Sazuna/UAT_keywords huggingface dataset:
On the Possibility of Generalized Wormhole Formation in the Galactic Halo Due to Dark Matter Using the Observational Data within the Matter Coupling Gravity Formalism. In this article, we find the possibility of generalized wormhole formation in the galactic halo due to dark matter using observational data within the matter coupling gravity formalism. Keeping this as a target, we specifically employ f(R, T) gravity with (i) a variational approach concerning the metric, and (ii) the anisotropic source of matter. To understand the features of the wormholes, we thoroughly calculated and analyzed the energy conditions under f(R, T) gravity. We discuss the second embedded wormhole solution, known as the generalized Ellis-Bronnikov spacetime (ultrastatic wormhole model), in terms of the tortoise coordinate. Thereafter we generate and compare different wormhole solutions depending on the parametric values. In the second part of our investigation, we presented dark matter halos and provided interesting features by considering a couple of profiles. For the dark matter halos models, we particularly use the observational data of the M87 galaxy and the Milky Way galaxy.

Keywords: Dark matter
Temperature Structures Associated with Different Components of the Atmospheric Circulation on Tidally Locked Exoplanets. Observations of time-resolved thermal emission from tidally locked exoplanets can tell us about their atmospheric temperature structure. Telescopes such as JWST and ARIEL will improve the quality and availability of these measurements. This motivates an improved understanding of the processes that determine atmospheric temperature structure, particularly atmospheric circulation. The circulation is important in determining atmospheric temperatures, not only through its ability to transport heat, but also because any circulation pattern needs to be balanced by horizontal pressure contrasts, therefore implying a particular temperature structure. In this work, we show how the global temperature field on a tidally locked planet can be decomposed into contributions that are balanced by different components of the atmospheric circulation. These are the superrotating jet, stationary Rossby waves, and the divergent circulation. To achieve this, we partition the geopotential field into components balanced by the divergent circulation and the rotational circulation, with the latter comprising the jet and Rossby waves. The partitioned geopotential then implies a corresponding partitioning of the temperature via the hydrostatic relation. We apply these diagnostics to idealized general circulation model simulations, to show how the separate rotational and divergent circulations together make up the total three-dimensional atmospheric temperature structure. We also show how each component contributes distinct signatures to the thermal phase curve of a tidally locked planet. We conclude that this decomposition is a physically meaningful separation of the temperature field that explains its global structure, and can be used to fit observations of thermal emission.

Keywords: Exoplanet atmospheres, Exoplanets, Atmospheric circulation
Dust Rings and Cavities in the Protoplanetary Disks around HD 163296 and DoAr 44. We model substructure in the protoplanetary disks around DoAr 44 and HD 163296 in order to better understand the conditions under which planets may form. We match archival millimeter-wavelength thermal emission against models of the disks' structure that are in radiation balance with the starlight heating and in vertical hydrostatic equilibrium, and then we compare to archival polarized scattered near-infrared images of the disks. The millimeter emission arises in the interior, while the scattered near-infrared radiation probes the disks' outer layers. Our best model of the HD 163296 disk has dust masses 81 ± 13 M ⊕ in the inner ring at 68 au and ${82}_{-16}^{+26}$ M ⊕ in the outer ring at 102 au, both falling within the range of estimates from previous studies. Our DoAr 44 model has total dust mass ${84}_{-3.5}^{+7.0}$ M ⊕. Unlike HD 163296, DoAr 44 as of yet has no detected planets. If the central cavity in the DoAr 44 disk is caused by a planet, the planet's mass must be at least 0.5 M J and is unlikely to be greater than 1.6 M J. We demonstrate that the DoAr 44 disk's structure with a bright ring offset within a fainter skirt can be formed by dust particles drifting through a plausible distribution of gas.

Keywords: Radiative transfer simulations, Protoplanetary disks, Planet formation
GRMHD Evolution of Interacting Double Accretion Tori Orbiting a Central Black Hole. The matter orbiting black holes (BHs) in microquasars or active galactic nuclei forms toroidal accretion disk structures, and multiple torus structures have been recently described as ringed accretion disks (RADs) in a full general relativistic approach. Here we realize full general relativistic magnetohydrodynamic (GRMHD) numerical simulations related to double toroidal structure immersed in the equatorial plane of the gravitomagnetic field of a central Schwarzschild BH in an asymptotically uniform magnetic field. We study the merging dynamics of an initial RAD structure constructed by two corotating or counterrotating tori, where accretion of matter from the outer torus is assumed onto the inner torus, using the 2.5D GRMHD simulation schemes with the HARM numerical code. We study the dynamics of the system assuming various initial conditions, and we have demonstrated that the initial matter density is the relevant factor governing the system evolution.

Keywords: Black hole physics
Uncertainty and Bias of Cosmology and Astrophysical Population Model from Statistical Dark Sirens. Gravitational-wave (GW) radiation from a coalescing compact binary is a standard siren, as the luminosity distance of each event can be directly measured from the amplitude of the signal. One possibility to constrain cosmology using the GW siren is to perform statistical inference on a population of binary black hole (BBH) events. In essence, this statistical method can be viewed as follows. We can modify the shape of the distribution of observed BBH events by changing the cosmological parameters until it eventually matches the distribution constructed from an astrophysical population model, thereby allowing us to determine the cosmological parameters. In this work, we derive the Cramér-Rao bound for both cosmological parameters and those governing the astrophysical population model from this statistical dark siren method by examining the Fisher information contained in the event distribution. Our study provides analytical insights and enables fast yet accurate estimations of the statistical accuracy of dark siren cosmology. Furthermore, we consider the bias in cosmology due to unmodeled substructures in the merger rate and mass distribution. We find that a 1% deviation in the astrophysical model can lead to a more than 1% error in the Hubble constant. This could limit the accuracy of dark siren cosmology when there are more than 104 BBH events detected.

Keywords: Hubble constant, Stellar mass black holes, Gravitational wave sources, Cosmological parameters
Meta-analysis of Photometric and Asteroseismic Measurements of Stellar Rotation Periods: The Lomb–Scargle Periodogram, Autocorrelation Function, and Wavelet and Rotational Splitting Analysis for 92 Kepler Asteroseismic Targets. We perform intensity variability analyses (photometric analyses: the Lomb–Scargle periodogram, autocorrelation, and wavelet) and asteroseismic analysis of 92 Kepler solar-like main-sequence stars to understand the reliability of the measured stellar rotation periods. We focus on the 70 stars without reported stellar companions, and classify them into four groups according to the quarter-to-quarter variance of the Lomb–Scargle period and the precision of the asteroseismic period. We present detailed individual comparison among photometric and asteroseismic constraints for these stars. We find that most of our targets exhibit significant quarter-to-quarter variances in the photometric periods, suggesting that the photometrically estimated period should be regarded as a simplified characterization of the true stellar rotation period, especially under the presence of the latitudinal differential rotation. On the other hand, there are a fraction of stars with a relatively small quarter-to-quarter variance in the photometric periods, most of which have consistent values for asteroseismically and photometrically estimated rotation periods. We also identify over 10 stars whose photometric and asteroseismic periods significantly disagree, which would be potentially interesting targets for further individual investigations.

Keywords: Stellar photometry, Starspots, Solar analogs, Astronomy data analysis, Stellar activity, Stellar rotation, Asteroseismology
Conditions for Proton Temperature Anisotropy to Drive Instabilities in the Solar Wind. Using high-resolution data from Solar Orbiter, we investigate the plasma conditions necessary for the proton temperature-anisotropy-driven mirror-mode and oblique firehose instabilities to occur in the solar wind. We find that the unstable plasma exhibits dependencies on the angle between the direction of the magnetic field and the bulk solar wind velocity which cannot be explained by the double-adiabatic expansion of the solar wind alone. The angle dependencies suggest that perpendicular heating in Alfvénic wind may be responsible. We quantify the occurrence rate of the two instabilities as a function of the length of unstable intervals as they are convected over the spacecraft. This analysis indicates that mirror-mode and oblique firehose instabilities require a spatial interval of length greater than 2-3 unstable wavelengths in order to relax the plasma into a marginally stable state and thus closer to thermodynamic equilibrium in the solar wind. Our analysis suggests that the conditions for these instabilities to act effectively vary locally on scales much shorter than the correlation length of solar wind turbulence.

Keywords: Space plasmas, Heliosphere, Plasma physics, Interplanetary turbulence, Solar wind, Alfven waves
Accretion Variability of the Multiple T Tauri System VW Cha. Classical T Tauri stars are low-mass objects that are still accreting material from the surrounding circumstellar disk. The accretion process is essential in the formation of Sun-like stars and in setting the properties of the disk at the time when planet formation occurs. We constructed a complex data set in order to examine the accretion process of VW Cha, a classical T Tauri multiple system, with the aim of studying the physical origin of the photometric and spectroscopic variability of the system. The TESS space telescope observed VW Cha between 2019 April 22 and June 19, and we complemented these data with contemporaneous ground-based I CJHK-band photometric measurements. In addition, we obtained high-resolution optical spectra with the VLT/ESPRESSO and the 2.2 m/FEROS instruments. Analyzing these data, we found that the TESS light curve shows photometric variations on timescales from minutes to weeks with a peak-to-peak amplitude of ~0.8 mag. The near-infrared light curves follow the shape of the optical measurements; however, the peak-to-peak amplitudes are slightly increasing toward the longer wavelengths. We took spectra in both fainter and brighter photometric states of the system, allowing us to examine the origin of a photometric brightening event. Our results show that this brightening event can be explained by increased accretion. In addition, our spectroscopic data also suggest that the primary component of VW Cha is a spectroscopic binary, as was proposed in earlier works.

Keywords: Circumstellar disks, Classical T Tauri stars, Pre-main sequence stars, Star formation, Variable stars, Pre-main sequence, Stellar accretion
A Population III-Generated Dust Screen at z   16. The search for alternative cosmological models is largely motivated by the growing discordance between the predictions of ΛCDM and the ever-improving observations, such as the disparity in the value of H 0 measured at low and high redshifts. One model in particular, known as the R h = ct universe, has been highly successful in mitigating or removing all of the inconsistencies. In this picture, however, the anisotropies in the cosmic microwave background (CMB) would have emerged at a redshift z ~ 16, rather than via fluctuations in the recombination zone at z ~ 1080. We demonstrate here that a CMB created in the early universe, followed by scattering through a Population III-generated dust screen, is consistent with all of the current data. Indeed, the Planck measurements provide a hint of an ~2%-4% frequency dependence in the CMB power spectrum, which would be naturally explained as a variation in the optical depth through the dust but not a Thomson scattering-dominated recombination environment. Upcoming measurements should be able to easily distinguish between these two scenarios, e.g., via the detection of recombination lines at z ~ 1080, which would completely eliminate the dust-reprocessing idea.

Keywords: Population III stars, Large-scale structure of the universe, Cosmological parameters, Cosmic microwave background radiation, Reionization
Searching for Candidates of Coalescing Binary Black Holes Formed through Chemically Homogeneous Evolution in GWTC-3. The LIGO, Virgo, and KAGRA (LVK) Collaboration has announced 90 coalescing binary black holes (BBHs) with p astro &gt; 50% to date; however, the origin of their formation channels is still an open scientific question. Given various properties of BBHs (BH component masses and individual spins) inferred using the default priors by the LVK, independent groups have been trying to explain the formation of the BBHs with different formation channels. Of all formation scenarios, the chemically homogeneous evolution (CHE) channel has stood out with distinguishing features, namely, nearly equal component masses and preferentially high individual spins aligned with the orbital angular momentum. We perform Bayesian inference on the BBH events officially reported in GWTC-3 with astrophysically predicted priors representing different formation channels of the isolated binary evolution (common-envelope evolution channel, CEE; CHE; stable mass transfer, SMT). Given assumed models, we report strong evidence for GW190517_055101 being most likely to have formed through the CHE channel. Assuming the BBH events in the subsample are all formed through one of the isolated binary evolution channels, we obtain the lower limits on the local merger rate density of these channels at 11.45 Gpc-3 yr-1 (CEE), 0.18 Gpc-3 yr-1 (CHE), and 0.63 Gpc-3 yr-1 (SMT) at 90% credible level.

Keywords: Close binary stars, Stellar mass black holes, Gravitational wave sources
Brighter and More Massive Galaxies in the Vicinity of Lyα Nebulae. It has been well established in the local universe that galaxy properties differ based on the large-scale environment in which they reside. As luminous Lyα nebulae have been shown to trace overdense environments at z ~ 2-3, comparing the properties of galaxies within Lyα nebulae systems to those in the field can provide insight into how and when locally observed trends between galaxy properties and environment emerged. Six Lyα nebulae were discovered at z ~ 2.3 in a blind search of the GOODS-S extragalactic field, a region also covered by the 3D-HST spectroscopic survey. Utilizing 3D-HST data, we identified 86 galaxies in the vicinity of these nebulae and used statistical tests to compare their physical properties to galaxies elsewhere in the field. Galaxies lying within 320 proper kpc of a Lyα nebula are roughly half a magnitude brighter than those in the field, with higher stellar masses, higher star formation rates, and larger effective radii. Even when considering the effects of sample incompleteness, our study suggests that galaxies in overdensities at z ~ 2.3 traced by Lyα nebulae are being influenced by their environment. Furthermore, Lyα-nebula-associated galaxies lie on the same main sequence of star formation as field galaxies but have a larger proportion of high-mass galaxies, consistent with the idea that galaxy evolution is accelerated in rich environments. Expanded surveys for Lyα nebulae in other deep extragalactic fields and galaxy spectroscopic follow-up with the James Webb Space Telescope (JWST) will better constrain the demographics of Lyα-nebula-associated galaxies.

Keywords: Protoclusters, High-redshift galaxies, Galaxy evolution, Galaxy environments
Deep Narrowband Photometry of the M101 Group: Strong-line Abundances of 720 H II Regions. We present deep, narrowband imaging of the nearby spiral galaxy M101 and its satellites to analyze the oxygen abundances of their H II regions. Using Case Western Reserve University's Burrell Schmidt telescope, we add to the narrowband data set of the M101 Group, consisting of Hα, Hβ, and [O III] emission lines and the blue [O II] λ3727 emission line for the first time. This allows for complete spatial coverage of the oxygen abundance of the entire M101 Group. We used the strong-line ratio R 23 to estimate oxygen abundances for the H II regions in our sample, utilizing three different calibration techniques to provide a baseline estimate of the oxygen abundances. This results in ~650 H II regions for M101, 10 H II regions for NGC 5477, and ~60 H II regions for NGC 5474, the largest sample for this Group to date. M101 shows a strong abundance gradient, while the satellite galaxies present little or no gradient. There is some evidence for a flattening of the gradient in M101 beyond R ~ 14 kpc. Additionally, M101 shows signs of azimuthal abundance variations to the west and southwest. The radial and azimuthal abundance variations in M101 are likely explained by an interaction it had with its most massive satellite, NGC 5474, ~300 Myr ago combined with internal dynamical effects such as corotation.

Keywords: Galaxy dynamics, Chemical abundances, Galaxy abundances, Narrow band photometry, Interacting galaxies
Effect of Dark Matter Distribution on Scalaron Gravity near the Galactic Center Black Hole and Its Prospects. In this paper, we report the effect of exponential and power-law dark matter density profiles near the Galactic Center black hole on the relative scalaron field amplitude , ψ 0/ϕ (ϕ being Newtonian potential and ψ 0 being the scalaron field amplitude), of f(R) gravity theory. Constraints on the density profiles derived earlier on the basis of orbital motion of the S-2 star are used in conjunction with scalarons having a mass range 10-22-10-16 eV to investigate the dependency of screening or unscreening of modified gravity on the dark matter density through the condition that the rate of pericenter shift due to dark matter is equal to that due to scalaron gravity + general relativistic effects. The semimajor axes are chosen as a = 45 au, 100 au, and 1000 au. It is found that scalarons get screened for extremely low and extremely high mass. This is found to be independent of the black hole spin in the range (χ = 0.1-0.9). For wider orbits scalarons of almost all the masses tend to remain unscreened for the dark matter profiles. It has been found that low dark matter density has a natural tendency to unscreen the scalaron gravity with extremely small coupling strength. We remap screened gravity in the available observational constraints on the scale of modified gravity near the black hole. Astrophysical prospects are presented.

Keywords: Gravitation, Black hole physics, Galactic center, Dark matter
The Fermi Paradox Revisited: Technosignatures and the Contact Era. A new solution to the Fermi Paradox is presented: probes or visits from putative alien civilizations have a very low probability until a civilization reaches a certain age (called the "Contact Era") after the onset of radio communications. If biotic planets are common, putative advanced civilizations may send probes not to any planet showing biosignatures, but rather to planets with technosignatures, such as radio broadcasts. The contact probability is defined as the chance to find a nearby civilization located close enough so that it could have detected the earliest radio emissions (the "radiosphere") and sent a probe that would reach the solar system at present. It is found that the current contact probability for Earth is very low unless civilizations are extremely abundant. Since the radiosphere expands with time, so does the contact probability. The Contact Era is defined as the time (since the onset of radio transmissions) at which the contact probability becomes of order unity. At that time alien probes (or messages) become more likely. Unless civilizations are highly abundant, the Contact Era is shown to be of the order of a few hundred to a few thousand years and may be applied not only to physical probes but also to transmissions (i.e., search for extraterrestrial intelligence). Consequently, it is shown that civilizations are unlikely to be able to intercommunicate unless their communicative lifetime is at least a few thousand years.

Keywords: Exoplanet astronomy, Astrobiology, Habitable planets
The Circumgalactic Hα Spectrograph (CHαS). I. Design, Engineering, and Early Commissioning. The Circumgalactic Hα Spectrograph (CHαS) is a ground-based optical integral field spectrograph designed to detect ultrafaint extended emission from diffuse ionized gas in the nearby universe. CHαS is particularly well suited for making direct detections of tenuous Hα emission from the circumgalactic medium (CGM) surrounding low-redshift galaxies. It efficiently maps large regions of the CGM in a single exposure, targeting nearby galaxies (d &lt; 35 Mpc) where the CGM is expected to fill the field of view. We are commissioning CHαS as a facility instrument at MDM Observatory. CHαS is deployed in the focal plane of the Hiltner 2.4 m telescope, utilizing nearly all of the telescope's unvignetted focal plane (10'-15') to conduct wide-field spectroscopic imaging. The catadioptric design provides excellent wide-field imaging performance. CHαS is a pupil-imaging spectrograph employing a microlens array to divide the field of view into &gt;60,000 spectra. CHαS achieves an angular resolution of [1.3-2.6] arcseconds and a resolving power of R = [10,000-20,000]. Accordingly, the spectrograph can resolve structure on the scale of 1-5 kpc (at 10 Mpc) and measure velocities down to 15-30 km s-1. CHαS intentionally operates over a narrow (30 Å) bandpass; however, it is configured to adjust the central wavelength and target a broad range of optical emission lines individually. A high-diffraction efficiency volume phase holographic grating ensures high throughput across configurations. CHαS maintains a high grasp and moderate spectral resolution, providing an ideal combination for mapping discrete, ultralow-surface brightness emission on the order of a few milli-Rayleigh.

Keywords: Astronomical instrumentation, Spectroscopy, Circumgalactic medium