Sazuna/UAT_keywords huggingface dataset:
Outside the Wall: Hydrodynamics of Type I Supernovae Interacting with a Partially Swept-up Circumstellar Medium. Explaining the observed diversity of supernovae (SNe) and the physics of explosion requires knowledge of their progenitor stars, which can be obtained by constraining the circumstellar medium (CSM). Models of the SN ejecta colliding with the CSM are necessary to infer the structure of the CSM and tie it back to a progenitor model. Recent SNe I revealed CSM concentrated at a distance r ∼ 1016 cm, for which models of SN interaction are extremely limited. In this paper, we assume the concentrated region is a "wall" representing swept-up material, and unswept material lies outside the wall. We simulate one-dimensional hydrodynamics of SNe Ia and Ib impacting 300 unique CSM configurations using RT1D, which captures the Rayleigh-Taylor instability. We find that the density ratio between the wall and ejecta—denoted A0 or "wall height"—is key, and higher walls deviate more from self-similar evolution. Functional fits accounting for A0 are presented for the forward-shock radius evolution. We show that higher walls have more degeneracy between CSM properties in the deceleration parameter, slower shocks, deeper-probing reverse shocks, slower shocked ejecta, less ejecta mass than CSM in the shock, and more mixing of ejecta into the CSM at early times. We analyze observations of SN 2014C (Type Ib) and suggest that it had a moderately high wall (10 ≲ A0 ≲ 200) and wind-like outer CSM. We also postulate an alternate interpretation for the radio data of SN 2014C, that the radio rise occurs in the wind rather than the wall. Finally, we find that hydrodynamic measurements at very late times cannot distinguish the presence of a wall, except perhaps as an anomalously wide shock region.

Keywords: Type Ib supernovae, Stellar mass loss, Type Ia supernovae, Shocks, Circumstellar gas
Magnetoacoustic Waves in a Magnetic Slab Embedded in an Asymmetric Magnetic Environment. II. Thin and Wide Slabs, Hot and Cold Plasmas. Wave propagation in magnetically structured atmospheres is a thoroughly studied, yet practically inexhaustible, well of investigations in the field of solar magneto-seismology. A simple but powerful example is the examination of wave behavior in a magnetic slab. Our previous study used an analytical approach to derive the general dispersion relation for magnetoacoustic waves in a magnetic slab of homogeneous plasma, which was enclosed in an asymmetric magnetic environment. In the present study, we focus on the analysis of wave propagation in various limiting cases applicable to solar and space plasma physics or astrophysics. The thin- and wide-slab approximations, as well as the limits of low and high plasma β values, are considered. Utilizing the fact that in a weakly asymmetric slab the dispersion relation can be decoupled, the behavior of quasi-sausage and quasi-kink modes is studied in further analytical and numerical detail, and their avoided crossings are described. The results highlight how asymmetry influences the wave properties, e.g., the phase speed of eigenmodes, depending on the ratios of external to internal densities and magnetic fields on the two sides. Notably, the phase speeds of surface modes will converge to different values for the quasi-sausage and quasi-kink modes in the wide-slab limit, and cutoff frequencies are introduced with respect to both surface and body modes, in thin as well as wide slabs, beyond which the solutions become leaky. These obtained properties of MHD wave behavior could be measured with suitable high-resolution instruments in the future.

Keywords: Solar atmosphere, Magnetohydrodynamics, Solar prominences, Plasma astrophysics, Solar filaments, Solar coronal waves, Solar oscillations, Solar coronal seismology, Solar magnetic bright points
Stochastic Processes as the Origin of the Double Power-law Shape of the Quasar Luminosity Function. The quasar luminosity function (QLF) offers insight into the early coevolution of black holes and galaxies. It has been characterized observationally up to redshift z ∼ 6 with clear evidence of a double power-law shape, in contrast to the Schechter-like form of the underlying dark-matter halo mass function. We investigate a physical origin for the difference in these distributions by considering the impact of stochasticity induced by the processes that determine the quasar luminosity for a given host halo and redshift. We employ a conditional luminosity function and construct the relation between median quasar magnitude versus halo mass ${M}_{\mathrm{UV},{\rm{c}}}({M}_{{\rm{h}}})$ with log-normal in luminosity scatter Σ, and duty-cycle ɛDC, and focus on high redshift z ≳ 4. We show that, in order to reproduce the observed QLF, the Σ = 0 abundance matching requires all of the brightest quasars to be hosted in the rarest most massive dark-matter halos (with an increasing ${M}_{\mathrm{UV},{\rm{c}}}/{M}_{{\rm{h}}}$ in halo mass). Conversely, for Σ &gt; 0 the brightest quasars can be overluminous outliers hosted in relatively common dark-matter halos. In this case, the median quasar magnitude versus halo mass relation, MUV,c, flattens at the high-end, as expected in self-regulated growth due to feedback. We sample the parameter space of Σ and ɛDC and show that MUV,c flattens above ${M}_{{\rm{h}}}\sim {10}^{12}{M}_{\odot }$ for ${\epsilon }_{\mathrm{DC}}\lt {10}^{-2}$ . Models with ɛDC ∼ 1 instead require a high mass threshold close to ${M}_{{\rm{h}}}\gtrsim {10}^{13}{M}_{\odot }$ . We investigate the impact of ɛDC and Σ on measurements of clustering and find there is no luminosity dependence on clustering for Σ &gt; 0.3, consistent with recent observations from Subaru HSC.

Keywords: Luminosity function, Supermassive black holes, Quasars
Redshift Evolution of Green Valley Galaxies in Different Environments from the Hyper Suprime-Cam Survey. Green valley galaxies represent the population that is likely to transition from star-forming to quiescent phases. To investigate the role of the environment in quenching star formation, we use the wide-field data from the Hyper Suprime-Cam Strategic Subaru Proposal survey to quantify the frequency of green valley galaxies in different environments and their redshift evolution. We find that the green valley fraction, in general, is less than 20% in any redshift and environment. The green valley fraction, when normalized to the total population, is higher in the field than that in groups or clusters and decreases with decreasing redshift and increasing mass. The lower fraction of transitional galaxies in denser environments could be a consequence of the lack of star-forming galaxies, which could be the progenitors of green valley galaxies. To assess the effect of the environment on star formation quenching, we define the effective green valley fraction as the ratio of the number of green valley galaxies to that of nonquiescent galaxies only. The effective green valley fraction for field galaxies is lower than that for group or cluster galaxies, which reveals a strong positive mass dependence and mild redshift evolution. Moreover, the specific star formation rate is reduced by 0.1-0.3 dex in groups or clusters. Our results thus imply that an ongoing slow quenching process has been acting in the dense environment since z ∼ 1.

Keywords: Galaxy clusters, Large-scale structure of the universe, Astronomy data analysis, Green valley galaxies, Galaxy groups
Gemini Multi-Object Spectrograph Integral Field Unit Spectroscopy of the Double-peaked Broad Emission Line of a Red Active Galactic Nucleus. Galaxy mergers are expected to produce multiple supermassive black holes (SMBHs) in close-separation, but the detection of such SMBHs has been difficult. 2MASS J165939.7 + 183436 is a red active galactic nucleus (AGN) that is a prospective merging SMBH candidate owing to its merging features in Hubble Space Telescope imaging and double-peaked broad emission lines (BELs). Herein, we report a Gemini Multi-Object Spectrograph Integral Field Unit observation of a double-peaked broad Hα line of 2MASS J165939.7+183436. Furthermore, we confirm the existence of two BEL peaks that are kinematically separated by 3000 km s-1, with the SMBH of each BEL component weighing at ${10}^{8.92\pm 0.06}\,{M}_{\odot }$ and ${10}^{7.13\pm 0.06}\,{M}_{\odot }$ , if they arise from independent BELs near the two SMBHs. The BEL components were not separated at &gt;0"1; however, under several plausible assumptions regarding the fitting of each spaxel, the two components are found to be spatially separated at 0"085 (∼250 pc). Different assumptions for the fitting can lead to a null (&lt;0"05) or a larger spatial separation (∼0"15). Given the uncertainty regarding the spatial separation, various models, such as the disk emitter and multiple SMBH models, are viable solutions to explain the double BEL components. These results will promote future research for finding more multiple SMBH systems in red AGNs, and higher-resolution imaging validates these different models.

Keywords: Quasars, Stellar tracking devices, Astrophysical black holes, Gravitational wave sources, Galaxy nuclei, Active galactic nuclei, Galaxy mergers, Galaxy evolution, Galaxies
The Gravitational Wave Treasure Map: A Tool to Coordinate, Visualize, and Assess the Electromagnetic Follow-up of Gravitational-wave Events. We present the Gravitational Wave (GW) Treasure Map, a tool to coordinate, visualize, and assess the electromagnetic (EM) followup of GW events. With typical GW localization regions of hundreds to thousands of square degrees and dozens of active follow-up groups, the pursuit of EM counterparts is a challenging endeavor, but the scientific payoff for early discovery of any counterpart is clear. With this tool, we provide a website and an application programming interface (API) that allows users to easily see where other groups have searched and better inform their own follow-up search efforts. A strong community of Treasure Map users will increase the overall efficiency of EM counterpart searches and will play a fundamental role in the future of multimessenger astronomy.

Keywords: Gravitational wave astronomy, Astronomy software
On the Ratios of Si IV Lines (λ1394/λ1403) in an Emerging Flux Region. The resonance lines of Si IV formed at λ1394 and 1403 Å are the most critical for the diagnostics of the solar transition region in the observations of the Interface Region Imaging Spectrograph (IRIS). Studying the intensity ratios of these lines (1394 Å/1403 Å), which under optically thin conditions is predicted to be two, helps us to diagnose the optical thickness of the plasma being observed. Here we study the evolution of the distribution of intensity ratios in 31 IRIS rasters recorded for four days during the emergence of an active region. We found that during the early phase of the development, the majority of the pixels show intensity ratios smaller than two. However, as the active region evolves, more and more pixels show the ratios closer to two. Besides, there are a substantial number of pixels with ratio values larger than 2. At the evolved stage of the active region, the pixels with ratios smaller than two were located on the periphery, whereas those with values larger than 2 were in the core. However, for quiet Sun regions, the obtained intensity ratios were close to two irrespective of the location on the disk. Our findings suggest that the Si IV lines observed in active regions are affected by the opacity during the early phase of the flux emergence. The results obtained here could have important implications for the modeling of the solar atmosphere, including the initial stage of the emergence of an active region as well as the quiet Sun.

Keywords: Quasar absorption line spectroscopy, Emerging flux tubes, The Sun, Stellar atmospheric opacity, Active sun, Atomic spectroscopy, Solar active regions
A Trend in the Effective Spin Distribution of LIGO Binary Black Holes with Mass. Binary black holes (BBHs) detected by gravitational wave (GW) observations could be broadly divided into two formation channels: those formed through field binary evolution and those assembled dynamically in dense stellar systems. Each of these formation channels, and their subchannels, populate a distinct region in the effective spin-mass ( ${\chi }_{\mathrm{eff}}$ $-M$) plane. Depending on the branching ratio of different channels, an ensemble of BBHs could show a trend in this plane. Here we fit a mass-dependent distribution for ${\chi }_{\mathrm{eff}}$ to the GWTC-1 BBHs from the first and second observing runs of Advanced LIGO and Advanced Virgo. We find a negative correlation between mass and the mean effective spin ( ${\bar{\chi }}_{\mathrm{eff}}$), and positive correlation with its dispersion ( ${\sigma }_{{\chi }_{\mathrm{eff}}}$) at 75% and 80% confidence. This trend is robust against the choice of mass variable, but most pronounced when the mass variable is taken to be the chirp mass of the binary. The result is consistent with significant contributions from both dynamically assembled and field binaries in the GWTC-1 catalog. The upcoming LIGO O3a data release will critically test this interpretation.

Keywords: LIGO, Laser interferometry, Stellar mass black holes, Astrophysical black holes
Survival of Primordial Planetary Atmospheres: Photodissociation-driven Mass Loss. The most widely studied mechanism of mass loss from extrasolar planets is photoevaporation via X-ray and ultraviolet ionization, primarily in the context of highly irradiated planets. However, the extreme ultraviolet dissociation of hydrogen molecules can also theoretically drive atmospheric evaporation on low-mass planets. For temperate planets such as the early Earth, impact erosion is expected to dominate in the traditional planetesimal accretion model, but it would be greatly reduced in pebble accretion scenarios, allowing other mass-loss processes to be major contributors. We apply the same prescription for photoionization to this photodissociation mechanism and compare it to an analysis of other possible sources of mass loss in pebble accretion scenarios. We find that there is no clear path to evaporating the primordial atmosphere accreted by an early Earth analog in a pebble accretion scenario. Impact erosion could remove ∼2300 bars of hydrogen if 1% of the planet's mass is accreted as planetesimals, while the combined photoevaporation processes could evaporate ∼750 bars of hydrogen. Photodissociation is likely a subdominant but significant component of mass loss. Similar results apply to super-Earths and mini-Neptunes. This mechanism could also preferentially remove hydrogen from a planet's primordial atmosphere, thereby leaving a larger abundance of primordial water compared to standard dry formation models. We discuss the implications of these results for models of rocky planet formation, including Earth's formation, and the possible application of this analysis to mass loss from observed exoplanets.

Keywords: Extrasolar rocky planets, Exoplanet evolution, Exoplanet formation, Exoplanet atmospheres
Active-region Tilt Angles from White-light Images and Magnetograms: The Role of Magnetic Tongues. The presence of elongations in active-region (AR) polarities, called magnetic tongues, is mostly visible during their emergence phase. AR tilts have been measured thoroughly using long-term white-light (WL) databases, sometimes combined with magnetic-field information. Since the influence of magnetic tongues on WL tilt measurements has not been taken into account before, we aim to investigate their role in tilt-angle values and to compare them with those derived from LOS magnetograms. We apply four methods to compute the tilt angle of generally bipolar ARs: one applies the k-means algorithm to WL data, a second one includes the magnetic-field sign of the polarities to WL data, and a third one uses the magnetic flux-weighted center of each polarity. The tilt values computed in any of these ways are affected by the presence of magnetic tongues. Therefore, we apply the newly developed Core Field Fit Estimator (CoFFE) method to separate the magnetic flux in the tongues from that in the AR core. We compare the four computed tilt-angle values, as well as these with the ones reported in long-term WL databases. For ARs with low-magnetic-flux tongues, the different methods report consistent tilt-angle values. But for ARs with high-flux tongues, there are noticeable discrepancies between all methods, indicating that magnetic tongues differently affect WL and magnetic data. However, in general, CoFFE achieves a better estimation of the main bipole tilt because it removes both the effect of tongues as well as the emergence of secondary bipoles when it occurs in between the main bipole magnetic polarities.

Keywords: Solar active region magnetic fields, Solar active regions, Sunspots, Bipolar sunspot groups
Radiolysis of Ices by Cosmic-Rays: CH<SUB>4</SUB> and H<SUB>2</SUB>O Ices Mixtures Irradiated by 40 MeV <SUP>58</SUP>Ni<SUP>11+</SUP> Ions. Physico-chemical modifications induced by swift heavy ions on methane-water (CH4:H2O) ices at 15 K are analyzed. Ice films, at concentrations of (1:3) and (1:15), were irradiated by 40 MeV 58Ni11+ ions. Fourier transform transmission spectroscopy in the mid-range was used to monitor the evolution ices at 15 K as a function of projectile fluence. New IR bands appearing for the irradiated (CH4:H2O) (1:3) ice are attributed to the synthesized molecules: C3H8, HCO, H2CO, CO, CO2, H2O2, HCOOH, CH3OH, C2H5OH, and CH3CHO. For the irradiated (CH4:H2O) (1:15) ice, the abundances of the compounds containing two carbons atoms are lower than those for the (1:3) ice; in contrast, CH3OH and H2O2 abundances increase when compared to the values obtained with the (1:3) ice. After irradiation, the ices were warmed up until 110 K, when the IR spectra reveal features of complex organic molecules. The destruction and formation cross sections and the sputtering yields of the ice mixtures are estimated. These findings provide possible pathways for the occurrence of compounds rich in C, O, and H, which are indeed observed in the cold regions of the universe such as ices in grain mantles of the interstellar medium and circumstellar envelopes.

Keywords: Interstellar molecules, Laboratory astrophysics, Astrochemistry, Surface ices, Spectroscopy
Hierarchical Bayesian Thermonuclear Rate for the <SUP>7</SUP>Be(n,p)<SUP>7</SUP>Li Big Bang Nucleosynthesis Reaction. Big Bang nucleosynthesis provides the earliest probe of standard model physics, at a time when the universe was less than 1000 seconds old. It determines the abundances of the lightest nuclides, which give rise to the subsequent history of the visible matter in the universe. This work derives new 7Be(n,p)7Li thermonuclear reaction rates based on all available experimental information. This reaction sensitively impacts the primordial abundances of 7Be and 7Li during big bang nucleosynthesis. We critically evaluate all available data and disregard experimental results that are questionable. For the nuclear model, we adopt an incoherent sum of single-level, two-channel, R-matrix approximation expressions, which are implemented into a hierarchical Bayesian model, to analyze the remaining six data sets we deem most reliable. In the fitting of the data, we consistently model all known sources of uncertainty, including discrepant absolute normalizations of different data sets, and also take the variation of the neutron and proton channel radii into account, hence providing less biased estimates of the 7Be(n,p)7Li thermonuclear rates. From the resulting posteriors, we extract R-matrix parameters (Er, ${\gamma }_{n}^{2}$ , ${\gamma }_{p}^{2}$) and derive excitation energies and partial and total widths. Our fit is sensitive to the contributions of the first three levels above the neutron threshold. Reaction rates were computed by integrating 10,000 samples of the reduced cross section. Our 7Be(n,p)7Li thermonuclear rates have uncertainties between 1.5% and 2.0% at temperatures of ≤1 GK. We compare our rates to previous results and find that the 7Be(n,p)7Li rates most commonly used in big bang simulations have uncertainties that are too optimistic.

Keywords: Nuclear astrophysics, Big Bang nucleosynthesis
The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. I. Survey Overview and First Results for Andromeda I. An optical monitoring survey in nearby dwarf galaxies was carried out with the 2.5 m Isaac Newton Telescope. Fifty-five dwarf galaxies and four isolated globular clusters in the Local Group were observed with the Wide Field Camera. The main aims of this survey are to identify the most evolved asymptotic giant branch (AGB) stars and red supergiants at the end-point of their evolution based on their pulsational instability, use their distribution over luminosity to reconstruct the star formation history, quantify the dust production and mass loss from modeling the multiwavelength spectral energy distributions (SEDs), and relate this to luminosity and radius variations. In this first of a series of papers, we present the methodology of the variability survey and describe the photometric catalog of the Andromeda I (And I) dwarf galaxy as an example of the survey, and we discuss the identified long period variable (LPV) stars. We detected 5581 stars and identified 59 LPV candidates within two half-light radii of the center of And I. The amplitudes of these candidates range from 0.2 to 3 mag in the I-band. Seventy-five percent of detected sources and 98% of LPV candidates are detected at mid-infrared wavelengths. We show evidence for the presence of dust-producing AGB stars in this galaxy including five extreme AGB (X-AGB) stars, and we model some of their SEDs. A distance modulus of 24.41 mag for And I was determined based on the tip of the red giant branch. Also, a half-light radius of 3'2 ± 0'3 was calculated.

Keywords: Local Group, Luminosity function, Galaxy distances, Surveys, Dwarf galaxies, Galaxy stellar content, Stellar mass loss, Stellar mass functions, Asymptotic giant branch stars, Long period variable stars, Stellar oscillations, Stellar evolution
Fast Acceleration of Transrelativistic Electrons in Astrophysical Turbulence. Highly energetic, relativistic electrons are commonly present in many astrophysical systems, from solar flares to the intracluster medium, as indicated by observed electromagnetic radiation. However, open questions remain about the mechanisms responsible for their acceleration, and possible reacceleration. Ubiquitous plasma turbulence is one of the possible universal mechanisms. We study the energization of transrelativistic electrons in turbulence using a hybrid particle-in-cell method, which provides a realistic model of Alfvénic turbulence from MHD to subion scales, and test particle simulations for electrons. We find that, depending on the electron initial energy and turbulence strength, electrons may undergo a fast and efficient phase of energization due to the magnetic curvature drift during the time they are trapped in dynamic magnetic structures. In addition, electrons are accelerated stochastically, which is a slower process that yields lower maximum energies. The combined effect of these two processes determines the overall electron acceleration. With appropriate turbulence parameters, we find that superthermal electrons can be accelerated up to relativistic energies. For example, with heliospheric parameters and a relatively high turbulence level, rapid energization to megaelectronvolt energies is possible.

Keywords: Interplanetary turbulence, Interplanetary particle acceleration, Plasma astrophysics