adsabs/SciX_UAT_keywords huggingface dataset:
Transit Analysis of Exoplanets TrES-5 b and WASP-43 b with the EXOplanet Transit Interpretation Code

In this study, we analyze light curves and corresponding transit attributes of the exoplanets TrES-5b and WASP-43b. The mid-transit time of an exoplanet is the time in which the planet is in the middle of its transit. Over time, due to variations that arise after many periods, the error in the mid-transit time of the exoplanet increases. Because of this, constant observations of exoplanet mid-transit times through light curves are necessary to update the transit timing predictions. We made light curves with the EXOplanet Transit Interpretation Code (EXOTIC). To run with EXOTIC, we were given raw, uncalibrated TrES-5b images taken by the SRO telescope, managed by the Boyce-Astro project. Additionally, we requested and obtained images of WASP-43b using the Las Cumbres Observatory 0.4 m robotic telescopes. Within this work, we will explore the newly calculated mid-transit times and other transit properties to gain a better understanding of TrES-5b and WASP-43b.

Keywords: exoplanet detection methods; exoplanet astronomy; exoplanets; exoplanet systems
Interplanetary Magnetic Field Effect on the Location of the Martian Bow Shock: MAVEN Observations

The Martian bow shock (BS) is generated with the mass-loading and magnetic pileup processes when the solar wind interacts with the Martian ionosphere. In this vein, the interplanetary magnetic field (IMF) frozen in the solar wind can affect the location of the Martian BS, which is less reported. Based on the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we manually identify 10,283 BS crossings during a period of the gradually declining solar cycle phase (2014 October-2020 December) and investigate the effects of the intensity and orientation of the IMF on the Martian BS. In the Mars Solar Orbital coordinate system, our results show the following: (1) The Martian BS, including the subsolar and flank regions, linearly moves away from Mars when the IMF intensity increases, which confirms the theoretical and the MHD simulation results. (2) Under the radial IMF condition, we first demonstrate that the subsolar and flank regions of the Martian BS are situated closer to Mars compared to other IMF situations. This might be caused by the weaker magnetic pileup process and the "low-pressure magnetosheath" model under the radial IMF condition. (3) Moreover, the cross section of the Martian BS is elongated in the north-south direction when the Y component of the IMF is dominant, which is on account of the fast magnetosonic speed effect and verifies the elongation phenomenon of the terrestrial BS. The IMF intensity and orientation effects cannot be ignored and should be considered in future models of the Martian BS.

Keywords: planetary bow shocks; interplanetary magnetic fields; mars; martian satellites
Study of Temporal and Spectral variability for Blazar PKS 1830-211 with Multiwavelength Data

A study of the gravitationally lensed blazar PKS 1830-211 was carried out using multi-wave band data collected by Fermi-LAT, Swift-XRT, and Swift-UVOT telescopes between MJD 58400 to MJD 58800 (2018 October 9-2019 November 13). Flaring states were identified by analyzing the γ-ray light curve. Simultaneous multi-wave band spectral energy distributions (SEDs) were obtained for these flaring periods. A cross-correlation analysis of the multi-wave band data was carried out, which suggested a common origin of the γ-ray and X-ray emission. The broadband emission mechanism was studied by modeling the SED using a leptonic model. Physical parameters of the blazar were estimated from the broadband SED modeling. The blazar PKS 1830-211 is gravitationally lensed by at least two galaxies and has been extensively studied in the literature because of this property. The self-correlation of the γ-ray light curve was studied to identify the signature of lensing, but no conclusive evidence of correlation was found at the expected time delay of 26 days.

Keywords: active galactic nuclei; blazars
Kinetic Features for the Identification of Kelvin-Helmholtz Vortices in In Situ Observations

The boundaries identification of Kelvin-Helmholtz vortices in observational data has been addressed by searching for single-spacecraft small-scale signatures. A recent hybrid Vlasov-Maxwell simulation of Kelvin-Helmholtz instability has pointed out clear kinetic features that uniquely characterize the vortex during both the nonlinear and turbulent stage of the instability. We compare the simulation results with in situ observations of Kelvin-Helmholtz vortices by the Magnetospheric Multiscale satellites. We find good agreement between simulation and observations. In particular, the edges of the vortex are associated with strong current sheets, while the center is characterized by a low value for the magnitude of the total current density and strong deviation of the ion distribution function from a Maxwellian distribution. We also find a significant temperature anisotropy parallel to the magnetic field inside the vortex region and strong agyrotropies near the edges. We suggest that these kinetic features can be useful for the identification of Kelvin-Helmholtz vortices in in situ data.

Keywords: space probes; space plasmas; planetary magnetospheres; interplanetary discontinuities
X-Ray Spectroscopy in the Microcalorimeter Era 4: Optical Depth Effects on the Soft X-Rays Studied with CLOUDY

In this paper, we discuss atomic processes modifying the soft X-ray spectra from optical depth effects like photoelectric absorption and electron scattering suppressing the soft X-ray lines. We also show the enhancement in soft X-ray line intensities in a photoionized environment via continuum pumping. We quantify the suppression/enhancement by introducing a "line modification factor (f mod)." If 0 ≤ f mod ≤ 1, the line is suppressed, which could be the case in both collisionally ionized and photoionized systems. If f mod ≥ 1, the line is enhanced, which occurs in photoionized systems. Hybrid astrophysical sources are also very common, where the environment is partly photoionized and partly collisionally ionized. Such a system is V1223 Sgr, an Intermediate Polar binary. We show the application of our theory by fitting the first-order Chandra Medium Energy Grating (MEG) spectrum of V1223 Sgr with a combination of CLOUDY-simulated additive cooling-flow and photoionized models. In particular, we account for the excess flux for O VII, O VIII, Ne IX, Ne X, and Mg XI lines in the spectrum found in a recent study, which could not be explained with an absorbed cooling-flow model.

Keywords: x-ray binary stars; atomic spectroscopy
Probing Patchy Reionization with the Void Probability Function of Lyα Emitters

We probe what constraints for the global ionized hydrogen fraction the void probability function (VPF) clustering can give for the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) narrowband survey as a function of area. Neutral hydrogen acts like a fog for Lyα emission, and measuring the drop in the luminosity function of Lyα emitters (LAEs) has been used to constrain the ionization fraction in narrowband surveys. However, the clustering of LAEs is independent of the luminosity function's inherent evolution, and can offer additional constraints for reionization under different models. The VPF measures how likely a given circle is to be empty. It is a volume-averaged clustering statistic that traces the behavior of higher-order correlations, and its simplicity offers helpful frameworks for planning surveys. Using the Jensen et al. simulations of LAEs within various amounts of ionized intergalactic medium, we predict the behavior of the VPF in one (301 × 150.5 × 30 Mpc3), four (5.44 × 106 Mpc3), or eight (1.1 × 107 Mpc3) fields of LAGER imaging. We examine the VPF at 5' and 13', corresponding to the minimum scale implied by the LAE density and the separation of the 2D VPF from random, and the maximum scale from the eight-field 15.5 deg2 LAGER area. We find that even a single DECam field of LAGER (2-3 deg2) could discriminate between mostly neutral versus ionized. Additionally, we find four fields allow for the distinction between 30%, 50%, and 95% ionized, and eight fields could even distinguish between 30%, 50%, 73%, and 95% ionized.

Keywords: reionization; clustering; lyman-alpha galaxies; astronomical simulations; large-scale structure of the universe
Understanding the Chemical Evolution of Blue Edge-on Low Surface Brightness Galaxies

We present a sample of 330 blue edge-on low surface brightness galaxies (ELSBGs). To understand the chemical evolution of ELSBGs, we derived the gas-phase abundance and the [α/Fe] ratio. Compared with star-forming galaxies, ELSBGs show a flatter trend in the mass-metallicity (M *-Z) relation, which suggests that the oxygen abundance enhancement is inefficient. We focused on 77 ELSBGs with H I data and found that the closed-box model cannot explain their gas fraction and metallicity relation, which implies that infall and/or outflow is needed. We derived the [α/Fe] ratio of normal ELSBG (<109.5 M ⊙) and massive ELSBG (> = 109.5 M ⊙) using single stellar population grids from the MILES stellar library. The mean [α/Fe] ratios are 0.18 and 0.4 for normal ELSBG and massive ELSBG, respectively. We suggest that the long timescales of star formation and/or metal-rich gas outflow events caused by SNe Ia winds are likely to be responsible for the α-enhancement of massive ELSBGs.

Keywords: galaxy abundances; metallicity; chemical abundances
Influence of the Galactic Gravitational Field on the Positional Accuracy of Extragalactic Sources. II. Observational Appearances and Detectability

We consider the possibility of detecting the jitter effect of apparent celestial positions of distant sources due to local fluctuations of the Galaxy gravitational field. The observation of two samples of extragalactic sources (target and control) in different sky directions using the high-precision radio interferometry is proposed. It is shown that on a scale of ∼2 yr, it is possible to detect a systematic increase in the standard deviation of measured arc lengths of pairs of target sources compared to the control ones at the 3σ level if the accuracy of differential astrometric observations is around 10 μas. For the current state-of-the-art accuracy of 30 μas achieved at the KVN or VERA interferometers, which have shorter baselines in comparison with very long baseline interferometry, the target and control samples will differ only at the 2σ level on the scale of 10 yr. To achieve the 3σ level on this time interval, it is necessary to improve the accuracy up to ∼20 μas. Other possible effects that can also affect the arc length measurements between two sources are discussed, and an observational strategy to minimize them is suggested.

Keywords: milky way galaxy; astrometry; gravitation
Shape Asymmetries and the Relation between Lopsidedness and Radial Alignment in Simulated Galaxies

Galaxies are observed to be lopsided, meaning that they are more massive and more extended along one side than the opposite side. In this work, we provide a statistical analysis of the lopsided morphology of 1780 isolated satellite galaxies generated by the TNG50-1 simulation, incorporating the effect of tidal fields from halo centers. The isolated satellites are galaxies without nearby substructures whose mass is over 1% of the satellites within their virial radii. We study the radial alignment (RA) between the major axes of satellites and the radial direction of their halo centers in radial ranges of 0-2, 2-5, and 5-10 R h , with R h being the stellar half-mass radius. According to our results, the RA is virtually undetectable in inner and intermediate regions, yet it is significantly evident in outer regions. We also calculate the far-to-near-side semiaxial ratios of the major axes, denoted by a -/a +, which measure the semiaxial ratios of the major axes in the hemispheres between those facing away from (far side) and facing toward (nearside) halo centers. In all the radial bins of the satellites, the numbers of satellites with longer semiaxes on the far side are found to be almost equal to those with longer semiaxes on the near side. Therefore, the tidal fields from halo centers play a minor role in the generation of lopsided satellites. The long semimajor-axes radial alignment (LRA), i.e., an alignment between the long semimajor axes of satellite galaxies and the radial directions to their halo centers, is further studied. No clear evidence of LRA is found in our sample within the framework of ΛCDM Newtonian dynamics. Finally, we briefly discuss the possible origins of the asymmetry of galaxies in TNG50-1.

Keywords: galaxy dynamics; galaxy dark matter halos; galaxy mass distribution; astronomical simulations
The Origin of the Slow-to-Alfvén Wave Cascade Power Ratio and Its Implications for Particle Heating in Accretion Flows

The partition of turbulent heating between ions and electrons in radiatively inefficient accretion flows plays a crucial role in determining the observational appearance of accreting black holes. Modeling this partition is, however, a challenging problem because of the large scale-separation between the macroscopic scales at which energy is injected by turbulence and the microscopic ones at which it is dissipated into heat. Recent studies of particle heating from collisionless damping of turbulent energy have shown that the partition of energy between ions and electrons is dictated by the ratio of the energy injected into the slow and Alfvén wave cascades as well as the plasma β parameter. In this paper, we study the mechanism of the injection of turbulent energy into slow- and Alfvén-wave cascades in magnetized shear flows. We show that this ratio depends on the particular (r ϕ) components of the Maxwell and Reynolds stress tensors that cause the transport of angular momentum, the shearing rate, and the orientation of the mean magnetic field with respect to the shear. We then use numerical magnetohydrodynamic shearing-box simulations with background conditions relevant to black hole accretion disks to compute the magnitudes of the stress tensors for turbulence driven by the magneto-rotational instability and derive the injection power ratio between slow and Alfvén wave cascades. We use these results to formulate a local subgrid model for the ion-to-electron heating ratio that depends on the macroscopic characteristics of the accretion flow.

Keywords: astrophysical black holes; black hole physics; supermassive black holes; plasma astrophysics; plasma physics
Coronagraphic Observations of Si X 1430 nm Acquired by DKIST/Cryo-NIRSP with Methods for Telluric Absorption Correction

We report commissioning observations of the Si X 1430 nm solar coronal line observed coronagraphically with the Cryogenic Near-Infrared Spectropolarimeter at the National Science Foundation's Daniel K. Inouye Solar Telescope. These are the first known spatially resolved observations of this spectral line, which has strong potential as a coronal magnetic field diagnostic. The observations target a complex active region located on the solar northeast limb on 2022 March 4. We present a first analysis of these data that extracts the spectral line properties through a careful treatment of the variable atmospheric transmission that is known to impact this spectral window. Rastered images are created and compared with extreme-UV observations from the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) instrument. A method for estimating the electron density from the Si X observations is then demonstrated that makes use of the forbidden line density-sensitive emissivity and an emission-measure analysis of the SDO/AIA bandpass observations. In addition, we derive an effective temperature and nonthermal line width across the region. This study informs the calibration approaches required for more routine observations of this promising diagnostic line.

Keywords: solar corona; solar coronal lines; solar e corona
X-Ray Hotspots in the Northwest Shell of the Supernova Remnant RX J1713.7-3946

The supernova remnant (SNR) RX J1713.7-3946 is one of the best-studied accelerators of cosmic rays because of its strong nonthermal X-ray and gamma-ray radiation. We have analyzed accumulated Chandra observations with a total exposure time of ∼266 ks in the northwest rim of RX J1713.7-3946. We detect a substantially large number of point-like sources, referred to as "hotspots," which are likely associated with the remnant. The spectra of the hotspots are well described by an absorbed power-law model. The spectral properties ( ${10}^{21}\ {\mathrm{cm}}^{-2}\lesssim {N}_{{\rm{H}}}\,\lesssim {10}^{23}\ {\mathrm{cm}}^{-2}$ and 0.5 ≲ Γ ≲ 6) are different from diffuse X-ray emission in RX J1713.7-3946, and the harder hotspot tends to have the larger NH. We also confirm yearly and monthly variabilities of flux for some hotspots. We propose that RX J1713.7-3946 is embedded in a complex surroundings where some dense molecular clumps and cores exist inside a wind-blown cavity, and that the hotspot traces synchrotron emission caused by an interaction of shock waves of the SNR and dense molecular cores with a number density of 105-107 cm-3. The X-ray radiation of the hotspot might be emitted both from primary electrons accelerated at the shocks and secondary electrons produced by the interaction of accelerated protons with the cores.

Keywords: interstellar medium; supernova remnants; non-thermal radiation sources; x-ray sources
A Geometric Origin for Quasi-periodic Oscillations in Black Hole X-Ray Binaries

We expand the relativistic precession model to include nonequatorial and eccentric trajectories and apply it to quasi-periodic oscillations (QPOs) in black hole X-ray binaries (BHXRBs) and associate their frequencies with the fundamental frequencies of the general case of nonequatorial (with Carter's constant, $Q\ne 0$ ) and eccentric ( $e\ne 0$ ) particle trajectories, around a Kerr black hole. We study cases with either two or three simultaneous QPOs and extract the parameters {e, rp, a, Q}, where rp is the periastron distance of the orbit, and a is the spin of the black hole. We find that the orbits with $\left[Q=0-4\right]$ should have e ≲ 0.5 and rp ∼ 2-20 for the observed range of QPO frequencies, where a ∈ [0, 1], and that the spherical trajectories {e = 0, $Q\ne 0$ } with Q = 2-4 should have rs ∼ 3-20. We find nonequatorial eccentric solutions for both M82 X-1 and GROJ 1655-40. We see that these trajectories, when taken together, span a torus region and give rise to a strong QPO signal. For two simultaneous QPO cases, we found equatorial eccentric orbit solutions for XTEJ 1550-564, 4U 1630-47, and GRS 1915+105, and spherical orbit solutions for BHXRBs M82 X-1 and XTEJ 1550-564. We also show that the eccentric orbit solution fits the Psaltis-Belloni-Klis correlation observed in BHXRB GROJ 1655-40. Our analysis of the fluid flow in the relativistic disk edge suggests that instabilities cause QPOs to originate in the torus region. We also present some useful formulae for trajectories and frequencies of spherical and equatorial eccentric orbits.

Keywords: astrophysical black holes; stellar mass black holes; kerr black holes; accretion; general relativity; x-ray binary stars; geodesics
Improved Infrared Photometry and a Preliminary Parallax Measurement for the Extremely Cold Brown Dwarf CWISEP J144606.62-231717.8

We present follow-up Spitzer observations at 3.6 μm (ch1) and 4.5 μm (ch2) of CWISEP J144606.62-231717.8, one of the coldest known brown dwarfs in the solar neighborhood. This object was found by mining the Wide-field Infrared Survey Explorer (WISE) and NEOWISE data via the CatWISE Preliminary Catalog by Meisner et al., where an initial Spitzer color of ch1-ch2 = 3.71 ± 0.44 mag was reported, implying it could be one of the reddest, and hence coldest, known brown dwarfs. Additional Spitzer data presented here allows us to revise its color to ch1-ch2 = 2.986 ± 0.048 mag, which makes CWISEP J144606.62-231717.8 the fifth reddest brown dwarf ever observed. A preliminary trigonometric parallax measurement, based on a combination of WISE and Spitzer astrometry, places this object at a distance of {10.1}-1.3+1.7 pc. Based on our improved Spitzer color and preliminary parallax, CWISEP J144606.62-231717.8 has a T eff in the 310-360 K range. Assuming an age of 0.5-13 Gyr, this corresponds to a mass between 2 and 20 M Jup.

Keywords: brown dwarfs; y dwarfs; solar neighborhood; trigonometric parallax; proper motions
Nonlinear Ion-acoustic Waves, Ion Holes, and Electron Holes in the Near-Sun Solar Wind

Nonlinear ion-acoustic waves, ion holes, and electron holes have been observed on the Parker Solar Probe at a heliocentric distance of 35 solar radii. These time domain structures contain millisecond duration electric field spikes of several mV m-1. They are observed inside or at boundaries of switchbacks in the background magnetic field. Their presence in switchbacks indicates that both electron- and ion-streaming electrostatic instabilities occur there to thermalize electron and ion beams.

Keywords: solar wind
The Drag Instability in a 1D Isothermal C-shock

We investigate whether the drag instability, proposed by Gu et al., occurs in a one-dimensional (1D) C-shock. The 1D background model proposed by Chen & Ostriker for a steady isothermal C-shock is adopted, and a 1D isothermal linear analysis is performed. We confirm the postulation of Gu et al. that the drift velocity between ions and neutrals is sufficiently high within a C-shock to allow for the drag instability. We also study the underlying physics of the decaying modes in the shock and postshock regions. The drag instability is an overstability phenomenon associated with an exponentially growing mode of a propagating wave. We find that the growing wave mode can only propagate downstream within the shock and subsequently decay in the postshock region. The maximum total growth for such an unstable wave before it is damped is estimated in typical environments of star-forming clouds, which is approximately 10-30 times larger than the initial perturbation at the modest shock velocities and can be significantly enhanced several hundred times for a stronger C-shock with a larger width.

Keywords: interstellar clouds; shocks; plasma astrophysics; molecular clouds; interstellar magnetic fields
Establishing Dust Rings and Forming Planets within Them

Radio images of protoplanetary disks demonstrate that dust grains tend to organize themselves into rings. These rings may be a consequence of dust trapping within gas pressure maxima, wherein the local high dust-to-gas ratio is expected to trigger the formation of planetesimals and eventually planets. We revisit the behavior of dust near gas pressure perturbations enforced by a planet in two-dimensional, shearing-box simulations. While dust grains collect into generally long-lived rings, particles with a small Stokes parameter τ s < 0.1 tend to advect out of the ring within a few drift timescales. Scaled to the properties of ALMA disks, we find that rings composed of larger particles (τ s ≥ 0.1) can nucleate a dust clump massive enough to trigger pebble accretion, which proceeds to ingest the entire dust ring well within ~1 Myr. To ensure the survival of the dust rings, we favor a nonplanetary origin and typical grain size τ s ≲ 0.05-0.1. Planet-driven rings may still be possible but if so we would expect the orbital distance of the dust rings to be larger for older systems.

Keywords: planet formation; protoplanetary disks; astrophysical dust processes; gas-to-dust ratio