Sazuna/UAT_keywords huggingface dataset:
Following the Lithium: Tracing Li-bearing Molecules across Age, Mass, and Gravity in Brown Dwarfs. Lithium is an important element for the understanding of ultracool dwarfs because it is lost to fusion at masses above ~68 MJ. Hence, the presence of atomic Li has served as an indicator of the nearby H-burning boundary at about 75 MJ between brown dwarfs and very low mass stars. Historically, the "lithium test," a search for the presence of the Li line at 670.8 nm, has been a marker if an object has a substellar mass. While the Li test could, in principle, be used to distinguish masses of later-type L-T dwarfs, Li is predominantly no longer found as an atomic gas but rather a molecular species such as LiH, LiF, LiOH, and LiCl in cooler atmospheres. The L- and T-type dwarfs are quite faint at 670 nm and thus challenging targets for high-resolution spectroscopy. But only recently have experimental molecular line lists become available for the molecular Li species, allowing molecular Li mass discrimination. Here we generated the latest opacity of these Li-bearing molecules and performed a thermochemical equilibrium atmospheric composition calculation of their abundances. Finally, we computed thermal emission spectra for a series of radiative-convective equilibrium models of cloudy and cloudless brown dwarf atmospheres (with Teff = 500-2400 K and $\mathrm{log}g=4.0\mbox{--}5.0$ ) to understand where the presence of atmospheric lithium-bearing species is most easily detected as a function of brown dwarf mass and age. After atomic Li, the best spectral signatures were found to be LiF at 10.5-12.5 μm and LiCl at 14.5-18.5 μm. Also, LiH shows a narrow feature at ~9.38 μm.

Keywords: Spectral line lists, Brown dwarfs, L dwarfs, T subdwarfs, T dwarfs
The Unusual Weak-line Quasar PG1407+265 and Its Foreground z   0.7 X-Ray Cluster. We present new observations of the odd z = 0.96 weak-line quasar PG1407+265, and report the discovery of CXOU J140927.9+261813, a z = 0.68 X-ray cluster. Archival X-ray photometry spanning nearly four decades reveals that PG1407+265 is variable at the 1 dex level on a timescale of years. V-band variability is observed with an amplitude less than 0.1 mag. The emission-line properties of PG1407+265 also reveal clear evidence for a powerful inflow or outflow due to near- or super-Eddington accretion, having a mechanical luminosity of order 1048 erg s-1. Our follow-up Chandra exposure centered on this object reveals a foreground z = 0.68 cluster roughly 1' × 1'5 in extent, offset to the east of PG1407+265, roughly coincident with the z = 0.68 radio galaxy FIRST J140927.8+261818. This non-cool-core cluster contributes about 10% of the X-ray flux of PG1407+265, has a mass of (0.6-5.5) × 1014 M☉, and an X-ray gas temperature of 2.2-4.3 keV. Because the projected position of the quasar lies at about twice that of the cluster's inferred Einstein radius, lensing by the cluster is unlikely to explain the quasar's unusual properties. We also discuss the evidence for a second cluster centered on and at the redshift of the quasar.

Keywords: Galaxy clusters, X-ray astronomy, High-luminosity active galactic nuclei, X-ray quasars, Active galactic nuclei, Intracluster medium
Probing Jets from Young Embedded Sources: Clues from HST Near-IR [Fe II] Images. We present near-infrared [Fe II] images of four Class 0/I jets (HH 1/2, HH 34, HH 111, HH 46/47) observed with the Hubble Space Telescope (HST) Wide Field Camera 3. The unprecedented angular resolution allows us to measure proper motions, jet widths and trajectories, and extinction along the jets. In all cases, we detect the counterjet, which was barely visible or invisible at shorter wavelengths. We measure tangential velocities of a few hundred kilometers per second, consistent with previous HST measurements over 10 years ago. We measure the jet width as close as a few tens of au from the star, revealing high collimations of about 2° for HH 1, HH 34, and HH 111 and about 8° for HH 46, all of which are preserved up to large distances. For HH 34, we find evidence of a larger initial opening angle of about 7°. Measurement of knot positions reveals deviations in trajectory of both the jet and counterjet of all sources. Analysis of asymmetries in the inner knot positions for HH 111 suggests the presence of a low mass stellar companion at separation 20-30 au. Finally, we find extinction values of 15-20 mag near the source, which gradually decrease moving downstream along the jet. These observations have allowed us to study the counterjet at unprecedentedly high angular resolution and will be a valuable reference for planning future JWST mid-infrared observations that will peer even closer into the jet engine.

Keywords: Jets, Stellar jets, Stellar winds, Young stellar objects, Star formation, Protostars
Detecting Neutrino Mass by Combining Matter Clustering, Halos, and Voids. We quantify the information content of the nonlinear matter power spectrum, the halo mass function, and the void size function, using the Quijote N-body simulations. We find that these three statistics exhibit very different degeneracies among the cosmological parameters, and thus the combination of all three probes enables the breaking of degeneracies, in turn yielding remarkably tight constraints. We perform a Fisher analysis using the full covariance matrix, including all auto- and cross correlations, finding that this increases the information content for neutrino mass compared to a correlation-free analysis. The multiplicative improvement of the constraints on the cosmological parameters obtained by combining all three probes compared to using the power spectrum alone are: 137, 5, 8, 20, 10, and 43, for Ωm, Ωb, h, ns, σ8, and Mν, respectively. The marginalized error on the sum of the neutrino masses is σ(Mν) = 0.018 eV for a cosmological volume of $1{\left({h}^{-1}\,\mathrm{Gpc}\right)}^{3}$ , using ${k}_{\max }=0.5\,h\,{\mathrm{Mpc}}^{-1}$ , and without cosmic microwave background (CMB) priors. We note that this error is an underestimate insomuch as we do not consider super-sample covariance, baryonic effects, and realistic survey noises and systematics. On the other hand, it is an overestimate insomuch as our cuts and binning are suboptimal due to restrictions imposed by the simulation resolution. Given upcoming galaxy surveys will observe volumes spanning $\sim 100{\left({h}^{-1}\,\mathrm{Gpc}\right)}^{3}$ , this presents a promising new avenue to measure neutrino mass without being restricted by the need for accurate knowledge of the optical depth, which is required for CMB-based measurements. Furthermore, the improved constraints on other cosmological parameters, notably Ωm, may also be competitive with CMB-based measurements.

Keywords: Galaxy dark matter halos, Large-scale structure of the universe, Cosmological parameters, Cosmological parameters from large-scale structure, Voids, Cosmological neutrinos, N-body simulations, Neutrino masses
The Stellar Mass in and around Isolated Central Galaxies: Connections to the Total Mass Distribution through Galaxy-Galaxy Lensing in the Hyper Suprime-Cam Survey. Using photometrically selected galaxies from the Hyper Suprime-Cam (HSC) survey, we measure the stellar-mass density profiles for satellite galaxies around isolated central galaxies (ICGs) from SDSS/DR7 at z ~ 0.1. By stacking HSC images, we also measure the projected stellar-mass density profiles for ICGs and their stellar halos. The total mass distributions are further measured from HSC weak-lensing signals. ICGs dominate within ~0.15 times the halo virial radius (0.15 R200). The stellar mass versus total mass fractions drop with the increase in projected distance up to ~0.15 R200, beyond which they are less than 1% while staying almost constant. The integrated stellar mass in satellites is proportional to the virial mass of the host halo, M200, for ICGs more massive than 1010.5M⊙, i.e., M*,sat ∝ M200, whereas the relation between the stellar mass of ICGs + stellar halos and M200 is close to ${M}_{* ,\mathrm{ICG}+\mathrm{diffuse}}\propto {M}_{200}^{1/2}$ . Below 1010.5M⊙, the change in M200 is much slower with the decrease in M*,ICG+diffuse. At fixed stellar mass, red ICGs are hosted by more massive dark matter halos and have more satellites. At M200 ~ 1012.7M⊙, both M*,sat and the fraction of stellar mass in satellites versus total stellar mass, fsat, tend to be marginally higher around blue ICGs. fsat increases with the increase in both M*,ICG+diffuse and M200, and scales more linearly with M200. We provide best-fitting relations to M200 versus M*,ICG+diffuse, M*,sat or M*,ICG+diffuse + M*,sat, and to fsat versus M200 or M*,ICG+diffuse, for red and blue ICGs separately.

Keywords: Galaxy dark matter halos, Galaxy mass distribution, Galaxy photometry, Galaxy evolution, Galaxy groups, Galaxy counts
A Near-infrared Survey of UV-excited Molecular Hydrogen in Photodissociation Regions. We present a comparative study of the near-infrared (NIR) H2 line emission from five regions near hot young stars: Sharpless 140, NGC 2023, IC 63, the Horsehead Nebula, and the Orion Bar. This emission originates in photodissociation or photon-dominated regions (PDRs), interfaces between photoionized and molecular gas near hot (O) stars or reflection nebulae illuminated by somewhat cooler (B) stars. In these environments, the dominant excitation mechanism for NIR emission lines originating from excited rotational-vibrational (rovibrational) levels of the ground electronic state is radiative or UV excitation (fluorescence), wherein absorption of far-UV photons pumps H2 molecules into excited electronic states from which they decay into the upper levels of the NIR lines. Our sources span a range of UV radiation fields (G0 = 102-105) and gas densities (nH = 104-106 cm-3), enabling examination of how these properties affect the emergent spectrum. We obtained high-resolution (R ≈ 45,000) spectra spanning 1.45-2.45 μm on the 2.7 m Harlan J. Smith Telescope at McDonald Observatory with the Immersion Grating INfrared Spectrometer (IGRINS), detecting up to over 170 transitions per source from excited vibrational states (v = 1-14). The populations of individual rovibrational levels derived from these data clearly confirm UV excitation. Among the five PDRs in our survey, the Orion Bar shows the greatest deviation of the populations and spectrum from pure UV excitation, while Sharpless 140 shows the least deviation. However, we find that all five PDRs exhibit at least some modification of the level populations relative to their values under pure UV excitation, a result we attribute to collisional effects.

Keywords: Interstellar molecules, Interstellar line emission, Molecular spectroscopy, Photodissociation regions, Near infrared astronomy
Two-dimensional Particle-in-cell Simulation of Magnetic Reconnection in the Downstream of a Quasi-perpendicular Shock. In this paper, by performing a two-dimensional particle-in-cell simulation, we investigate magnetic reconnection in the downstream of a quasi-perpendicular shock. The shock is nonstationary, and experiences cyclic reformation. At the beginning of the reformation process, the shock front is relatively flat, and part of the upstream ions are reflected by the shock front. The reflected ions move upward in the action of the Lorentz force, which leads to the upward bending of the magnetic field lines at the foot of the shock front, and then a current sheet is formed due to the squeezing of the bending magnetic field lines. The formed current sheet is brought toward the shock front by the solar wind, and the shock front becomes irregular after interacting with the current sheet. Both the current sheet carried by the solar wind and the current sheet associated with the shock front are then fragmented into many small filamentary current sheets. Electron-scale magnetic reconnection may occur in several of these filamentary current sheets when they are convected into the downstream, and magnetic islands are generated. A strong reconnection electric field and energy dissipation are also generated around the X line, and a high-speed electron outflow is also formed.

Keywords: Space plasmas, Planetary bow shocks, Solar magnetic reconnection, Plasma physics
An M Dwarf's Chromosphere, Corona, and Wind Connection via Nonlinear Alfvén Waves. An M dwarf's atmosphere is expected to be highly magnetized. The magnetic energy can be responsible for heating the stellar chromosphere and corona and driving the stellar wind. The nonlinear propagation of Alfvén waves is a promising mechanism for both heating the stellar atmosphere and driving the stellar wind. Based on this Alfvén wave scenario, we carried out a 1D compressive magnetohydrodynamic simulation to reproduce the stellar atmospheres and winds of TRAPPIST-1, Proxima Centauri, YZ CMi, AD Leo, AX Mic, and the Sun. The nonlinear propagation of Alfvén waves from the stellar photosphere to the chromosphere, corona, and interplanetary space is directly resolved in our study. The simulation result particularly shows that the slow shock generated through the nonlinear mode coupling of Alfvén waves is crucially involved in both the dynamics of the stellar chromosphere (stellar spicule) and stellar wind acceleration. Our parameter survey further revealed the following general trends of the physical quantities of the stellar atmosphere and wind. (1) The M dwarf coronae tend to be cooler and denser than the solar corona. (2) The M dwarf stellar winds can be characterized by a relatively faster velocity and much smaller mass-loss rate compared to those of the solar wind. The physical mechanisms behind these tendencies are clarified in this paper, where the stronger stratification of the M dwarf's atmosphere and relatively smaller Alfvén wave energy input from the M dwarf's photosphere are remarkable.

Keywords: M dwarf stars, Magnetohydrodynamics, Stellar chromospheres, Stellar winds, Alfven waves, Stellar coronae
Measurements of the Dust Properties in z ≃ 1-3 Submillimeter Galaxies with ALMA. We present Atacama Large Millimeter/submillimeter Array (ALMA) 2 mm continuum observations of a complete and unbiased sample of 99 870 μm selected submillimeter galaxies (SMGs) in the Extended Chandra Deep Field South (ALESS). Our observations of each SMG reach average sensitivities of 53 μJy beam-1. We measure the flux densities for 70 sources, for which we obtain a typical 870 μm-to-2 mm flux ratio of 14 ± 5. We do not find a redshift dependence of this flux ratio, which would be expected if the dust emission properties of our SMGs were the same at all redshifts. By combining our ALMA measurements with existing Herschel/SPIRE observations, we construct a (biased) subset of 27 galaxies for which the cool dust emission is sufficiently well sampled to obtain precise constraints on their dust properties using simple isothermal models. Thanks to our new 2 mm observations, the dust emissivity index is well constrained and robust against different dust opacity assumptions. The median dust emissivity index of our SMGs is β ≃ 1.9 ± 0.4, consistent with the emissivity index of dust in the Milky Way and other local and high-redshift galaxies, as well as classical dust-grain model predictions. We also find a negative correlation between the dust temperature and β, similar to low-redshift observational and theoretical studies. Our results indicate that β ≃ 2 in high-redshift dusty star-forming galaxies, implying little evolution in dust-grain properties between our SMGs and local dusty galaxy samples, and suggesting that these high-mass and high-metallicity galaxies have dust reservoirs driven by grain growth in their interstellar medium.

Keywords: Submillimeter astronomy, High-redshift galaxies, Interstellar medium
Spatially Resolving the Kinematics of the ≲100 μas Quasar Broad-line Region Using Spectroastrometry. II. The First Tentative Detection in a Luminous Quasar at z = 2.3. Direct measurements of the masses of supermassive black holes are key to understanding their growth and constraining their symbiotic relationship to their host galaxies. However, current methods used to directly measure black hole masses in active quasars become challenging or impossible beyond z ≳ 0.2. Spectroastrometry (SA) measures the spatial centroid of an object's spectrum as a function of wavelength, delivering angular resolution far better than the point-spread function (PSF) for high signal-to-noise ratio observations. We observed the luminous quasar SDSS J212329.47-005052.9 at z = 2.279 with the aim of resolving its ~100 μas Hα broad emission-line region (BLR) and present the first SA constraints on the size and kinematic structure of the BLR. Using a novel pipeline to extract the SA signal and reliable uncertainties, we achieved a centroiding precision of ≃100 μas, or &gt;2000× smaller than the K-band AO-corrected PSF, yielding a tentative 3.2σ detection of an SA signal from the BLR. Modeling the BLR emission as arising from an inclined rotating disk with a mixture of coherent and random motions we constrain ${r}_{\mathrm{BLR}}={454}_{-162}^{+565}\,\mu \mathrm{as}$ ( ${3.71}_{-1.28}^{+4.65}\,\mathrm{pc}$ ), providing a 95% confidence upper limit on the black hole mass ${M}_{\mathrm{BH}}\,{\sin }^{2}i\leqslant 1.8\times {10}^{9}\,{M}_{\odot }$ . Our results agree with the rBLR-L relation measured for lower-z quasars but expands its dynamic range by an order of magnitude in luminosity. We did not detect the potentially stronger SA signal from the narrow-line region but discuss in detail why it may be absent. Already with existing instrumentation, SA can deliver ~6× smaller uncertainties (~15 μas) than achieved here, enabling ~10% measurements of supermassive black hole masses in high-z quasars.

Keywords: Supermassive black holes, Quasars, Astronomical techniques, Active galactic nuclei, High angular resolution
On the Hard Gamma-Ray Spectrum of the Potential PeVatron Supernova Remnant G106.3 + 2.7. The Tibet ASγ experiment has measured a γ-ray flux of supernova remnant G106.3+2.7 of up to 100 TeV, suggesting it is potentially a "PeVatron." Challenges arise when the hadronic scenario requires a hard proton spectrum (with spectral index ≈1.8), while usual observations and numerical simulations prefer a soft proton spectrum (with spectral index ≥2). In this paper, we explore an alternative scenario to explain the γ-ray spectrum of G106.3+2.7 within the current understanding of acceleration and escape processes. We consider that cosmic ray particles are scattered by turbulence driven by Bell instabilities. The resulting hadronic γ-ray spectrum is novel, dominating the contribution to the emission above 10 TeV, and can explain the bizarre broadband spectrum of G106.3+2.7 in combination with leptonic emission from the remnant.

Keywords: Supernova remnants, Cosmic ray sources
Relation of Cyclotron Resonant Energy and Luminosity in a Strongly Magnetized Neutron Star GRO J1008-57 Observed by Insight-HXMT. Cyclotron line scattering features are detected in a few tens of X-ray pulsars (XRPs) and used as direct indicators of a strong magnetic field at the surface of accreting neutron stars (NSs). In a few cases, cyclotron lines are known to be variable with the accretion luminosity of XRPs. It is accepted that the observed variations of cyclotron line scattering features are related to variations of geometry and dynamics of accretion flow above the magnetic poles of an NS. A positive correlation between the line centroid energy and luminosity is typical for subcritical XRPs, where the accretion results in hot spots at the magnetic poles. The negative correlation was proposed to be a specific feature of bright supercritical XRPs, where radiation pressure supports accretion columns above the stellar surface. The cyclotron line in the spectra of the Be-transient XRP GRO J1008-57 is detected at energies from ~75 to 90 keV, the highest observed energy of a cyclotron line feature in XRPs. We report the peculiar relation of cyclotron line centroid energies with luminosity in GRO J1008-57 during the Type II outburst in 2017 August observed by Insight-HXMT. The cyclotron line energy was detected to be negatively correlated with the luminosity at 3.2 × 1037 erg s-1 &lt; L &lt; 4.2 × 1037 erg s-1 and positively correlated at L ≳ 5 × 1037 erg s-1. We speculate that the observed peculiar behavior of a cyclotron line would be due to variations of accretion channel geometry.

Keywords: Neutron stars, X-ray binary stars
The Formation Process of the First Halo Coronal Mass Ejection in Solar Cycle 25: Magnetic Cancellation, Bidirectional Jet, and Hot Channel. To better understand the trigger mechanism of a coronal mass ejection (CME), we present the evolution of a CME source region (active region NOAA 12790) and the formation of a hot channel before the occurrence of the first halo CME in solar cycle 25. Through analyzing the evolution of Solar Dynamics Observatory/Helioseismic and Magnetic Imager line-of-sight magnetograms, it is found that continuous magnetic cancellation occurs at the polarity inversion line (PIL) in this active region. With ongoing magnetic cancellation, several bidirectional jets and unidirectional jets occur along the large-scale arched magnetic loops. A hot channel forms during the first bidirectional jet. After the occurrence of the fourth bidirectional jet, the hot channel immediately erupts and produces a C-class flare, a cusp structure, and a halo CME. It is worth pointing out that the cusp structure only appears in the 131 Å and 94 Å observations (temperature about 10 MK). The obvious contraction of the newly formed loops is observed at the top of the cusp structure. The observations reveal a clear physics process: magnetic cancellation of a bipolar magnetic field at the PIL results in the occurrence of the bidirectional/unidirectional jets and the formation of the hot channel. The axial magnetic flux feeding for the hot channel through the continued magnetic cancellation leads to the hot channel eruption, which results in the formation of the hot cusp structure and the occurrence of the C-class flare and the halo CME.

Keywords: Jets, Solar magnetic reconnection, Solar photosphere, Solar coronal mass ejections, Solar filament eruptions, Solar activity, Magnetic fields
On the Three-dimensional Structure of Local Molecular Clouds. We leverage the 1 pc spatial resolution of the Leike et al. three-dimensional (3D) dust map to characterize the 3D structure of nearby molecular clouds (d ≲ 400 pc). We start by "skeletonizing" the clouds in 3D volume density space to determine their "spines," which we project on the sky to constrain cloud distances with ≈1% uncertainty. For each cloud, we determine an average radial volume density profile around its 3D spine and fit the profiles using Gaussian and Plummer functions. The radial volume density profiles are well described by a two-component Gaussian function, consistent with clouds having broad, lower-density outer envelopes and narrow, higher-density inner layers. The ratio of the outer to inner envelope widths is ≈3:1. We hypothesize that these two components may be tracing a transition between atomic and diffuse molecular gas or between the unstable and cold neutral medium. Plummer-like models can also provide a good fit, with molecular clouds exhibiting shallow power-law wings with density, n, falling off like n-2 at large radii. Using Bayesian model selection, we find that parameterizing the clouds' profiles using a single Gaussian is disfavored. We compare our results with two-dimensional dust extinction maps, finding that the 3D dust recovers the total cloud mass from integrated approaches with fidelity, deviating only at higher levels of extinction (AV ≳ 2-3 mag). The 3D cloud structure described here will enable comparisons with synthetic clouds generated in simulations, offering unprecedented insight into the origins and fates of molecular clouds in the interstellar medium.

Keywords: Interstellar reddening, Solar neighborhood, Astronomy data visualization, Molecular clouds