Sazuna/UAT_keywords huggingface dataset:
Inpainting Galactic Foreground Intensity and Polarization Maps Using Convolutional Neural Networks. The Deep Convolutional Neural Networks (DCNNs) have been a popular tool for image generation and restoration. In this work, we applied DCNNs to the problem of inpainting non-Gaussian astrophysical signal, in the context of Galactic diffuse emissions at the millimetric and submillimetric regimes, specifically Synchrotron and Thermal Dust emissions. Both signals are affected by contamination at small angular scales due to extragalactic radio sources (the former) and dusty star-forming galaxies (the latter). We compare the performance of the standard diffusive inpainting with that of two novel methodologies relying on DCNNs, namely Generative Adversarial Networks and Deep-Prior. We show that the methods based on the DCNNs are able to reproduce the statistical properties of the ground-truth signal more consistently with a higher confidence level. The Python Inpainter for Cosmological and AStrophysical SOurces (PICASSO) is a package encoding a suite of inpainting methods described in this work and has been made publicly available at http://giuspugl.github.io/picasso/.

Keywords: Extragalactic radio sources, Cosmic microwave background radiation, Convolutional neural networks, Dust continuum emission, Interstellar synchrotron emission
Role of the Fan Beam Model in Population Synthesis of Isolated Radio Pulsars. On the basis of the PSRPOPPY software package, we developed an evolution model of population synthesis for isolated radio pulsars by incorporating the fan beam model, an alternative radio emission beam model to the widely used conal beam model. With proper choice of related models and parameters, we successfully reproduced the observational distributions of Galactic longitude (l) and latitude (b), spin period, period derivative, dispersion measure and 1.4 GHz flux density for the 1214 isolated pulsars discovered by the Parkes multibeam and Swinburne pulsar surveys. The size of the underlying population of radio-loud pulsars is found to be 2.27 × 106, which is larger than the underlying population of radio-loud pulsars simulated with the conal beam model. The model is used to estimate the number of isolated radio pulsars detected by the Galactic-plane pulsar survey with Five hundred-meter Aperture Spherical Telescope (FAST). Approximately 2700 and 240 new isolated pulsars are expected to be discovered in the inner galactic plane (20° &lt; l &lt; 90°, ∣b∣ &lt; 10°) and the outer galactic plane (150° &lt; l &lt; 210°, ∣b∣ &lt; 10°), respectively. These numbers are smaller than those estimated by the evolution models with conal beams and the snapshot models.

Keywords: Radio pulsars
Kilonova Luminosity Function Constraints Based on Zwicky Transient Facility Searches for 13 Neutron Star Merger Triggers during O3. We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run (O3). We searched binary neutron star (BNS) and neutron star black hole (NSBH) merger localizations with the Zwicky Transient Facility (ZTF) and undertook follow-up with the Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration. The GW triggers had a median localization area of 4480 deg2, a median distance of 267 Mpc, and false-alarm rates ranging from 1.5 to 10-25 yr-1. The ZTF coverage in the g and r bands had a median enclosed probability of 39%, median depth of 20.8 mag, and median time lag between merger and the start of observations of 1.5 hr. The O3 follow-up by the GROWTH team comprised 340 UltraViolet/Optical/InfraRed (UVOIR) photometric points, 64 OIR spectra, and three radio images using 17 different telescopes. We find no promising kilonovae (radioactivity-powered counterparts), and we show how to convert the upper limits to constrain the underlying kilonova luminosity function. Initially, we assume that all GW triggers are bona fide astrophysical events regardless of false-alarm rate and that kilonovae accompanying BNS and NSBH mergers are drawn from a common population; later, we relax these assumptions. Assuming that all kilonovae are at least as luminous as the discovery magnitude of GW170817 (-16.1 mag), we calculate that our joint probability of detecting zero kilonovae is only 4.2%. If we assume that all kilonovae are brighter than -16.6 mag (the extrapolated peak magnitude of GW170817) and fade at a rate of 1 mag day-1 (similar to GW170817), the joint probability of zero detections is 7%. If we separate the NSBH and BNS populations based on the online classifications, the joint probability of zero detections, assuming all kilonovae are brighter than -16.6 mag, is 9.7% for NSBH and 7.9% for BNS mergers. Moreover, no more than &lt;57% (&lt;89%) of putative kilonovae could be brighter than -16.6 mag assuming flat evolution (fading by 1 mag day-1) at the 90% confidence level. If we further take into account the online terrestrial probability for each GW trigger, we find that no more than &lt;68% of putative kilonovae could be brighter than -16.6 mag. Comparing to model grids, we find that some kilonovae must have Mej &lt; 0.03 M☉, Xlan &gt; 10-4, or φ &gt; 30° to be consistent with our limits. We look forward to searches in the fourth GW observing run; even 17 neutron star mergers with only 50% coverage to a depth of -16 mag would constrain the maximum fraction of bright kilonovae to &lt;25%.

Keywords: Neutron stars, Sky surveys, Black holes, Nucleosynthesis, R-process, Gravitational waves, Compact objects, Spectroscopy, Photometry
Probing the Milky Way's Dark Matter Halo for the 3.5 keV Line. We present a comprehensive search for the 3.5 keV line using ∼51 Ms of archival Chandra observations peering through the Milky Way's dark matter halo from across the entirety of the sky, gathered via the Chandra Source Catalog Release 2.0. We consider the data's radial distribution, organizing observations into four data subsets based on angular distance from the Galactic center. All data are modeled using both background-subtracted and background-modeled approaches to account for the particle instrument background, demonstrating the statistical limitations of the currently available ∼1 Ms of particle background data. A nondetection is reported in the total data set, allowing us to set an upper limit on 3.5 keV line flux and constrain the sterile neutrino dark matter mixing angle. The upper limit on sin2(2θ) is $2.58\times {10}^{-11}$ (though systematic uncertainty may increase this by a factor of ∼2), corresponding to an upper limit on 3.5 keV line flux of $2.34\times {10}^{-7}$ photons s-1 cm-2. These limits show consistency with recent constraints and several prior detections. Nondetections are reported in all radial data subsets, allowing us to constrain the spatial profile of 3.5 keV line intensity, which does not conclusively differ from Navarro-Frenk-White predictions. Thus, while offering heavy constraints, we do not entirely rule out the sterile neutrino dark matter scenario or the more general decaying dark matter hypothesis for the 3.5 keV line. We have also used the nondetection of any unidentified emission lines across our continuum to further constrain the sterile neutrino parameter space.

Keywords: Warm dark matter, X-ray astronomy, Cosmology, Milky Way dark matter halo, Neutrino astronomy, Cosmological neutrinos, Diffuse x-ray background, Dark matter, Particle astrophysics
The ALPINE-ALMA [C II] Survey: [C II] 158 μm Emission Line Luminosity Functions at z ∼ 4-6. We present the [C II] 158 μm line luminosity functions (LFs) at z ∼ 4-6 using the ALMA observations of 118 sources, which are selected to have UV luminosity M1500Å &lt; -20.2 and optical spectroscopic redshifts in COSMOS and ECDF-S. Of the 118 targets, 75 have significant [C II] detections and 43 are upper limits. This is by far the largest sample of [C II] detections, which allows us to set constraints on the volume density of [C II] emitters at z ∼ 4-6. But because this is a UV-selected sample, we are missing [C II]-bright but UV-faint sources, making our constraints strict lower limits. Our derived LFs are statistically consistent with the z ∼ 0 [C II] LF at 108.25-109.75L☉. We compare our results with the upper limits of the [C II] LF derived from serendipitous sources in the ALPINE maps. We also infer the [C II] LFs based on published far-IR and CO LFs at z ∼ 4-6. Combining our robust lower limits with these additional estimates, we set further constraints on the true number density of [C II] emitters at z ∼ 4-6. These additional LF estimates are largely above our LF at L[CII] &gt; 109L☉, suggesting that UV-faint but [C II]-bright sources likely make significant contributions to the [C II] emitter volume density. When we include all the LF estimates, we find that available model predictions underestimate the number densities of [C II] emitters at z ∼ 4-6. Finally, we set a constraint on the molecular gas mass density at z ∼ 4-6, with ρmol ∼ (2-7) × 107M☉ Mpc-3. This is broadly consistent with previous studies.

Keywords: Luminosity function, Molecular gas, Emission line galaxies, Warm ionized medium, Warm neutral medium, High-redshift galaxies
Chandra View of the LINER-type Nucleus in the Radio-loud Galaxy CGCG 292-057: Ionized Iron Line and Jet-ISM Interactions. We present an analysis of the new, deep (94 ksec) Chandra ACIS-S observation of radio-loud active galaxy CGCG 292-057, characterized by a LINER-type nucleus and a complex radio structure that indicates intermittent jet activity. On the scale of the host galaxy bulge, we detected excess X-ray emission with a spectrum best fit by a thermal plasma model with a temperature of ∼0.8 keV. We argue that this excess emission results from compression and heating of the hot diffuse fraction of the interstellar medium displaced by the expanding inner, ∼20 kpc-scale lobes observed in this restarted radio galaxy. The nuclear X-ray spectrum of the target clearly displays an ionized iron line at ∼6.7 keV, and is best fitted with a phenomenological model consisting of a power-law (photon index ≃ 1.8) continuum absorbed by a relatively large amount of cold matter (hydrogen column density ≃0.7 × 1023 cm-2), and partly scattered (fraction ∼3%) by ionized gas, giving rise to a soft excess component and Kα line from iron ions. We demonstrate that the observed X-ray spectrum, particularly the equivalent width of Fe XXV Kα (of order 0.3 keV) can in principle, be explained in a scenario involving a Compton-thin gas located at the scale of the broad-lined region in this source and photoionized by nuclear illumination. We compare the general spectral properties of the CGCG 292-057 nucleus, with those of other nearby LINERs studied in X-rays.

Keywords: Relativistic jets, Active galaxies, LINER galaxies, Low-luminosity active galactic nuclei, X-ray active galactic nuclei, Radio galaxies, Intergalactic medium
Background Microwave Emission and Microflares in Young Active Region 12635. The goal of this work is to study the atmospheric heating above isolated AR 12635 during a period in which a quasistationary increase in microwave and soft X-ray emission is combined with a series of B- and C-class microflares. Analysis of photospheric vector magnetograms showed that an increase in the SXR brightness lasting 14 hours was observed during the simplification of the magnetic structure and the growth of vertical currents in the head part of the active region. A long-term increase of SXR and microwave emission occurred when the total unsigned vertical current exceeded the critical value and coincided in time with the increased level of the emission measure calculated from the GOES X-ray data. Against the background of quasistationary emission, microflares lasting 6-10 minutes occurred. In the hard X-ray range, bursts are recorded with RHESSI channels up to 25 keV. In microwave emission, pulsed and smooth components are distinguished during microflares. The first component was recorded in the 4.5-7.5 GHz range at the beginning of microflares and it is generated by a small population of relativistic electrons by the gyrosychrotron mechanism. The smooth component of the bursts dominated at 17 GHz and was emitted by bremsstrahlung. It is shown that the sources of quasistationary emission and microflares coincide with each other and with the bremsstrahlung source calculated from the differential emission measure obtained from the EUV maps. Coronal magnetic field reconstruction shows that the release of energy on both timescales occurs in a stably existing bundle of magnetic field lines.

Keywords: Solar radio flares, Solar physics, Solar flares, Solar flare spectra
Magnetic Reconnection Invoked by Sweeping of the CME-driven Fast-mode Shock. Coronal waves exist ubiquitously in the solar atmosphere. They are important not only because of their rich physics but also because they are essential candidates for triggering remote magnetic eruptions. However, the latter mechanism has never been directly confirmed. By revisiting the successive eruptions on 2012 March 7, fast-mode shocks are identified to account for the X5.4 flare-related Extreme UltraViolet wave with a velocity of 550 km s-1, and appeared faster than 2060 ± 270 km s-1 at the front of the corresponding coronal mass ejection in the slow-rising phase. They not only propagated much faster than the local Alfvén speed of about 260 km s-1, but also were simultaneously accompanied by a type II radio burst, i.e., a typical feature of a shock wave. The observations show that the shock wave disturbs the coronal loops C1 connecting active regions (ARs) 11429 and 11430, which neighbor a null point region. Following a 40 minute oscillation, an external magnetic reconnection (EMR) occurred in the null point region. About 10 minutes later, a large-scale magnetic flux rope overlaid by C1 became unstable and erupted quickly. It is thought that the fast-mode shock triggered EMR in the null point region and caused the subsequent eruptions. This scenario is directly observed for the first time, and provides new hints for understanding the physics of solar activities and eruptions.

Keywords: Solar flares, Solar magnetic reconnection, Solar coronal waves, Solar magnetic fields, Solar activity
Photoevaporation of Minihalos During Cosmic Reionization: Primordial and Metal-enriched Halos. The density distribution of the intergalactic medium is an uncertain but highly important issue in the study of cosmic reionization. It is expected that there are abundant gas clouds hosted by low-mass "minihalos" in the early universe, which act as photon sinks until being photoevaporated by the emerging ultraviolet background (UVB) radiation. We perform a suite of radiation-hydrodynamic simulations to study the photoevaporation of minihalos. Our simulations follow hydrodynamics, nonequilibrium chemistry, and the associated cooling processes in a self-consistent manner. We conduct a parametric study by considering a wide range of gas metallicities (0 Z⊙ ≤ Z ≤ 10-3 Z⊙), halo mass (103 M⊙ ≤ M ≤ 108 M⊙), UVB intensity (0.01 ≤ J21 ≤ 1), and turn-on redshift of ionizing sources (10 ≤ zIN ≤ 20). We show that small halos are evaporated in a few tens of millions of years, whereas larger mass halos survive 10 times longer. The gas mass evolution of a minihalo can be characterized by a scaling parameter that is given by a combination of the halo mass, background radiation intensity, and redshift. Efficient radiative cooling in metal-enriched halos induces fast condensation of the gas to form a dense, self-shielded core. The cold, dense core can become gravitationally unstable in halos with high metallicities. Early metal enrichment may allow star formation in minihalos during cosmic reionization.

Keywords: Hydrodynamical simulations, Chemical enrichment, Star formation, Reionization, Metallicity
[N II] Fine-structure Emission at 122 and 205 μm in a Galaxy at z = 2.6: A Globally Dense Star-forming Interstellar Medium. We present new observations with the Atacama Large Millimeter/submillimeter Array of the 122 and 205 μm fine-structure line emission of singly ionized nitrogen in a strongly lensed starburst galaxy at z = 2.6. The 122/205 μm [N II] line ratio is sensitive to electron density, ${n}_{{\rm{e}}}$, in the ionized interstellar medium, and we use this to measure ne ≍ 300 cm-3, averaged across the galaxy. This is over an order of magnitude higher than the Milky Way average, comparable to localized Galactic star-forming regions. Combined with observations of the atomic carbon (C I) and carbon monoxide (CO J = 4-3) in the same system, we reveal the conditions in this intensely star-forming system. The majority of the molecular interstellar medium has been driven to high density, and the resultant conflagration of star formation produces a correspondingly dense ionized phase, presumably colocated with myriad H II regions that litter the gas-rich disk.

Keywords: Gravitational lensing, Warm ionized medium, Ultraluminous infrared galaxies
The Formation of an Atypical Sunspot Light Bridge as a Result of Large-scale Flux Emergence. We use a combination of full-disk data from the Solar Dynamics Observatory and high-resolution data from the Dunn Solar Telescope (DST) to study the formation, structure, and evolution of an atypical light bridge (LB) in a regular sunspot. The LB results from the emergence of magnetic flux with one footpoint rooted in a pore outside the parent sunspot that appears about 17 hr before the LB. The pore has a polarity opposite to that of the sunspot and recedes from it at a speed of about 0.4 km s-1. This is accompanied by the development of an elongated magnetic channel in the outer penumbra that triggers the formation of the LB when it reaches the inner penumbral boundary. The LB is a nearly horizontal structure with a field strength of about 1.2 kG that exhibits long-lived photospheric blueshifts of about 0.85 km s-1 along its entire length. The emergence of the LB leads to dynamic surges in the chromosphere and transition region about 13 minutes later. We derive the photospheric and chromospheric structure of the LB in the DST data from spectral line parameters and inversions of He I at 1083 nm, Si I at 1082.7 nm, Ca II IR at 854 nm, and Hα at 656 nm and speckle-reconstructed imaging at 700 and 430 nm. The LB shows an elongated filamentary shape in the photosphere without lateral extrusions. The thermal inversion of Ca II IR reveals the LB to be about 600-800 K hotter than the umbra. Different sections of the LB are elevated to heights between 400 and 700 km. Our results indicate that LB formation is part of a flux emergence event with the LB envelope reaching a height of about 29 Mm before dissolving after about 13 hr. We conclude that the existence of persistent, large-scale photospheric blueshifts in LBs is the most likely criterion for distinguishing between flux emergence events and overturning convection in field-free umbral intrusions.

Keywords: Solar magnetic flux emergence, Solar photosphere, Sunspots, Solar magnetic fields, Solar corona, Solar chromosphere
Frequency of Tidal Features Correlates with Age and Internal Structure of Early-type Galaxies. Previous studies suggest that compact young early-type galaxies (ETGs) were formed by recent mergers. However, it has not yet been revealed whether tidal features that are direct evidence of recent mergers are detected frequently around compact young ETGs. Here, we investigate how the fraction of ETGs having tidal features (fT) depends on age and internal structure (compactness, color gradient, and dust lanes) of ETGs, using 650 ETGs with Mr ≤ -19.5 in 0.015 ≤ z ≤ 0.055 that are in deep coadded images of the Stripe 82 region of the Sloan Digital Sky Survey. We find that tidal features are more frequent in younger ETGs and more compact ETGs, so that compact young ETGs with ages ≲6 Gyr have high fT of ∼0.7 compared to their less compact or old counterparts with ages ≳ 9 Gyr that have fT ≲ 0.1. Among compact young ETGs, those with blue cores have ∼3 times higher fT than those with red cores. In addition, ETGs with dust lanes have ∼4 times higher fT than those without dust lanes. Our results provide direct evidence that compact young ETGs especially with blue cores and ETGs with dust lanes are involved in recent mergers. Based on our results and several additional assumptions, we roughly estimate the typical visible time of tidal features after a merger, which is ∼3 Gyr in the depth of the Stripe 82 coadded images.

Keywords: Galaxy properties, Galaxy structure, Galaxy colors, Galaxy ages, Tidal tails, Galaxy mergers, Early-type galaxies
Toward Extremely Precise Radial Velocities. II. A Tool for Using Multivariate Gaussian Processes to Model Stellar Activity. The radial velocity method is one of the most successful techniques for the discovery and characterization of exoplanets. Modern spectrographs promise measurement precision of 0.2-0.5 m s-1 for an ideal target star. However, the intrinsic variability of stellar spectra can mimic and obscure true planet signals at these levels. Rajpaul et al. and Jones et al. proposed applying a physically motivated, multivariate Gaussian process (GP) to jointly model the apparent Doppler shift and multiple indicators of stellar activity as a function of time, so as to separate the planetary signal from various forms of stellar variability. These methods are promising, but performing the necessary calculations can be computationally intensive and algebraically tedious. In this work, we present a flexible and computationally efficient software package, GPLinearODEMaker.jl, for modeling multivariate time series using a linear combination of univariate GPs and their derivatives. The package allows users to easily and efficiently apply various multivariate GP models and different covariance kernel functions. We demonstrate GPLinearODEMaker.jl by applying the Jones et al. model to fit measurements of the apparent Doppler shift and activity indicators derived from simulated active solar spectra time series affected by many evolving starspots. We show how GPLinearODEMaker.jl makes it easy to explore the effect of different choices for the GP kernel. We find that local kernels could significantly increase the sensitivity and precision of Doppler planet searches relative to the widely used quasiperiodic kernel.

Keywords: Astronomy software, Stellar activity, Gaussian Processes regression, Exoplanet detection methods, Time series analysis
The Emergence of the X-Ray Luminosity/Cluster Richness Relation for Radio Galaxies. The idea that mergers are more likely in dense groups or clusters coupled with the assumption that such events lead to cold gas flows onto black holes suggests a direct relationship between the radiative efficiency of an active galactic nucleus and environmental richness. Observations, however, increasingly challenge this and other basic expectations. Mounting evidence, for example, shows an inverse trend between near-Eddington accreting objects and environmental richness. Broken down by radio galaxy subgroup, recent work has explored connections between low excitation radio galaxies with Fanaroff-Riley II jet morphology (FR II LERGs) and other radio galaxies. We make contact with that work by adding a discussion of the recently discovered FR0 radio galaxies and show how to fit them in a picture in which FRII LERGs are not initial or final phases in the lifetime of a radio galaxy, but de facto transition states. We describe how to understand the observed X-ray luminosity/cluster richness relation as a fundamental correlation to the nature of the jet-disk connection.

Keywords: Radio galaxies