Sazuna/UAT_keywords huggingface dataset:
BICEP/Keck XV: The BICEP3 Cosmic Microwave Background Polarimeter and the First Three-year Data Set. We report on the design and performance of the BICEP3 instrument and its first three-year data set collected from 2016 to 2018. BICEP3 is a 52 cm aperture refracting telescope designed to observe the polarization of the cosmic microwave background (CMB) on degree angular scales at 95 GHz. It started science observation at the South Pole in 2016 with 2400 antenna-coupled transition-edge sensor bolometers. The receiver first demonstrated new technologies such as large-diameter alumina optics, Zotefoam infrared filters, and flux-activated SQUIDs, allowing ~10× higher optical throughput compared to the Keck design. BICEP3 achieved instrument noise equivalent temperatures of 9.2, 6.8, and 7.1 $\mu {{\rm{K}}}_{{\rm\small{CMB}}}\sqrt{{\rm{s}}}$ and reached Stokes Q and U map depths of 5.9, 4.4, and 4.4 μK arcmin in 2016, 2017, and 2018, respectively. The combined three-year data set achieved a polarization map depth of 2.8 μK arcmin over an effective area of 585 square degrees, which is the deepest CMB polarization map made to date at 95 GHz.

Keywords: Polarimeters, Cosmic microwave background radiation, Gravitational waves, Cosmic inflation
A Carbon/Oxygen-dominated Atmosphere Days after Explosion for the "Super-Chandrasekhar" Type Ia SN 2020esm. Seeing pristine material from the donor star in a type Ia supernova (SN Ia) explosion can reveal the nature of the binary system. In this paper, we present photometric and spectroscopic observations of SN 2020esm, one of the best-studied SNe of the class of "super-Chandrasekhar" SNe Ia (SC SNe Ia), with data obtained -12 to +360 days relative to peak brightness, obtained from a variety of ground- and space-based telescopes. Initially misclassified as a type II supernova, SN 2020esm peaked at M  B  = -19.9 mag, declined slowly (∆m 15(B) = 0.92 mag), and had particularly blue UV and optical colors at early times. Photometrically and spectroscopically, SN 2020esm evolved similarly to other SC SNe Ia, showing the usual low ejecta velocities, weak intermediate-mass elements, and the enhanced fading at late times, but its early spectra are unique. Our first few spectra (corresponding to a phase of ≳10 days before peak) reveal a nearly pure carbon/oxygen atmosphere during the first days after explosion. This composition can only be produced by pristine material, relatively unaffected by nuclear burning. The lack of H and He may further indicate that SN 2020esm is the outcome of the merger of two carbon/oxygen white dwarfs. Modeling its bolometric light curve, we find an 56Ni mass of ${1.23}_{-0.14}^{+0.14}$ M ☉ and an ejecta mass of ${1.75}_{-0.20}^{+0.32}$ M ☉, in excess of the Chandrasekhar mass. Finally, we discuss possible progenitor systems and explosion mechanisms of SN 2020esm and, in general, the SC SNe Ia class.

Keywords: White dwarf stars, Supernovae
Further Evidence for the Minifilament-eruption Scenario for Solar Polar Coronal Jets. We examine a sampling of 23 polar-coronal-hole jets. We first identified the jets in soft X-ray (SXR) images from the X-ray telescope (XRT) on the Hinode spacecraft, over 2014-2016. During this period, frequently the polar holes were small or largely obscured by foreground coronal haze, often making jets difficult to see. We selected 23 jets among those adequately visible during this period, and examined them further using Solar Dynamics Observatory's (SDO) Atmospheric Imaging Assembly (AIA) 171, 193, 211, and 304 Å images. In SXRs, we track the lateral drift of the jet spire relative to the jet base's jet bright point (JBP). In 22 of 23 jets, the spire either moves away from (18 cases) or is stationary relative to (4 cases) the JBP. The one exception where the spire moved toward the JBP may be a consequence of line-of-sight projection effects at the limb. From the AIA images, we clearly identify an erupting minifilament in 20 of the 23 jets, while the remainder are consistent with such an eruption having taken place. We also confirm that some jets can trigger the onset of nearby "sympathetic" jets, likely because eruption of the minifilament field of the first jet removes magnetic constraints on the base-field region of the second jet. The propensity for spire drift away from the JBP, the identification of the erupting minifilament in the majority of jets, and the magnetic-field topological changes that lead to sympathetic jets, all support or are consistent with the minifilament-eruption model for jets.

Keywords: Solar activity, Solar filament eruptions, Solar extreme ultraviolet emission, Solar x-ray emission
Deep Low-frequency Radio Observations of A2256. I. The Filamentary Radio Relic. We present deep and high-fidelity images of the merging galaxy cluster A2256 at low frequencies using the upgraded Giant Metrewave Radio Telescope (uGMRT) and LOw-Frequency ARray (LOFAR). This cluster hosts one of the most prominent known relics with a remarkably spectacular network of filamentary substructures. The new uGMRT (300-850 MHz) and LOFAR (120-169 MHz) observations, combined with the archival Karl G. Jansky Very Large Array (VLA; 1-4 GHz) data, allowed us to carry out the first spatially resolved spectral analysis of the exceptional relic emission down to 6″ resolution over a broad range of frequencies. Our new sensitive radio images confirm the presence of complex filaments of magnetized relativistic plasma also at low frequencies. We find that the integrated spectrum of the relic is consistent with a single power law, without any sign of spectral steepening, at least below 3 GHz. Unlike previous claims, the relic shows an integrated spectral index of -1.07 ± 0.02 between 144 MHz and 3 GHz, which is consistent with the (quasi)stationary shock approximation. The spatially resolved spectral analysis suggests that the relic surface very likely traces the complex shock front, with a broad distribution of Mach numbers propagating through a turbulent and dynamically active intracluster medium. Our results show that the northern part of the relic is seen edge-on and the southern part close to face-on. We suggest that the complex filaments are regions where higher Mach numbers dominate the (re)acceleration of electrons that are responsible for the observed radio emission.

Keywords: Galaxy clusters, Intracluster medium, Large-scale structure of the universe, Radio continuum emission
Sizes of Lensed Lower-luminosity z = 4-8 Galaxies from the Hubble Frontier Field Program. We constrain the rest-UV size-luminosity relation for star-forming galaxies at z ~ 4 and z ~ 6, 7, and 8 identified behind clusters from the Hubble Frontier Fields (HFF) program. The size-luminosity relation is key to deriving accurate luminosity functions (LF) for faint galaxies. Making use of the latest lensing models and full data set for these clusters, lensing-corrected sizes and luminosities are derived for 68 z ~ 4, 184 z ~ 6, 93 z ~ 7, and 53 z ~ 8 galaxies. We show that size measurements can be reliably measured up to linear magnifications of ~30×, where the lensing models are well calibrated. The sizes we measure span a &gt;1 dex range, from &lt;50 pc to ≳500 pc. Uncertainties are based on both the formal fit errors and systematic differences between the public lensing models. These uncertainties range from ~10 pc for the smallest sources to 100 pc for the largest. Using a forward-modeling procedure to model the impact of incompleteness and magnification uncertainties, we characterize the size-luminosity relation at both z ~ 4 and z ~ 6-8. We find that the source sizes of star-forming galaxies at z ~ 4 and z ~ 6-8 scale with luminosity L as L 0.54±0.08 and L 0.40±0.04, respectively, such that lower-luminosity (≳-18 mag) galaxies are smaller than expected from extrapolating the size-luminosity relation at high luminosities (≲-18 mag). The new evidence for a steeper size-luminosity relation (3σ) adds to earlier evidence for small sizes based on the prevalence of highly magnified galaxies in high-shear regions, theoretical arguments against upturns in the LFs, and other independent determinations of the size-luminosity relation from the HFF clusters.

Keywords: Dwarf galaxies, Gravitational lensing
On Single-pulse Energies of Some Bright Pulsars Observed at 1.7 GHz. We present Arecibo observations of the bright pulsars B0301+19, B0525+21, B0540+23, B0611+22, and B0823+26 at 1.7 GHz with 100 MHz bandwidth. No giant pulses were found, except for B0823+26, where we recorded a giant interpulse with 230 times the average peak intensity. The postcursor in B0823+26 shows a symmetric double-peaked structure, indicating that it is frequency dependent. In all pulsars, for a given single-pulse peak intensity there is a range of equivalent widths up to a maximum, which becomes smaller the stronger the pulses are, thereby apparently limiting the energy output. Forming average profiles from pulses with certain equivalent widths leads to profiles with changing component characteristics and could allow exploring the magnetosphere at different heights, assuming a dipolar field geometry. We found that the normalized lag-1 autocorrelation coefficient for single-pulse energies can be over 0.5, indicating high correlations. From the first peak of the energy autocorrelation function a so-far-unobserved 15-period modulation is found for B0540+23, as well as a possible 10-period modulation for B0611+22. We also show that a fit of the Weibull distribution to the cumulative probability for the energies yields a better fit than the usual lognormal distribution. The cumulative probability distributions permit an estimate of the nulling fraction, which ranges from 0.6% for B0611+22 to 24% for B0525+21.

Keywords: Radio pulsars
Extracting the Subhalo Mass Function from Strong Lens Images with Image Segmentation. Detecting substructure within strongly lensed images is a promising route to shed light on the nature of dark matter. However, it is a challenging task, which traditionally requires detailed lens modeling and source reconstruction, taking weeks to analyze each system. We use machine learning to circumvent the need for lens and source modeling and develop a neural network to both locate subhalos in an image as well as determine their mass using the technique of image segmentation. The network is trained on images with a single subhalo located near the Einstein ring across a wide range of apparent source magnitudes. The network is then able to resolve subhalos with masses m ≳ 108.5 M ⊙. Training in this way allows the network to learn the gravitational lensing of light, and, remarkably, it is then able to detect entire populations of substructure, even for locations further away from the Einstein ring than those used in training. Over a wide range of the apparent source magnitude, the false-positive rate is around three false subhalos per 100 images, coming mostly from the lightest detectable subhalo for that signal-to-noise ratio. With good accuracy and a low false-positive rate, counting the number of pixels assigned to each subhalo class over multiple images allows for a measurement of the subhalo mass function (SMF). When measured over three mass bins from 109-1010 M ⊙ the SMF slope is recovered with an error of 36% for 50 images, and this improves to 10% for 1000 images with Hubble Space Telescope-like noise.

Keywords: Cosmology, Strong gravitational lensing, Dark matter, Neural networks
Diagnosing the Circumburst Environment with Multiband Gamma-Ray Burst Radio Afterglows. It has been widely recognized that gamma-ray burst (GRB) afterglows arise from interactions between the GRB outflow and circumburst medium, while their evolution follows the behaviors of relativistic shock waves. Assuming the distribution of circumburst medium follows a general power-law form, that is, n = A * R -k , where R denotes the distance from the burst, it is obvious that the value of the density-distribution index k can affect the behaviors of the afterglow. In this paper, we analyze the temporal and spectral behaviors of GRB radio afterglows with arbitrary k values. In the radio band, a standard GRB afterglow produced by a forward shock exhibits a late-time flux peak, and the relative peak fluxes, as well as peak times at different frequencies, show dependencies on k. Thus, with multiband radio-peak observations, one can determine the density profile of the circumburst medium by comparing the relations between peak flux/time and frequency at each observing band. Also, the effects of transrelativistic shock waves, as well as jets in afterglows, are discussed. By analyzing 31 long and 1 short GRB with multiband data of radio afterglows, we find that nearly half of them can be explained with a uniform interstellar medium (k = 0), ~1/5 can be constrained to exhibiting a stellar-wind environment (k = 2), while less than ~1/3 of the samples show 0 &lt; k &lt; 2.

Keywords: Burst astrophysics
Finding Universal Relations in Subhalo Properties with Artificial Intelligence. We use a generic formalism designed to search for relations in high-dimensional spaces to determine if the total mass of a subhalo can be predicted from other internal properties such as velocity dispersion, radius, or star formation rate. We train neural networks using data from the Cosmology and Astrophysics with MachinE Learning Simulations project and show that the model can predict the total mass of a subhalo with high accuracy: more than 99% of the subhalos have a predicted mass within 0.2 dex of their true value. The networks exhibit surprising extrapolation properties, being able to accurately predict the total mass of any type of subhalo containing any kind of galaxy at any redshift from simulations with different cosmologies, astrophysics models, subgrid physics, volumes, and resolutions, indicating that the network may have found a universal relation. We then use different methods to find equations that approximate the relation found by the networks and derive new analytic expressions that predict the total mass of a subhalo from its radius, velocity dispersion, and maximum circular velocity. We show that in some regimes, the analytic expressions are more accurate than the neural networks. The relation found by the neural network and approximated by the analytic equation bear similarities to the virial theorem.

Keywords: Computational methods, Galactic and extragalactic astronomy, Astrostatistics, Large-scale structure of the universe
Magnetic Imprints of Eruptive and Noneruptive Solar Flares as Observed by Solar Dynamics Observatory. The abrupt and permanent changes of the photospheric magnetic field in the localized regions of active regions during solar flares, called magnetic imprints (MIs), have been observed for nearly the past three decades. The well-known coronal implosion model is assumed to explain such flare-associated changes but the complete physical understanding is still missing and debatable. In this study, we made a systematic analysis of flare-related changes of the photospheric magnetic field during 21 flares (14 eruptive and seven noneruptive) using the 135 s cadence vector magnetogram data obtained from the Helioseismic and Magnetic Imager. The MI regions for eruptive flares are found to be strongly localized, whereas the majority of noneruptive events (&gt;70%) have scattered imprint regions. To quantify the strength of the MIs, we derived the integrated change of horizontal field and the total change of Lorentz force over an area. These quantities correlate well with the flare strength, irrespective of whether flares are eruptive or not, or have a short or long duration. Further, the free energy (FE), determined from virial theorem estimates, exhibits a statistically significant downward trend that starts around the flare time and is observed in the majority of flares. The change of FE during flares does not depend on eruptivity but has a strong positive correlation (≈0.8) with the Lorentz force change, indicating that part of the FE released would penetrate the photosphere. While these results strongly favor the idea of significant feedback from the corona on the photospheric magnetic field, the characteristics of MIs are quite indistinguishable from flares being eruptive or not.

Keywords: Solar activity, Solar coronal mass ejections, Solar flares, Solar photosphere
A Comprehensive Study of the Spectral Variation and the Brightness Profile of Young Pulsar Wind Nebulae. We present a systematic study of particle transport by diffusion in young pulsar wind nebulae (PWNe). We selected nine bright sources that are well resolved with the Chandra X-ray Observatory. We analyzed archival data to obtain their radial profiles of photon index (Γ) and surface brightness (Σ) in a consistent way. These profiles were then fit with a pure diffusion model that was tested on Crab, 3C 58, and G21.5-0.9 before. In addition to the spectral softening due to the diffusion, we calculated the synchrotron power and built up the theoretical surface brightness profile. For each source, we performed separate fits to the Γ and Σ profiles. We found that these two profiles of most PWNe are similar, except for Crab and Vela. Both profiles can be well described by our model, suggesting that diffusion dominates the particle transport in most sampled PWNe. The discrepancy of parameters between the Γ and Σ profiles is relatively large for 3C 58 and G54.1+0.3. This difference could be attributed to the elongated shape, reflecting boundary, and the nonuniform magnetic field. Finally, we found no significant correlations between diffusion parameters and physical parameters of PWNe and pulsars.

Keywords: Neutron stars, Rotation powered pulsars, Supernova remnants, X-ray sources, Interstellar synchrotron emission
Evolution and Kinematics of Protostellar Envelopes in the Perseus Molecular Cloud. We present a comprehensive analysis of the evolution of envelopes surrounding protostellar systems in the Perseus molecular cloud using data from the MASSES survey. We focus our attention to the C18O(2-1) spectral line, and we characterize the shape, size, and orientation of 54 envelopes and measure their fluxes, velocity gradients, and line widths. To look for evolutionary trends, we compare these parameters to the bolometric temperature T bol, a tracer of protostellar age. We find evidence that the angular difference between the elongation angle of the C18O envelope and the outflow axis direction generally becomes increasingly perpendicular with increasing T bol, suggesting the envelope evolution is directly affected by the outflow evolution. We show that this angular difference changes at T bol = 53 ± 20 K, which includes the conventional delineation between Class 0 and I protostars of 70 K. We compare the C18O envelopes with larger gaseous structures in other molecular clouds and show that the velocity gradient increases with decreasing radius ( $| { \mathcal G }| \sim {R}^{-0.72\pm 0.06}$ ). From the velocity gradients we show that the specific angular momentum follows a power-law fit J/M ∝ R 1.83±0.05 for scales from 1 pc down to ~500 au, and we cannot rule out a possible flattening out at radii smaller than ~1000 au.

Keywords: Circumstellar envelopes, Protostars, Early stellar evolution
An Absolute Calibration of the Near-infrared Period-Luminosity Relations of Type II Cepheids in the Milky Way and in the Large Magellanic Cloud. We present time-series photometry of 21 nearby type II Cepheids in the near-infrared J, H, and K  s  passbands. We use this photometry, together with the Third Gaia Early Data Release parallaxes, to determine for the first time period-luminosity relations (PLRs) for type II Cepheids from field representatives of these old pulsating stars in the near-infrared regime. We found PLRs to be very narrow for BL Herculis stars, which makes them candidates for precision distance indicators. We then use archival photometry and the most accurate distance obtained from eclipsing binaries to recalibrate PLRs for type II Cepheids in the Large Magellanic Cloud (LMC). Slopes of our PLRs in the Milky Way and in the LMC differ by slightly more than 2σ and are in a good agreement with previous studies of the LMC, Galactic bulge, and Galactic globular cluster type II Cepheids samples. We use PLRs of Milky Way type II Cepheids to measure the distance to the LMC, and we obtain a distance modulus of 18.540 ± 0.026(stat.) ± 0.034(syst.) mag in the W  JK  Wesenheit index. We also investigate the metallicity effect within our Milky Way sample, and we find a rather significant value of about -0.2 mag dex-1 in each band meaning that more metal-rich type II Cepheids are intrinsically brighter than their more metal-poor counterparts, in agreement with the value obtained from type II Cepheids in Galactic globular clusters. The main source of systematic error on our Milky Way PLRs calibration, and the LMC distance, is the current uncertainty of the Gaia parallax zero-point.

Keywords: Galaxy distances, Pulsating variable stars, Population II Cepheid variable stars, Large Magellanic Cloud, Distance indicators, Type II Cepheid variable stars, Population II stars, Stellar distance, Milky Way Galaxy
The Relevance of Ram Pressure Stripping for the Evolution of Blue Cluster Galaxies as Seen at Optical Wavelengths. Ram pressure stripping is one of the most efficient mechanisms able to affect the gas reservoir in cluster galaxies, and in the last decades many studies have characterized the properties of stripped galaxies. A definite census of the importance of this process in local clusters is still missing, though. Here, we characterize the fraction of galaxies showing signs of stripping at optical wavelengths, using the data of 66 clusters from the WINGS and OMEGAWINGS surveys. We focus on the infalling galaxy population, and hence only consider blue, bright (B &lt; 18.2), late-type, spectroscopically confirmed cluster members within two virial radii. In addition to "traditional" stripping candidates (SC)-i.e., galaxies showing unilateral debris and tails-we also consider unwinding galaxies (UG) as potentially stripped galaxies. Recent work has indeed unveiled a connection between unwinding features and ram pressure stripping, and even though only integral field studies can inform on how often these features are indeed due to ram pressure, it is important to include them in the global census. We performed a visual inspection of B-band images, and here we release a catalog of 143 UG. SC and UG each represent ~15%-20% of the inspected sample. If we make the assumption that they both are undergoing ram pressure stripping, we can conclude that, at any given time in the low-z universe, about 35% of the infalling cluster population show signs of stripping in their morphology at optical wavelengths. These fractions depend on color, mass, and morphology, and little on clustercentric distance. Making some rough assumptions regarding the duration of the tail visibility and the time that cluster galaxies can maintain blue colors, we infer that almost all bright blue late-type cluster galaxies undergo a stripping phase during their life, boosting the importance of ram pressure stripping in cluster galaxy evolution.

Keywords: Galaxy clusters, Spiral galaxies, Disk galaxies, Ram pressure stripped tails, Galaxies