Sazuna/UAT_keywords huggingface dataset:
The Nature of the IMBH Candidate CXO J133815.6+043255: High-frequency Radio Emission. The ultraluminous X-ray source CXO J133815.6+043255 is a strong candidate for a bona fide intermediate-mass black hole residing in the outskirts of NGC 5252. We present 22 GHz radio observations of this source obtained serendipitously in an ongoing high-frequency imaging survey of radio-quiet Active Galactic Nuclei (AGNs), and use this new data point to construct the broadband radio spectral energy distribution (SED). We find that the SED exhibits a spectral slope of α = -0.66 ± 0.02, consistent with a steep spectrum from optically thin synchrotron emission from an unresolved jet. We also find that the L R/L X ratio is approximately 10-3, inconsistent with radio-quiet AGN and many ULXs but consistent with low-luminosity AGN and radio-loud quasars. Together, these observations support the conclusion that CXO J133815.6+043255 is an intermediate-mass black hole producing a low-mass analog of radio jets seen in classical quasars.

Keywords: Intermediate-mass black holes, Active galactic nuclei, Black holes
Forming Gas Giants around a Range of Protostellar M-dwarfs by Gas Disk Gravitational Instability. Recent discoveries of gas giant exoplanets around M-dwarfs from transiting and radial velocity surveys are difficult to explain with core-accretion models. We present here a homogeneous suite of 162 models of gravitationally unstable gaseous disks. These models represent an existence proof for gas giants more massive than 0.1 Jupiter masses to form by the gas disk gravitational instability (GDGI) mechanism around M-dwarfs for comparison with observed exoplanet demographics and protoplanetary disk mass estimates for M-dwarf stars. We use the Enzo 2.6 adaptive mesh refinement (AMR) 3D hydrodynamics code to follow the formation and initial orbital evolution of gas giant protoplanets in gravitationally unstable gaseous disks in orbit around M-dwarfs with stellar masses ranging from 0.1 M ⊙ to 0.5 M ⊙. The gas disk masses are varied over a range from disks that are too low in mass to form gas giants rapidly to those where numerous gas giants are formed, therefore revealing the critical disk mass necessary for gas giants to form by the GDGI mechanism around M-dwarfs. The disk masses vary from 0.01 M ⊙ to 0.05 M ⊙ while the disk to star mass ratios explored the range from 0.04 to 0.3. The models have varied initial outer disk temperatures (10-60 K) and varied levels of AMR grid spatial resolution, producing a sample of expected gas giant protoplanets for each star mass. Broadly speaking, disk masses of at least 0.02 M ⊙ are needed for the GDGI mechanism to form gas giant protoplanets around M-dwarfs.

Keywords: Gravitational instability, Protoplanetary disks, Extrasolar gaseous giant planets
Observations of Locally Generated Whistler-mode Waves in the Martian Magnetotail Current Sheet. The whistler-mode wave is an electromagnetic wave that commonly occurs in space plasma and has been extensively studied, especially within the Earth's magnetosphere. They have also been reported in the near-Mars space, such as Martian upstream solar wind, crustal magnetic field, ionopause, and the magnetic reconnection ion diffusion region. However, the generation of whistler-mode waves in the Martian magnetotail current sheet is still unclear. Based on observations made by Mars Atmosphere and Volatile Evolution spacecraft, we report whistler-mode waves observed within a train of proton-scale magnetic dips during a Martian magnetotail current sheet crossing. The linear growth rate analyses demonstrate that the whistler-mode waves are locally generated within the magnetic dips. Unlike in Earth's plasma environment, the train of magnetic dips in the Martian plasma sheet is attributed to electron mirror-mode instability. Our finding suggests that the mirror-mode structure in the Martian magnetotail can be an important source region for generating whistler-mode waves. This provides a new insight into how whistler-mode waves are generated in unmagnetized planets.

Keywords: Mars, Solar system terrestrial planets
ELVES. IV. The Satellite Stellar-to-halo Mass Relation Beyond the Milky Way. Quantifying the connection between galaxies and their host dark matter halos has been key for testing cosmological models on various scales. Below M ⋆ ~ 109 M ⊙, such studies have primarily relied on the satellite galaxy population orbiting the Milky Way (MW). Here we present new constraints on the connection between satellite galaxies and their host dark matter subhalos using the largest sample of satellite galaxies in the Local Volume (D ≲ 12 Mpc) to date. We use 250 confirmed and 71 candidate dwarf satellites around 27 MW-like hosts from the Exploration of Local VolumE Satellites (ELVES) Survey and use the semianalytical SatGen model for predicting the population of dark matter subhalos expected in the same volume. Through a Bayesian model comparison of the observed and the forward-modeled satellite stellar mass functions (SSMFs), we infer the satellite stellar-to-halo mass relation. We find that the observed SSMF is best reproduced when subhalos at the low-mass end are populated by a relation of the form ${M}_{\star }\propto {M}_{\mathrm{peak}}^{\alpha }$ , with a moderate slope of ${\alpha }_{\mathrm{const}}=2.10\pm 0.01$ and a low scatter, constant as a function of the peak halo mass, of ${\sigma }_{\mathrm{const}}={0.06}_{-0.05}^{+0.07}$ . A model with a steeper slope (α grow = 2.39 ± 0.06) and a scatter that grows with decreasing M peak is also consistent with the observed SSMF but is not required. Our new model for the satellite-subhalo connection, based on hundreds of Local Volume satellite galaxies, is in line with what was previously derived using only MW satellites.

Keywords: Observational astronomy, Bayesian statistics, Surveys, Dwarf galaxies, Observational cosmology, Scaling relations, Galaxy groups, Dark matter
Meteoritic Molybdenum and Ruthenium Isotopic Abundances Document Nucleosynthetic p-process Components. Anomalies in isotopic abundances of Mo and Ru in solar system matter were found to document variable contributions of the nucleosynthetic s-process component. We report isotopic relations of ϵ 92Mo versus ϵ 100Ru in meteorites from chondritic parent bodies, iron meteorites, and achondrites that reveal deviations from expected s-process abundance variations. We show that two p-process isotopes 92Mo and 94Mo require the presence of distinct p-process components in meteoritic materials. The nucleosynthetic origin of abundant magic (N = 50) p-process nuclides, covering the mass range of Zr, Mo, and Ru, has long been an enigma, but contributions by several recognized pathways, including alpha and νp-antineutrino reactions on protons, may account for the observed relatively large solar system abundances. Specific core-collapse supernovae explosive regions may carry proton-rich matter. Since Mo and Ru isotopic records in solar system matter reveal the presence of more than one nucleosynthetic p-process component, these records are expected to be helpful in documenting different explosive synthesis pathways and the implied galactic evolution of p-nuclides.

Keywords: Meteorites, Isotopic abundances, Nucleosynthesis
High-energy Neutrinos from the Inner Circumnuclear Region of NGC 1068. High-energy neutrinos are detected by the IceCube Observatory in the direction of NGC 1068, the archetypical type II Seyfert galaxy. The neutrino flux, surprisingly, is more than an order of magnitude higher than the γ-ray upper limits at measured TeV energy, posing tight constraints on the physical conditions of a neutrino production site. We report an analysis of the submillimeter, mid-infrared, and ultraviolet observations of the central 50 pc of NGC 1068 and suggest that the inner dusty torus and the region where the jet interacts with the surrounding interstellar medium (ISM) may be a potential neutrino production site. Based on radiation and magnetic field properties derived from observations, we calculate the electromagnetic cascade of the γ-rays accompanying the neutrinos. When injecting protons with a hard spectrum, our model may explain the observed neutrino flux above ~10 TeV. It predicts a unique sub-TeV γ-ray component, which could be identified by a future observation. Jet-ISM interactions are commonly observed in the proximity of jets of both supermassive and stellar-mass black holes. Our results imply that such interaction regions could be γ-ray-obscured neutrino production sites, which are needed to explain the IceCube diffuse neutrino flux.

Keywords: Radio hot spots, Gamma-ray sources, Seyfert galaxies, High-energy cosmic radiation
Grain Growth and Dust Segregation Revealed by Multiwavelength Analysis of the Class I Protostellar Disk WL 17. The first step toward planet formation is grain growth from (sub)micrometer to millimeter/centimeter sizes. Grain growth has been reported not only in Class II protoplanetary disks but also in Class 0/I protostellar envelopes. However, early-stage grain growth occurring in Class 0/I stages has rarely been observed on the protostellar disk scale. Here we present the results from the Atacama Large Millimeter/submillimeter Array Band 3 (λ = 3.1 mm) and 7 (λ = 0.87 mm) archival data of the Class I protostellar disk WL 17 in the ρ Ophiuchus molecular cloud. Disk substructures are found in both bands, but they are different: while a central hole and a symmetric ring appear in Band 3, an off-center hole and an asymmetric ring are shown in Band 7. Furthermore, we obtain an asymmetric spectral index map with a low mean value of α = 2.28 ± 0.02, suggestive of grain growth and dust segregation on the protostellar disk scale. Our radiative transfer modeling verifies these two features by demonstrating that 10 cm sized large grains are symmetrically distributed, whereas 10 μm sized small grains are asymmetrically distributed. In addition, the analysis shows that the disk is expected to be massive and gravitationally unstable. We thus suggest a single Jupiter-mass protoplanet formed by gravitational instability as the origin of the ring-like structure, grain growth, and dust segregation identified in WL 17.

Keywords: Protostars, Circumstellar dust, Circumstellar grains, Circumstellar disks
3HWC J0631+107/LHAASO J0631+1040: A TeV Halo Powered by the Pulsar J0631+1036?. PSR J0631+1036 is a middle-aged pulsar with properties similar to those of the nearby Geminga pulsar. It is bright in γ-rays, and has been noted as the only source possibly associated with the TeV source 3HWC J0631+107 (also the LHAASO J0631+1040). For understanding the nature of the TeV source, we analyze the GeV γ-ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope for the source region. We are able to remove the pulsar's emission from the region from timing analysis, and find that the region is rather clean without possible GeV γ-ray emission present as the counterpart to the TeV source. By comparing this pulsar to Geminga and considering the spectral feature of the TeV source, we argue that it is likely the TeV halo powered by the pulsar.

Keywords: Gamma-rays, Pulsars
JWST/NIRSpec Measurements of Extremely Low Metallicities in High Equivalent Width Lyα Emitters. Deep Very Large Telescope/MUSE optical integral field spectroscopy has recently revealed an abundant population of ultra-faint galaxies (M UV ≈ -15; 0.01 L ⋆) at z = 2.9-6.7 due to their strong Lyα emission with no detectable continuum. The implied Lyα equivalent widths can be in excess of 100-200 Å, challenging existing models of normal star formation and indicating extremely young ages, small stellar masses, and a very low amount of metal enrichment. We use JWST/NIRSpec's microshutter array to follow up 45 of these galaxies (11 hr in G235M/F170LP and 7 hr in G395M/F290LP), as well as 45 lower-equivalent width Lyα emitters. Our spectroscopy covers the range 1.7-5.1 micron in order to target strong optical emission lines: Hα, [O III], Hβ, and [N II]. Individual measurements as well as stacks reveal line ratios consistent with a metal-poor nature (2%-40% Z ⊙, depending on the calibration). The galaxies with the highest equivalent widths of Lyα, in excess of 90 Å, have lower [N II]/Hα (1.9σ) and [O III]/Hβ (2.2σ) ratios than those with lower equivalent widths, implying lower gas-phase metallicities at a combined significance of 2.4σ. This implies a selection based on Lyα equivalent width is an efficient technique for identifying younger, less chemically enriched systems.

Keywords: Galaxy abundances, High-redshift galaxies, Galaxy evolution, Galaxy chemical evolution
Hybrid Emission Modeling of GRB 221009A: Shedding Light on TeV Emission Origins in Long GRBs. Observations of long-duration gamma-ray bursts (GRBs) with TeV emission during their afterglow have been on the rise. Recently, GRB 221009A, the most energetic GRB ever observed, was detected by the Large High Altitude Air Shower Observatory experiment in the energy band 0.2-7 TeV. Here, we interpret its afterglow in the context of a hybrid model in which the TeV spectral component is explained by the proton-synchrotron process while the low-energy emission from optical to X-ray is due to synchrotron radiation from electrons. We constrained the model parameters using the observed optical, X-ray, and TeV data. By comparing the parameters of this burst and of GRB 190114C, we deduce that the VHE emission at energies ≥1 TeV in the GRB afterglow requires large explosion kinetic energy, E ≳ 1054 erg and a reasonable circumburst density, n ≳ 10 cm-3. This results in a small injection fraction of particles accelerated to a power law, ~10-2. A significant fraction of shock energy must be allocated to a near equipartition magnetic field, ϵ  B  ~ 10-1, while electrons should only carry a small fraction of this energy, ϵ  e  ~ 10-3. Under these conditions required for a proton-synchrotron model, namely ϵ  B  ≫ ϵ  e , the SSC component is substantially subdominant over proton-synchrotron as a source of TeV photons. These results lead us to suggest that proton-synchrotron process is a strong contender for the radiative mechanisms explaining GRB afterglows in the TeV band.

Keywords: Gamma-ray bursts, Gamma-ray transient sources, High energy astrophysics
Exploring Asymmetric Substructures of the Outer Disk Based on the Conjugate Angle of the Radial Action. We use the conjugate angle of radial action (θ  R ), the best representation of the orbital phase, to explore the "midplane," "north branch," "south branch," and "Monoceros area" disk structures that were previously revealed in the LAMOST K giants. The former three substructures, identified by their 3D kinematical distributions, have been shown to be projections of the phase space spiral (resulting from nonequilibrium phase mixing). In this work, we find that all of these substructures associated with the phase spiral show high aggregation in conjugate angle phase space, indicating that the clumping in conjugate angle space is a feature of ongoing, incomplete phase mixing. We do not find the Z-V  Z  phase spiral located in the "Monoceros area," but we do find a very highly concentrated substructure in the quadrant of conjugate angle space with the orbital phase from the apocenter to the guiding radius. The existence of the clump in conjugate angle space provides a complementary way to connect the "Monoceros area" with the direct response to a perturbation from a significant gravitationally interactive event. Using test particle simulations, we show that these features are analogous to disturbances caused by the impact of the last passage of the Sagittarius dwarf spheroidal galaxy.

Keywords: Galaxy anticenters, Galaxy kinematics
Toward Robust Detections of Nanohertz Gravitational Waves. The recent observation of a common red-noise process in pulsar timing arrays (PTAs) suggests that the detection of nanohertz gravitational waves might be around the corner. However, in order to confidently attribute this red process to gravitational waves, one must observe the Hellings-Downs curve-the telltale angular correlation function associated with a gravitational-wave background. This effort is complicated by the complex modeling of pulsar noise. Without proper care, misspecified noise models can lead to false-positive detections. Background estimation using "quasi-resampling" methods such as sky scrambles and phase shifts, which use the data to characterize the noise, are therefore important tools for assessing significance. We investigate the ability of current PTA experiments to estimate their background with "quasi-independent" scrambles-characterized by a statistical "match" below the fiducial value: ∣M∣ &lt; 0.1. We show that sky scrambling is affected by "saturation" after ${ \mathcal O }(10)$ quasi-independent realizations; subsequent scrambles are no longer quasi-independent. We show that phase scrambling saturates after ${ \mathcal O }(100)$ quasi-independent realizations. With so few independent scrambles, it is difficult to make reliable statements about the ≳5σ tail of the null distribution of the detection statistic. We sketch out various methods by which one may increase the number of independent scrambles. We also consider an alternative approach, wherein one reframes the background estimation problem so that the significance is calculated using statistically dependent scrambles. The resulting p-value is in principle well defined, but may be susceptible to failure if assumptions about the data are incorrect.

Keywords: Gravitational waves, Astronomy data analysis, Millisecond pulsars
Carbon Stars as Standard Candles: An Empirical Test for the Reddening, Metallicity, and Age Sensitivity of the J-region Asymptotic Giant Branch (JAGB) Method. The J-region Asymptotic Giant Branch (JAGB) method is a standard candle based on the intrinsic luminosities of carbon stars in the near-infrared. We directly constrain the impact of metallicity, age, and reddening on the JAGB method. We assess how the mode, skew, and spread of the JAGB star LF change throughout diverse stellar environments in M31's NE disk from 13 &lt; d &lt; 18 kpc using data from the Panchromatic Hubble Andromeda Treasury (PHAT). As expected, the mode is found to be fainter in higher-reddening regions. To cross-check this result, we also measure a fiducial J-band ground-based JAGB distance using data from the UKIRT/WFCam in M31's outermost disk (18 &lt; d &lt; 40 kpc) where internal reddening is minimal. We find that this J-band distance modulus agrees well with the F110W distance moduli measured in the lowest-reddening regions of the PHAT data, demonstrating the JAGB method is most accurate if measured in the low-reddening outer disks of galaxies. On the other hand, the mode of the JAGB star LF appears empirically to show no dependence on age or metallicity within the range -0.18 &lt; [M/H] &lt; -0.26 dex. In conclusion, the JAGB method proves to be a robust standard candle capable of calibrating the luminosities of Type Ia supernovae and therefore providing a high-accuracy, high-precision measurement of the Hubble constant.

Keywords: Galaxy distances, Carbon stars, Observational cosmology, Distance indicators, Asymptotic giant branch stars, Andromeda Galaxy
Interaction of Inner Heliosheath Ions with Electromagnetic Ion Cyclotron Waves. Inner heliosheath (IHS) ions are expected to be exposed to various waves, shocks, and turbulence, which can affect ion distributions and thus their charge-exchange rates with interstellar neutral atoms. This work addresses the potential significance of electromagnetic ion cyclotron (EMIC) waves under expected IHS conditions. From a kinetic dispersion relation, we find the possibility of frequent triggering of EMIC instability in the IHS. The threshold anisotropy of proton temperatures required for the instability is small, (T ⊥-T ∣∣)/T ∣∣ ≈ 0.1 or less, mainly due to high plasma β (ratio of the plasma to magnetic pressures). Numerical calculations on the scattering of ions (protons, He+, and He2+ with energy of 0.01-50 keV) based on two models for EMIC waves with a moderate intensity indicate significant scattering in the pitch angle (mostly a few tens of degrees) and energy (mostly a few tens of percent) although details depend on the energy and pitch angle of each species and adopted EMIC wave models. This occurs on a short timescale (&lt;100 times the gyro-period of each ion species). Resonant scattering in a few to a few tens of keV (corresponding to the expected pickup ion energy in the IHS) is easily expected unless the wavenumber is too large. The scattering effect is distinguished among different species such that for lower gyrofrequency ions (He+ versus He2+and He2+ versus protons), the main scattering effect moves toward a lower energy domain. All these results imply continuous disturbance of ion distributions by possibly prevailing EMIC waves in the IHS.

Keywords: Heliosheath, Solar wind, Termination shock
Resonant Excitation of Planetary Eccentricity due to a Dispersing Eccentric Protoplanetary Disk: A New Mechanism of Generating Large Planetary Eccentricities. We present a new mechanism of generating large planetary eccentricities. This mechanism applies to planets within the inner cavities of their companion protoplanetary disks. A massive disk with an inner truncation may become eccentric due to nonadiabatic effects associated with gas cooling and can retain its eccentricity in long-lived coherently precessing eccentric modes; as the disk disperses, the inner planet will encounter a secular resonance with the eccentric disk when the planet and the disk have the same apsidal precession rates; the eccentricity of the planet is then excited to a large value as the system goes through the resonance. In this work, we solve the eccentric modes of a model disk for a wide range of masses. We then adopt an approximate secular dynamics model to calculate the long-term evolution of the "planet + dispersing disk" system. The planet attains a large eccentricity (between 0.1 and 0.6) in our calculations even though the disk eccentricity is quite small (≲0.05). This eccentricity excitation can be understood in terms of the mode conversion ("avoided crossing" between two eigenstates) phenomenon associated with the evolution of the "planet + disk" eccentricity eigenstates.

Keywords: Exoplanet dynamics, Celestial mechanics, Protoplanetary disks, Hydrodynamics
Experimental Study of the Response of Sheared E × B Flow to Varying Ion-Neutral Collisions. Partially ionized plasma is a common occurrence in astrophysical and space environments. The emergence and development of plasma instabilities are significantly impacted by the inelastic collisions between the ions and neutrals in the partially ionized plasma, such as the charge exchange. In this study, the effect of the ion-neutral collisions on the sheared E × B flow was experimentally investigated. In the weak collision range, the shear-driven plasma instability, such as Kelvin-Helmholtz instability, was excited by the velocity-sheared flow. However, increasing ion-neutral collisions resulted in a decrease in the magnitude of the sheared E × B flow due to charge exchange-induced drag forces. Consequently, the Kelvin-Helmholtz instability is suppressed, and the Rayleigh-Taylor instability is triggered. The underlying mechanism was elucidated through experimental findings and numerical analysis. The result of this study proposes that a transition between the two modes occurred with increasing ion-neutral collision strength. It could be applied to the study of the solar chromosphere and prominence and planetary ionospheres, where plasma is partially ionized and the sheared E × B flow is often encountered.

Keywords: Solar atmosphere, Laboratory astrophysics, Planetary ionospheres, Earth ionosphere