Sazuna/UAT_keywords huggingface dataset:
Deflection of Global Ion Flow by the Martian Crustal Magnetic Fields. Without the protection of a global magnetic field, erosion of the Martian ionosphere by the solar wind leads to abundant loss of atmospheric particles. Although the crustal magnetic fields in the Martian southern hemisphere are strong enough to affect the dayside-induced magnetosphere, there is still limited evidence for the deflection of the solar winds by the crustal magnetic fields. With 4 years of ion data measured by the Mars Atmosphere and Volatile EvolutioN mission, we investigate the flow pattern of protons, O+, and ${{{\rm{O}}}_{2}}^{+}$ when the crustal fields rotate to different local times. Our result is the first evidence that suggests the crustal magnetic fields can withstand the solar wind flows on the Martian dayside and can effectively trap heavy ions below 1000 km. The gyroradii of heavy ions in the strong crustal fields regions are one order of magnitude smaller than in other regions. The trapping effect causes different flow patterns, while the crustal fields rotate to different subsolar regions but are attenuated at higher altitudes. Observations provide essential information to investigate the effect of the crustal magnetic fields on heavy-ion flows and understand the role of the crustal magnetic fields in the interaction between the solar wind and the Martian atmosphere.

Keywords: Magnetic anomalies, Planetary magnetospheres, Mars, Solar-planetary interactions
FRB 200428: An Impact between an Asteroid and a Magnetar. A fast radio burst (FRB) was recently detected to be associated with a hard X-ray burst from the Galactic magnetar SGR 1935+2154. Scenarios involving magnetars for FRBs are hence highly favored. In this work, we suggest that the impact between an asteroid and a magnetar could explain such a detection. According to our calculations, an asteroid of mass 1020 g will be disrupted at a distance of 7 × 109 cm when approaching the magnetar. The accreted material will flow along the magnetic field lines from the Alfvén radius ∼107 cm. After falling onto the magnetar's surface, an instant accretion column will be formed, producing a Comptonized X-ray burst and an FRB in the magnetosphere. We show that all the observational features of FRB 200428 could be interpreted self-consistently in this scenario. We predict quasi-periodic oscillations in this specific X-ray burst, which can serve as an independent observational test.

Keywords: Neutron stars, Astronomical radiation sources, Pulsars, Soft gamma-ray repeaters, Burst astrophysics, Radio bursts, Non-thermal radiation sources, Magnetars, Radio pulsars
Detections of Simultaneous Brightening of γ-Ray and Optical Emissions of a Distant Blazar GB 1508+5714 at Redshift 4.3. GB 1508+5714 is a high-redshift blazar (z = 4.3), and a spectrally soft γ-ray source has been detected in its direction. By analyzing 11.4 yr Fermi Large Area Telescope data, significant long-term variability of the γ-ray source is confirmed. More importantly, a γ-ray emission flare appeared in an epoch of several tens of days in 2018, when the flux was about four times the value from the global fit. Meanwhile, optical flares were displayed in both the r and i bands from the Zwicky Transient Facility light curves. Detections of the simultaneous γ-ray and optical brightening provide decisive evidence to pin down the association between the γ-ray source and GB 1508+5714, which makes it the first identified γ-ray blazar beyond redshift 4. A broadband spectral energy distribution in the high flux state is constructed, and the origin of the multiwavelength brightening is also briefly discussed. Upcoming wide-deep-fast optical telescopes together with the γ-ray sky surveyors will shed light on the role that the active galactic nucleus jets play in the early cosmic time.

Keywords: Quasars, Gamma-ray sources, Galaxy jets, Non-thermal radiation sources, High-redshift galaxies
Revisiting the Relation between Nonthermal Line Widths and Transverse MHD Wave Amplitudes. Observations and 3D MHD simulations of the transverse MHD waves in the solar corona have established that true wave energies hide in the nonthermal line widths of the optically thin emission lines. This displays the need for a relation between the nonthermal line widths and transverse wave amplitudes for estimating the true wave energies. In the past decade, several studies have assumed that the root mean square (rms) wave amplitudes are larger than the nonthermal line widths by a factor of $\sqrt{2}$ . However, a few studies have ignored this factor while estimating rms wave amplitudes. Thus, there appears to exist a discrepancy in this relation. In this study, we investigate the dependence of nonthermal line widths on wave amplitudes by constructing a simple mathematical model followed by 3D MHD simulations. We derive this relation for the linearly and circularly polarized oscillations, as well as oscillations excited by multiple velocity drivers. We note a fairly good match between mathematical models and numerical simulations. We conclude that the rms wave amplitudes are never greater than the nonthermal line widths, which raises questions about earlier studies claiming transverse waves carry enough energy to heat the solar corona.

Keywords: Magnetohydrodynamics, Alfven waves, Solar corona
Jet Properties of Compact Steep-spectrum Sources and an Eddington-ratio-driven Unification Scheme of Jet Radiation in Active Galactic Nuclei. Compact steep-spectrum sources (CSSs) likely represent a population of young radio-loud active galactic nuclei (AGNs) and have been identified as γ-ray-emitting sources. We present a comprehensive analysis of their γ-ray emission observed with Fermi/LAT and establish their broadband spectral energy distributions (SEDs). We derive their jet properties using SED fits with a two-zone leptonic model for radiation from the compact core and the large-scale extended region, and explore the possible signature of a unification picture of jet radiation among subclasses of AGNs. We show that the observed γ-rays of CSSs with significant variability are contributed by the radiation of their compact cores via the inverse-Compton process of the torus photons. The derived power-law distribution index of the radiating electrons is p1 ∼ 1.5-1.8, magnetic field strength is B ∼ 0.15-0.6 G, and Doppler-boosting factor is δ ∼ 2.8-8.9. Assuming that the jet is composed of e± pairs, the compact cores of CSSs are magnetized and have a high radiation efficiency, similar to that of flat-spectrum radio quasars. The γ-ray-emitting CSSs on average have higher Eddington ratio and black hole mass than those non-GeV-detected CSSs, and they follow the correlation between the jet power in units of Eddington luminosity ( ${P}_{\mathrm{jet}}^{{e}^{\pm }}/{L}_{\mathrm{Edd}}$ ) and Eddington ratio (REdd) with other subclasses of AGNs, ${P}_{\mathrm{jet}}^{{e}^{\pm }}/{L}_{\mathrm{Edd}}\propto {R}_{\mathrm{Edd}}^{0.52\pm 0.03}$ , indicating that REdd would be a key physical driver for the unification scheme of AGN jet radiation.

Keywords: Compact galaxies, Relativistic jets, Non-thermal radiation sources, Active galactic nuclei, Gamma-rays
The Complex Space Weather Events of 2017 September. Interplanetary coronal mass ejections (ICMEs), magnetic clouds (MCs), sheaths, corotating interaction regions (CIRs), solar wind high-speed streams (HSSs), fast forward shocks (FSs), reverse waves (RWs), stream interfaces, and heliospheric current sheet crossings detected upstream of the Earth and their geoeffectiveness are studied during 2017 September. The most intense geomagnetic storm (SYM-H peak = -146 nT) starting on September 7 had a three-step main phase. A compound interplanetary structure resulting from an FS encountering and compressing the upstream MC southward interplanetary magnetic fields (IMFs) caused the first two steps of the storm. A magnetospheric supersubstorm (SSS; SML peak = -3712 nT) led to the third and most intense step. An MC portion of an ICME created an intense storm (SYM-H peak = -115 nT) on September 8. A second SSS (SML peak = -2642 nT) occurred during the main phase of this storm. Intense geomagnetically induced currents (GICs) occurred during the SSSs. Two moderate magnetic storms with peak SYM-H indices of -65 and -74 nT occurring on September 13 and 27 were caused by sheath and CIR southward IMFs, respectively. Six FSs and their associated sheaths caused sudden impulses (SI+s) of magnitude ranging from +11 to +56 nT. The shocks/sheaths led to magnetospheric relativistic electron flux decreases. The RWs caused SI-s and substorm recoveries by reducing southward IMFs. The high-intensity long-duration continuous AE activities (HILDCAAs) caused by the HSSs were related to the increase/acceleration of relativistic electron fluxes.

Keywords: Corotating streams, Solar flares, Solar coronal mass ejections, Interplanetary shocks
Bayesian Inference of the Symmetry Energy of Superdense Neutron-rich Matter from Future Radius Measurements of Massive Neutron Stars. Using as references the posterior probability distribution functions of the equation of state (EOS) parameters inferred from the radii of canonical neutron stars (NSs) reported by the LIGO/VIRGO and NICER Collaborations based on their observations of GW170817 and PSR J0030+0451, we investigate how future radius measurements of more massive NSs will improve our current knowledge about the EOS of superdense neutron-rich nuclear matter, especially its symmetry energy term. Within the Bayesian statistical approach using an explicitly isospin-dependent parametric EOS for the core of NSs, we infer the EOS parameters of superdense neutron-rich nuclear matter from three sets of imagined mass-radius correlation data representing typical predictions by various nuclear many-body theories, that is, the radius stays the same, decreases, or increases with increasing NS mass within ±15% between 1.4 and 2.0 M⊙. The corresponding NS average density increases quickly or slowly or slightly decreases as the NS mass increases from 1.4 to 2.0 M⊙. While the EOSs of symmetric nuclear matter (SNM) inferred from the three data sets are approximately the same, the corresponding symmetry energies above about twice the saturation density of nuclear matter are very different, indicating that the radii of massive NSs carry important information about the high-density behavior of nuclear symmetry energy with little influence from the remaining uncertainties of the SNM EOS at suprasaturation densities.

Keywords: Neutron stars
The UV Luminosity Function of Protocluster Galaxies at z ∼ 4: The Bright-end Excess and the Enhanced Star Formation Rate Density. We report the rest-frame ultraviolet luminosity function of g-dropout galaxies in 177 protocluster candidates (PC UVLF) at z ∼ 4 selected in the Hyper Suprime-Cam Subaru Strategic Program. Comparing it with the UVLF of field galaxies at the same redshift, we find that the PC UVLF shows a significant excess toward the bright end. This excess cannot be explained by the contribution of only active galactic nuclei, and we also find that this excess is more significant in higher density regions. Assuming that all protocluster members are located on the star formation main sequence, the PC UVLF can be converted into a stellar mass function. Consequently, our protocluster members are inferred to have a 2.8 times more massive characteristic stellar mass than that of the field Lyman break galaxies at the same redshift. This study, for the first time, clearly shows that the enhancement in star formation or stellar mass in overdense regions can generally be seen as early as at z ∼ 4. We also estimate the star formation rate density (SFRD) in protocluster regions as ≃6%-20% of the cosmic SFRD, based on the measured PC UVLF after correction for the selection incompleteness in our protocluster sample. This high value suggests that protoclusters make a nonnegligible contribution to the cosmic SFRD at z ∼ 4, as previously suggested by simulations. Our results suggest that protoclusters are essential components for galaxy evolution at z ∼ 4.

Keywords: Protoclusters, High-redshift galaxies, Galaxy evolution
Connecting 3D Evolution of Coronal Mass Ejections to Their Source Regions. Since coronal mass ejections (CMEs) are the major drivers of space weather, it is crucial to study their evolution starting from the inner corona. In this work we use graduated cylindrical shell model to study the 3D evolution of 59 CMEs in the inner (&lt;3 R⊙) and outer (&gt;3 R⊙) corona using observations from COR-1 and COR-2 on board the Solar TErrestrial RElations Observatory (STEREO) spacecraft. We identify the source regions of these CMEs and classify them as CMEs associated with active regions (ARs), active prominences (APs), and prominence eruptions. We find 27% of CMEs show true expansion and 31% show true deflections as they propagate outwards. Using 3D kinematic profiles of CMEs, we connect the evolution of true acceleration with the evolution of true width in the inner and outer corona, thereby providing observational evidence for the influence of the Lorentz force on the kinematics to lie in the height range 2.5-3 R⊙. We find a broad range in the distribution of peak 3D speeds and accelerations, ranging from 396 to 2465 km s-1 and 176 to 10,922 m s-2 respectively, with a long tail toward high values coming mainly from CMEs originating from ARs or APs. Further, we find that the magnitude of true acceleration is inversely correlated with its duration with a power-law index of -1.19. We believe that these results will provide important inputs for the planning of upcoming space missions that will observe the inner corona and for models that study CME initiation and propagation.

Keywords: Solar active region filaments, Quiescent solar prominence, Solar active regions, Solar coronal mass ejections, Solar corona
MCSED: A Flexible Spectral Energy Distribution Fitting Code and Its Application to z ∼ 2 Emission-line Galaxies. We present MCSED, a new spectral energy distribution (SED) fitting code that mates flexible stellar evolution calculations with the Markov Chain Monte Carlo algorithms of the software package emcee. It takes broad-, intermediate-, and narrowband photometry, emission-line fluxes, and/or absorption-line spectral indices and returns probability distributions and covariance plots for all model parameters. It includes a variety of dust attenuation curves with parameters for varying the UV slopes and bump strengths, a prescription for continuum and polycyclic aromatic hydrocarbon emission from dust, models for continuum and line emission from ionized gas, options for fixed and variable stellar metallicity, and a selection of star formation rate (SFR) histories. The code is well suited for exploring parameter interdependencies in sets of galaxies with known redshifts for which there is multiband photometry and/or spectroscopy. We apply MCSED to a sample of ∼2000 $1.90\lt z\lt 2.35$ galaxies in the five CANDELS fields that were selected via their strong [O III] λ5007 emission, and we explore the systematic behavior of their SEDs. We find that the galaxies become redder with stellar mass due to both increasing internal attenuation and a greater population of older stars. The slope of the UV extinction curve also changes with stellar mass, and at least some galaxies exhibit an extinction excess at 2175 Å. Finally, we demonstrate that below M ≲ 109 M⊙, the shape of the star-forming galaxy main sequence is highly dependent on the galaxies' assumed SFR history, as calculations that assume a constant SFR produce stellar masses that are ∼1 dex smaller than those found using more realistic SFR histories.

Keywords: Galaxy formation, Observational cosmology, Galaxy stellar content, Astrophysical dust processes, Galaxy evolution
Detecting Black Hole Occultations by Stars with Space Interferometric Telescopes. We show that the occultation of Sagittarius A* by stars can be detected with space-based or space-ground very-long-baseline interferometers, with an expected event rate that is high due to relativistic precession. We compute the tell-tale signal of an occultation event and describe methods to flag nonoccultation events that can masquerade as the signal.

Keywords: Galactic center, Black holes
Model-independent Constraints on Type Ia Supernova Light-curve Hyperparameters and Reconstructions of the Expansion History of the Universe. We reconstruct the expansion history of the universe using type Ia supernovae (SN Ia) in a manner independent of any cosmological model assumptions. To do so, we implement a nonparametric iterative smoothing method on the Joint Light-curve Analysis (JLA) data while exploring the SN Ia light-curve hyperparameter space by Markov Chain Monte Carlo (MCMC) sampling. We test to see how the posteriors of these hyperparameters depend on cosmology, whether using different dark energy models or reconstructions shift these posteriors. Our constraints on the SN Ia light-curve hyperparameters from our model-independent analysis are very consistent with the constraints from using different parameterizations of the equation of state of dark energy, namely the flat ΛCDM cosmology, the Chevallier-Polarski-Linder model, and the Phenomenologically Emergent Dark Energy (PEDE) model. This implies that the distance moduli constructed from the JLA data are mostly independent of the cosmological models. We also studied that the possibility the light-curve parameters evolve with redshift and our results show consistency with no evolution. The reconstructed expansion history of the universe and dark energy properties also seem to be in good agreement with the expectations of the standard ΛCDM model. However, our results also indicate that the data still allow for considerable flexibility in the expansion history of the universe.

Keywords: Deceleration parameter, Cosmological parameters, Astrostatistics techniques, Type Ia supernovae, Dark energy
On the Production of He<SUP>+</SUP> of Solar Origin in the Solar Wind. Solar wind measurements in the heliosphere predominantly comprise protons, alphas, and minor elements in a highly ionized state. The majority of low-charge states, such as He+, measured in situ are often attributed to pick-up ions of nonsolar origin. However, through inspection of the velocity distribution functions of near-Earth measurements, we find a small but significant population of He+ ions in the normal solar wind whose properties indicate that it originated from the Sun and has evolved as part of the normal solar wind. Current ionization models, largely governed by electron impact and radiative ionization and recombination processes, underestimate this population by several orders of magnitude. Therefore, to reconcile the singly ionized He observed, we investigate the recombination of solar He2+ through charge exchange with neutrals from circumsolar dust as a possible formation mechanism of solar He+. We present an empirical profile of neutrals necessary for charge exchange to become an effective vehicle to recombine He2+ to He+ such that it meets observational He+ values. We find that the formation of He+ is not only sensitive to the density of neutrals but also to the inner boundary of the neutral distribution encountered along the solar wind path. However, further observational constraints are necessary to confirm that the interaction between solar α particles and dust neutrals is the primary source of the He+ observations.

Keywords: Interplanetary dust, Solar wind, Charge exchange recombination
Extensive Study of a Coronal Mass Ejection with UV and White-light Coronagraphs: The Need for Multiwavelength Observations. Coronal mass ejections (CMEs) often show different features in different bandpasses. By combining data in white-light (WL) and ultraviolet (UV) bands, we have applied different techniques to derive plasma temperatures, electron density, internal radial speed, and so on, within a fast CME. They serve as extensive tests of the diagnostic capabilities developed for the observations provided by future multichannel coronagraphs (such as Solar Orbiter/Metis, Chinese Advanced Space-based Solar Observatory/Lyα Solar Telescope (LST), and PROBA-3/ASPIICS). The data involved include WL images acquired by Solar and Heliospheric Observatory (SOHO)/Large Angle Spectroscopic Coronagraph (LASCO) coronagraphs, and intensities measured by the SOHO/UV Coronagraph Spectrometer (UVCS) at 2.45 R⊙ in the UV (H I Lyα and O VI 1032 Å lines) and WL channels. Data from the UVCS WL channel have been employed for the first time to measure the CME position angle with the polarization-ratio technique. Plasma electron and effective temperatures of the CME core and void are estimated by combining UV and WL data. Due to the CME expansion and the possible existence of prominence segments, the transit of the CME core results in decreases in the electron temperature down to 105 K. The front is observed as a significant dimming in the Lyα intensity, associated with a line broadening due to plasma heating and flows along the line of sight. The 2D distribution of plasma speeds within the CME body is reconstructed from LASCO images and employed to constrain the Doppler dimming of the Lyα line and simulate future CME observations by Metis and LST.

Keywords: Solar ultraviolet emission, Solar coronal mass ejections, Solar corona
GASP. XXI. Star Formation Rates in the Tails of Galaxies Undergoing Ram Pressure Stripping. Using MUSE observations from the GASP survey, we study 54 galaxies undergoing ram pressure stripping (RPS) and spanning a wide range in galaxy mass and host cluster mass. We use this rich sample to study how the star formation rate (SFR) in the tails of stripped gas depends on the properties of the galaxy and its host cluster. We show that the interplay between all the parameters involved is complex and that there is not a single, dominant one in shaping the observed amount of SFR. Hence, we develop a simple analytical approach to describe the mass fraction of stripped gas and the SFR in the tail, as a function of the cluster velocity dispersion, galaxy stellar mass, clustercentric distance, and speed in the intracluster medium. Our model provides a good description of the observed gas truncation radius and of the fraction of SFR observed in the stripped tails, once we take into account the fact that the star formation efficiency in the tails is a factor of ∼5 lower than in the galaxy disk, in agreement with GASP ongoing H I and CO observations. Finally, we estimate the contribution of RPS to the intracluster light (ICL) and find that the average SFR in the tails of ram pressure stripped gas is $\sim 0.22\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$ per cluster. By extrapolating this result to evaluate the contribution to the ICL at different epochs, we compute an integrated average value per cluster of ∼4 × 109 M☉ of stars formed in the tails of RPS galaxies since z ∼ 1.

Keywords: Galaxy evolution, Ram pressure stripped tails