Sazuna/UAT_keywords huggingface dataset:
UniverseMachine: Predicting Galaxy Star Formation over Seven Decades of Halo Mass with Zoom-in Simulations. We apply the empirical galaxy-halo connection model UNIVERSEMACHINE to dark-matter-only zoom-in simulations of isolated Milky Way (MW)-mass halos, along with their parent cosmological simulations. This application extends UNIVERSEMACHINE predictions into the ultrafaint dwarf galaxy regime (102 M⊙ ≤ M* ≤ 105 M⊙) and yields a well-resolved stellar mass-halo mass (SMHM) relation over the peak halo mass range of 108-1015 M⊙. The extensive dynamic range provided by the zoom-in simulations allows us to assess specific aspects of dwarf galaxy evolution predicted by UNIVERSEMACHINE. In particular, although UNIVERSEMACHINE is not constrained for dwarf galaxies with M* ≲ 108 M⊙, our predicted SMHM relation is consistent with that inferred for MW satellite galaxies at z = 0 using abundance matching. However, UNIVERSEMACHINE predicts that nearly all galaxies are actively star-forming below M* ~ 107 M⊙ and that these systems typically form more than half of their stars at z ≲ 4, which is discrepant with the star formation histories of Local Group dwarf galaxies that favor early quenching. This indicates that the current UNIVERSEMACHINE model does not fully capture galaxy quenching physics at the low-mass end. We highlight specific improvements necessary to incorporate environmental and reionization-driven quenching for dwarf galaxies, and we provide a new tool to connect dark matter accretion to star formation over the full dynamic range that hosts galaxies.

Keywords: Galaxy evolution, Computational methods, Dwarf galaxies, Dark matter
The Power Spectrum and Structure Function of the Gamma-Ray Emission from the Large Magellanic Cloud. The Fermi-LAT observational data of the diffuse γ ray emission from the Large Magellanic Cloud (LMC) were examined to test for the existence of underlying long-range correlations. A statistical test applied to the data indicated that the probability that data are random is extremely small. Thus we proceeded and have used the counts-number data to compute 2D spatial autocorrelation, power spectrum, and structure function. The most important result of the present study is a clear indication for large-scale spatial underlying correlations. This is evident in all the functions mentioned above. The 2D power spectrum has a logarithmic slope of -3 on large spatial scales and a logarithmic slope of -4 on small spatial scales. The structure function has logarithmic slopes equaling 1 and 2 for the large and small scales, respectively. The logarithmic slopes of the structure function and the power spectrum are consistent. A plausible interpretation of these results is the existence of a large-scale supersonic compressible turbulence with a 3D logarithmic slope of -4 extending over scales comparable to the size of the LMC. Both the power spectrum and structure function exhibit steeper logarithmic slopes for smaller spatial scales. This is interpreted as an indication that the turbulent region has an effective depth of about 1.5 kpc.

Keywords: Interstellar medium, Galaxies
Primordial Black Holes Formation and Secondary Gravitational Waves in Nonminimal Derivative Coupling Inflation. We study the possibility of the primordial black holes (PBHs) formation with the aim of finding a considerable fraction of dark matter (DM), using the gravitationally enhanced friction mechanism which arises from a nonminimal derivative coupling between the scalar field and the gravity. Assuming the nonminimal coupling parameter as a special function of the scalar field and considering the potential of natural inflation, we find three parameter sets that produce a period of ultra slow-roll inflation. This leads to sufficiently large enhancement in the curvature power spectra to form PBHs. We show that under the gravitationally enhanced friction mechanism, PBHs with a mass around ${ \mathcal O }\left({10}^{-12}\right){M}_{\odot }$ can constitute around 96% of the total DM and so this class of PBHs can be taken as a great candidate for DM. We further study the secondary gravitational waves (GWs) in our setting and show that our model predicts the peak of the present fractional energy density as ΩGW0 ~ 10-8 at different frequencies for all the three parameter sets. This value lies well inside the sensitivity region of some GWs detectors at some frequencies, and therefore the observational compatibility of our model can be appraised by the data from these detectors.

Keywords: Cosmic inflation, Gravitational waves, Primordial black holes
Identification of Lensed Gravitational Waves with Deep Learning. Similar to light, gravitational waves (GWs) can be lensed. Such lensing phenomena can magnify the waves, create multiple images observable as repeated events, and superpose several waveforms together, inducing potentially discernible patterns on the waves. In particular, when the lens is small, ≲105 M⊙, it can produce lensed images with time delays shorter than the typical gravitational-wave signal length that conspire together to form "beating patterns." We present a proof-of-principle study utilizing deep learning for identification of such a lensing signature. We bring the excellence of state-of-the-art deep learning models at recognizing foreground objects from background noise to identifying lensed GWs from noisy spectrograms. We assume the lens mass is around 103-105 M⊙, which can produce time delays of the order of milliseconds between two images of lensed GWs. We discuss the feasibility of distinguishing lensed GWs from unlensed ones and estimating physical and lensing parameters. The suggested method may be of interest to the study of more complicated lensing configurations for which we do not have accurate waveform templates.

Keywords: Weak gravitational lensing, Convolutional neural networks, Astronomy data analysis, Gravitational waves
New Candidate Extreme T Subdwarfs from the Backyard Worlds: Planet 9 Citizen Science Project. Schneider et al. presented the discovery of WISEA J041451.67-585456.7 and WISEA J181006.18-101000.5, which appear to be the first examples of extreme T-type subdwarfs (esdTs; metallicity ≤-1 dex, Teff ≲ 1400 K). Here, we present new discoveries and follow-up of three T-type subdwarf candidates, with an eye toward expanding the sample of such objects with very low metallicity and extraordinarily high kinematics, properties that suggest membership in the Galactic halo. Keck/NIRES near-infrared spectroscopy of WISEA J155349.96+693355.2, a fast-moving object discovered by the Backyard Worlds: Planet 9 citizen science project, confirms that it is a mid-T subdwarf. With HW2 = 22.3 mag, WISEA J155349.96+693355.2 has the largest W2 reduced proper motion among all spectroscopically confirmed L and T subdwarfs, suggesting that it may be kinematically extreme. Nevertheless, our modeling of the WISEA J155349.96+693355.2 near-infrared spectrum indicates that its metallicity is only mildly subsolar. In analyzing the J155349.96+693355.2 spectrum, we present a new grid of low-temperature, low-metallicity model atmosphere spectra. We also present the discoveries of two new esdT candidates, CWISE J073844.52-664334.6 and CWISE J221706.28-145437.6, based on their large motions and colors similar to those of the two known esdT objects. Finding more esdT examples is a critical step toward mapping out the spectral sequence and observational properties of this newly identified population.

Keywords: Brown dwarfs, T subdwarfs, T dwarfs
The Exotic Type Ic Broad-lined Supernova SN 2018gep: Blurring the Line between Supernovae and Fast Optical Transients. In the last decade a number of rapidly evolving transients have been discovered that are not easily explained by traditional supernova models. We present optical and UV data on one such object, SN 2018gep, that displayed a fast rise with a mostly featureless blue continuum around peak, and evolved to develop broad features typical of an SN Ic-bl while retaining significant amounts of blue flux throughout its observations. This blue excess is most evident in its near-UV flux, which is over 4 mag brighter than other stripped-envelope supernovae, and is still visible in optical g-r colors. Its fast rise time of trise,V = 5.6 ± 0.5 days puts it squarely in the emerging class of Fast Evolving Luminous Transients, or Fast Blue Optical Transients. With a peak absolute magnitude of Mv = -19.53 ± 0.23 mag it is on the extreme end of both the rise time and peak magnitude distribution for SNe Ic-bl. These observations are consistent with a simple SN Ic-bl model that has an additional form of energy injection at early times that drives the observed rapid, blue rise. We show that SN 2018gep and the literature SN iPTF16asu have similar photometric and spectroscopic properties and that they overall share many similarities with both SNe Ic-bl and Fast Evolving Transients. Based on our SN 2018gep host galaxy data we derive a number of properties, and we show that the derived host galaxy properties for both SN 2018gep and iPTF16asu are consistent with the SNe Ic-bl and gamma-ray burst/supernova sample while being on the extreme edge of the observed Fast Evolving Transient sample.

Keywords: Core-collapse supernovae, Transient sources, Time domain astronomy, Supernovae, Ultraviolet transient sources
Depolarization of MgH Solar Lines by Collisions with Hydrogen Atoms. Interpretations of the very rich second solar spectrum of the MgH molecule face serious problems owing to the complete lack of any information about rates of collisions between the MgH and hydrogen atoms. This work seeks to begin the process of filling this lacuna by providing, for the first time, quantum excitation, depolarization, and polarization transfer collisional rates of the MgH ground state X2Σ. To achieve the goals of this work, potential energy surfaces are calculated and then are included in the Schrödinger equation to obtain the probabilities of collisions and, thus, all collisional rates. Our rates are obtained for temperatures ranging from T = 2000 to 15,000 K. Sophisticated genetic programming methods are adopted in order to fit all depolarization rates with useful analytical functions of two variables: the total molecular angular momentum and temperatures. We study the solar implications of our results, and we find that the X2Σ state of MgH is partially depolarized by isotropic collisions with neutral hydrogen in its ground state 2S. Our findings show the limits of applicability of the widely used approximation in which the lower-level polarization is neglected.

Keywords: Solar atmosphere, Solar physics, Solar magnetic fields
Influence of the Bounds of the Hyperparameters on the Reconstruction of the Hubble Constant with the Gaussian Process. The cosmological model-independent method known as the Gaussian process (GP) has been widely used in the reconstruction of the Hubble constant H0, and the hyperparameters inside GP influence the reconstructed result derived from GP. Different hyperparameters inside GP are used in the constraint of H0 derived from GP with observational Hubble parameter H(z) data, and the influence of the hyperparameters inside GP on the reconstruction of H0 with GP is discussed. The discussion about the hyperparameters inside GP and the forecasts for future data show that the consideration of the lower and upper bounds on the GP's hyperparameters are necessary in order to get an extrapolated result of H0 from GP reliably and robustly.

Keywords: Hubble constant, Computational methods, Observational cosmology, Astronomy data analysis
Thermodynamic Evolution of Solar Flare Supra-arcade Downflows. Solar flares are rapid energy release phenomena that appear as bright ribbons in the chromosphere and high temperature loops in the corona, respectively. Supra-arcade Downflows (SADs) are plasma voids that first come out above the flare loops and then move quickly toward the flare loop top during the decay phase of the flare. In our work, we study 20 SADs appearing in three flares. By differential emission measure (DEM) analysis, we calculate the DEM weighted average temperature and emission measure of the front region and the main body of SADs. It is found that the temperatures of the SAD front and body tend to increase during the course of SADs flowing downwards. The relationship between the pressure and temperature fits well with the adiabatic equation for both the SAD front and body, suggesting that the heating of SADs is mainly caused by adiabatic compression. Moreover, we also estimate the velocities of SADs via the Fourier Local Correlation Tracking method and find that increase of the temperature of the SAD front presents a correlation with the decrease of the SAD kinetic energy, while the SAD body does not, implying that the viscous process may also heat the SAD front in spite of a limited role.

Keywords: Solar coronal heating, Solar flares, Solar magnetic reconnection
The Effect of the Angular Momentum in the Formation and Evolution of Low Surface Brightness Galaxies. Using observed data from the literature, we compare in one single publication the angular momentum (AM) of low surface brightness galaxies (LSBGs), with that of high surface brightness galaxies (HSBGs), a comparison that either is currently spread across many unconnected references, or simply does not exist. Partly because of the subject, this has received little attention outside the realm of simulations. We use previous results of the stellar specific AM j* from the SPARC database containing Spitzer 3.6 μm photometry and accurate H I rotation curves from Lelli et al. using a sample of 38 LSBGs and 82 HSBGs. We do this with the objective of comparing both galaxy populations, finding that LSBGs are higher in the Fall relation by about 0.174 dex. Additionally, we apply and test different masses and formation models to estimate the spin parameter λ, which quantifies the rotation obtained from the tidal torque theory, finding no clear evidence of a difference in the spin of LSBGs and HSBGs under a classic disk formation model that assumes the ratio (fj) between j* and the specific AM of the halo is ~1. In another respect, by using the biased collapse model, where fj depends on the star formation efficiency, it was found that LSBGs clearly show higher spin values, having an average spin of ~2 times the average spin of HSBGs. This latter result is consistent with those obtained from simulations by Dalcanton et al.

Keywords: Galaxy dark matter halos, Galaxy formation, Galaxy dynamics, Galaxy rotation, Galaxy kinematics, Galaxy evolution, Galaxy rotation curves, Low surface brightness galaxies
The Discovery of a Remnant Radio Galaxy in A2065 Using GMRT. The upgraded Giant Metrewave Radio Telescope (GMRT) has been used to map the cluster A2065 at z = 0.0726. We report the discovery of a remnant radio galaxy at the peripheral cluster region. The spatially resolved radio emission from the remnant radio galaxy shows an elongated, bar-shaped structure, whose size is ≈52″ × 110″ (≃72 × 152 kpc2). Our study with multiwavelength GMRT data and Chandra data shows that across the remnant radio galaxy there is a hint of a surface-brightness edge in the hot X-ray gas. We detect tentative flattening of the radio spectral index as the old plasma at the near end of the surface-brightness edge is reinvigorated by the passage of a possible shock front and shows the expected change in radio emission characteristics. We suggest that the remnant radio galaxy has been seeded by the lobes of the active galactic nucleus (AGN) hosted by the WISEA J152228.01+274141.3 source, demonstrating the connection between AGNs and remnant radio sources. Although the number of known remnant radio sources is beginning to increase, we emphasize the need for better data to understand the physics and nature of poorly understood remnant radio sources.

Keywords: Galaxy clusters, Extragalactic radio sources, Galaxy structure, Active galactic nuclei, Fanaroff-Riley radio galaxies, Radio continuum emission
Radio Emission by Soliton Formation in Relativistically Hot Streaming Pulsar Pair Plasmas. A number of possible pulsar radio emission mechanisms are based on streaming instabilities in relativistically hot electron-positron pair plasmas. At saturation, the unstable waves can, in principle, form stable solitary waves, which could emit the observed intense radio signals. We searched for the proper plasma parameters that would lead to the formation of solitons, and investigated their properties and dynamics as well as the resulting oscillations of electrons and positrons that possibly lead to radio wave emission. We utilized a one-dimensional version of the relativistic particle-in-cell code ACRONYM initialized with an appropriately parameterized one-dimensional Maxwell-Jüttner particle distribution in velocity space to study the evolution of the resulting streaming instability in a pulsar pair plasma. We found that strong electrostatic superluminal L-mode solitons are formed for plasmas with normalized inverse temperatures ρ ≥ 1.66 or relative beam drift speeds with Lorentz factors γ &gt; 40. The parameters of the solitons fulfill the conditions for wave emission. For appropriate pulsar parameters the resulting energy densities of superluminal solitons can reach 1.1 × 105 erg cm-3, while those of subluminal solitons reach only 1.2 × 104 erg cm-3. Estimated energy densities of up to 7 × 1012 erg cm-3 suffice to explain pulsar nanoshots.

Keywords: Computational methods, Plasma physics, Magnetic fields, Radio pulsars
Monte Carlo Investigation of the Ratios of Short-lived Radioactive Isotopes in the Interstellar Medium. Short-lived radioactive nuclei (SLR) with mean lives below ~100 Myr provide us with unique insights into current galactic nucleosynthetic events, as well as events that contributed to the material of our solar system more that 4.6 Gyr ago. Here we present a statistical analysis of the ratios of these radioactive nuclei at the time of the early solar system (ESS) using both analytical derivations and Monte Carlo methods. We aim to understand the interplay between the production frequency and the mean lives of these isotopes, and its impact on their theoretically predicted ratios in the interstellar medium. We find that when the ratio of two SRLs, instead of the ratios of each single SLR relative to its stable or long-lived isotope, is considered, not only are the uncertainties related to the galactic chemical evolution of the stable isotope completely eliminated, but the statistical uncertainties are also much lower. We identify four ratios, 247Cm/129I, 107Pd/182Hf, 97Tc/98Tc, and 53Mn/97Tc, that have the potential to provide us with new insights into the r-, s-, and p-process nucleosynthesis at the time of the formation of the Sun, and need to be studied using variable stellar yields. Additionally, the latter two ratios need to be better determined in the ESS to allow us to fully exploit them to investigate the galactic sites of the p process.

Keywords: Meteorites, Interstellar abundances, Abundance ratios, Solar system formation
Taking a Long Look: A Two-decade Reverberation Mapping Study of High-luminosity Quasars. Reverberation mapping (RM) of active galactic nuclei (AGNs) has been used over the past three decades to determine AGN broad-line region (BLR) sizes and central black hole masses, and their relations with the AGN luminosity. Until recently, the sample of objects with RM data was limited to low-luminosity AGNs (Lopt ≲ 1046 erg s-1) and low redshifts (z ≲ 0.5). Here we present results from an RM project of some of the most luminous and highest-redshift quasars that have been mapped to date. The study is based on almost 20 years of photometric monitoring of 11 quasars, 6 of which were monitored spectrophotometrically for 13 yr. This is the longest RM project carried out so far on this type of AGNs. We successfully measure a time lag between the C IV λ 1549 broad emission line and the quasar continuum in three objects, and measure a C III] λ 1909 lag in one quasar. Together with recently published data on C IV RM, the BLR size is found to scale as the square root of the UV luminosity over eight orders of magnitude in AGN luminosity. There is a significant scatter in the relation, part of which may be intrinsic to the AGNs. Although the C IV line is probably less well suited than Balmer lines for determination of the mass of the black hole, virial masses are tentatively computed, and in spite of a large scatter, we find that the mass of the black hole scales as the square root of the UV luminosity.

Keywords: High-luminosity active galactic nuclei, Quasars, Active galaxies, Galaxy nuclei, Low-luminosity active galactic nuclei, Active galactic nuclei
The Sandwich Mode for Vertical Shear Instability in Protoplanetary Disks. Turbulence has a profound impact on the evolution of gas and dust in protoplanetary disks (PPDs), from driving the collisions and the diffusion of dust grains, to the concentration of pebbles in giant vortices, thus, facilitating planetesimal formation. The vertical shear instability (VSI) is a hydrodynamic mechanism, operating in PPDs if the local rate of thermal relaxation is high enough. Previous studies of the VSI have, however, relied on the assumption of constant cooling rates, or neglected the finite coupling time between the gas particles and the dust grains. Here, we present the results of hydrodynamic simulations of PPDs with the PLUTO code that include a more realistic thermal relaxation prescription, which enables us to study the VSI in the optically thick and optically thin parts of the disk under consideration of the thermal dust-gas coupling. We show the VSI to cause turbulence even in the optically thick inner regions of PPDs in our two- and three-dimensional simulations. The collisional decoupling of dust and gas particles in the upper atmosphere and the correspondingly inefficient thermal relaxation rates lead to the damping of the VSI turbulence. Long-lived anticyclonic vortices form in our three-dimensional simulation. These structures emerge from the turbulence in the VSI-active layer, persist over hundreds of orbits and extend vertically over the whole extent of the turbulent region. We conclude that the VSI leads to turbulence and the formation of long-lived dust traps within ±3 pressure scale heights distance from the disk midplane.

Keywords: Accretion, Hydrodynamical simulations, Protoplanetary disks, Planet formation
The Architecture of the V892 Tau System: The Binary and Its Circumbinary Disk. We present high-resolution millimeter continuum and CO line observations for the circumbinary disk around V892 Tau to constrain the stellar and disk properties. The total mass of the two near-equal-mass A stars is estimated to be 6.0 ± 0.2 M⊙ based on our models of the Keplerian-dominated gas disk rotation. The detection of strong ionized gas emission associated with the two stars at 8 mm, when combined with previous astrometric measurements in the near-infrared, provides an updated view of the binary orbit with a = 7.1 ± 0.1 au, e = 0.27 ± 0.1, and P = 7.7 ± 0.2 yr, which is about half of a previously reported orbital period. The binary orbital plane is proposed to be nearly coplanar to the circumbinary disk plane (with a mutual inclination of only Δ = 8 ± 4°2; another solution with Δ = 113° is less likely given the short realignment timescale). An asymmetric dust disk ring peaking at a radius of 0"2 is detected at 1.3 mm and its fainter counterparts are also detected at the longer 8 and 9.8 mm. The CO gas disk, though dominated by Keplerian rotation, presents a mild inner and outer disk misalignment. The radial extension of the disk, its asymmetric dust ring, and the presence of a disk warp could all be explained by the interaction between the eccentric binary and the circumbinary disk, which we assume were formed with nonzero mutual inclination. Some tentatively detected gas spirals in the outer disk are likely produced by interactions with the low-mass tertiary component located 4″ to the northeast. Our analyses demonstrate the promising usage of V892 Tau as an excellent benchmark system to study the details of binary-disk interactions.

Keywords: Pre-main sequence stars, Binary stars, Protoplanetary disks