Sazuna/UAT_keywords huggingface dataset:
Solar Polar Flux Redistribution Based on Observed Coronal Holes. We explore the use of observed polar coronal holes (CHs) to constrain the flux distribution within the polar regions of global solar magnetic field maps in the absence of reliable quality polar field observations. Global magnetic maps, generated by the Air Force Data Assimilative Photospheric flux Transport (ADAPT) model, are modified to enforce field unipolarity thresholds both within and outside observed CH boundaries. The polar modified and unmodified maps are used to drive Wang-Sheeley-Arge (WSA) models of the corona and solar wind (SW). The WSA-predicted CHs are compared with the observations, and SW predictions at the WIND and Ulysses spacecraft are also used to provide context for the new polar modified maps. We find that modifications of the polar flux never worsen and typically improve both the CH and SW predictions. We also confirm the importance of the choice of the domain over which WSA generates the coronal magnetic field solution but find that solutions optimized for one location in the heliosphere can worsen predictions at other locations. Finally, we investigate the importance of low-latitude (i.e., active region) magnetic fields in setting the boundary of polar CHs, determining that they have at least as much impact as the polar fields themselves.

Keywords: Slow solar wind, Solar active region magnetic fields, Solar photosphere, Fast solar wind, Solar magnetic fields, Solar coronal holes
Luminous Millimeter, Radio, and X-Ray Emission from ZTF 20acigmel (AT 2020xnd). Observations of the extragalactic (z = 0.0141) transient AT 2018cow established a new class of energetic explosions shocking a dense medium, producing luminous emission at millimeter and submillimeter wavelengths. Here we present detailed millimeter- through centimeter-wave observations of a similar transient, ZTF 20acigmel (AT 2020xnd), at z = 0.2433. Using observations from the NOrthern Extended Millimeter Array and the Very Large Array, we model the unusual millimeter and radio emission from AT 2020xnd under several different assumptions and ultimately favor synchrotron radiation from a thermal electron population (relativistic Maxwellian). The thermal electron model implies a fast but subrelativistic (v ≈ 0.3c) shock and a high ambient density (n  e  ≈ 4 × 103 cm-3) at Δt ≈ 40 days. The X-ray luminosity of L  X  ≈ 1043 erg s-1 exceeds simple predictions from the radio and UVOIR luminosity and likely has a separate physical origin, such as a central engine. Using the fact that month-long luminous (L  ν  ≈ 2 × 1030 erg s-1 Hz-1 at 100 GHz) millimeter emission appears to be a generic feature of transients with fast (t 1/2 ≈ 3 days) and luminous (M peak ≈ -21 mag) optical light curves, we estimate the rate at which transients like AT 2018cow and AT 2020xnd will be detected by future wide-field millimeter transient surveys such as CMB-S4 and conclude that energetic explosions in dense environments may represent a significant population of extragalactic transients in the 100 GHz sky.

Keywords: Core-collapse supernovae, Millimeter astronomy, Shocks, Transient sources, Submillimeter astronomy, Spectral index, Radio astronomy, Supernovae
The Proper Motion of the Pulsar J1124-5916 in the Galactic Supernova Remnant G292.0+1.8. We present the first direct measurement of the proper motion of pulsar J1124-5916 in the young, oxygen-rich supernova remnant G292.0+1.8. Using deep Chandra ACIS-I observations from 2006 to 2016, we measure a positional change of 0.″21 ± 0.″05 over the ~10 yr baseline, or ~0.″02 yr-1. At a distance of 6.2 ± 0.9 kpc, this corresponds to a kick velocity in the plane of the sky of 612 ± 152 km s-1. We compare this direct measurement against the velocity inferred from estimates based on the center of mass of the ejecta. Additionally, we use this new proper-motion measurement to compare the motion of the neutron star to the center of expansion of the optically emitting ejecta. We derive an age estimate for the supernova remnant of ≳2000 yr. The high measured kick velocity is in line with recent studies of high proper motion neutron stars in other Galactic supernova remnants and consistent with a hydrodynamic origin to the neutron star kick.

Keywords: Stellar kinematics, Pulsars
Searching for Anomalies in the ZTF Catalog of Periodic Variable Stars. Periodic variables illuminate the physical processes of stars throughout their lifetime. Wide-field surveys continue to increase our discovery rates of periodic variable stars. Automated approaches are essential to identify interesting periodic variable stars for multiwavelength and spectroscopic follow-up. Here we present a novel unsupervised machine-learning approach to hunt for anomalous periodic variables using phase-folded light curves presented in the Zwicky Transient Facility Catalogue of Periodic Variable Stars by Chen et al. We use a convolutional variational autoencoder to learn a low-dimensional latent representation, and we search for anomalies within this latent dimension via an isolation forest. We identify anomalies with irregular variability. Most of the top anomalies are likely highly variable red giants or asymptotic giant branch stars concentrated in the Milky Way galactic disk; a fraction of the identified anomalies are more consistent with young stellar objects. Detailed spectroscopic follow-up observations are encouraged to reveal the nature of these anomalies.

Keywords: Periodic variable stars, Late stellar evolution, Convolutional neural networks, Peculiar variable stars, Astrophysical dust processes, Semi-regular variable stars, Mira variable stars, Asymptotic giant branch stars, Young stellar objects, Red giant stars, Late-type giant stars
Formation and Abundance of Late-forming Primordial Black Holes as Dark Matter. We propose a novel mechanism where primordial black hole (PBH) dark matter is formed much later in the history of the universe, between the epochs of Big Bang nucleosynthesis and cosmic microwave background photon decoupling. In our setup, one does not need to modify the scale-invariant inflationary power spectra; instead, a late-phase transition in a strongly interacting fermion-scalar fluid (which occurs naturally around redshift 106 ≤ z  T  ≤ 108) creates an instability in the density perturbation as the sound speed turns imaginary. As a result, the dark matter perturbation grows exponentially in sub-Compton scales. This follows the immediate formation of an early dense dark matter halo, which finally evolves into PBHs due to cooling through scalar radiation. We calculate the variance of the density perturbations and the PBH fractional abundances f(M) by using a nonmonochromatic mass function. We find that the peak of our PBH mass function lies between 10-16 and 10-14 solar mass for z  T  ≃ 106, and thus that it can constitute the entire dark matter of the universe. In PBH formation, one would expect a temporary phase where an attractive scalar balances the Fermi pressure. We numerically confirm that such a state indeed exists, and we find the radius and density profile of the temporary static structure of the dark matter halo, which finally evolves into PBHs due to cooling through scalar radiation.

Keywords: Cosmology, Early universe, Dark matter, Primordial black holes
Measurement of the Gamma-Ray Energy Spectrum beyond 100 TeV from the HESS J1843-033 Region. HESS J1843-033 is a very high energy gamma-ray source whose origin remains unidentified. This work presents, for the first time, the energy spectrum of gamma rays beyond 100 TeV from the HESS J1843-033 region using the data recorded by the Tibet air shower array and its underground muon detector array. A gamma-ray source with an extension of 0.°34 ± 0.°12 is successfully detected above 25 TeV at (α, δ) = (281.°09 ± 0.°10, -3.°76 ± 0.°09) near HESS J1843-033 with a statistical significance of 6.2σ, and the source is named TASG J1844-038. The position of TASG J1844-038 is consistent with those of HESS J1843-033, eHWC J1842-035, and LHAASO J1843-0338. The measured gamma-ray energy spectrum in 25 TeV &lt; E &lt; 130 TeV is described with ${dN}/{dE}=(9.70\pm 1.89)\times {10}^{-16}$ (E/40 TeV)-3.26±0.30 TeV-1 cm-2 s-1, and the spectral fit to the combined spectra of HESS J1843-033, LHAASO J1843-0338, and TASG J1844-038 implies the existence of a cutoff at 49.5 ± 9.0 TeV. Associations of TASG J1844-038 with SNR G28.6-0.1 and PSR J1844-0346 are also discussed in detail for the first time.

Keywords: Gamma-ray observatories, Gamma-ray sources, Galactic cosmic rays, Cosmic ray sources, Gamma-ray astronomy
Model-independent Reconstruction of Dark Energy Density from Current Observations. The evolution of the dark energy (DE) density is a crucial quantity for understanding the nature of DE. Often, the quantity is described by the so-called equation of state; that is, the ratio of the DE pressure to its density. In this scenario, the DE density is always positive throughout cosmic history, and a negative value is not allowed. Assuming a homogeneous and isotropic universe, we reconstruct the DE density directly from observational data and investigate its evolution throughout cosmic history. We consider the latest Type Ia supernova, baryon acoustic oscillation, and cosmic chronometer data, and reconstruct the DE density in both flat and nonflat universes up to redshift z ~ 3. The results are well in agreement with ΛCDM up to redshift z ~ 1.5, but we see a weak sign of negative DE density at high redshifts.

Keywords: Cosmology, Observational cosmology, Dark energy
Cloudlet Capture Model for Asymmetric Molecular Emission Lines Observed in TMC-1A with ALMA. TMC-1A is a protostellar source harboring a young protostar, IRAS 04365+2353, and shows highly asymmetric features of a few 100 au scale in its molecular emission lines. Blueshifted emission is much stronger in the CS (J = 5-4) line than redshifted emission. This asymmetry can be explained if the gas accretion is episodic and takes the form of cloudlet capture, given that the cloudlet is approaching toward us. The gravity of the protostar transforms the cloudlet into a stream and changes its velocity along the flow. The emission from the cloudlet should be blueshifted before the periastron, while it should be redshifted after the periastron. If a major part of cloudlet has not reached the periastron, the former should be dominant. We perform hydrodynamical simulations to examine the validity of the scenario. Our numerical simulations can reproduce the observed asymmetry if the orbit of the cloudlet is inclined to the disk plane. The inclination can explain the slow infall velocity observed in the C18O (J = 2-1) line emission. Such episodic accretion may occur in various protostellar cores since actual clouds could have inhomogeneous density distributions. We also discuss the implication of the cloudlet capture on observations of related objects.

Keywords: Interstellar molecules, Young stellar objects, Star formation, Interstellar medium, Protostars
A Comparison of Chemical Models of Exoplanet Atmospheres Enabled by TauREx 3.1. Thermochemical equilibrium is one of the most commonly used assumptions in current exoplanet retrievals. As science operations with the James Webb Space Telescope (JWST) draw near and with the planned launch of Ariel, it is crucial to assess the underlying biases and assumptions made when applying self-consistent chemistry to spectral retrievals. Here we use the flexibility of TauREx 3.1 to cross-compare three state-of-the-art chemical equilibrium codes: ACE, FastChem, and GGchem. We simulate JWST spectra for ACE, FastChem, GGchem, and GGchem+condensation containing only the elements C, H, O, and N and spectra for FastChem, GGchem, and GGchem+condensation with a more extensive range of elements, giving seven simulated JWST spectra in total, and then cross-retrieve, giving a total of 56 retrievals. Our analysis demonstrates that, like-for-like, all chemical codes retrieve the correct parameters to within 1% of the truth. However, in retrievals, where the contained elements do not match the truth, parameters such as metallicity deviate by 20% while maintaining extremely low uncertainties &lt;1%, giving false confidence. This point is of major importance for future analyses on JWST and Ariel, highlighting that self-consistent chemical schemes that do not employ the proper assumptions (missing species, fixed elemental ratios, condensation) are at risk of confidently biasing interpretations. Free chemistry retrievals employing parametric descriptions of the chemical profiles can provide alternative unbiased explorations.

Keywords: Publicly available software, Exoplanet atmospheric composition , Open source software, Bayesian statistics, Exoplanets, Chemical abundances, Exoplanet astronomy, Radiative transfer, Exoplanet atmospheres
GENGA. II. GPU Planetary N-body Simulations with Non-Newtonian Forces and High Number of Particles. We present recent updates and improvements of the graphical processing unit (GPU) N-body code GENGA. Modern state-of-the-art simulations of planet formation require the use of a very high number of particles to accurately resolve planetary growth and to quantify the effect of dynamical friction. At present the practical upper limit is in the range of 30,000-60,000 fully interactive particles; possibly a little more on the latest GPU devices. While the original hybrid symplectic integration method has difficulties to scale up to these numbers, we have improved the integration method by (i) introducing higher level changeover functions and (ii) code improvements to better use the most recent GPU hardware efficiently for such large simulations. We added treatments of non-Newtonian forces such as general relativity, tidal interaction, rotational deformation, the Yarkovsky effect, and Poynting-Robertson drag, as well as a new model to treat virtual collisions of small bodies in the solar system. We added new tools to GENGA, such as semi-active test particles that feel more massive bodies but not each other, a more accurate collision handling and a real-time openGL visualization. We present example simulations, including a 1.5 billion year terrestrial planet formation simulation that initially started with 65,536 particles, a 3.5 billion year simulation without gas giants starting with 32,768 particles, the evolution of asteroid fragments in the solar system, and the planetesimal accretion of a growing Jupiter simulation. GENGA runs on modern NVIDIA and AMD GPUs.

Keywords: Solar system formation, Asteroid dynamics, Celestial mechanics, Computational methods, N-body problem, GPU computing, N-body simulations, Planet formation
EstrellaNueva: An Open-source Software to Study the Interactions and Detection of Neutrinos Emitted by Supernovae. Supernovae emit large fluxes of neutrinos, which can be detected by detectors on Earth. Future multi-kiloton scale detectors will be sensitive to several neutrino interaction channels, with thousands of events expected if a supernova emerges in the galaxy neighborhood. There are a limited number of tools to study the interaction rates of supernova neutrinos, although a plethora of available supernova models exist. EstrellaNueva is an open-source software to calculate expected rates of supernova neutrinos in detectors using target materials with typical compositions, and additional compositions can be easily added. This software considers the flavor transformation of neutrinos in the supernova through the adiabatic Mikheyev-Smirnov-Wolfenstein effect, and their interaction in detectors through several channels. Most of the interaction cross sections, such as neutrino-electron and neutrino-proton elastic scattering, inverse beta decay, and coherent elastic neutrino-nucleus scattering, have been analytically implemented. This software provides a link between supernova simulations and the expected events in detectors by calculating fluences and event rates in order to ease any comparison between theory and observation. It provides a simple and standalone tool to explore many physics scenarios, offering an option to add analytical cross sections and define any target material.

Keywords: Supernova neutrinos
A New Method for Direct Measurement of Isotopologue Ratios in Protoplanetary Disks: A Case Study of the <SUP>12</SUP>CO/<SUP>13</SUP>CO Ratio in the TW Hya Disk. Planetary systems are thought to be born in protoplanetary disks. Isotope ratios are a powerful tool for investigating the material origin and evolution from molecular clouds to planetary systems via protoplanetary disks. However, it is challenging to measure the isotope (isotopologue) ratios, especially in protoplanetary disks, because the emission lines of major species are saturated. We developed a new method to overcome these challenges by using optically thin line wings induced by thermal broadening. As a first application of the method, we analyzed two carbon monoxide isotopologue lines, 12CO 3-2 and 13CO 3-2, from archival observations of a protoplanetary disk around TW Hya with the Atacama Large Millimeter/submillimeter Array. The 12CO/13CO ratio was estimated to be 21 ± 5 at disk radii of 70-110 au, which is significantly smaller than the value observed in the local interstellar medium, ~69. It implies that an isotope exchange reaction occurs in a low-temperature environment with C/O &gt; 1. In contrast, it is suggested that 12CO/13CO is higher than ~84 in the outer disk (r &gt; 130 au), which can be explained by the difference in the binding energy of the isotopologues on dust grains and the CO gas depletion processes. Our results imply that the gas-phase 12CO/13CO can vary by a factor of &gt;4 even inside a protoplanetary disk and therefore can be used to trace material evolution in disks.

Keywords: Isotopic abundances, Protoplanetary disks, Planet formation, Astrochemistry
Energetic Particle Perpendicular Diffusion: Simulations and Theory in Noisy Reduced Magnetohydrodynamic Turbulence. The transport of energetic charged particles (e.g., cosmic rays) in turbulent magnetic fields is usually characterized in terms of the diffusion parallel and perpendicular to a large-scale (or mean) magnetic field. The nonlinear guiding center theory has been a prominent perpendicular diffusion theory. A recent version of this theory, based on the random ballistic spreading of magnetic field lines and a backtracking correction (RBD/BC), has shown good agreement with test particle simulations for a two-component magnetic turbulence model. The aim of the present study is to test the generality of the improved theory by applying it to the noisy reduced magnetohydrodynamic (NRMHD) turbulence model, determining perpendicular diffusion coefficients that are compared with those from the field line random walk (FLRW) and unified nonlinear (UNLT) theories and our test particle simulations. The synthetic NRMHD turbulence model creates special conditions for energetic particle transport, with no magnetic fluctuations at higher parallel wavenumbers so there is no resonant parallel scattering if the particle Larmor radius R L is even slightly smaller than the minimum resonant scale. This leads to nonmonotonic variation in the parallel mean free path λ ∥ with R L. Among the theories considered, only RBD/BC matches simulations within a factor of 2 over the range of parameters considered. This accuracy is obtained even though the theory depends on λ ∥ and has no explicit dependence on R L. In addition, the UNLT theory often provides accurate results, and even the FLRW limit provides a very simple and reasonable approximation in many cases.

Keywords: Magnetic fields, Particle astrophysics, Cosmic rays
Milky Way Satellite Census. IV. Constraints on Decaying Dark Matter from Observations of Milky Way Satellite Galaxies. We use a recent census of the Milky Way (MW) satellite galaxy population to constrain the lifetime of particle dark matter (DM). We consider two-body decaying dark matter (DDM) in which a heavy DM particle decays with lifetime τ comparable to the age of the universe to a lighter DM particle (with mass splitting ϵ) and to a dark radiation species. These decays impart a characteristic "kick velocity," V kick = ϵ c, on the DM daughter particles, significantly depleting the DM content of low-mass subhalos and making them more susceptible to tidal disruption. We fit the suppression of the present-day DDM subhalo mass function (SHMF) as a function of τ and V kick using a suite of high-resolution zoom-in simulations of MW-mass halos, and we validate this model on new DDM simulations of systems specifically chosen to resemble the MW. We implement our DDM SHMF predictions in a forward model that incorporates inhomogeneities in the spatial distribution and detectability of MW satellites and uncertainties in the mapping between galaxies and DM halos, the properties of the MW system, and the disruption of subhalos by the MW disk using an empirical model for the galaxy-halo connection. By comparing to the observed MW satellite population, we conservatively exclude DDM models with τ &lt; 18 Gyr (29 Gyr) for V kick = 20 kms-1 (40 kms-1) at 95% confidence. These constraints are among the most stringent and robust small-scale structure limits on the DM particle lifetime and strongly disfavor DDM models that have been proposed to alleviate the Hubble and S 8 tensions.

Keywords: Milky Way dark matter halo, Galaxy abundances, Dark matter
Multiwavelength Observations of the Blazar VER J0521+211 during an Elevated TeV Gamma-Ray State. We report on a long-lasting, elevated gamma-ray flux state from VER J0521+211 observed by VERITAS, MAGIC, and Fermi-LAT in 2013 and 2014. The peak integral flux above 200 GeV measured with the nightly binned light curve is (8.8 ± 0.4) × 10-7 photons m-2 s-1, or ~37% of the Crab Nebula flux. Multiwavelength observations from X-ray, UV, and optical instruments are also presented. A moderate correlation between the X-ray and TeV gamma-ray fluxes was observed, and the X-ray spectrum appeared harder when the flux was higher. Using the gamma-ray spectrum and four models of the extragalactic background light (EBL), a conservative 95% confidence upper limit on the redshift of the source was found to be z ≤ 0.31. Unlike the gamma-ray and X-ray bands, the optical flux did not increase significantly during the studied period compared to the archival low-state flux. The spectral variability from optical to X-ray bands suggests that the synchrotron peak of the spectral energy distribution (SED) may become broader during flaring states, which can be adequately described with a one-zone synchrotron self-Compton model varying the high-energy end of the underlying particle spectrum. The synchrotron peak frequency of the SED and the radio morphology of the jet from the MOJAVE program are consistent with the source being an intermediate-frequency-peaked BL Lac object.

Keywords: BL Lacertae objects, High energy astrophysics, Blazars, Relativistic jets, Active galactic nuclei, Non-thermal radiation sources, Gamma-rays