Sazuna/UAT_keywords huggingface dataset:
Predicting the Spectrum of UGC 2885, Rubin's Galaxy with Machine Learning. Wu &amp; Peek predict SDSS-quality spectra based on Pan-STARRS broadband grizy images using machine learning (ML). In this article, we test their prediction for a unique object, UGC 2885 ("Rubin's galaxy"), the largest and most massive, isolated disk galaxy in the local universe (D &lt; 100 Mpc). After obtaining the ML predicted spectrum, we compare it to all existing spectroscopic information that is comparable to an SDSS spectrum of the central region: two archival spectra, one extracted from the VIRUS-P observations of this galaxy, and a new, targeted MMT/Binospec observation. Agreement is qualitatively good, though the ML prediction prefers line ratios slightly more toward those of an active galactic nucleus (AGN), compared to archival and VIRUS-P observed values. The MMT/Binospec nuclear spectrum unequivocally shows strong emission lines except Hβ, the ratios of which are consistent with AGN activity. The ML approach to galaxy spectra may be a viable way to identify AGN supplementing NIR colors. How such a massive disk galaxy (M* = 1011 M⊙), which uncharacteristically shows no sign of interaction or mergers, manages to fuel its central AGN remains to be investigated.

Keywords: Giant galaxies, Disk galaxies, Galaxy nuclei
The Deviation of the Size of the Broad-line Region between Reverberation Mapping and Spectroastrometry. The combination of the linear size from reverberation mapping (RM) and the angular distance of the broad-line region (BLR) from spectroastrometry (SA) in active galactic nuclei can be used as a "standard ruler" to measure the Hubble constant H0. Recently, Wang et al. successfully employed this approach and estimated H0 from 3C 273. However, there may be a systematic deviation between the response-weighted radius (RM measurement) and luminosity-weighted radius (SA measurement), especially when different broad lines are adopted for size indicators (e.g., Hβ for RM and Paα for SA). Here we evaluate the size deviations measured by six pairs of hydrogen lines (e.g., Hβ, Hα, and Paα) via the locally optimally emitting cloud (LOC) models of the BLR. We find that the radius ratios K (=RSA/RRM) of the same line deviated systematically from 1 (0.85-0.88) with dispersions between 0.063 and 0.083. Surprisingly, the K values from the Paα(SA)/Hβ(RM) and Hα(SA)/Hβ(RM) pairs not only are closest to 1 but also have considerably smaller uncertainty. Considering the current technology of infrared interferometry, the Paα(SA)/Hβ(RM) pair is the ideal choice for low-redshift objects in the SARM project. In the future, the Hα(SA)/Hβ(RM) pair could be used for high-redshift luminous quasars. These theoretical estimations of the SA/RM radius pave the way for future SARM measurements to further constrain the standard cosmological model.

Keywords: Distance measure, Reverberation mapping, Standard candles, Hubble constant, Active galactic nuclei, Interferometry
Modeling the Multiwavelength Variability of Mrk 335 Using Gaussian Processes. The optical and UV variability of the majority of active galactic nuclei may be related to the reprocessing of rapidly changing X-ray emission from a more compact region near the central black hole. Such a reprocessing model would be characterized by lags between X-ray and optical/UV emission due to differences in light travel time. Observationally, however, such lag features have been difficult to detect due to gaps in the lightcurves introduced through factors such as source visibility or limited telescope time. In this work, Gaussian process regression is employed to interpolate the gaps in the Swift X-ray and UV lightcurves of the narrow-line Seyfert 1 galaxy Mrk 335. In a simulation study of five commonly employed analytic Gaussian process kernels, we conclude that the Matern $\tfrac{1}{2}$ and rational quadratic kernels yield the most well-specified models for the X-ray and UVW2 bands of Mrk 335. In analyzing the structure functions of the Gaussian process lightcurves, we obtain a broken power law with a break point at 125 days in the UVW2 band. In the X-ray band, the structure function of the Gaussian process lightcurve is consistent with a power law in the case of the rational quadratic kernel while a broken power law with a break point at 66 days is obtained from the Matern $\tfrac{1}{2}$ kernel. The subsequent cross-correlation analysis is consistent with previous studies and furthermore shows tentative evidence for a broad X-ray-UV lag feature of up to 30 days in the lag-frequency spectrum where the significance of the lag depends on the choice of Gaussian process kernel.

Keywords: Accretion, Bayesian statistics, Galaxy accretion disks, Active galaxies, Galaxy nuclei, Gaussian Processes regression
A Phase-space View of Cold-gas Properties of Virgo Cluster Galaxies: Multiple Quenching Processes at Work?. We investigate the cold-gas properties of massive Virgo galaxies (&gt;109 M⊙) at &lt;3R200 (R200 is the radius where the mean interior density is 200 times the critical density) on the projected phase-space diagram with the largest archival data set to date to understand the environmental effects on galaxy evolution in the Virgo cluster. We find lower H I and H2 mass fractions and higher star formation efficiencies (SFEs) from H I and H2 in the Virgo galaxies than in the field galaxies for matched stellar masses; the Virgo galaxies generally follow the field relationships between the offset from the main sequence of the star-forming galaxies [Δ(MS)] and the gas fractions and SFEs, to the slight offset to lower gas fractions or higher SFEs compared to field galaxies at Δ(MS) &lt; 0; lower gas fractions in galaxies with smaller clustocentric distance and velocity; and lower gas fractions in the galaxies in the W cloud, a substructure of the Virgo cluster. Our results suggest the cold-gas properties of some Virgo galaxies are affected by their environment at least at 3R200 maybe via strangulation and/or preprocesses, and H I and H2 in some galaxies are removed by ram pressure at &lt;1.5R200. Our data cannot rule out the possibility of other processes such as strangulation and galaxy harassment accounting for gas reduction in some galaxies at &lt;1.5R200. Future dedicated observations of a mass-limited complete sample are required for definitive conclusions.

Keywords: Virgo Cluster, Molecular gas, Interstellar atomic gas, Galaxy environments
Zooming into the Collimation Zone in a Massive Protostellar Jet. Protostellar jets have a fundamental role at the earliest evolution of protostars of all masses. In the case of low-mass (≲8 M⊙) protostars, strong observational evidence exists that the launching and collimation is due to the X- and/or disk-wind mechanisms. In these models, it is the protostar/disk system that creates all the necessary conditions to launch and collimate the jets near the protostar via strong magnetic fields. The origin of jets from more massive protostars has been investigated much less, in part because of the difficulty of resolving the collimation zone in these more distant objects. Here we present the highest angular resolution observations of a jet powered by a massive protostar, the Cep A HW2 radio jet. We imaged the radio emission at projected distances of only ∼20 au from the protostar, resolving the innermost 100 au of a massive protostellar jet for the first time. The morphology of the radio jet emission in this massive object is very different than what is usually observed in jets from low-mass protostars. We found that the outflowing material in HW2 has two components: a wide-angle wind launched from the protostar/disk system, and a highly collimated jet starting at 20-30 au from the protostar. We discuss two possible scenarios: an extension of the classical disk-wind to a massive protostar, or external collimation of a wide-angle wind. These results have important consequences for our understanding of how stars of different masses are formed.

Keywords: Massive stars, Star formation, Radio jets
Supernova Luminosity Powered by Magnetar-Disk System. Magnetars are one of the potential power sources for some energetic supernova explosions such as type I superluminous supernovae (SLSNe I) and broad-lined type Ic supernovae (SNe Ic-BL). In order to explore the possible link between these two subclasses of supernovae (SNe), we study the effect of fallback accretion disk on magnetar evolution and magnetar-powered SNe. In this scenario, the interaction between a magnetar and a fallback accretion disk would accelerate the spin of the magnetar in the accretion regime but could result in substantial spin-down of the magnetars in the propeller regime. Thus, the initial rotation of the magnetar plays a less significant role in the spin evolution. Such a magnetar-disk interaction scenario can explain well the light curves of both SNe Ic-BL and SLSNe I, for which the observed differences are sensitive to the initial magnetic field of the magnetar and the fallback mass and timescale for the disk. Compared to the magnetars powering the SNe Ic-BL, those accounting for more luminous SNe usually maintain faster rotation and have relatively lower effective magnetic fields around peak time. In addition, the association between SLSNe I and long gamma-ray bursts, if observed in the future, could be explained in the context of a magnetar-disk system.

Keywords: Magnetars, Supernovae
8.9 hr Rotation in the Partly Burnt Runaway Stellar Remnant LP 40-365 (GD 492). We report the detection of 8.914 hr variability in both optical and ultraviolet light curves of LP 40-365 (also known as GD 492), the prototype for a class of partly burnt runaway stars that have been ejected from a binary due to a thermonuclear supernova event. We first detected this 1.0% amplitude variation in optical photometry collected by the Transiting Exoplanet Survey Satellite (TESS). Reanalysis of observations from the Hubble Space Telescope at the TESS period and ephemeris reveal a 5.8% variation in the ultraviolet of this 9800 K stellar remnant. We propose that this 8.914 hr photometric variation reveals the current surface rotation rate of LP 40-365, and is caused by some kind of surface inhomogeneity rotating in and out of view, though a lack of observed Zeeman splitting puts an upper limit on the magnetic field of &lt;20 kG. We explore ways in which the present rotation period can constrain progenitor scenarios if angular momentum was mostly conserved, which suggests that the survivor LP 40-365 was not the donor star but was most likely the bound remnant of a mostly disrupted white dwarf that underwent advanced burning from an underluminous (Type Iax) supernova.

Keywords: Supernova remnants, White dwarf stars, Stellar rotation
Redox Hysteresis of Super-Earth Exoplanets from Magma Ocean Circulation. Internal redox reactions may irreversibly alter the mantle composition and volatile inventory of terrestrial and super-Earth exoplanets and affect the prospects for atmospheric observations. The global efficacy of these mechanisms, however, hinges on the transfer of reduced iron from the molten silicate mantle to the metal core. Scaling analysis indicates that turbulent diffusion in the internal magma oceans of sub-Neptunes can kinetically entrain liquid iron droplets and quench core formation. This suggests that the chemical equilibration between core, mantle, and atmosphere may be energetically limited by convective overturn in the magma flow. Hence, molten super-Earths possibly retain a compositional memory of their accretion path. Redox control by magma ocean circulation is positively correlated with planetary heat flow, internal gravity, and planet size. The presence and speciation of remanent atmospheres, surface mineralogy, and core mass fraction of primary envelope-stripped exoplanets may thus constrain magma ocean dynamics.

Keywords: Extrasolar rocky planets, Super Earths, Exoplanet surfaces, Planetary interior, Exoplanet atmospheres
Hybrid Comptonization and Electron-Positron Pair Production in the Black-hole X-Ray Binary MAXI J1820+070. We study X-ray and soft gamma-ray spectra from the hard state of the accreting black-hole binary MAXI J1820+070. We perform an analysis of two joint spectra from NuSTAR and INTEGRAL, covering the range of 3-650 keV, and of an average joint spectrum over the rise of the hard state, covering the 3-2200 keV range. The spectra are well modeled by Comptonization of soft seed photons. However, the distributions of the scattering electrons are not purely thermal; we find they have substantial high-energy tails, well modeled as power laws. The photon tail in the average spectrum is detected well beyond the threshold for electron-positron pair production, 511 keV. This allows us to calculate the rate of the electron-positron pair production and put a lower limit on the size of the source from pair equilibrium. At the fitted Thomson optical depth of the Comptonizing plasma, the limit is about 4 gravitational radii. If we adopt the sizes estimated by us from the reflection spectroscopy of &gt;20 gravitational radii, the fractional pair abundance becomes much less than unity. The low pair abundance is confirmed by the lack of both an annihilation feature and of a pair absorption cutoff above 511 keV in the average spectrum.

Keywords: Accretion, Low-mass x-ray binary stars, X-ray binary stars, Non-thermal radiation sources
Small-scale Induced Large-scale Transitions in Solar Wind Magnetic Field. We investigate the role of small-scale dynamics in inducing large-scale transitions in the solar wind magnetic field by means of dynamical system metrics based on instantaneous fractal dimensions. By looking at the corresponding multiscale features, we observe a break in the average attractor dimension occurring at the crossover between the inertial and the kinetic/dissipative regime. Our analysis suggests that large-scale transitions are induced by small-scale dynamics through an inverse cascade mechanism driven by local correlations, while electron contributions (if any) are hidden by instrumental noise.

Keywords: Interplanetary turbulence, Space plasmas, Magnetohydrodynamics, Solar wind
Origin of Galactic Sub-PeV Diffuse Gamma-Ray Emission: Constraints from High-energy Neutrino Observations. Very recently, diffuse gamma-rays with 0.1 PeV &lt; Eγ &lt; 1 PeV have been discovered from the Galactic disk by the Tibet air shower array and muon detector array (Tibet AS+MD array). While the measured sub-PeV flux may be compatible with the hadronic origin in the conventional Galactic cosmic-ray propagation model, we find that it is in possible tension with the nondetection of Galactic neutrino emissions by the IceCube neutrino telescope. We further find that the presence of an extra cosmic-ray component of relatively hard spectrum, which is probably related to the Cygnus Cocoon region and other PeV cosmic-ray sources in the Galactic disk, would alleviate the tension. This scenario implies the existence of an extreme accelerator of either protons or electrons beyond PeV in the Cygnus region, and predicts the continuation of the gamma-ray spectrum of Cygnus Cocoon up to 1 PeV with a possible hardening beyond ∼30-100 TeV.

Keywords: Galactic cosmic rays, Diffuse radiation, Gamma-ray sources
An Observational Study of a "Rosetta Stone" Solar Eruption. This Letter reports observations of an event that connects all major classes of solar eruptions: those that erupt fully into the heliosphere versus those that fail and are confined to the Sun, and those that eject new flux into the heliosphere, in the form of a flux rope, versus those that eject only new plasma in the form of a jet. The event originated in a filament channel overlying a circular polarity inversion line and occurred on 2016 March 13 during the extended decay phase of the active region designated NOAA 12488/12501. The event was especially well observed by multiple spacecraft and exhibited the well-studied null-point topology. We analyze all aspects of the eruption using Solar Dynamics Observatory Atmospheric Imaging Assembly and Helioseismic and Magnetic Imager, Solar-Terrestrial Relations Observatory Extreme Ultraviolet Imager, and Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph (SOHO LASCO) imagery. One section of the filament undergoes a classic failed eruption with cool plasma subsequently draining onto the section that did not erupt, but a complex structured coronal mass ejection/jet is clearly observed by SOHO/LASCO C2 shortly after the failed filament eruption. We describe in detail the slow buildup to eruption, the lack of an obvious trigger, and the immediate reappearance of the filament after the event. The unique mixture of major eruption properties observed during this event places severe constraints on the structure of the filament channel field and, consequently, on the possible eruption mechanism.

Keywords: Solar magnetic reconnection, Solar coronal mass ejections, Solar corona, Solar magnetic fields, Solar coronal holes
ALMA View of the ρ Ophiuchi A PDR with a 360 au Beam: The [C I] Emission Originates from the Plane-parallel PDR and Extended Gas. We present the results of data analysis of the [C I] (3P1-3P0) emission from the ρ Ophiuchi A photon-dominated region (PDR) obtained in the ALMA ACA standalone mode with a spatial resolution of 2.6 arcsec (360 au). The [C I] emission shows filamentary structures with a width of ∼1000 au, which are adjacent to the shell structure seen in the 4.5 μm map. We found that the 4.5 μm emission, C0, and CO are distributed in this order from the excitation star (S1) in a complementary pattern. These results indicate that [C I] is emitted from a thin layer in the PDR generated by the excitation star, as predicted in the plane-parallel PDR model. In addition, extended [C I] emission was also detected, which shows nearly uniform integrated intensity over the entire field of view (1'6 × 1'6). The line profile of the extended component is different from that of the above shell component. The column density ratio of C0 to CO in the extended component was ∼2, which is significantly higher than those of Galactic massive star-forming regions (0.1-0.2). These results suggest that [C I] is emitted also from the extended gas with a density of ${n}_{{{\rm{H}}}_{2}}\sim {10}^{3}$ cm-3, which is not greatly affected by the excitation star.

Keywords: Interstellar medium, Photodissociation regions, Interstellar atomic gas
Formation of an Extended Stellar Halo around an Ultra-faint Dwarf Galaxy Following One of the Earliest Mergers from Galactic Building Blocks. Ultra-faint dwarf galaxies (UFDs) are promising observable proxies to building blocks of galaxies formed in the early universe. We study the formation and evolution of UFDs using cosmological hydrodynamic simulations. In particular, we show that a major merger of two building block galaxies with 3900 M⊙ and 7500 M⊙ at the cosmic age of 510 Myr results in a system with an extended stellar distribution consistent with the de Vaucouleurs profile. The simulated galaxy has an average stellar metallicity of [Fe/H] = -2.7 and features a metallicity gradient. These results closely resemble the properties of a recently discovered UFD, Tucana II, which is extremely metal-poor and has a spatially extended stellar halo with the more distant stars being more metal-poor. Our simulation suggests that the extended stellar halo of Tucana II may have been formed through a past major merger. Future observational searches for spatially extended structures around other UFDs, combined with further theoretical studies, will provide tangible measures of the evolutionary history of the ancient, surviving satellite galaxies.

Keywords: Local Group, Hydrodynamical simulations, Galaxy formation, Dwarf galaxies, Galaxy mergers
Diffuse Synchrotron Emission Associated with the Starburst in the Circumnuclear Disk of NGC 1275. Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations found a positive correlation between the mass of dense molecular gas in the circumnuclear disks (CNDs) and accretion rate to the active galactic nuclei (AGNs). This indicates that star formation activity in the CNDs is essential for triggering the accretion of mass to AGNs. Although the starburst-driven turbulence is a key mechanism for the transfer of angular momentum and the resultant mass accretion from the CND scale to the inner radius, the observational evidence is lacking. We report the very-long-baseline-interferometry detection of the diffuse synchrotron emission on a scale of several tens of parsecs coinciding spatially with the molecular gas disk recently discovered by ALMA observations in NGC 1275. The synchrotron emissions most likely resulted from the relativistic electrons produced by the supernova explosions. This is unambiguous evidence of the star formation activity in a CND. The turbulent velocity and the scale height of the CND predicted from the supernova-driven turbulence model agree with the observations, although the model-predicted accretion rate disagrees with the bolometric luminosity. This might indicate that additional mechanisms to enhance the turbulence are required for the inner disk. We discuss the multiphase nature of the CND by combining the information of the CO emission, synchrotron emission, and free-free absorption.

Keywords: Very long baseline interferometry, Galaxy accretion disks, Low-luminosity active galactic nuclei, Radio galaxies, Radio active galactic nuclei, Radio interferometry, Perseus Cluster
A Tip of the Red Giant Branch Distance of 22.1 ± 1.2 Mpc to the Dark Matter Deficient Galaxy NGC 1052-DF2 from 40 Orbits of Hubble Space Telescope Imaging. The large and diffuse galaxies NGC 1052-DF2 and NGC 1052-DF4 have been found to have very low dark matter content and a population of luminous globular clusters (GCs). Accurate distance measurements are key to interpreting these observations. Recently, the distance to NGC 1052-DF4 was found to be 20.0 ± 1.6 Mpc by identifying the tip of the red giant branch (TRGB) in 12 orbits of Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) imaging. Here we present 40 orbits of HST ACS data for NGC 1052-DF2 and use these data to measure its TRGB. The TRGB is readily apparent in the color-magnitude diagram. Using a forward model that incorporates photometric uncertainties, we find a TRGB magnitude of mF814W,TRGB = 27.67 ± 0.10 mag. The inferred distance is DTRGB = 22.1 ± 1.2 Mpc, consistent with the previous surface brightness fluctuation distances to the bright elliptical galaxy NGC 1052. The new HST distance rules out the idea that some of NGC 1052-DF2's unusual properties can be explained if it were at ∼13 Mpc; instead, it implies that the galaxy's GCs are even more luminous than had been derived using the previous distance of 20 Mpc. The distance from NGC 1052-DF2 to NGC 1052-DF4 is well-determined at 2.1 ± 0.5 Mpc, significantly larger than the virial diameter of NGC 1052. We discuss the implications for formation scenarios of the galaxies and for the external field effect, which has been invoked to explain the intrinsic dynamics of these objects in the context of modified Newtonian dynamics.

Keywords: Galaxy dark matter halos, Red giant tip, Distance indicators, Galaxy photometry, Dark matter