Sazuna/UAT_keywords huggingface dataset:
Parallel Electron Heating through Landau Resonance with Lower Hybrid Waves at the Edge of Reconnection Ion Jets. We investigate lower hybrid waves in magnetic reconnection at the flank magnetopause using Magnetospheric Multiscale data. Intense emissions of lower hybrid waves are observed at the density boundary of the reconnection ion jet. Associated with the lower hybrid waves, electrons exhibit signatures of heating in the direction parallel to the magnetic field. Near the Landau resonance energy, the electron fluxes parallel to the magnetic field show oscillations at the same frequency as the lower hybrid waves. The electron flux oscillations are in phase or antiphase with the wave parallel electric field. These observations provide direct evidence for Landau resonance. Our analysis indicates that the density gradient at the edge of the ion jets provides free energy for the lower hybrid waves that further contribute to electron heating through Landau damping. These results shed light on the role of wave-particle interactions in the energy conversion chain of reconnection ion jets.

Keywords: Planetary magnetospheres, Solar magnetic reconnection
Machine Learning Classification to Identify Catastrophic Outlier Photometric Redshift Estimates. We present results of using a basic binary classification neural network model to identify likely catastrophic outlier photometric redshift estimates of individual galaxies, based only on the galaxies' measured photometric band magnitude values. We find that a simple implementation of this classification can identify a significant fraction of galaxies with catastrophic outlier photometric redshift estimates while falsely categorizing only a much smaller fraction of non-outliers. These methods have the potential to reduce the errors introduced into science analyses by catastrophic outlier photometric redshift estimates.

Keywords: Astrostatistics techniques, Redshift surveys, Neural networks
Density Profile of the Ambient Circumnuclear Medium in Seyfert 1 Galaxies. The shape of the ambient circumnuclear medium (ACM) density profile can probe the history of accretion onto the central supermassive black holes in galaxies and the circumnuclear environment. However, due to the limitations of instrument resolution, the density profiles of the ACM for most galaxies remain largely unknown. In this work, we propose a novel method to measure the ACM density profile of active galactic nuclei (AGNs) by the equilibrium between the radiation pressure on the warm absorbers (WAs, a type of AGN outflow) and the drag pressure from the ACM. We study the correlation between the outflow velocity and ionization parameter of WAs in each of the five Seyfert 1 galaxies (NGC 3227, NGC 3783, NGC 4051, NGC 4593, and NGC 5548), inferring that the density profile of the ACM is between n ∝ r -1.7 and n ∝ r -2.15 (n is number density and r is distance) from 0.01 pc to parsec scales in these five AGNs. Our results indicate that the ACM density profile in Seyfert 1 galaxies is steeper than the prediction by the spherically symmetric Bondi accretion model and the simulated results of the hot accretion flow, but more in line with the prediction by the standard thin-disk model.

Keywords: Accretion, Galaxy nuclei, Seyfert galaxies, Active galactic nuclei, Interstellar medium
New Time-resolved, Multi-band Flares in the GJ 65 System with gPhoton. Characterizing the distribution of flare properties and occurrence rates is important for understanding habitability of M-dwarf exoplanets. The Galaxy Evolution Explorer (GALEX) space telescope observed the GJ 65 system, composed of the active, flaring M stars BL Cet and UV Cet, for 15,900 s (~4.4 hr) in two ultraviolet (UV) bands. The contrast in flux between flares and the photospheres of cool stars is maximized at UV wavelengths, and GJ 65 is the brightest and nearest flaring M-dwarf system with significant GALEX coverage. It therefore represents the best opportunity to measure low-energy flares with GALEX. We construct high-cadence lightcurves from calibrated photon events and find 13 new flare events with near-UV (NUV) energies ranging from 1028.5-1029.5 erg and recover one previously reported flare with an energy of 1031 erg. The newly reported flares are among the smallest M-dwarf flares observed in the UV with sufficient time resolution to discern lightcurve morphology. The estimated flare frequency at these low energies is consistent with extrapolation from the distributions of higher-energy flares on active M dwarfs measured by other surveys. The largest flare in our sample is bright enough to exceed the local nonlinearity threshold of the GALEX detectors, which precludes color analysis. However, we detect quasi-periodic pulsations during this flare in both the far-UV and NUV bands at a period of ~50 s, which we interpret as a modulation of the flare's chromospheric thermal emission through periodic triggering of reconnection by external MHD oscillations in the corona.

Keywords: M dwarf stars, Stellar flares, Near ultraviolet astronomy, Flare stars
Constraining the Cosmic Baryon Distribution with Fast Radio Burst Foreground Mapping. The dispersion measure of fast radio bursts (FRBs) encodes the integrated electron density along the line of sight, which is typically dominated by the intergalactic medium contribution in the case of extragalactic FRBs. In this paper, we show that incorporating wide-field spectroscopic galaxy survey data in the foreground of localized FRBs can significantly improve constraints on the partition of diffuse cosmic baryons. Using mock dispersion measures and realistic light-cone galaxy catalogs derived from the Millennium simulation, we define spectroscopic surveys that can be carried out with 4 and 8 m class wide-field spectroscopic facilities. On these simulated surveys, we carry out Bayesian density reconstructions in order to estimate the foreground matter density field. In comparison with the "true" matter density field, we show that these can help reduce the uncertainties in the foreground structures by ~2-3× compared to cosmic variance. We calculate the Fisher matrix to forecast that N = 30 (96) localized FRBs should be able to constrain the diffuse cosmic baryon fraction to ~10% (~5%) and parameters governing the size and baryon fraction of galaxy circumgalactic halos to within ~20%-25% (~8%-12%). From the Fisher analysis, we show that the foreground data increase the sensitivity of localized FRBs toward our parameters of interest by ~25×. We briefly introduce FLIMFLAM, an ongoing galaxy redshift survey that aims to obtain foreground data on ~30 localized FRB fields.

Keywords: Missing mass, Intergalactic gas, Cosmic web, Circumgalactic medium, Redshift surveys
Constructing the Emission-line Galaxy-Host Halo Connection through Auto and Cross Correlations. We investigate the [O II] emission-line galaxy (ELG)-host halo connection via auto and cross correlations, and propose a concise and effective method to populate ELGs in dark matter halos without assuming a parameterized halo occupation distribution (HOD) model. Using the observational data from VIMOS Public Extragalactic Redshift Survey, we measure the auto and cross correlation functions between ELGs selected by [O II] luminosity and normal galaxies selected by stellar mass. Combining the stellar-halo mass relation derived for the normal galaxies and the fraction of ELGs observed in the normal galaxy population, we demonstrate that we can establish an accurate ELG-halo connection. With the ELG-halo connection, we can accurately reproduce the auto and cross correlation functions of ELGs and normal galaxies both in real space and in redshift space, once the satellite fraction is properly reduced. Our method provides a novel strategy to generate ELG mock catalogs for ongoing and upcoming galaxy redshift surveys. We also provide a simple description for the HOD of ELGs.

Keywords: Galaxy dark matter halos, Observational cosmology, Emission line galaxies, Redshift surveys, Dark energy
Insight-HXMT, NuSTAR, and INTEGRAL Data Show Disk Truncation in the Hard State of the Black Hole X-Ray Binary MAXI J1820+070. We study X-ray and soft gamma-ray spectra from the hard state of the accreting black hole binary MAXI J1820+070. We perform an analysis of joint spectra from HXMT, NuSTAR, and INTEGRAL. We find an overall agreement between the spectra from all three satellites. Satisfactory fits to the data require substantial spectral complexity, with our models including two Comptonization regions and their associated disk reflection, a disk blackbody, and a narrow Fe Kα line. Our fits confirm the presence of the truncation of the reflecting optically thick disk at least at &gt;10 gravitational radii. However, we find that the HXMT data alone cannot significantly constrain the disk inner radii.

Keywords: Low-mass x-ray binary stars, X-ray binary stars, Non-thermal radiation sources, Galaxy accretion
The Contribution of M-dwarf Flares to the Thermal Escape of Potentially Habitable Planet Atmospheres. The habitability of planets around M dwarfs (≲0.5 M ⊙) can be affected by the X-rays + extreme UV (XUV) emission of these stars, with flares occasionally increasing the XUV flux by more than 2 orders of magnitude above quiescent levels. This wavelength range can warm and ionize terrestrial planets' upper atmospheres, which expands the planetary radius and promotes atmospheric loss. In this work, we study the contribution of the XUV flux due to flares on the atmospheric escape of Earth-like planets orbiting M dwarfs through numerical simulations. We considered the first Gyr of planets with initial surface water abundances between 1 and 10 terrestrial oceans (TO), a small primordial hydrogen envelope (≤10-3 M ⊕), and with host-star masses between 0.2 and 0.6 M ⊙. In this parameter range, we find that flares can remove up to two TO more than nonflaring stars, which, in some cases, translates to a doubling of the total water loss. We also find that flaring can increase atmospheric oxygen partial pressures by hundreds of bars in some cases. These results were obtained by adding a new module for flares to the VPLanet software package and upgrading its atmospheric escape module to account for Roche lobe overflow and radiation/recombination-limited escape.

Keywords: Star-planet interactions, Habitable planets, Stellar flares, Exoplanet atmospheres
Detectability of Black Hole Binaries with Gaia: Dependence on Binary Evolution Models. The astrometric satellite Gaia is expected to observe noninteracting black hole (BH) binaries with luminous companions (LCs; hereafter BH-LC binaries), a different population from BH X-ray binaries previously discovered. The detectability of BH-LC binaries with Gaia might be dependent on binary evolution models. We investigated the Gaia's detectability of BH-LC binaries formed through isolated binary evolution by means of the binary population synthesis technique and examined its dependence on single and binary star models: supernova models, common envelope (CE) ejection efficiency α, and BH natal kick models. We estimated that 1.1-46 BH-LC binaries can be detected within the five-year observation, and found that α has the largest impact on the detectable number. In each model, observable and intrinsic BH-LC binaries have similar distributions. Therefore, we found three important implications: (1) if the lower BH mass gap is not intrinsic (i.e., 3-5 M ⊙ BHs exist), Gaia will observe ≤5 M ⊙ BHs; (2) we may observe short orbital period binaries with light LCs if CE efficiency is significantly high; and (3) we may be able to identify the existence of natal kick from eccentricity distribution.

Keywords: Astrometry, Binary stars, Stellar mass black holes
Hot Extended Galaxy Halos around Local L* Galaxies from Sunyaev-Zeldovich Measurements. Most of the baryons in L* galaxies are unaccounted for and are predicted to lie in hot gaseous halos (T ~ 106.5 K) that may extend beyond R 200. A hot gaseous halo will produce a thermal Sunyaev-Zeldovich signal that is proportional to the product of the gas mass and the mass-weighted temperature. To best detect this signal, we used a Needlet Independent Linear Combination all-sky Planck map that we produced from the most recent Planck data release, also incorporating WMAP data. The sample is 12 L* spiral galaxies with distances of 3-10 Mpc, which are spatially resolved so that contamination from the optical galaxy can be excluded. One galaxy, NGC 891, has a particularly strong SZ signal, and when excluding it, the stack of 11 galaxies is detected at about 4σ (declining with radius) and is extended to at least 250 kpc (≈R 200) at &gt;99% confidence. The gas mass within a spherical volume to a radius of 250 kpc is 9.8 ± 2.8 × 1010 M ⊙, for T avg = 3 × 106 K. This is about 30% of the predicted baryon content of the average galaxy (3.1 × 1011 M ⊙), and about equal to the mass of stars, disk gas, and warm halo gas. The remaining missing baryons (≈1.4 × 1011 M ⊙, 40%-50% of the total baryon content) are likely to be hot and extend to the 400-500 kpc volume, if not beyond. The result is higher than predictions, but within the uncertainties.

Keywords: Sunyaev-Zeldovich effect, Spiral galaxies, Interstellar plasma
The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER). III. The Mass Function of Young Stellar Clusters in M33. We measure the star cluster mass function (CMF) for the Local Group galaxy M33. We use the catalog of stellar clusters selected from the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region survey. We analyze 711 clusters in M33 with $7.0\lt \mathrm{log}(\mathrm{Age}/\mathrm{yr})\lt 8.5$ , and log(M/M ⊙) &gt; 3.0 as determined from color-magnitude diagram fits to individual stars. The M33 CMF is best described by a Schechter function with power-law slope α = - ${2.06}_{-0.13}^{+0.14}$ , and truncation mass log(M  c /M ⊙) $=\,{4.24}_{-0.13}^{+0.16}$ . The data show strong evidence for a high-mass truncation, thus strongly favoring a Schechter function fit over a pure power law. M33's truncation mass is consistent with the previously identified linear trend between M  c , and star formation rate surface density, ΣSFR. We also explore the effect that individual cluster mass uncertainties have on derived mass function parameters, and find evidence to suggest that large cluster mass uncertainties have the potential to bias the truncation mass of fitted mass functions at the 1σ level.

Keywords: Triangulum Galaxy, Star formation, Star clusters
Assessing the Importance of Noise from Thermal Sunyaev-Zel'dovich Signals for CMB Cluster Surveys and Cluster Cosmology. We explore the significance of noise from thermal Sunyaev-Zel'dovich (tSZ) signals for cluster detection using cosmic microwave background (CMB) surveys. The noise arises both from neighboring objects and also from haloes below the detection limit. A wide range of surveys are considered: SPT-SZ, SPTpol, and SPT-3G from the South Pole Telescope; SO-Baseline and SO-Goal configurations for Simons Observatory; CMB-S4's wide-area (S4-Wide) and deep (S4-Ultra deep) surveys; and the futuristic CMB-HD experiment. We find that the noise from tSZ signals has a significant impact on CMB-HD and to some extent on S4-Ultra deep. For other experiments, the effect is negligible as the noise in the tSZ map is dominated by residual foregrounds or experimental noise. In the limit when the noise from tSZ signals is important, we find that removing the detected clusters and rerunning the cluster finder allows us to find a new set of less massive and distant clusters. Since the detected clusters are the dominant source of the tSZ power, removing them reduces the power at ℓ = 3000 by ×5 for CMB-HD; ×3.1 of S4-Ultra deep; ×2.4 for S4-Wide and SPT-3G; ×1.5 for SO-Goal and SPTpol; ×1.35 for SO-Baseline; and ×1.08 for SPT-SZ. We forecast the expected number of clusters and also derive parameter constraints by combining cluster counts with primary CMB and tSZ power spectra finding that the future surveys can reduce the error on the dark energy equation of state parameter to sub-percent levels and can also enable ≥3σ detection of the sum of neutrino masses.

Keywords: Cosmology, Galaxy clusters, Cosmic microwave background radiation, Sunyaev-Zeldovich effect
Diagnosing Triggered Star Formation in the Galactic H II region Sh 2-142. Stars are formed by gravitational collapse, spontaneously or, in some cases under the constructive influence of nearby massive stars, out of molecular cloud cores. Here we present an observational diagnosis of such triggered formation processes in the prominent H II region Sh 2-142, which is associated with the young star cluster NGC 7380, and with some bright-rimmed clouds as the signpost of photoionization of molecular cloud surfaces. Using near- (2MASS) and mid-infrared (WISE) colors, we identified candidate young stars at different evolutionary stages, including embedded infrared sources having spectral energy distributions indicative of active accretion. We have also used data from our optical observations to be used in SEDs, and from Gaia EDR3 to study the kinematics of young objects. With this young stellar sample, together with the latest CO line emission data (spectral resolution ~0.16 km s-1, sensitivity ~0.5 K), a positional and aging sequence relative to the neighboring cloud complex, and to the bright-rimmed clouds, is inferred. The propagating stellar birth may be responsible, at least partially, for the formation of the cluster a few million years ago, and for the ongoing activity now witnessed in the cloud complex.

Keywords: Molecular gas, Star forming regions, Protostars, Young stellar objects, Emission nebulae, Star formation, Open star clusters, H II regions, Star clusters
Can We Estimate the Intensities of Great Geomagnetic Storms (ΔSYM-H ≤ -200 nT) with the Burton Equation or the O'Brien and McPherron Equation?. We input the solar wind parameters responsible for the main phases of 15 great geomagnetic storms (GGSs; ΔSYM-H ≤ -200 nT) into the empirical formulae created by Burton et al. (hereafter the Burton equation) and by OBrien &amp; McPherron (hereafter the OM equation) to evaluate whether these two equations can correctly estimate the intensities of GGSs. The results show that the intensities of most GGSs estimated by the OM equation are much smaller than the observed intensities. The rms error between the intensities estimated by the OM equation and the observed intensities is 203 nT, implying that the estimated storm intensity deviates significantly from the observed one. The rms error between the intensities estimated by the Burton equation and the observed intensities is 130.8 nT. The relative error caused by the Burton equation for storms with intensities ΔSYM-H&lt;-400 nT is larger than 27%, implying that the absolute error will be large for storms with ΔSYM-H &lt; -400 nT. The results indicate that the two equations cannot predict the intensities of GGSs correctly. On the contrary, the intensity of a GGS estimated by the empirical formula created by Wang et al. can approximate observations better if we select the right weight for the solar wind dynamic pressure, proving that solar wind dynamic pressure is an important factor of GGS intensity. This pressure is overlooked by the ring current injection terms of the Burton and OM equations. This is the reason why the two equations do not effectively estimate GGSs.

Keywords: Solar-terrestrial interactions, Space weather, Solar wind
Unresolved Sources Naturally Contribute to PeV Gamma-Ray Diffuse Emission Observed by Tibet ASγ. The Tibet ASγ experiment provided the first measurement of the total diffuse gamma-ray emission from the Galactic disk in the sub-PeV energy range. Based on the analysis of TeV sources included in the H.E.S.S. Galactic Plane Survey catalog, we predict the expected contribution of unresolved pulsar-powered sources in the two angular windows of the Galactic plane observed by Tibet ASγ. We show that the sum of this additional diffuse component due to unresolved sources and the truly diffuse emission, due to cosmic-ray interaction with the interstellar medium, well saturates the Tibet data, without the need to introduce a progressive hardening of the cosmic-ray spectrum toward the Galactic center.

Keywords: Gamma-ray astronomy
New Variable Hot Subdwarf Stars Identified from Anomalous Gaia Flux Errors, Observed by TESS, and Classified via Fourier Diagnostics. Hot subdwarf stars are mostly stripped red giants that can exhibit photometric variations due to stellar pulsations, eclipses, the reflection effect, ellipsoidal modulation, and Doppler beaming. Detailed studies of their light curves help constrain stellar parameters through asteroseismological analyses or binary light-curve modeling and generally improve our capacity to draw a statistically meaningful picture of this enigmatic stage of stellar evolution. From an analysis of Gaia DR2 flux errors, we have identified around 1200 candidate hot subdwarfs with inflated flux errors for their magnitudes-a strong indicator of photometric variability. As a pilot study, we obtained 2 minute cadence TESS Cycle 2 observations of 187 candidate hot subdwarfs with anomalous Gaia flux errors. More than 90% of our targets show significant photometric variations in their TESS light curves. Many of the new systems found are cataclysmic variables, but we report the discovery of several new variable hot subdwarfs, including HW Vir binaries, reflection-effect systems, pulsating sdBV s  stars, and ellipsoidally modulated systems. We determine atmospheric parameters for select systems using follow-up spectroscopy from the 3 m Shane telescope. Finally, we present a Fourier diagnostic plot for classifying binary light curves using the relative amplitudes and phases of their fundamental and harmonic signals in their periodograms. This plot makes it possible to identify certain types of variables efficiently, without directly investigating their light curves, and may assist in the rapid classification of systems observed in large photometric surveys.

Keywords: Binary stars, Surveys, Close binary stars, B subdwarf stars, Short period variable stars, Eclipsing binary stars
Prospects for Measuring Off-axis Spins of Binary Black Holes with Plus-era Gravitational-wave Detectors. The mass and spin properties of binary black holes (BBHs) inferred from their gravitational-wave signatures reveal important clues about how these systems form. BBHs originating from isolated binary evolution are expected to have spins preferentially aligned with their orbital angular momentum, whereas there is no such preference in binaries formed via dynamical assembly. The fidelity with which near-future gravitational-wave detectors can measure off-axis spins will have implications for the study of BBH formation channels. In this work, we examine the degree to which the Advanced LIGO Plus (A+) and Advanced Virgo Plus (AdV+) interferometric detectors can measure both aligned and misaligned spins. We compare spin resolution between the LIGO-Virgo network operating at either A+/AdV+ ("Plus") sensitivity or Advanced-era design ("Design") sensitivity using simulated BBH gravitational-wave signals injected into synthetic detector noise. The signals are distributed over the mass-spin parameter space of likely BBH systems, accounting for the effects of precession and higher-order modes. We find that the Plus upgrades yield significant improvements in spin estimation for systems with unequal masses and moderate or large spins. Using simulated signals modeled after different types of hierarchical BBH mergers, we also conclude that the Plus detector network will yield substantially improved spin estimates for 1G+2G binaries compared to the Design network.

Keywords: Stellar mass black holes, Compact binary stars, Gravitational waves