Sazuna/UAT_keywords huggingface dataset:
The Nature of Ultra-diffuse Galaxies in Distant Massive Galaxy Clusters: A370 in the Hubble Frontier Fields. We report the discovery of ultra-diffuse galaxies (UDGs) in Abell 370 (A370; z = 0.375). We find 46 UDGs in A370 from the images of the Hubble Frontier Fields. Most UDGs are low-luminosity red sequence galaxies, while a few of them are blue UDGs. We estimate the abundance of UDGs in A370, N(UDG) = 644 ± 104. Combining these results with those of Abell S1063 (z = 0.348) and Abell 2744 (z = 0.308), we derive a mean radial number density profile of UDGs in the three clusters. The number density profiles of UDGs and bright galaxies show a discrepancy in the central region of the clusters: the profile of UDGs shows a flattening as clustercentric distance decreases, while that of bright galaxies shows a continuous increase. This implies that UDGs are prone to disruption in the central region of the clusters. The relation between the abundance of UDGs and virial masses of their host systems is described by a power law with an index of nearly one: $N({\rm{UDG}})\propto {M}_{200}^{0.99\pm 0.05}$ for M200 &gt; 1013 M⊙. We estimate approximately dynamical masses of UDGs using the fundamental manifold method and find that most UDGs have dwarf-like masses (M200 &lt; 1011M⊙). This implies that most UDGs have a dwarf-like origin and a small number of them could be failed L* galaxies. These results suggest that multiple origins may contribute to the formation and evolution of UDGs in massive galaxy clusters.

Keywords: Galaxy clusters, Dwarf galaxies, Low surface brightness galaxies
The MESAS Project: ALMA Observations of the F-type Stars γ Lep, γ Vir A, and γ Vir B. The spectrum of stars in the submillimeter to centimeter wavelength range remains poorly constrained due to a lack of data for most spectral types. An accurate characterization of stellar emission in this regime is needed to test stellar atmosphere models, and is also essential for revealing emission associated with unresolved circumstellar debris. We present Atacama Large Millimeter/submillimeter Array observations of the three nearby, main-sequence, debris-poor, F-type stars γ Lep, γ Vir A, and γ Vir B at 0.87 and 1.29 mm. We use these data to constrain semiempirical atmospheric models. We discuss the atmospheric structure of these stars, explore potential short-term variability, and the potential impact on debris disk studies. These results are part of an ongoing campaign to obtain long wavelength observations of debris-poor stars, entitled Measuring the Emission of Stellar Atmospheres at Submillimeter/millimeter wavelengths.

Keywords: Millimeter astronomy, Radio continuum emission, Submillimeter astronomy, Debris disks, Stellar atmospheres
Curious Changes in Association of Complex Sunspot Groups with X-Ray Flares (≥M1) in Solar Cycles 22-24. We investigate the variations in the probabilities of complex sunspot groups (SGs)—large, asymmetric, or δ-type SGs—producing X-ray flares (≥M1) in solar cycles (SCs) 22, 23, and 24 based on the SG data collected by the United States Air Force/Mount Wilson Observatory and the flare data recorded by Geostationary Operational Environmental Satellites. The following are the main findings. (1) For complex SGs in the whole disk as well as the northern and southern hemispheres during SC 22, their numbers and probabilities of producing flares change almost synchronously. (2) For complex SGs during SC 23, probabilities of producing flares during the early declining phase in the whole disk do not decrease with decreasing complex SG number; in the northern hemisphere, the probability of producing flares during the declining phase is significantly higher than that during the maximum phase; in the southern hemisphere, there is no definite variation trend in the probabilities of producing flares during the maximum and declining phases. (3) For complex SGs during SC 24, the probabilities of producing flares during the later rising and early declining phases are significantly higher than or comparable to those during the maximum phase no matter how their numbers change; in the northern hemisphere, the probability of producing flares during the rising phase is significantly higher than or at least comparable to that during the maximum phase; in the southern hemisphere, there is no definite variation trend in the probabilities of producing flares during the maximum and declining phases.

Keywords: Solar cycle, Sunspot groups, Solar x-ray flares
Finding Strong Gravitational Lenses in the DESI DECam Legacy Survey. We perform a semi-automated search for strong gravitational lensing systems in the 9000 deg2 Dark Energy Camera Legacy Survey (DECaLS), part of the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys. The combination of the depth and breadth of these surveys are unparalleled at this time, making them particularly suitable for discovering new strong gravitational lensing systems. We adopt the deep residual neural network architecture developed by Lanusse et al. for the purpose of finding strong lenses in photometric surveys. We compile a training sample that consists of known lensing systems in the Legacy Surveys and the Dark Energy Survey as well as non-lenses in the footprint of DECaLS. In this paper we show the results of applying our trained neural network to the cutout images centered on galaxies typed as ellipticals in DECaLS. The images that receive the highest scores (probabilities) are visually inspected and ranked. Here we present 335 candidate strong lensing systems, identified for the first time.

Keywords: Galaxy clusters, Strong gravitational lensing, Galaxy groups, High-redshift galaxies, Galaxies
Using Transverse Waves to Probe the Plasma Conditions at the Base of the Solar Wind. It has long been suggested that magnetohydrodynamic (MHD) waves may supply a significant proportion of the energy required to heat the corona and accelerate the solar wind. Depending on the properties of the local plasma, MHD wave modes may exhibit themselves as a variety of incompressible, transverse waves. The local magnetic field and particle density influence the properties of these waves (e.g., amplitude), thus direct measurements of transverse waves provide a mechanism to indirectly probe the local plasma conditions. We present the first statistical approach to magnetoseismology of a localized region of the solar corona, analyzing transverse waves above the south polar coronal hole on 2011 May 23. Automated methods are utilized to examine 4 hr of EUV imaging data to study how the waves evolve as a function of height (I.e., altitude) through the low corona. Between heights of 15 and 35 Mm, we find that the measured wave periods are approximately constant, and that observed displacement and velocity amplitudes increase at rates that are consistent with undamped waves. This enables us to derive a relative density profile for the coronal hole environment in question, without the use of spectroscopic data. Furthermore, our results indicate that between 5 and 15 Mm above the limb, the relative density is larger than that expected from 1D hydrostatic models, and signals a more extended transition region with a gradual change in density. This has implications for self-consistent models of wave propagation from the photosphere to the corona and beyond.

Keywords: Solar coronal holes, Solar coronal plumes, Solar coronal waves, Solar extreme ultraviolet emission
A Method for the Estimation of f- and p-mode Parameters and Rotational Splitting Coefficients from Un-averaged Solar Oscillation Power Spectra. We present a new methodology for the fitting of the peaks in solar oscillation power spectra that is equally well-suited for the estimation of low-, medium, and high-degree f- and p-mode parameters and frequency-splitting coefficients. The method can provide accurate input data over a wide portion of the dispersion plane for both structural and rotational inversions. This method, which we call the Multiple-Peak, Tesseral-Spectrum (MPTS) method, operates directly upon of all of the modes in a multiplet (n, l) of radial order n and degree l, and employs a fitting profile that consists of the sum of numerous individual overlapping profiles whose relative amplitudes are determined by the leakage matrix appropriate to the targeted mode. Hence, 2l + 1 sets of modal parameters are obtained simultaneously for each multiplet (n, l). By fitting an appropriate polynomial to the run of the fitted frequencies versus the azimuthal order, frequency-splitting coefficients are also obtained for the same multiplet. Using power spectra obtained from the 66 day long 2010 MDI Dynamics Run, we present sample structural and rotational inversions that employed frequencies and frequency-splitting coefficients from modes in the degree range of 0-1000 and the frequency range of 965-4600 μHz. The structural inversion confirms evidence for a pronounced departure of the sound speed in the outer solar convection zone from the radial sound-speed profile contained in Model S of Christensen-Dalsgaard and his collaborators that we obtained previously using a different fitting method.

Keywords: Helioseismology, The Sun, Astronomy data analysis
Atmospheric Convection Plays a Key Role in the Climate of Tidally Locked Terrestrial Exoplanets: Insights from High-resolution Simulations. Using a 3D general circulation model (GCM), we investigate the sensitivity of the climate of tidally locked Earthlike exoplanets, Trappist-1e and Proxima Centauri b, to the choice of a convection parameterization. Compared to a mass-flux convection parameterization, a simplified convection adjustment parameterization leads to a &gt;60% decrease of the cloud albedo, increasing the mean dayside temperature by $\approx 10\,{\rm{K}}$ . The representation of convection also affects the atmospheric conditions of the night side, via a change in planetary-scale wave patterns. As a result, using the convection adjustment scheme makes the nightside cold traps warmer by 17-36 K for the planets in our simulations. The day-night thermal contrast is sensitive to the representation of convection in 3D GCM simulations, so caution should be taken when interpreting emission phase curves. The choice of convection treatment, however, does not alter the simulated climate enough to result in a departure from habitable conditions, at least for the atmospheric composition and planetary parameters used in our study. The near-surface conditions both in the Trappist-1e and Proxima b cases remain temperate, allowing for an active water cycle. We further advance our analysis using high-resolution model experiments, in which atmospheric convection is simulated explicitly. Our results suggest that in a hypothetical global convection-permitting simulation, the surface temperature contrast would be higher than in the coarse-resolution simulations with parameterized convection. In other words, models with parameterized convection may overestimate the inter-hemispheric heat redistribution efficiency.

Keywords: Water vapor, Atmospheric circulation, Planetary atmospheres, Habitable zone, Habitable planets, Exoplanet atmospheres
Initiation and Early Kinematic Evolution of Solar Eruptions. We investigate the initiation and early evolution of 12 solar eruptions, including six active-region hot channel and six quiescent filament eruptions, which were well observed by the Solar Dynamics Observatory, as well as by the Solar Terrestrial Relations Observatory for the latter. The sample includes one failed eruption and 11 coronal mass ejections, with velocities ranging from 493 to 2140 km s-1. A detailed analysis of the eruption kinematics yields the following main results. (1) The early evolution of all events consists of a slow-rise phase followed by a main-acceleration phase, the height-time profiles of which differ markedly and can be best fit, respectively, by a linear and an exponential function. This indicates that different physical processes dominate in these phases, which is at variance with models that involve a single process. (2) The kinematic evolution of the eruptions tends to be synchronized with the flare light curve in both phases. The synchronization is often but not always close. A delayed onset of the impulsive flare phase is found in the majority of the filament eruptions (five out of six). This delay and its trend to be larger for slower eruptions favor ideal MHD instability models. (3) The average decay index at the onset heights of the main acceleration is close to the threshold of the torus instability for both groups of events (although, it is based on a tentative coronal field model for the hot channels), suggesting that this instability initiates and possibly drives the main acceleration.

Keywords: Solar storm, Solar coronal mass ejections, Stellar coronal mass ejections
Optical and Infrared Study of the Obscured B[e] Supergiant High-mass X-Ray Binary IGR J16318-4848. The supergiant high-mass X-ray binary IGR J16318-4848 was the first source detected by the INTErnational Gamma-Ray Astrophysics Laboratory satellite in 2003 and distinguishes itself by its high intrinsic absorption and B[e] phenomenon. It is the perfect candidate to study both binary interaction and the environment of supergiant B[e] stars. This study targets the local properties of IGR J16318-4848. We aim to clarify the geometry of this system and distinguish different key emitting regions in the binary. We provide optical to near-infrared (NIR) spectra from the Very Large Telescope/X-Shooter and analyze both fine structures of the lines and the broadband spectral energy distribution by adding archival mid-infrared Spitzer and Herschel data. We also perform a stellar atmosphere and wind modeling of the optical to NIR spectrum using the Potsdam Wolf-Rayet code. We determine the contribution of the irradiated inner edge of the dusty circumbinary disk, derive the velocity of an equatorial stellar wind, and suggest the compact object orbits within the cavity between the star and the disk. We report on flat-topped lines originating from a spherically symmetric disk wind, along with the first detection of what is likely the polar component of the stellar wind. Stellar atmosphere and wind modeling shows that the central star may have a helium-enhanced atmosphere, likely because of its intense wind shedding part of its hydrogen envelope. Finally, we compare the properties of IGR J16318-4848 with a similar source, CI Cameleopardis. * Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 089.D-0056.

Keywords: Optical observation, High mass x-ray binary stars, Stellar winds, Stellar atmospheres, Near infrared astronomy
The γ-Ray Emission of Star-forming Galaxies. A majority of the γ-ray emission from star-forming galaxies is generated by the interaction of high-energy cosmic rays with the interstellar gas and radiation fields. Star-forming galaxies are expected to contribute to both the extragalactic γ-ray background and the IceCube astrophysical neutrino flux. Using roughly 10 yr of γ-ray data taken by the Fermi Large Area Telescope, in this study we constrain the γ-ray properties of star-forming galaxies. We report the detection of 11 bona fide γ-ray-emitting galaxies and 2 candidates. Moreover, we show that the cumulative γ-ray emission of below-threshold galaxies is also significantly detected at ∼5σ confidence. The γ-ray luminosity of resolved and unresolved galaxies is found to correlate with the total (8-1000 μm) infrared luminosity as previously determined. Above 1 GeV, the spectral energy distribution of resolved and unresolved galaxies is found to be compatible with a power law with a photon index of ≈2.2-2.3. Finally, we find that star-forming galaxies account for roughly 5% and 3% of the extragalactic γ-ray background and the IceCube neutrino flux, respectively.

Keywords: Starburst galaxies, Neutrino astronomy, Gamma-rays
Particle Acceleration and Transport during 3D CME Eruptions. We calculate particle acceleration during coronal mass ejection (CME) eruptions using combined magnetohydrodynamic and test-particle models. The 2.5D/3D CMEs are generated via the breakout mechanism. In this scenario a reconnection at the "breakout" current sheet (CS) above the flux rope initiates the CME eruption by destabilizing a quasi-static force balance. Reconnection at the flare CS below the erupting flux rope drives the fast acceleration of the CME, which forms flare loops below and produces the energetic particles observed in flares. For test-particle simulations, two times are selected during the impulsive and decay phases of the eruption. Particles are revealed to be accelerated more efficiently in the flare CS rather than in the breakout CS even in the presence of large magnetic islands. Particles are first accelerated in the CSs (with or without magnetic islands) by the reconnection electric field mainly through particle curvature drift. We find, as expected, that accelerated particles precipitate into the chromosphere, become trapped in the loop top by magnetic mirrors, or escape to interplanetary space along open field lines. Some trapped particles are reaccelerated, either via reinjection to the flare CS or through a local Betatron-type acceleration associated with compression of the magnetic field. The energetic particles produce relatively hard energy spectra during the impulsive phase. During the gradual phase, the relaxation of magnetic field shear reduces the guiding field in the flare CS, which leads to a decrease in particle energization efficiency. Important implications of our results for observations of particle acceleration in the solar coronal jets are also discussed.

Keywords: Solar coronal mass ejections, Solar flares, Solar magnetic reconnection
Energy Dissipation in Coronal Loops: Statistical Analysis of Intermittent Structures in Magnetohydrodynamic Turbulence. The power-law energy distribution observed in dissipation events ranging from flares down to nanoflares has been associated either to intermittent turbulence or to self-organized criticality. Despite the many studies conducted in recent years, it is unclear whether these two paradigms are mutually exclusive or they are complementary manifestations of the complexity of the system. We numerically integrate the magnetohydrodynamic equations to simulate the dynamics of coronal loops driven at their bases by footpoint motions. After a few photospheric turnover times, a stationary turbulent regime is reached, displaying a broadband power spectrum and a dissipation rate consistent with the cooling rates of the plasma confined in these loops. Our main goal is to determine whether the intermittent features observed in this turbulent flow can also be regarded as manifestations of self-organized criticality. A statistical analysis of the energy, area, and lifetime of the dissipative structures observed in these simulations displays robust scaling laws. We calculated the critical exponents characterizing the avalanche dynamics, and the spreading exponents that quantify the growth of these structures over time. In this work we also calculate the remaining critical exponents for several activity thresholds and verify that they satisfy the conservation relations predicted for self-organized critical systems. These results can therefore be regarded as a bona fide test supporting that the stationary turbulent regimes characterizing coronal loops also correspond to states of self-organized criticality.

Keywords: Interplanetary turbulence, Solar coronal heating
The MOSDEF Survey: Kinematic and Structural Evolution of Star-forming Galaxies at 1.4 ≤ z ≤ 3.8. We present ionized gas kinematics for 681 galaxies at $z\sim 1.4\mbox{--}3.8$ from the MOSFIRE Deep Evolution Field survey, measured using models that account for random galaxy-slit misalignments together with structural parameters derived from CANDELS Hubble Space Telescope (HST) imaging. Kinematics and sizes are used to derive dynamical masses. Baryonic masses are estimated from stellar masses and inferred gas masses from dust-corrected star formation rates (SFRs) and the Kennicutt-Schmidt relation. We measure resolved rotation for 105 galaxies. For the remaining 576 galaxies we use models based on HST imaging structural parameters together with integrated velocity dispersions and baryonic masses to statistically constrain the median ratio of intrinsic ordered to disordered motion, $V/{\sigma }_{V,0}$ . We find that $V/{\sigma }_{V,0}$ increases with increasing stellar mass and decreasing specific SFR (sSFR). These trends may reflect marginal disk stability, where systems with higher gas fractions have thicker disks. For galaxies with detected rotation we assess trends between their kinematics and mass, sSFR, and baryon surface density ( ${{\rm{\Sigma }}}_{\mathrm{bar},e}$). Intrinsic dispersion correlates most with ${{\rm{\Sigma }}}_{\mathrm{bar},e}$ , and velocity correlates most with mass. By comparing dynamical and baryonic masses, we find that galaxies at $z\sim 1.4\mbox{--}3.8$ are baryon dominated within their effective radii ( ${R}_{E}$), with ${M}_{\mathrm{dyn}}$ / ${M}_{\mathrm{baryon}}$ increasing over time. The inferred baryon fractions within ${R}_{E}$ , ${f}_{\mathrm{bar}}$ , decrease over time, even at fixed mass, size, or surface density. At fixed redshift, ${f}_{\mathrm{bar}}$ does not appear to vary with stellar mass but increases with decreasing ${R}_{E}$ and increasing ${{\rm{\Sigma }}}_{\mathrm{bar},e}$ . For galaxies at $z\gtrsim 2$ , the median inferred baryon fractions generally exceed 100%. We discuss possible explanations and future avenues to resolve this tension.

Keywords: Galaxy evolution, Galaxy dynamics, Galaxy kinematics, High-redshift galaxies
Direct Measurement of the H I-halo Mass Relation through Stacking. We present accurate measurements of the total H I mass in dark matter halos of different masses at z ∼ 0, by stacking the H I spectra of entire groups from the Arecibo Fast Legacy ALFA Survey. The halos are selected from the optical galaxy group catalog constructed from the Sloan Digital Sky Survey DR7 Main Galaxy sample, with reliable measurements of halo mass and halo membership. We find that the H I-halo mass relation is not a simple monotonic function, as assumed in several theoretical models. In addition to the dependence of halo mass, the total H I gas mass shows a strong dependence on the halo richness, with larger H I masses in groups with more members at fixed halo masses. Moreover, halos with at least three member galaxies in the group catalog have a sharp decrease of the H I mass, potentially caused by the virial halo shock-heating and the active galactic nucleus (AGN) feedback. The dominant contribution of the H I gas comes from the central galaxies for halos of ${M}_{{\rm{h}}}\lt {10}^{12.5}{h}^{-1}{M}_{\odot }$ , while the satellite galaxies dominate over more massive halos. Our measurements are consistent with a three-phase formation scenario of the H I-rich galaxies. The smooth cold gas accretion is driving the H I mass growth in halos of ${M}_{{\rm{h}}}\lt {10}^{11.8}{h}^{-1}{M}_{\odot }$ , with late-forming halos having more H I accreted. The virial halo shock-heating and AGN feedback will take effect to reduce the H I supply in halos of ${10}^{11.8}{h}^{-1}{M}_{\odot }\lt {M}_{{\rm{h}}}\lt {10}^{13}{h}^{-1}{M}_{\odot }$ . The H I mass in halos more massive than ${10}^{13}{h}^{-1}{M}_{\odot }$ generally grows by mergers, with the dependence on halo richness becoming much weaker.

Keywords: Galaxy dark matter halos, Galaxy environments, Galactic and extragalactic astronomy, H I line emission, Active galactic nuclei, Galaxy groups, Galaxy accretion, Circumgalactic medium