Sazuna/UAT_keywords huggingface dataset:
The Cepheid Distance to the Seyfert 1 Galaxy NGC 4151. We derive a distance of 15.8 ± 0.4 Mpc to the archetypal Seyfert 1 galaxy NGC 4151 based on the near-infrared Cepheid period-luminosity relation and new Hubble Space Telescope multiband imaging. This distance determination, based on measurements of 35 long-period (P &gt; 25 days) Cepheids, will support the absolute calibration of the supermassive black hole mass in this system, as well as studies of the dynamics of the feedback or feeding of its active galactic nucleus.

Keywords: AGN host galaxies, Galaxy distances, Hubble Space Telescope, Distance measure, HST photometry, Distance indicators, Cepheid variable stars, Cepheid distance, Optical observatories, Time series analysis, Near infrared astronomy
Atmospheric Circulation of Tidally Locked Gas Giants with Increasing Rotation and Implications for White Dwarf-Brown Dwarf Systems. Tidally locked gas giants, which exhibit a novel regime of day-night thermal forcing and extreme stellar irradiation, are typically in several-day orbits, implying a modest role for rotation in the atmospheric circulation. Nevertheless, there exist a class of gas-giant, highly irradiated objects—brown dwarfs orbiting white dwarfs in extremely tight orbits—whose orbital and hence rotation periods are as short as 1-2 hr. Phase curves and other observations have already been obtained for this class of objects, raising fundamental questions about the role of an increasing planetary rotation rate in controlling the circulation. So far, most modeling studies have investigated rotation periods exceeding a day, as appropriate for typical hot Jupiters. In this work, we investigate atmospheric circulation of tidally locked atmospheres with decreasing rotation periods (increasing rotation rate) down to 2.5 hr. With a decreasing rotation period, we show that the width of the equatorial eastward jet decreases, consistent with the narrowing of the equatorial waveguide due to a decrease of the equatorial deformation radius. The eastward-shifted equatorial hot-spot offset decreases accordingly, and the off-equatorial westward-shifted hot areas become increasingly distinctive. At high latitudes, winds become weaker and more rotationally dominated. The day-night temperature contrast becomes larger due to the stronger influence of rotation. Our simulated atmospheres exhibit variability, presumably caused by instabilities and wave interactions. Unlike typical hot Jupiter models, the thermal phase curves of rapidly rotating models show a near alignment of peak flux to secondary eclipse. This result helps to explain why, unlike hot Jupiters, brown dwarfs closely orbiting white dwarfs tend to exhibit IR flux peaks nearly aligned with secondary eclipse. Our results have important implications for understanding fast-rotating, tidally locked atmospheres.

Keywords: Brown dwarfs, Hydrodynamics, Hot Jupiters, White dwarf stars, Exoplanet atmospheres
Extraplanar Gas in Edge-on Galaxies Traced by SOFIA Observations of [C II]. Bursts of localized star formation in galaxies can levitate material from the midplane. Spiral galaxies that are edge-on allow a clear distinction of material that is levitated off the galaxies' midplanes. We used SOFIA to measure the vertical distribution of [C II] 157.7 μm line emission for two nearby, edge-on galaxies, NGC 891 and NGC 5907. We find that for the central region and actively star-forming regions in the northern portion of NGC 891, and for NGC 5907, a thin (0.3 kpc) disk is supplemented by a thick disk with an exponential scale height of ∼2 kpc. The [C II] is far more extended than mid-infrared emission (0.1 kpc, tracing present-day massive star formation) but not as extended as the H I (100 kpc, tracing low-metallicity circum/intergalactic matter). The extraplanar [C II] may arise in walls of chimneys that connect the disk to the halo.

Keywords: Disk galaxies, Spiral galaxies, Galaxies, Circumgalactic medium
Multifrequency Observations of the Candidate Neutrino-emitting Blazar BZB J0955+3551. The recent spatial and temporal coincidence of the blazar TXS 0506+056 with the IceCube-detected neutrino event IC-170922A has opened up a realm of multimessenger astronomy with blazar jets as a plausible site of cosmic-ray acceleration. After TXS 0506+056, a second blazar, BZB J0955+3551, was recently found to be spatially coincident with the IceCube-detected neutrino event IC-200107A and undergoing its brightest X-ray flare measured so far. Here we present the results of our multifrequency campaign to study this peculiar event that includes observations with the NuSTAR, Swift, Neutron star Interior Composition Explorer (NICER), and 10.4 m Gran Telescopio Canarias (GTC). The optical spectroscopic observation from GTC secured its redshift as $z={0.55703}_{-0.00021}^{+0.00033}$ and the central black hole mass as ${10}^{8.90\pm 0.16}$ ${M}_{\odot }$ . Both NuSTAR and NICER data reveal a rapid flux variability, albeit at low significance ( $\lesssim 3.5\sigma $ ). We explore the origin of the target photon field needed for the photopion production using analytical calculations and considering the observed optical-to-X-ray flux level. We conclude that seed photons may originate from outside the jet, similar to that reported for TXS 0506+056, although a scenario invoking a comoving target photon field (e.g., electron synchrotron) cannot be ruled out. The electromagnetic output from the neutrino-producing photohadronic processes are likely to make only a subdominant contribution to the observed spectral energy distribution, suggesting that the X-ray flaring event may not be directly connected with IC-200107A.

Keywords: Neutrino astronomy, Relativistic jets, BL Lacertae objects, X-ray active galactic nuclei
Center-to-limb Variation of the Inverse Evershed Flow. We present the properties of the inverse Evershed flow (IEF) based on the center-to-limb variation of the plasma speed and loop geometry of chromospheric superpenumbral fibrils in eleven sunspots that were located at a wide range of heliocentric angles from 12° to 79°. The observations were acquired at the Dunn Solar Telescope in the spectral line of Hα at 656 nm to determine chromospheric flows and the photospheric Si I line at 1082.7 nm to estimate the photospheric umbral magnetic field strength. All sunspots display opposite line-of-sight (LOS) velocities on the limb and center side with a distinct shock signature near the outer penumbral edge. We developed a simplified flexible sunspot model assuming axisymmetry and prescribing the radial flow speed profile at a known loop geometry to replicate the observed two-dimensional IEF patterns under different viewing angles. The simulated flow maps match the observations for chromospheric loops with 10-20 Mm length starting at 0.8-1.1 sunspot radii, an apex height of 1-3 Mm, and a flow speed of 2-9 km s-1. We find on average a good agreement of the simulated velocities and the observations on elliptical annuli around the sunspot. Individual IEF channels show a significant range of variation in their properties and reach maximal LOS speeds of up to 12 km s-1. Upwards or downwards directed flows do not show a change of sign in the LOS velocities for heliocentric angles above 30°. Our results are consistent with the IEF being caused by a siphon flow mechanism driving a flow at about sonic speed along elevated loops with a flattened top in the chromosphere.

Keywords: Sunspots, Solar chromosphere, Solar photosphere
On the Coronal Temperature in Solar Microflares. We present a study of solar imaging and spectral observations of a microflare, focusing on the temperature diagnostics provided by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, and the Extreme-Ultraviolet Imaging Spectrometer (EIS) on board Hinode. Our data analysis, in particular from the emission in the 131 and 94 Å channels, indicates that the heated plasma reaches temperatures of ≳10 MK, at odds with a previous analysis of the same event, and we discuss the reason for the discrepancy. A particularly interesting aspect is the likely presence of the Fe XXIII 263.76 Å line, though weak, in EIS spectra in the early phases of the event, supporting the presence of high temperature plasma. Hydrodynamic 1D modeling of a single loop heated with a 3 minute pulse to 12-15 MK reproduces well most observed features along one of the brightening loops, including intensities in the AIA hot channels and their temporal variability, as well as the intensity, Doppler shift, and line width of the EIS Fe XXIII line, and its timing relative to the AIA emission. Overall, we obtain a coherent scenario of a typical microflaring loop system and provide constraints on the intensity of the energy release as well as its spatial and temporal distribution, both along and across the loop.

Keywords: Solar extreme ultraviolet emission, Solar coronal loops, Solar coronal heating, Solar active regions, Solar corona, Active solar corona
Non-Newtonian Gravity in Strange Quark Stars and Constraints from the Observations of PSR J0740+6620 and GW170817. We investigate the effects of non-Newtonian gravity on the properties of strange quark stars (QSs) and constrain the parameters of the standard MIT bag model used to describe strange quark matter (SQM) by employing the mass of PSR J0740+6620 and the tidal deformability of GW170817. We find that, for the standard MIT bag model, these mass and tidal deformability observations would rule out the existence of QSs if non-Newtonian gravity effects are ignored. For a strange quark mass of ms = 95 MeV, we find that QSs can exist for values of the non-Newtonian gravity parameter g2/μ2 in the range of 1.37 GeV-2 ≤ g2/μ2 ≤ 7.28 GeV-2 and limits on the bag constant and the strong interaction coupling constant of the SQM model given by 141.3 MeV ≤ B1/4 ≤ 150.9 MeV and αS ≤ 0.56. For a strange quark mass of ms = 150 MeV, QSs can exist for 1.88 GeV-2 ≤ g2/μ2 ≤ 6.27 GeV-2 and limits on the parameters of the SQM model given by 139.7 MeV ≤ B1/4 ≤ 147.3 MeV and αS ≤ 0.49.

Keywords: Neutron stars, Non-standard theories of gravity, Gravitational waves
A Generalized Fisk-type HMF: Implications of Spatially Dependent Photospheric Differential Rotation. The existence of a Fisk-type heliospheric magnetic field (HMF) has been debated ever since Fisk proposed an alternative to the traditional view of the HMF first proposed by Parker. Several modifications of the original Fisk field model have been published in the past, for example, the Schwadron field and the Fisk-Parker hybrid HMF model. This study presents a new generalized Fisk HMF model that implements for the first time a spatially dependent differential rotation rate of the photosphere, by mapping magnetic field lines from the solar wind source surface to the photosphere. Data analysis methods of Forsyth et al. are used to search for a signature of a Fisk-type field during solar minimum conditions, using the magnetic field data from the first solar orbit of the Ulysses spacecraft. The new generalized Fisk field agrees better with the observed magnetic field winding angle than a standard Parker field during the majority of intervals scanned by Ulysses.

Keywords: Solar wind, Solar magnetic fields, Heliosphere
Comparing Turbulent Cascades and Heating versus Spectral Anisotropy in Solar Wind via Direct Simulations. In a previous work (MGV18), we showed numerically that the turbulent cascade generated by quasi-2D structures (with wavevectors mostly perpendicular to the mean magnetic field) is able to generate a temperature profile close to the one observed in solar wind (≃1/R) in the range 0.2 ≤ R ≤ 1 au. Theory, observations, and numerical simulations point to another robust structure, the radial slab, with dominant wavevectors along the radial: we study here the efficiency of the radial-slab cascade in building the 1/R temperature profile. As in MGV18, we solve the three-dimensional magnetohydrodynamic equations including expansion to simulate the turbulent evolution. We find that an isotropic distribution of wavevectors with large cross-helicity at 0.2 au, along with a large wind expansion rate, lead again to a temperature decay rate close to 1/R but with a radial-slab anisotropy at 1 au. Surprisingly, the turbulent cascade concentrates in the plane transverse to the radial direction, displaying 1D spectra with scalings close to k-5/3 in this plane. This supports both the idea of turbulent heating of the solar wind, and the existence of two different turbulent cascades, associated to quasi-2D and radial-slab geometries. We conclude that sampling the radial spectrum in the solar wind may give poor information on the real cascade regime and rate when the radial slab is a non-negligible part of turbulence.

Keywords: Interplanetary turbulence, Magnetohydrodynamics, Solar wind, Heliosphere
VVV Survey Microlensing: Candidate Events with a Source in the Far Disk. The VVV microlensing search has recently surveyed the region of the Galactic plane at b = 0 within -10.00 ≤ l ≤ 10.44 deg. in the near-infrared (IR) discovering hundreds of microlensing events. In this paper we explore the microlensing events with background sources that might be located in the far disk of the Galaxy, beyond the bulge. We discuss the possible configurations for the microlensing lenses and sources located at different places within the Galactic plane. Then we search for these events using the local red clump centroids of the VVV near-IR color-magnitude diagrams. According to the estimated distances and proper motions, N = 20 events may have sources located in the far disk. The candidates for far-disk sources show on average longer timescales (tE = 49.3 ± 7.9 days) than the mean of the timescale distribution for the bulge red clump sources (tE = 36.4 ± 1.1 days). We conclude that the population of microlensing events in the region -10.00 ≤ l ≤ 10.44, -0.46 ≤ b ≤ 0.65 deg. contains a non-negligible number of events with candidate far-disk sources (∼11%). Our results are relevant in view of future microlensing plans with the Roman Space Telescope (formerly WFIRST) in the near-IR.

Keywords: Surveys, Galaxy structure, Galactic bulge, Microlensing optical depth, Gravitational lensing, Interstellar extinction, Gravitational microlensing, Microlensing event rate, Near infrared astronomy
Sun-as-a-star Spectral Irradiance Observations of Transiting Active Regions. Major solar flares are prone to occur in active-region (AR) atmospheres associated with large, complex, dynamically evolving sunspots. This points to the importance of monitoring the evolution of starspots, not only in visible but also in ultraviolet (UV) and X-rays, in understanding the origin and occurrence of stellar flares. To this end, we perform spectral irradiance analysis on different types of transiting solar ARs by using a variety of full-disk synoptic observations. The target events are an isolated sunspot, spotless plage, and emerging flux in prolonged quiet-Sun conditions selected from the past decade. We find that the visible continuum and total solar irradiance become darkened when the spot is at the central meridian, whereas it is bright near the solar limb; UV bands sensitive to the chromosphere correlate well with the variation of total unsigned magnetic flux in the photosphere; amplitudes of extreme ultraviolet (EUV) and soft X-ray increase with the characteristic temperature, whose light curves are flat-topped due to their sensitivity to the optically thin corona; the transiting spotless plage does not show the darkening in the visible irradiance, while the emerging flux produces an asymmetry in all light curves about the central meridian. The multiwavelength Sun-as-a-star study described here indicates that the time lags between the coronal and photospheric light curves have the potential to probe the extent of coronal magnetic fields above the starspots. In addition, EUV wavelengths that are sensitive to temperatures just below 1 MK sometimes show antiphased variations, which may be used for diagnosing plasmas around starspots.

Keywords: Starspots, Solar flares, Solar analogs, Sunspots, Solar spectral irradiance, Solar active regions, Stellar flares, Time domain astronomy
The Ionized- and Cool-gas Content of the BR1202-0725 System as Seen by MUSE and ALMA. We present Multi Unit Spectroscopic Explorer (MUSE) observations of the gas-rich major merger BR1202-0725 at z ∼ 4.7, which constitutes one of the most overdense fields known in the early universe. We utilize these data in conjunction with existing Atacama Large Millimeter/submillimeter Array (ALMA) observations to compare and contrast the spatially resolved ionized- and cool-gas content of this system, which hosts a quasar (QSO), a submillimeter galaxy (SMG), the two known optical companion Lyα emitters ("LAE 1" and "LAE 2"), and an additional companion discovered in this work "LAE 3" just 5″ to the north of the QSO. We find that QSO BR1202-0725 exhibits a large Lyα halo, covering ≍55 pkpc on-sky at surface-brightness levels of SB ≥ 1 × 10-17 erg s-1 cm-2 arcsec-2. In contrast, the SMG, of similar far-infrared luminosity and star formation rate (SFR), does not exhibit such a Lyα halo. The QSO's halo exhibits high velocity widths (∼1000 km s-1) but the gas motion is to some extent kinematically coupled with the previously observed [C II] bridge between the QSO and the SMG. We note that the object known in the literature as LAE 2 shows no local peak of Lyα emission, rather, its profile is more consistent with being part of the QSO's extended Lyα halo. The properties of LAE 3 are typical of high-redshift LAEs; we measure FLyα(LAE 3) = 0.24 ± 0.03 × 10-16 erg s-1 cm-2, corresponding to SFRLyα ≍ 5.0 ± 0.5 M☉ yr-1. The velocity width is ∆v(LAE 3) ≍ 400 km s-1, and the equivalent width is EW0( $\mathrm{Ly}{\alpha }_{5\sigma }^{\mathrm{lim}})\geqslant 34.05$ Å, consistent with star formation being the primary driver of Lyα emission. We also note a coherent absorption feature at ∼-400 km s-1 in spectra from at least three objects; the QSO, LAE 1, and LAE 2, which could imply the presence of an expanding neutral gas shell with an extent of at least 24 pkpc.

Keywords: Quasars, Broad-absorption line quasar
GW190814's Secondary Component with Mass 2.50-2.67 M<SUB>⊙</SUB> as a Superfast Pulsar. We use Stergioulas's RNS code for investigating fast pulsars with equations of state (EOSs) on the causality surface (where the speed of sound is equal to that of light) of the high-density EOS parameter space satisfying all known constraints from both nuclear physics and astrophysics. We show that one possible explanation for GW190814's secondary component, which has mass 2.50-2.67 M⊙, is that it is a superfast pulsar spinning faster than 971 Hz, about 42% below its Kepler frequency. If confirmed, it would be the fastest pulsar with the highest mass yet observed. There is a large and physically allowed EOS parameter space below the causality surface where pulsars heavier than 2.50 M⊙ are supported if they can rotate even faster with critical frequencies that depend strongly on the high-density behavior of nuclear symmetry energy.

Keywords: Pulsars
Systematically Measuring Ultradiffuse Galaxies in H I: Results from the Pilot Survey. We present neutral hydrogen (H I) observations using the Robert C. Byrd Green Bank Telescope (GBT) of 70 optically detected UDG candidates in the Coma region from the Systematically Measuring Ultra-Diffuse Galaxies survey (SMUDGes). We detect H I in 18 targets, confirming nine to be gas-rich UDGs and the remainder to be foreground dwarfs. None of our H I-detected UDGs are Coma Cluster members and all but one are in low-density environments. The H I-detected UDGs are bluer and have more irregular morphologies than the redder, smoother candidates not detected in H I, with the combination of optical color and morphology being a better predictor of gas richness than either parameter alone. There is little visual difference between the gas-rich UDGs and the foreground dwarfs in the SMUDGes imaging, and distances are needed to distinguish between them. We find that the gas richnesses of our H I-confirmed UDGs and those from other samples scale with their effective radii in two stellar mass bins, possibly providing clues to their formation. We attempt to place our UDGs on the baryonic Tully-Fisher relation (BTFR) using optical ellipticities and turbulence-corrected H I line widths to estimate rotation velocities, but the potential systematics associated with fitting smooth Sérsic profiles to clumpy, low-inclination disks of low surface brightness precludes a meaningful analysis of potential BTFR offsets. These observations are a pilot for a large campaign now under way at the GBT to use the H I properties of gas-rich UDGs to quantitatively constrain how these galaxies form and evolve.

Keywords: Galaxy formation, Dwarf galaxies, Galaxy evolution, H I regions, Low surface brightness galaxies
On the Spectral Peak Energy of Swift Gamma-Ray Bursts. Owing to the narrow energy band of the Swift Burst Alert Telescope (BAT), several urgent issues remain unsolved. We systematically study the properties of a refined sample of 283 Swift/BAT gamma-ray bursts (GRBs) with well-measured spectral peak energy (Ep) at a high confidence level greater than 3σ. We find that the duration (T90) distribution of Swift bursts still exhibits an evident bimodality with a more reliable boundary of T90 ≃ 1.06 s instead of 2 s as found for previously contaminated samples, including bursts without well-peaked spectra, which is very close to the ∼1.27 and ∼0.8 s values suggested in the literature for the Fermi/Gamma-ray Burst Monitor and Swift/BAT catalogs, respectively. The Swift/BAT short and long bursts have comparable mean Ep values of ${87}_{-49}^{+112}$ and ${85}_{-46}^{+101}$ keV, similar to what was found for both types of BATSE bursts, which indicates that the traditional short-hard/long-soft scheme may not be tenable for certain detector energy windows. We also statistically investigate the consistency of distinct methods for Ep estimates and find that a Bayesian approach and BAND function (Band et al.) can always provide consistent evaluations. In contrast, the frequently used cutoff power-law model matches two other methods for lower Ep and overestimates the Ep by more than 70%, as Ep &gt; 100 keV. Peak energies of X-ray flashes, X-ray-rich bursts, and classical GRBs could be an evolutionary consequence of moving from thermal-dominated to nonthermal-dominated radiation mechanisms. Finally, we find that the Ep and the observed fluence (Sγ) in the observer frame are correlated as ${E}_{p}\simeq {[{S}_{\gamma }/({10}^{-5}\mathrm{erg}{\mathrm{cm}}^{-2})]}^{0.28}\times {117.5}_{-32.4}^{+44.7}$ keV, which might be a useful indicator of GRB peak energies.

Keywords: Gamma-ray bursts, High energy astrophysics, Interstellar thermal emission, Astronomy data analysis, Astrostatistics distributions, Interstellar synchrotron emission, Extragalactic astronomy