Sazuna/UAT_keywords huggingface dataset:
Solar-cycle Variations of South Atlantic Anomaly Proton Intensities Measured with the PAMELA Mission. We present a study of the solar-cycle variations of &gt;80 MeV proton flux intensities in the lower edge of the inner radiation belt, based on the measurements of the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) mission. The analyzed data sample covers an ~8 yr interval from 2006 July to 2014 September, thus spanning from the decaying phase of the 23rd solar cycle to the maximum of the 24th cycle. We explored the intensity temporal variations as a function of drift shell and proton energy, also providing an explicit investigation of the solar modulation effects at different equatorial pitch angles. PAMELA observations offer new important constraints for the modeling of low-altitude particle radiation environment at the highest trapping energies.

Keywords: Van Allen radiation belts, Cosmic rays
Bayesian Inference of Strange Star Equation of State Using the GW170817 and GW190425 Data. The observations of compact star inspirals from LIGO/Virgo provide a valuable tool to study the highly uncertain equation of state (EOS) of dense matter at the densities in which the compact stars reside. It is not clear whether the merging stars are neutron stars or quark stars containing self-bound quark matter. In this work, we explore the allowed bag-model-like EOSs by assuming the merging stars are strange quark stars (SQSs) from a Bayesian analysis employing the tidal deformability observational data of the GW170817 and GW190425 binary mergers. We consider two extreme states of strange quark matter, either nonsuperfluid or color-flavor locked (CFL) and find the results in these two cases essentially reconcile. In particular, our results indicate that the sound speed in the SQS matter is approximately a constant close to the conformal limit of $c/\sqrt{3}$ . The universal relations between the mass, the tidal deformability, and the compactness are provided for the SQSs. The most probable values of the maximum mass are found to be ${M}_{\mathrm{TOV}}={2.10}_{-0.12}^{+0.12}\,({2.15}_{-0.14}^{+0.16})\,{M}_{\odot }$ for normal (CFL) SQSs at a 90% confidence level. The corresponding radius and tidal deformability for a 1.4 M⊙ star are ${R}_{1.4}={11.50}_{-0.55}^{+0.52}\,({11.42}_{-0.44}^{+0.52})\,\mathrm{km}$ and ${{\rm{\Lambda }}}_{1.4}={650}_{-190}^{+230}\,({630}_{-150}^{+220})$ , respectively. We also investigate the possibility of GW190814's secondary component m2 of mass ${2.59}_{-0.09}^{+0.08}\,{M}_{\odot }$ being an SQS, and find that it could be a CFL SQS with the pairing gap Δ larger than 244 MeV and the effective bag parameter ${B}_{\mathrm{eff}}^{1/4}$ in the range of 170-192 MeV, at a 90% confidence level.

Keywords: High energy astrophysics, Gravitational waves, Compact objects
Second Harmonic Electromagnetic Emissions by an Electron Beam in Solar Wind Plasmas with Density Fluctuations. Two-dimensional particle-in-cell simulations are performed to study the electromagnetic radiation emitted at the second harmonic 2ωp of the plasma frequency by a weak electron beam propagating in a background plasma with random density fluctuations, in solar wind conditions relevant to Type III solar radio bursts. The dynamics of the waves, the beam, and the plasma are calculated over several thousands of plasma periods. For relevant comparisons, simulations with and without applied density fluctuations are performed for the same parameters. This Letter evidences for the first time the impact of density fluctuations on the physical mechanisms driving the generation of electromagnetic waves emitted at 2ωp. Results obtained show that (i) the beam radiates electromagnetic waves at 2ωp as a result of nonlinear processes of Langmuir waves' coalescence, despite wave scattering on the density fluctuations that strongly affect the Langmuir spectra; (ii) the fraction of initial beam energy transferred asymptotically to the electromagnetic waves at 2ωp is by one order of magnitude smaller when the plasma involves density fluctuations of average level around 5%; (iii) compared to the homogeneous case, the ratio of electromagnetic energy radiated at 2ωp to the energy carried by the Langmuir wave turbulence is significantly larger during all the nonlinear stage; (iv) asymptotically, when the plasma is inhomogeneous, electromagnetic emissions at 2ωp present isotropized spectra whereas quadrupolar radiation occurs for the homogeneous plasma case.

Keywords: Solar radio flares, Solar radio emission, Space plasmas, Plasma physics
Mass-Velocity Dispersion Relation in MaNGA Brightest Cluster Galaxies. We investigate a kinematic scaling relation between the baryonic mass and the flat velocity dispersion, i.e., mass-velocity dispersion relation (MVDR), from the brightest cluster galaxies (BCGs) to the galaxy clusters. In our studies, the baryonic mass of BCGs is mainly estimated by photometry. The velocity dispersion profiles are explored with the integrated field unit by Mapping Nearby Galaxies at Apache Point Observatory (MaNGA). For the first time, we reveal two significant results with 54 MaNGA BCGs: (1) the flat velocity dispersion profiles; (2) a tight empirical relation on the BCG-cluster scale together with cluster samples, i.e., MVDR, $\mathrm{log}({M}_{\mathrm{bar}}/{M}_{\odot })={4.1}_{-0.1}^{+0.1}$ $\mathrm{log}({\sigma }_{\mathrm{los}}/\mathrm{km}\,{{\rm{s}}}^{-1})\,+{1.6}_{-0.3}^{+0.3}$ , with a tiny lognormal intrinsic scatter of ${10}_{-1}^{+2} \%$ . This slope is identical to the acceleration relation in galaxy clusters, which is reminiscent of the spiral galaxies, albeit at a larger characteristic acceleration scale. The residuals of the MVDR represent a Gaussian distribution, displaying no correlations with four properties: baryonic mass, scale length, surface density, and redshift. Notably, the MVDR on the BCG-cluster scale provides a strict test, which disfavors the general prediction of the slope of three in the dark matter model.

Keywords: Galaxy clusters, Giant elliptical galaxies, Galaxy kinematics, Brightest cluster galaxies, Dark matter
Constraints on Planetesimal Accretion Inferred from Particle-size Distribution in CO Chondrites. The formation of planetesimals was a key step in the assemblage of planetary bodies, yet many aspects of their formation remain poorly constrained. Notably, the mechanism by which chondrules-submillimetric spheroids that dominate primitive meteorites-were incorporated into planetesimals remains poorly understood. Here we classify and analyze particle-size distributions in various CO carbonaceous chondrites found in the Atacama Desert. Our results show that the average circle-equivalent diameters of chondrules define a positive trend with the petrographic grade, which reflects the progressive role of thermal metamorphism within the CO parent body. We show that this relationship could not have been established by thermal metamorphism alone but rather by aerodynamic sorting during accretion. By modeling the self-gravitational contraction of clumps of chondrules, we show that (i) the accretion of the CO parent body(ies) would have generated a gradual change of chondrule size with depth in the parent body, with larger chondrules being more centrally concentrated than smaller ones, and (ii) any subsequent growth by pebble accretion would have been insignificant. These findings give substantial support to the view that planetesimals formed via gravitational collapse.

Keywords: Accretion, Chondrites, Asteroids, Protoplanetary disks, Planetesimals
Is Solar Minimum 24/25 Another Unusual One?. Solar minimum 23/24 is considered to be unusual because it exhibits features that differ notably from those commonly seen in previous minima. In this Letter, we analyze the solar polar magnetic field, the potential-field solution of the solar corona, and the in situ solar wind measurements to see if the recent solar minimum 24/25 is another unusual one. While the dipolar configuration that is commonly seen during minimum 22/23 and earlier minima persist for about half a year after the absolute minimum of solar cycle 24, the corona has a morphology that is more complex than a simple dipole before the absolute minimum. The fast solar wind streams are less dominant than minimum 23/24. The interplanetary magnetic field strength, density, and mass flux that are historically low in the minimum 23/24 are regained during minimum 24/25, but still do not reach the minimum 22/23 level. From the analysis of this Letter, it seems that the minimum 24/25 is only partly unusual, and the recovery of the commonly minimum features may result from the enhancement of the polar field.

Keywords: Solar cycle, Solar wind, Interplanetary magnetic fields, Solar corona
Pre-merger Localization of Compact-binary Mergers with Third-generation Observatories. We present the prospects for the pre-merger detection and localization of binary neutron star mergers with third-generation gravitational-wave (GW) observatories. We consider a wide variety of GW networks that may be operating in the 2030s and beyond; these networks include up to two Cosmic Explorer (CE) sites, the Einstein Telescope (ET), and continued observation with the existing second-generation ground-based detectors. For a fiducial local merger rate of 300 Gpc-3 yr-1, we find that the ET on its own is able to detect six and two sources per year at 5 and 30 minutes before merger, respectively, while providing a localization of &lt;10 deg2. A single CE would detect but be unable to localize sources on its own. A two-detector CE network, however, would detect 22 and 0.4 mergers per year using the same criteria. A full three-detector network with the operation of dual CEs and the ET would allow for &lt;1 deg2 source localization at 5 minutes before merger for ~seven sources per year. Given the dramatic increase in localization and detection capabilities, third-generation observatories will enable the regular observation of the prompt emission of mergers by a broad array of observatories including gamma-ray, X-ray, and optical telescopes. Moreover, sub-degree localizations minutes before merger, combined with narrow-field-of-view high-energy telescopes, could strongly constrain the high-energy pre-merger emission models proposed in the last decade.

Keywords: Neutron stars, Gravitational wave detectors, Gravitational waves
High-energy Neutrinos from Stellar Explosions in Active Galactic Nuclei Accretion Disks. Some catastrophic stellar explosions, such as supernovae (SNe), compact binary coalescences, and microtidal disruption events, are believed to be embedded in the accretion disks of active galactic nuclei (AGNs). We show high-energy neutrinos can be produced efficiently through pp interactions between shock-accelerated cosmic rays and AGN disk materials shortly after the explosion ejecta shock breaks out of the disk. AGN stellar explosions are ideal targets for joint neutrino and electromagnetic (EM) multimessenger observations. Future EM follow-up observations of neutrino bursts can help us search for yet-discovered AGN stellar explosions. We suggest that AGN stellar explosions could potentially be important astrophysical neutrino sources. The contribution from AGN stellar explosions to the observed diffuse neutrino background depends on the uncertain local event rate densities of these events in AGN disks. By considering thermonuclear SNe, core-collapse SNe, gamma-ray burst associated SNe, kilonovae, and choked GRBs in AGN disks with known theoretical local event rate densities, we show that these events may contribute to ≲10% of the observed diffuse neutrino background.

Keywords: Supernovae, Active galactic nuclei, Cosmological neutrinos, High energy astrophysics
Magnetic Flux and Magnetic Nonpotentiality of Active Regions in Eruptive and Confined Solar Flares. With the aim of understanding how the magnetic properties of active regions (ARs) control the eruptive character of solar flares, we analyze 719 flares of Geostationary Operational Environmental Satellite (GOES) class ≥C5.0 during 2010-2019. We carry out the first statistical study that investigates the flare-coronal mass ejection (CME) association rate as a function of the flare intensity and the AR characteristics that produce the flare, in terms of its total unsigned magnetic flux (ΦAR). Our results show that the slope of the flare-CME association rate with flare intensity reveals a steep monotonic decrease with ΦAR. This means that flares of the same GOES class but originating from an AR of larger ΦAR, are much more likely to be confined. Based on an AR flux as high as 1.0 × 1024 Mx for solar-type stars, we estimate that the CME association rate in X100-class "superflares" is no more than 50%. For a sample of 132 flares ≥M2.0 class, we measure three nonpotential parameters including the length of steep gradient polarity-inversion line (LSGPIL), the total photospheric free magnetic energy (Efree), and the area with large shear angle (AΨ). We find that confined flares tend to have larger values of LSGPIL, Efree, and AΨ compared to eruptive flares. Each nonpotential parameter shows a moderate positive correlation with ΦAR. Our results imply that ΦAR is a decisive quantity describing the eruptive character of a flare, as it provides a global parameter relating to the strength of the background field confinement.

Keywords: Solar active region magnetic fields, Solar flares, Stellar activity, Solar coronal mass ejections, Solar activity
Comparison of Planetary Hα-emission Models: A New Correlation with Accretion Luminosity. Accreting planets have been detected through their hydrogen-line emission, specifically Hα. To interpret this, stellar-regime empirical correlations between the Hα luminosity LHα and the accretion luminosity Lacc or accretion rate $\dot{M}$ have been extrapolated to planetary masses, however without validation. We present a theoretical Lacc-LHα relationship applicable to a shock at the surface of a planet. We consider wide ranges of accretion rates and masses and use detailed spectrally resolved, nonequilibrium models of the postshock cooling. The new relationship gives a markedly higher Lacc for a given LHα than fits to young stellar objects, because Lyα, which is not observable, carries a large fraction of Lacc. Specifically, an LHα measurement needs 10 to 100 times higher Lacc and $\dot{M}$ than previously predicted, which may explain the rarity of planetary Hα detections. We also compare the $\dot{M}$ -LHα relationships coming from the planet-surface shock or implied by accretion-funnel emission. Both can contribute simultaneously to an observed Hα signal, but at low (high) $\dot{M}$ the planetary-surface shock (heated funnel) dominates. Only the shock produces Gaussian line wings. Finally, we discuss accretion contexts in which different emission scenarios may apply, putting recent literature models in perspective, and also present Lacc-Lline relationships for several other hydrogen lines.

Keywords: Accretion, H alpha photometry, H I line emission, Scaling relations, Classical T Tauri stars, Extrasolar gaseous giant planets, Planet formation
Beamed Emission from a Neutron-star ULX in a GRRMHD Simulation. We perform a global 2.5D general-relativistic radiation magnetohydrodynamic simulation of supercritical accretion onto a neutron star with a 2 × 1010 G dipolar magnetic field, as a model of a neutron-star-powered ultraluminous X-ray source (ULX). We compute a lower limit on the total luminosity of ~2.5 LEdd, and find the radiation to be highly beamed by the accretion disk outflows. The apparent isotropic luminosity, which is a function of the viewing angle, reaches a maximum above 100 LEdd, consistent with the luminosities observed in ULXs.

Keywords: Neutron stars, Ultraluminous x-ray sources, Magnetohydrodynamical simulations
First Frequency-time-resolved Imaging Spectroscopy Observations of Solar Radio Spikes. Solar radio spikes are short duration and narrow bandwidth fine structures in dynamic spectra observed from the GHz to tens of MHz range. Their very short duration and narrow frequency bandwidth are indicative of subsecond small-scale energy release in the solar corona, yet their origin is not understood. Using the LOw Frequency ARray, we present spatially, frequency, and time resolved observations of individual radio spikes associated with a coronal mass ejection. Individual radio spike imaging demonstrates that the observed area is increasing in time and the centroid positions of the individual spikes move superluminally parallel to the solar limb. Comparison of spike characteristics with that of individual Type IIIb striae observed in the same event show similarities in duration, bandwidth, drift rate, polarization, and observed area, as well the spike and striae motion in the image plane suggesting fundamental plasma emission with the spike emission region on the order of ~108 cm, with brightness temperature as high as 1013 K. The observed spatial, spectral, and temporal properties of the individual spike bursts are also suggestive of the radiation responsible for spikes escaping through anisotropic density turbulence in closed loop structures with scattering preferentially along the guiding magnetic field oriented parallel to the limb in the scattering region. The dominance of scattering on the observed time profile suggests the energy release time is likely to be shorter than what is often assumed. The observations also imply that the density turbulence anisotropy along closed magnetic field lines is higher than along open field lines.

Keywords: Solar radio emission, Solar corona
TOI-942b: A Prograde Neptune in a   60 Myr Old Multi-transiting System. Mapping the orbital obliquity distribution of young planets is one avenue toward understanding mechanisms that sculpt the architectures of planetary systems. TOI-942 is a young field star, with an age of ~60 Myr, hosting a planetary system consisting of two transiting Neptune-sized planets in 4.3 and 10.1 day period orbits. We observed the spectroscopic transits of the inner Neptune TOI-942b to determine its projected orbital obliquity angle. Through two partial transits, we find the planet to be in a prograde orbit, with a projected obliquity angle of $| \lambda | ={1}_{-33}^{+41}$ deg. In addition, incorporating the light curve and the stellar rotation period, we find the true 3D obliquity to be ${2}_{-23}^{+27}$ deg. We explored various sources of uncertainties specific to the spectroscopic transits of planets around young active stars, and showed that our reported obliquity uncertainty fully encompassed these effects. TOI-942b is one of the youngest planets to have its obliquity characterized, and one of even fewer residing in a multi-planet system. The prograde orbital geometry of TOI-942b is in line with systems of similar ages, none of which have yet been identified to be in strongly misaligned orbits. * This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Keywords: Exoplanet dynamics, Exoplanets, Exoplanet systems, Planetary system formation, Planetary science, Mini Neptunes
PAH Spectroscopy from 1 to 5 μm. The PAH model predicts many weak emission features in the 1-5 μm region that can resolve significant questions that it has faced since its inception in the mid-80s. These features contain fundamental information about the PAH population that is inaccessible via the much stronger PAH bands in the 5-20 μm region. Apart from the 3.3 μm band and plateau, PAH spectroscopy across most of the 1-5 μm region has been unexplored due to its low intrinsic intensity. ISO and Akari covered some of this wavelength range, but lacked the combined sensitivity and resolution to measure the predicted bands with sufficient fidelity. The spectroscopic capabilities of the NIRSpec instrument on board JWST will make it possible to measure and fully characterize many of the PAH features expected in this region. These include the fundamental, overtone and combination C-D and C ≅ N stretching bands of deuterated PAHs, cyano-PAHs (PAH-C≅N), and the overtones and combinations of the strong PAH bands that dominate the 5-20 μm region. These bands will reveal the amount of D tied up in PAHs, the PAH D/H ratio, the D distribution between PAH aliphatic and aromatic subcomponents, and delineate key stages in PAH formation and evolution on an object-by-object basis and within extended objects. If cyano-PAHs are present, these bands will also reveal the amount of cyano groups tied up in PAHs, determine the N/C ratio within that PAH subset, and distinguish between the bands near 4.5 μm that arise from CD versus C ≅ N.

Keywords: Infrared astronomy, Molecular spectroscopy, Polycyclic aromatic hydrocarbons, Astrochemistry
The Detection of Ionized Carbon Emission at z   8. We present deep Keck/MOSFIRE H-band spectroscopic observations covering the [C III],C III]λλ1907, 1909 doublet for three z ~ 8 galaxy candidates in the AEGIS field. Along with nondetections in two galaxies, we obtain one of the highest-redshift detections to date of [C III]λ1907 for the galaxy AEGIS-33376, finding zspec = 7.945 ± 0.001. We measure a [C III]λ1907 flux of 2.24 ± 0.71 × 10-18erg s-1cm-2, corresponding to a rest-frame equivalent width of 20.3 ± 6.5 Å for the single line. Given the not very constraining upper limit for C III]λ1909 based on strong sky-line contamination, we assume a [C III]λ1907/C III]λ1909 doublet ratio of 1.5 and infer a total [C III][C III]λλ1907, 1909 equivalent width of 33.7 ± 10.8 Å. We repeat the same reductions and analysis on multiple subsets of our raw data divided on the basis of time and observing conditions, verifying that the [C III]λ1907 emission is present for AEGIS-33376 throughout our observations. We also confirm that the significance of the [C III]λ1907 detection in different subsets of our data tracks that of brighter emission features detected on the same multi-slit mask. These multiple tests suggest that the observed emission line is real and associated with the z ~ 8 target. The strong observed [C III],C III]λλ1907, 1909 in AEGIS-33376 likely indicates ISM conditions of low metallicity, high ionization parameter, and a hard ionizing spectrum, although AGN contributions are possible. This single detection represents a sizable increase in the current sample [C III],C III]λλ1907, 1909 detections at z &gt; 7, while JWST will provide the first statistical samples of such measurements at these redshifts. * Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W.M. Keck Foundation.

Keywords: High-redshift galaxies, Galaxy evolution