adsabs/SciX_UAT_keywords huggingface dataset:
Modeling Redshift-space Clustering with Abundance Matching

We explore the degrees of freedom required to jointly fit projected and redshift-space clustering of galaxies selected in three bins of stellar mass from the Sloan Digital Sky Survey Main Galaxy Sample (SDSS MGS) using a subhalo abundance matching (SHAM) model. We employ emulators for relevant clustering statistics in order to facilitate our analysis, leading to large speed gains with minimal loss of accuracy. We are able to simultaneously fit the projected and redshift-space clustering of the two most massive galaxy samples that we consider with just two free parameters: scatter in stellar mass at fixed SHAM proxy, and the dependence of the SHAM proxy on dark matter halo concentration. We find some evidence for models that include velocity bias, but including orphan galaxies improves our fits to the lower-mass samples significantly. We also model the clustering signals of specific star formation rate (sSFR) selected samples using conditional abundance matching (CAM). We obtain acceptable fits to projected and redshift-space clustering as a function of sSFR and stellar mass using two CAM variants, although the fits are worse than for stellar-mass-selected samples alone. By incorporating nonunity correlations between the CAM proxy and sSFR, we are able to resolve previously identified discrepancies between CAM predictions and SDSS observations of the environmental dependence of quenching for isolated central galaxies.

Keywords: large-scale structure of the universe; galaxy quenching; cosmology; astrostatistics techniques; n-body simulations
MAXI and NuSTAR Observations of the Faint X-Ray Transient MAXI J1848-015 in the GLIMPSE-C01 Cluster

We present the results of Monitor of All-sky X-ray Image (MAXI) monitoring and two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the recently discovered faint X-ray transient MAXI J1848015. Analysis of the MAXI light curve shows that the source underwent a rapid flux increase beginning on 2020 December 20, followed by a rapid decrease in flux after only ~5 days. NuSTAR observations reveal that the source transitioned from a bright soft state with unabsorbed, bolometric (0.1-100 keV) flux F = 6.9 ± 0.1 × 10-10 erg cm-2 s-1, to a low hard state with flux F = 2.85 ± 0.04 × 10-10 erg cm-2 s-1. Given a distance of 3.3 kpc, inferred via association of the source with the GLIMPSE-C01 cluster, these fluxes correspond to an Eddington fraction of the order of 10-3 for an accreting neutron star (NS) of mass M = 1.4M ⊙, or even lower for a more massive accretor. However, the source spectra exhibit strong relativistic reflection features, indicating the presence of an accretion disk that extends close to the accretor, for which we measure a high spin, a = 0.967 ± 0.013. In addition to a change in flux and spectral shape, we find evidence for other changes between the soft and hard states, including moderate disk truncation with the inner disk radius increasing from R in ≈ 3 R g to R in ≈ 8 R g, narrow Fe emission whose centroid decreases from 6.8 ± 0.1 keV to 6.3 ± 0.1 keV, and an increase in low-frequency (10-3-10-1 Hz) variability. Due to the high spin, we conclude that the source is likely to be a black hole rather than an NS, and we discuss physical interpretations of the low apparent luminosity as well as the narrow Fe emission.

Keywords: black holes; high energy astrophysics; compact objects; stellar mass black holes; x-ray binary stars; accretion; neutron stars
Proton and Electron Temperatures in the Solar Wind and Their Correlations with the Solar Wind Speed

The heating and acceleration of the solar wind remains one of the unsolved fundamental problems in heliophysics. It is usually observed that the proton temperature T i is highly correlated with the solar wind speed V SW, while the electron temperature T e shows anticorrelation or no clear correlation with the solar wind speed. Here, we inspect both Parker Solar Probe (PSP) and WIND data, and compare the observations with simulation results. PSP observations below 30 solar radii clearly show a positive correlation between the proton temperature and the wind speed and a negative correlation between the electron temperature and the wind speed. One year (2019) of WIND data confirm that the proton temperature is positively correlated with the solar wind speed, but the electron temperature increases with the solar wind speed for slow wind, while it decreases with the solar wind speed for fast wind. Using a 1D Alfvén-wave-driven solar wind model with different proton and electron temperatures, we find, for the first time, that if most of the dissipated Alfvén wave energy heats the ions instead of the electrons, a positive T i -V SW correlation and a negative T e -V SW correlation arise naturally. If the electrons gain a small but finite portion of the dissipated wave energy, the T e -V SW correlation evolves with the radial distance to the Sun, such that the negative correlation gradually turns positive. The model results show that Alfvén waves are one of the possible explanations for the observed evolution of the proton and electron temperatures in the solar wind.

Keywords: solar wind; alfven waves; solar coronal heating
A Supercritical Accretion Disk with Radiation-driven Outflows

Outflows are inevitably driven from the disk if the vertical component of the black hole (BH) gravity cannot resist the radiation force. We derive the mass-loss rate in the outflows by solving a dynamical equation for the vertical gas motion in the disk. The structure of a supercritical accretion disk is calculated with the radial energy advection included. We find that most inflowing gas is driven into outflows if the disk is accreting at a moderate Eddington-scaled rate (up to ~100) at its outer edge, i.e., only a small fraction of gas is accreted by the BH, which is radiating at several Eddington luminosities, while it reaches around ten for extremely high accretion rate cases ( $\dot{m}\equiv \dot{M}/{\dot{M}}_{\mathrm{Edd}}\sim 1000$ ). Compared with a normal slim disk, the disk luminosity is substantially suppressed due to the mass loss in the outflows. We apply the model to the light curves of the tidal disruption events (TDEs) and find that the disk luminosity declines very slowly with time even if a typical accretion rate $\dot{m}\propto {t}^{-5/3}$ is assumed at the outer edge of the disk, which is qualitatively consistent with the observed light curves in some TDEs and helps us to understand the energy deficient phenomenon observed in the TDEs. Strong outflows from supercritical accretion disks surrounding supermassive BHs may play crucial roles in their host galaxies, which can be taken as an ingredient in the mechanical feedback models. The implications of the results on the growth of supermassive BHs are also discussed.

Keywords: galaxy accretion disks; accretion
Sequential Remote Brightenings and Co-spatial Fast Downflows during Two Successive Flares

Remote brightenings often appear at the outskirts of the active regions of solar eruptive events. Nevertheless, their origin remains to be ascertained. In this study, we report imaging and spectroscopic observations of sequential remote brightenings with a combination of observations from the Hα Imaging Spectrograph on board the Chinese Hα Solar Explorer, which is the first space-based solar telescope of China, and from the Solar Dynamics Observatory. It is found that during two successive M-class flares occurring on 2022 August 17 multiple ribbon-like brightenings appeared in sequence away from the flaring active region. Meanwhile, abundant cool filament materials moved downward to the sequential remote brightenings, which were visible at the Hα red wing with a line-of-sight speed of up to 70 km s‑1. The extrapolated three-dimensional magnetic field configuration shows that the sequential remote brightenings correspond to the footpoints of closed ambient field lines whose conjugate footpoints are rooted in the main flare site. We suggest that the sequential remote brightenings are most likely to be caused by the heating of the interchange reconnection between the erupting flux rope and the closed ambient field, during which the rope-hosting filament materials are transferred to the periphery of the flaring active region along the closed ambient field rather than to the interplanetary space, such as in the scenario of slow solar wind formation.

Keywords: solar flares; active solar corona; solar magnetic reconnection; solar magnetic fields
The HETDEX Survey Emission-line Exploration and Source Classification

The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) is an untargeted spectroscopic survey that aims to measure the expansion rate of the universe at z ~ 2.4 to 1% precision for both H(z) and D A (z). HETDEX is in the process of mapping in excess of one million Lyα emitting (LAE) galaxies and a similar number of lower-z galaxies as a tracer of the large-scale structure. The success of the measurement is predicated on the post-observation separation of galaxies with Lyα emission from the lower-z interloping galaxies, primarily [O II], with low contamination and high recovery rates. The Emission Line eXplorer (ELiXer) is the principal classification tool for HETDEX, providing a tunable balance between contamination and completeness as dictated by science needs. By combining multiple selection criteria, ELiXer improves upon the 20 Å rest-frame equivalent width cut commonly used to distinguish LAEs from lower-z [O II] emitting galaxies. Despite a spectral resolving power, R ~ 800, that cannot resolve the [O II] doublet, we demonstrate the ability to distinguish LAEs from foreground galaxies with 98.1% accuracy. We estimate a contamination rate of Lyα by [O II] of 1.2% and a Lyα recovery rate of 99.1% using the default ELiXer configuration. These rates meet the HETDEX science requirements. * Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.

Keywords: dark energy; emission line galaxies; lyman-alpha galaxies; redshift surveys
Inefficient Growth of SiOx Grains: Implications for Circumstellar Outflows

To explain observations of abundant circumstellar dust and high stellar wind velocity, most models simply postulate the efficient nucleation and growth of silicate dust particles. Here, we report measurement of the SiO-(SiOx)n grain sticking coefficient in a microgravity sounding rocket experiment, indicating very inefficient (0.005-0.016) grain formation from the vapor. Application of this measurement to radiative-driven winds in oxygen-rich asymptotic giant branch stars indicates that the initial grain condensate population should consist of very tiny dust particles in very large numbers. Aggregation of this dust population will produce low-dimension fractal aggregates that should couple well to the stellar radiation field and efficiently drive stellar mass loss.

Keywords: circumstellar dust
Statistical Properties of Whistler-mode Waves in the Dayside Terrestrial Space: MMS Observations

Whistler-mode waves have been extensively observed and investigated in terrestrial space. In this study, we present the dynamic response of whistler-mode waves to different solar wind conditions in the dayside terrestrial space based on Magnetospheric Multiscale (MMS) data. Statistical results show that the occurrence rate, amplitudes, and corresponding electron temperature anisotropy of whistler-mode waves increase with P sw in the dayside terrestrial space, which is attributed to the compression of magnetic fields in these magnetosheath and outer magnetosphere. Furthermore, whistler-mode waves under the southward interplanetary magnetic fields (IMFs) show a higher occurrence rate than that under the northward IMFs, mostly corresponding to T e⊥/T e∥ > 1, and have a higher occurrence rate during quasi-radial IMFs. These results present that whistler-mode waves in these magnetosheath and outer magnetosphere are also modulated by the solar wind as clearly as the inner magnetosphere. This work advanced our understanding in the solar–terrestrial interaction.

Keywords: solar-terrestrial interactions; interplanetary magnetic fields; solar wind
Some Aspects of the Tachyon Inflation with Superpotential in Confrontation with Planck2018 Data

We study tachyon inflation in the presence of the superpotential as an inflationary potential. We study the primordial perturbations and their non-Gaussian feature in the equilateral configuration. We use the Planck2018 TT, TE, EE+lowE+lensing+BK14+BAO joint data at 68% CL and 95% CL to perform numerical analysis on the scalar perturbations and seek the observational viability of the tachyon inflation with superpotential. We also check the observational viability of the model by studying the tensor part of the perturbations and comparing the results with Planck2018 TT, TE, EE+lowE+lensing+BK14+BAO+ LIGO&Virgo2016 joint data at 68% CL and 95% CL. By studying the phase space of the model's parameters, we predict the amplitude of the equilateral non-Gaussianity in this model. The reheating phase after inflation is another issue that is explored in this paper. We show that, in some ranges of the model's parameters, it is possible to have an observationally viable tachyon model with superpotential.

Keywords: inflationary universe; observational cosmology; early universe
TESS Observations of the WASP-121 b Phase Curve

We study the red-optical photometry of the ultrahot Jupiter WASP-121 b as observed by the Transiting Exoplanet Survey Satellite (TESS) and model its atmosphere through a radiative transfer simulation. Given its short orbital period of ∼1.275 days, inflated state, and bright host star, WASP-121 b is exceptionally favorable for detailed atmospheric characterization. Toward this purpose, we use allesfitter to characterize its full red-optical phase curve, including the planetary phase modulation and secondary eclipse. We measure the day- and nightside brightness temperatures in the TESS passband as ${3012}_{-42}^{+40}$ and ${2022}_{-602}^{+254}$ K, respectively, and do not find a statistically significant phase shift between the brightest and substellar points. This is consistent with inefficient heat recirculation on the planet. We then perform an atmospheric retrieval analysis to infer the dayside atmospheric properties of WASP-121 b, such as its bulk composition, albedo, and heat recirculation. We confirm the temperature inversion in the atmosphere and suggest H-, TiO, and VO as potential causes of the inversion, absorbing heat at optical wavelengths at low pressures. Future Hubble Space Telescope and James Webb Space Telescope observations of WASP-121 b will benefit from its first full phase curve measured by TESS.

Keywords: exoplanet atmospheres; exoplanet atmospheric composition; exoplanet astronomy; hot jupiters; extrasolar gaseous giant planets
First Observation of Lower Hybrid Drift Waves at the Edge of the Current Sheet in the Martian Magnetotail

Lower hybrid drift waves are commonly observed at plasma boundaries, playing an important role in plasma dynamics. Such waves have been widely investigated in the terrestrial magnetosphere but have never been reported in other planetary environments. Here, using the measurements from the Mars Atmosphere and Volatile EvolutioN mission, we present the first observation of electromagnetic lower hybrid drift waves at the edge of the current sheet on the dusk side of the Martian magnetotail, which should be locally excited rather than propagated from other regions. These plasma waves are associated with significant density gradients and magnetic field gradients. Based on the measured local plasma parameters and the sufficient condition for lower hybrid drift instability to be excited, we find that the proton density gradient is sharp enough to excite the lower hybrid drift instability. The analysis of the existence condition for lower hybrid drift instability indicates that these lower hybrid drift waves at the edge of the current sheet are generated through lower hybrid drift instability. The above results can improve our understanding of Mars' magnetospheric dynamics.

Keywords: mars; planetary magnetospheres; space plasmas
Stellar Cycle and Evolution of Polar Spots in an M+WD Binary

Stellar activity cycles reveal continuous relaxation and induction of magnetic fields. The activity cycle is typically traced through the observation of cyclic variations in total brightness or Ca H&K emission flux of stars, as well as cyclic variations in the orbital periods of binary systems. In this work, we report the identification of a semidetached binary system (TIC 16320250) consisting of a white dwarf (0.67 M ⊙) and an active M dwarf (0.56 M ⊙). The long-term multiband optical light curves spanning twenty years revealed three repeated patterns, suggestive of a possible activity cycle of about 10 years of the M dwarf. Light-curve fitting indicates the repeated variation is caused by the evolution, particularly the motion, of polar spots. The significant Ca H&K, Hα, ultra-violet, and X-ray emissions imply that the M dwarf is one of the most magnetically active stars. We propose that in the era of large time-domain photometric sky surveys (e.g., ASAS-SN, Zwicky Transient Facility, LSST, Sitian), long-term light-curve modeling can be a valuable tool for tracing and revealing stellar activity cycle, especially for stars in binary systems.

Keywords: neutron stars; white dwarf stars; binary stars; stellar activity
Local Group Analogs in ΛCDM Cosmological Simulations

We use semi-analytic galaxy catalogs based on two high-resolution cosmological N-body simulations, Millennium-WMAP7 and Millennium-II, to investigate the formation of Local Group (LG) analogs. Unlike previous studies, we use the observed stellar masses to select the LG member (Milky Way (MW) and M31) analogs, and then impose constraints using the observed separation, isolation, and kinematics of the two main member galaxies. By comparing radial and low-ellipticity orbits between the MW and M31, we find higher tangential velocity results in higher total mass, which are ${4.4}_{-1.5}^{+2.4}\,\times $ 10 ${}^{12}{M}_{\odot }$ and ${6.6}_{-1.5}^{+2.7}\,\times $ 10 ${}^{12}{M}_{\odot }$ for radial and low-ellipticity orbits. The orbits also influence the individual mass distribution of MW and M31 analogs. For radial orbits, typical host halo masses of the MW and M31 are ${1.5}_{-0.7}^{+1.4}\,\times $ 10 ${}^{12}{M}_{\odot }$ and ${2.5}_{-1.1}^{+1.3}\,\times $ 10 ${}^{12}{M}_{\odot };$ for low-ellipticity orbits, the masses are ${2.5}_{-1.4}^{+2.2}\,\times $ 10 ${}^{12}{M}_{\odot }$ and ${3.8}_{-1.8}^{+2.8}\,\times $ 10 ${}^{12}{M}_{\odot }$ . The LG is located primarily in filaments with tails extending toward higher densities up to $\delta \sim 4.5$ . The dark matter velocity anisotropy parameters β of both the MW and M31 analogs are close to zero in the center, increasing to 0.2-0.3 at 50-80 kpc and decreasing slowly outward. The slope is much flatter than computed from the MW satellites, and the amplitude is smaller than traced by halo stars. Values of β from different tracers agree at ∼120 kpc where β ∼ 0.2. We also find that model predictions agree broadly with observations in the radial distribution and luminosity function of satellites around the MW and M31.

Keywords: cold dark matter; local group; cosmology
UV-Optical Disk Reverberation Lags despite a Faint X-Ray Corona in the Active Galactic Nucleus Mrk 335

We present the first results from a 100-day Swift, NICER, and ground-based X-ray-UV-optical reverberation mapping campaign of the Narrow-line Seyfert 1 Mrk 335, when it was in an unprecedented low X-ray flux state. Despite dramatic suppression of the X-ray variability, we still observe UV-optical lags as expected from disk reverberation. Moreover, the UV-optical lags are consistent with archival observations when the X-ray luminosity was >10 times higher. Interestingly, both low- and high-flux states reveal UV-optical lags that are 6-11 times longer than expected from a thin disk. These long lags are often interpreted as due to contamination from the broad line region; however the u-band excess lag (containing the Balmer jump from the diffuse continuum) is less prevalent than in other active galactic nuclei. The Swift campaign showed a low X-ray-to-optical correlation (similar to previous campaigns), but NICER and ground-based monitoring continued for another 2 weeks, during which the optical rose to the highest level of the campaign, followed ~10 days later by a sharp rise in X-rays. While the low X-ray countrate and relatively large systematic uncertainties in the NICER background make this measurement challenging, if the optical does lead X-rays in this flare, this indicates a departure from the zeroth-order reprocessing picture. If the optical flare is due to an increase in mass accretion rate, this occurs on much shorter than the viscous timescale. Alternatively, the optical could be responding to an intrinsic rise in X-rays that is initially hidden from our line of sight.

Keywords: black hole physics
Optical Studies of Eight AM Herculis-type Cataclysmic Variable Stars

We report detailed follow-up observations of eight cataclysmic variable stars (CVs) that are apparently AM Her stars, also called polars. For all, we either determine orbital periods for the first time or improve on existing determinations. The seven for which we have spectra show the high-amplitude radial-velocity curves and prominent He II λ4686 emission lines characteristic of strongly magnetic CVs, and their periods, which range from 81 to 219 minutes, are also typical for AM Her stars. Two objects from the Gaia-alerts index, Gaia18aot and Gaia18aya, are newly identified as CVs. Another, RX J0636.3+6554, eclipses deeply, while CSS 080228:081210+040352 shows a sharp dip that is apparently a partial eclipse. The spectrum of Gaia18aya has a cyclotron harmonic near λ5500 Å that constrains the surface field to ∼49 MG or greater.

Keywords: cataclysmic variable stars; am herculis stars; eclipsing binary stars; close binary stars; interacting binary stars; white dwarf stars
Wavelength-dependent Extinction and Grain Sizes in "Dippers"

We have examined internight variability of K2-discovered "dippers" that are not close to being viewed edge-on, as determined from previously reported ALMA images, using the SpeX spectrograph on NASA's Infrared Telescope Facility. The three objects observed were EPIC 203850058, EPIC 205151387, and EPIC 204638512 (=2MASS J16042165-2130284). Using the ratio of the fluxes between two successive nights, we find that for EPIC 204638512 and EPIC 205151387, we find that the properties of the dust differ from that seen in the diffuse interstellar medium and denser molecular clouds. However, the grain properties needed to explain the extinction does resemble those used to model the disks of many young stellar objects. The wavelength-dependent extinction models of both EPIC 204638512 and EPIC 205151387 includes grains at least 500 μm in size, but lacks grains smaller than 0.25 μm. The change in extinction during the dips, and the timescale for these variations to occur, imply obscuration by the surface layers of the inner disks. The recent discovery of a highly misinclined inner disk in EPIC 204638512 is suggests that the variations in this disk system may point to due to rapid changes in obscuration by the surface layers of its inner disk, and that other "face-on" dippers might have similar geometries. The He I line at 1.083 μm in EPIC 205151387 and EPIC 20463851 were seen to change from night to night, suggesting that we are seeing He I gas mixed in with the surface dust.

Keywords: protoplanetary disks; protostars; circumstellar dust