass spectrum can be very well approximated by that of a single-mass, monochromatic, population. When the spatial resolution (physically defined by the source size) is small compared with the Einstein radius, the mass of the monochromatic population matches the geometric mean (GM) of the mass spectrum. Otherwise, the best-fit mass can be larger. Taking into account the degeneracy with the GM, the interpretation of quasar microlensing observations under the hypothesis of a mixed population of primordial black holes and stars makes the existence of a significant population of intermediate mass black holes (∼100M⊙) unlikely but allows, within a 2σ confidence interval, the presence of a large population (≳40% of the total mass) of substellar black holes (∼0.01M⊙).

Keywords: Gravitational microlensing, Black hole physics
Properties of the Sheath Regions of Coronal Mass Ejections with or without Shocks from STEREO in situ Observations near 1 au. We examine 188 coronal mass ejections (CMEs) measured by the twin Solar Terrestrial Relations Observatory spacecraft during 2007-2016 to investigate the generic features of the CME sheath and the magnetic ejecta (ME) and dependencies of average physical parameters of the sheath on the ME. We classify the CMEs into three categories, focusing on whether the ME drives both a shock and sheath, or only a sheath, or neither, near 1 au. We also re-evaluate our initial classification through an automated algorithm and visual inspection. We observe that even for leading-edge speeds greater than 500 km s-1, 1 out of 4 MEs do not drive shocks near 1 au. MEs driving both shocks and sheaths are the fastest and propagate in high magnetosonic solar wind, whereas MEs driving only sheaths are the slowest and propagate in low magnetosonic solar wind. Our statistical and superposed epoch analyses indicate that all parameters are more enhanced in the sheath regions following shocks than in sheaths without shocks. However, differences within sheaths become statistically less significant for similar driving MEs. We also find that the radial thickness of ME-driven sheaths apparently has no clear linear correlation with the speed profile and associated Mach numbers of the driver.

Keywords: Solar cycle, Interplanetary shocks, Heliosphere, Solar wind, Interplanetary magnetic fields, Solar coronal mass ejections
Coronal Electron Densities Derived with Images Acquired during the 2017 August 21 Total Solar Eclipse. The total solar eclipse of 2017 August 21 was observed with a digital single lens reflex (DSLR) camera equipped with a linear polarizing filter. A method was developed to combine images acquired with 15 different exposure times (from 1/4000 s to 4 s), identifying in each pixel the best interval of detector linearity. The resulting mosaic image of the solar corona extends up to more than 5 solar radii, with a projected pixel size of 3.7 arcsec/pixel and an effective image resolution of 10"2, as determined with visible α-Leo and ν-Leo stars. Image analysis shows that in the inner corona the intensity gradients are so steep that nearby pixels show a relative intensity difference of up to ∼10%; this implies that care must be taken when analyzing single exposures acquired with polarization cameras. Images acquired with two different orientations of the polarizer have been analyzed to derive the degree of linear polarization and the polarized brightness pB in the solar corona. After intercalibration with pB measurements by the K-Cor instrument on Mauna Loa Solar Observatory (MLSO), the data analysis provided the 2D coronal electron density distribution from 1.1 up to ∼3 solar radii. The absolute radiometric calibration was also performed with the full Sun image and with magnitudes of visible stars. The resulting absolute calibrations show a disagreement by a factor of ∼2 with respect to MLSO; interestingly, this is the same disagreement recently found with eclipse predictions provided by MHD numerical simulations.

Keywords: Amateur astronomy, CCD photometry, Total eclipses, Solar eclipses, Amateur astronomers, Coronagraphic imaging, Solar corona, Ground-based astronomy, Photometry, Polarimeters, Polarimetry
Investigating Orientation Effects Considering Angular Resolution for a Sample of Radio-loud Quasars Using VLA Observations. Radio core dominance measurements, an indicator of jet orientation, sometimes rely on core flux density measurements from large-area surveys like Faint Images of the Radio Sky at Twenty cm (FIRST) that have an angular resolution of only 5″. Such low-resolution surveys often fail to resolve cores from the extended emission, resulting in an erroneous measurement. We focus on investigating this resolution effect for a sample of 119 radio-loud quasars. We obtained continuum observations from NSF's Karl G. Jansky Very Large Array (VLA) at 10 GHz in A configuration with a 0"2 resolution. Our measurements show that at FIRST spatial resolution, core flux measurements are indeed systematically high even after considering the core variability. For a handful of quasars, 10 GHz images reveal extended features, whereas the FIRST image shows a point source. We found that the resolution effect is more prominent for quasars with smaller angular sizes. We further computed two radio core dominance parameters R and R5100 for use in statistical orientation investigations with this sample. We also present the spectral energy distributions between 74 MHz and 1.4 GHz, which we used to measure the spectral index of the extended emission of these quasars. Our results empirically confirm that determination of radio core dominance requires high spatial resolution data. We highlight the practical issues associated with the choice of frequency and resolution in the measurement of core and extended flux densities.

Keywords: Radio cores, Very Large Array, Quasars, Radio loud quasars, Active galactic nuclei
Broadband Selection, Spectroscopic Identification, and Physical Properties of a Population of Extreme Emission-line Galaxies at 3 &lt; z &lt; 3.7. We present the selection, spectroscopic identification, and physical properties of extreme emission-line galaxies (EELGs) at 3 &lt; z &lt; 3.7, aiming at studying physical properties of an analog population of star-forming galaxies (SFGs) at the epoch of reionization. The sample is selected based on the excess in the observed Ks broadband flux relative to the best-fit stellar continuum model flux. By applying a 0.3 mag excess as a primary criterion, we select 240 EELG candidates with intense emission lines and estimated an observed-frame equivalent width (EW) of ≳1000 Å over the UltraVISTA-DR2 ultra-deep stripe in the COSMOS field. We then carried out HK-band follow-up spectroscopy for 23 of the candidates with Subaru/MOIRCS, and we find that 19 and 2 of them are at z &gt; 3 with intense [O III] emission and Hα emitters at z ≃ 2, respectively. These spectroscopically identified EELGs at z ≃ 3.3 show, on average, higher specific star formation rates (sSFRs) than the star-forming main sequence, low dust attenuation of E(B - V) ≲ 0.1 mag, and high [O III]/[O II]ratios of ≳3. We also find that our EELGs at z ≃ 3.3 have higher hydrogen-ionizing photon production efficiencies (ξion) than the canonical value (≃1025.2 erg-1 Hz), indicating that they are efficient in ionizing their surrounding interstellar medium. These physical properties suggest that they are low-metallicity galaxies with higher ionizing parameters and harder UV spectra than normal SFGs, which is similar to galaxies with Lyman continuum (LyC) leakage. Among our EELGs, those with the largest [O III]/[O II] and EW([O III]) values would be the most promising candidates to search for LyC leakage. * Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, with a proposal ID of S17A-049.

Keywords: Galaxy formation, Galaxy properties, Emission line galaxies, Galaxy evolution, Reionization, High-redshift galaxies
ALMA View of the Infalling Envelope around a Massive Protostar in S255IR SMA1. The massive young stellar object S255IR NIRS3 embedded in the star-forming core SMA1 has been recently observed with a luminosity burst, which is conjectured as a disk-mediated variable accretion event. In this context, it is imperative to characterize the gas properties around the massive young stellar object. With this in mind, we carried out high angular resolution observations with the Atacama Large Millimeter/submillimeter Array and imaged the 900 μm dust continuum and the CH3CN J = 19-18 K = 0-10 transitions of S255IR SMA1. The integrated CH3CN emission exhibits an elongated feature with an extent of 1800 au in the northwest-southeast direction at a position angle of 165°, which is nearly perpendicular to the bipolar outflow. We confirm the presence of dense (a few $\times {10}^{9}$ cm-3) and hot (∼400 K) gas immediately surrounding the central protostar. The CH3CN emission features a velocity gradient along the elongated ridge, and by modeling the gas kinematics based on features in the position-velocity diagram, we infer that the gas is best described by a flattened rotating infalling envelope (or pseudo-disk). A mass infall rate of a few × 10-4 M⊙ yr-1 is derived. If there exists a putative Keplerian disk directly involved in the mass accretion onto the star and jet/outflow launching, it is likely smaller than 125 au and unresolved by our observations. We show qualitative resemblances between the gas properties (such as density and kinematics) in 255IR SMA1 inferred from our observations and those in a numerical simulation particularly tailored for studying the burst mode of massive star formation.

Keywords: Accretion, Protostars, Star formation, Submillimeter astronomy
Cross-correlation between Subaru Hyper Suprime-Cam Galaxy Weak Lensing and Planck Cosmic Microwave Background Lensing. Cross-correlations between galaxy weak lensing (WL) and cosmic microwave background (CMB) lensing are powerful tools to probe matter fluctuations at intermediate redshifts and to detect residual systematics in either probe. In this paper, we study the cross-correlation of galaxy WL from the Hyper Suprime-Cam Subaru Strategic Program (HSC) first data release and CMB lensing from the final Planck data release, for HSC source galaxies at 0.3 ≤ z ≤ 1.5. HSC is the deepest Stage-III galaxy WL survey, and provides a great opportunity to study the high-redshift universe. It also presents new challenges related to its exceptionally high source density, such as source blending. The cross-correlation signal is measured at a significance level of 3.1σ. The amplitude of our best-fit model with respect to the best-fit 2018 Planck cosmology is A = 0.81 ± 0.25, consistent with A = 1. Our result is also consistent with previous CMB lensing and galaxy WL cross-correlation studies using different surveys. We perform tests with respect to the WL B-modes, the point-spread-function, photometric redshift errors, and thermal Sunyaev-Zel'dovich leakage, and find no significant evidence of residual systematics.

Keywords: Weak gravitational lensing, Cosmic microwave background radiation, Observational cosmology, Large-scale structure of the universe
Estimation of Thermal and Epithermal Neutron Fluences at the Lunar Surface from Isotopic Compositions of Rare Earth Elements. Thermalized neutrons arising at the surface of solar planets are produced from the interaction of cosmic rays with the nucleus consisting of surficial materials. The neutron energy spectrum in the range between thermal and epithermal regions at the lunar surface was investigated based on the combination of the isotopic variations of Sm and Gd caused by the thermal neutron-capture reactions in our previous study, with those of Dy, Er, and Yb caused by the epithermal neutron-capture reactions in this study. The detailed comparison of the systematic isotopic variations among Sm, Gd, Dy, Er, and Yb helps to construct a neutron energy spectrum at the surface of the Moon. Seven kinds of lunar soils at different depths of the drill core recovered from the Apollo 15 landing site (A-15) were used in this study. Isotopic variations of 164Dy/161Dy, 168Er/167Er, and 168Yb/174Yb were newly found in the A-15 samples, and showed the depth dependence caused by the interaction with cosmic-ray irradiation. In particular, the combination of the isotopic shifts of 168Er/167Er and 150Sm/149Sm could be effectively used to evaluate the epithermal neutron fluences of 5.4-8.1 × 1017 n cm-2 that were more than 10 times higher than thermal neutron fluences of 0.48-0.69 × 1017 n cm-2 reestimated in this study.

Keywords: Galactic cosmic rays, Lunar surface, Isotope shifts
Pair Plasma in Super-QED Magnetic Fields and the Hard X-Ray/Optical Emission of Magnetars. The photon spectrum emitted by a transrelativistic pair plasma is calculated in the presence of an ultrastrong magnetic field, and is shown to bear a remarkable resemblance to the rising hard X-ray spectra of quiescent magnetars. This emission is powered by pair annihilation which, in contrast with a weakly magnetized pair plasma, shows an extended low-frequency tail similar to bremsstrahlung. Cross sections for electron-positron annihilation/scattering, two-photon pair creation, and photon-e± scattering are adopted from our earlier ab initio quantum electrodynamic calculations in the regime $10{\alpha }_{\mathrm{em}}^{-1}{B}_{{\rm{Q}}}$ ≫ B ≫ BQ. Careful attention is given to the u-channel scattering resonance. Magnetospheric arcades anchored in zones of intense crustal shear and reaching about twice the magnetar radius are identified as the sites of the persistent hard X-ray emission. We deduce a novel and stable configuration for the magnetospheric circuit, with a high plasma density sustained by ohmic heating and in situ pair creation. Pairs are sourced nonlocally by photon collisions in zones with weak currents, such as the polar cap. Annihilation bremsstrahlung extends to the optical-IR band, where the plasma cutoff is located. The upper magnetar atmosphere experiences strong current-driven growth of ion-acoustic turbulence, which may limit positron diffusion. Coherent optical-IR emission is bounded near the observed flux by induced scattering. This model accommodates the rapid X-ray brightening of an activating magnetar, concentrated thermal hotspots, and the subdominant thermal X-ray emission of some active magnetars. Current injection is ascribed to continuous magnetic braiding, as seen in the global yielding calculations of Thompson, Yang, and Ortiz.

Keywords: Compact radiation sources, Plasma astrophysics, Magnetars, Magnetic fields, Gamma-rays
Substructures in the Disk-forming Region of the Class 0 Low-mass Protostellar Source IRAS 16293-2422 Source A on a 10 au Scale. We have observed the Class 0 protostellar source IRAS 16293-2422 A in the C17O and H2CS lines as well as the 1.3 mm dust continuum with the Atacama Large Millimeter/submillimeter Array at an angular resolution of ∼0"1 (14 au). The continuum emission of the binary component, Source A, reveals the substructure consisting of five intensity peaks within 100 au from the protostar. The C17O emission mainly traces the circummultiple structure on a 300 au scale centered at the intensity centroid of the continuum, while it is very weak within a radius of 50 au from the centroid. The H2CS emission, by contrast, traces the rotating disk structure around one of the continuum peaks (A1). Therefore, it seems that the rotation centroid of the circummultiple structure is slightly different from that of the disk around A1. We derive the rotation temperature by using the multiple lines of H2CS. Approaching the protostar A1, the rotation temperature steeply rises up to 300 K or higher at the radius of 50 au from the protostar. It is likely due to a local accretion shock and/or the preferential protostellar heating of the transition zone from the circummultiple structure to the disk around A1. This position corresponds to the place where the organic molecular lines are reported to be enhanced. Since the rise of the rotation temperature of H2CS most likely represents the rise of the gas and dust temperatures, it would be related to the chemical characteristics of this prototypical hot corino.

Keywords: Interstellar molecules, Interstellar dynamics, Interstellar emissions, Interstellar medium, Protostars
The Short-period S-stars S4711, S62, S4714 and the Lense-Thirring Effect due to the Spin of Sgr A*. Recently, some S-stars (S4711, S62, S4714) orbiting the supermassive black hole (SMBH) in Sgr A* with short orbital periods (7.6 yr ≤ Pb ≤ 12 yr) were discovered. It was suggested that they may be used to measure the general relativistic Lense-Thirring (LT) precessions of their longitudes of ascending node Ω induced by the SMBH's angular momentum J•. In fact, the proposed numerical estimates hold only in the particular case of a perfect alignment of J• with the line of sight, which does not seem to be the case. Moreover, the inclination I and the argument of perinigricon ω also undergo LT precessions for an arbitrary orientation of J• in space. We explicitly show the analytical expressions of ${\dot{I}}^{\mathrm{LT}},{\dot{{\rm{\Omega }}}}^{\mathrm{LT}},{\omega }^{\mathrm{LT}}$ in terms of the SMBH's spin polar angles i•, ɛ•. It turns out that the LT precessions, in arcseconds per year $\left(^{\prime\prime} \,{\mathrm{yr}}^{-1}\right)$ , range within $\left|{\dot{I}}^{\mathrm{LT}}\right|\lesssim {7}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}$ , $\left|{\dot{{\rm{\Omega }}}}^{\mathrm{LT}}\right|\lesssim {9}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}$ , and $-{13}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}\lesssim {\dot{\omega }}^{\mathrm{LT}}\lesssim {14}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}$ for S4714, $\left|{\dot{I}}^{\mathrm{LT}}\right|\lesssim {5}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}$ , $\left|{\dot{{\rm{\Omega }}}}^{\mathrm{LT}}\right|\lesssim {5}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}$ , and $\left|{\dot{\omega }}^{\mathrm{LT}}\right|\lesssim {10}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}$ for S62, and $\left|{\dot{I}}^{\mathrm{LT}}\right|\lesssim {0.3}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}$ , $\left|{\dot{{\rm{\Omega }}}}^{\mathrm{LT}}\right|\lesssim {0.3}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}$ , and $\left|{\dot{\omega }}^{\mathrm{LT}}\right|\lesssim {0.7}^{{\prime\prime} }\,{\mathrm{yr}}^{-1}$ for S4711. For each star, the corresponding values of ${i}_{\max }^{\bullet },{\varepsilon }_{\max }^{\bullet }$ , and ${i}_{\min }^{\bullet },{\varepsilon }_{\min }^{\bullet }$ are determined as well, along with those ${i}_{0}^{\bullet },{\varepsilon }_{0}^{\bullet }$ that cancel the LT precessions. The LT perinigricon precessions ${\dot{\omega }}^{\mathrm{LT}}$ are overwhelmed by the systematic uncertainties in the Schwarzschild ones due to the current errors in the stars' orbital parameters and the mass of Sgr A* itself.

Keywords: General relativity, Orbital elements, Kerr black holes
Lifting the Veil on Quark Matter in Compact Stars with Core g-mode Oscillations. Compact stars containing quark matter may masquerade as neutron stars in the range of measured mass and radius, making it difficult to draw firm conclusions on the phase of matter inside the star. The sensitivity of core g-mode oscillations to the presence of a mixed phase may alleviate this difficulty. In hybrid stars that admit quark matter in a mixed phase, the g-mode frequency rises sharply due to a marked decrease in the equilibrium sound speed. Resonant excitation of g-modes can leave an imprint in the waveform of coalescing binary compact stars. We present analytic and numeric results to assess the sensitivity displayed by g-mode oscillations to quark matter in a homogeneous or mixed phase and also compute relevant damping times in quark matter due to viscosity.

Keywords: Neutron stars, Stellar oscillations, Gravitational waves
Deciphering the Origin of the GeV-TeV Gamma-Ray Emission from SS 433. We investigate hadronic and leptonic scenarios for the GeV-TeV gamma-ray emission from jets of the microquasar SS 433. The emission region of the TeV photons coincides with the X-ray knots, where electrons are efficiently accelerated. On the other hand, the optical high-density filaments are also located close to the X-ray knots, which may support a hadronic scenario. We calculate multiwavelength photon spectra of the extended jet region by solving the transport equations for the electrons and protons. We find that both hadronic and leptonic models can account for the observational data, including the latest Fermi Large Area Telescope result. The hadronic scenarios predict higher-energy photons than the leptonic scenarios, and future observations such as with the Cherenkov Telescope Array, the Large High-Altitude Air Shower Observatory, and the Southern Wide-field Gamma-ray Observatory may distinguish between these scenarios and unravel the emission mechanism of GeV-TeV gamma rays. Based on our hadronic scenario, the analogy between microquasars and radio galaxies implies that the X-ray knot region of the radio-galaxy jets may accelerate heavy nuclei up to ultrahigh energies.

Keywords: Gamma-ray astronomy, Non-thermal radiation sources, Jets, Cosmic ray sources
Cosmic-Ray Tracks in Astrophysical Ices: Modeling with the Geant4-DNA Monte Carlo Toolkit. Cosmic rays are ubiquitous in interstellar environments, and their bombardment of dust-grain ice mantles is a possible driver for the formation of complex, even prebiotic molecules. Yet, critical data that are essential for accurate modeling of this phenomenon, such as the average radii of cosmic-ray tracks in amorphous solid water (ASW) remain unconstrained. It is shown that cosmic-ray tracks in ASW can be approximated as a cylindrical volume with an average radius that is mostly independent of the initial particle energy. Interactions between energetic ions and both low-density amorphous (LDA) and high-density amorphous (HDA) ice targets are simulated using the Geant4-DNA Monte Carlo toolkit, which allows for tracking secondary electrons down to subexcitation energies in the material. We find the peak track-core radii, rcyl, for LDA and HDA ices to be 9.9 nm and 8.4 nm, respectively—somewhat less than double the value of 5 nm often assumed in astrochemical models.

Keywords: Laboratory astrophysics, Molecular clouds, Astrochemistry, Molecular physics, Cosmic rays
Forward Modeling of Double Neutron Stars: Insights from Highly Offset Short Gamma-Ray Bursts. We present a detailed analysis of two well-localized, highly offset short gamma-ray bursts—GRB 070809 and GRB 090515—investigating the kinematic evolution of their progenitors from compact object formation until merger. Calibrating to observations of their most probable host galaxies, we construct semi-analytic galactic models that account for star formation history and galaxy growth over time. We pair detailed kinematic evolution with compact binary population modeling to infer viable post-supernova velocities and inspiral times. By populating binary tracers according to the star formation history of the host and kinematically evolving their post-supernova trajectories through the time-dependent galactic potential, we find that systems matching the observed offsets of the bursts require post-supernova systemic velocities of hundreds of kilometers per second. Marginalizing over uncertainties in the stellar mass-halo mass relation, we find that the second-born neutron star in the GRB 070809 and GRB 090515 progenitor systems received a natal kick of $\gtrsim 200\,\mathrm{km}\,{{\rm{s}}}^{-1}$ at the $78 \% $ and $91 \% $ credible levels, respectively. Applying our analysis to the full catalog of localized short gamma-ray bursts will provide unique constraints on their progenitors and help unravel the selection effects inherent to observing transients that are highly offset with respect to their hosts.

Keywords: Neutron stars, Gamma-ray bursts, Compact binary stars, Galaxy evolution, Supernova dynamics, Stellar evolution