Sazuna/UAT_keywords huggingface dataset:
The Origin of Star Formation in Early-type Galaxies Inferred from Spatially Resolved Spectroscopy. We investigate the origin of star formation activity in early-type galaxies with current star formation using spatially resolved spectroscopic data from the Mapping Nearby Galaxies at Apache Point Observatory in the Sloan Digital Sky Survey (SDSS). We first identify star-forming early-type galaxies from the SDSS sample, which are morphologically early-type but show current star formation activity in their optical spectra. We then construct comparison samples with different combinations of star formation activity and morphology, which include star-forming late-type galaxies, quiescent early-type galaxies, and quiescent late-type galaxies. Our analysis of the optical spectra reveals that the star-forming early-type galaxies have two distinctive episodes of star formation, which is similar to late-type galaxies but different from quiescent early-type galaxies with a single star formation episode. Star-forming early-type galaxies have properties in common with star-forming late-type galaxies, which include stellar population, gas and dust content, mass, and environment. However, the physical properties of star-forming early-type galaxies derived from spatially resolved spectroscopy differ from those of star-forming late-type galaxies in the sense that the gas in star-forming early-type galaxies is more concentrated than their stars, and is often kinematically misaligned with stars. The age gradient of star-forming early-type galaxies also differs from those of star-forming late-type galaxies. Our findings suggest that the current star formation in star-forming early-type galaxies has an external origin including galaxy mergers or accretion gas from the cosmic web.

Keywords: Galaxy formation, Galaxy structure, Star formation, Galaxy evolution, Elliptical galaxies
Constraining the Evolution of the Unstable Accretion Disk in SMC X-1 with NICER. Neutron star high-mass X-ray binaries with superorbital modulations in luminosity host warped inner accretion disks that occult the neutron star during precession. In SMC X-1, the instability in the warped disk geometry causes superorbital period "excursions": times of instability when the superorbital period decreases from its typical value of 55 to ~40 days. Disk instability makes SMC X-1 an ideal system in which to investigate the effects of variable disk geometry on the inner accretion flow. Using the high-resolution spectral and timing capabilities of the Neutron Star Interior Composition Explorer, we examined the high state of four different superorbital cycles of SMC X-1 to search for changes in spectral shape and connections to the unstable disk geometry. We performed pulse phase-averaged and phase-resolved spectroscopy to closely compare the changes in spectral shape and any cycle-to-cycle variations. While some parameters, including the photon index and absorbing column density, show slight variations with superorbital phase, these changes are most evident during the intermediate state of the superorbital cycle. Few spectral changes are observed within the high state of the superorbital cycle, possibly indicating the disk instability does not significantly change SMC X-1's accretion process.

Keywords: Neutron stars, Pulsars
Excited Hydroxyl Outflow in the High-mass Star-forming Region G34.26 + 0.15. G34.26 + 0.15 is a region of high-mass star formation that contains a broad range of young stellar objects in different stages of evolution, including a hot molecular core, hypercompact H II regions, and a prototypical cometary ultracompact H II region. Previous high-sensitivity single-dish observations by our group resulted in the detection of broad 6035 MHz OH absorption in this region; the line showed a significant blueshifted asymmetry indicative of molecular gas expansion. We present high-sensitivity Karl G. Jansky Very Large Array (VLA) observations of the 6035 MHz OH line conducted to image the absorption and investigate its origin with respect to the different star formation sites in the region. In addition, we report detection of 6030 MHz OH absorption with the VLA and further observations of 4.7 GHz and 6.0 GHz OH lines obtained with the Arecibo Telescope. The 6030 MHz OH line shows a very similar absorption profile as the 6035 MHz OH line. We found that the 6035 MHz OH line absorption region is spatially unresolved at ~2″ scales, and it is coincident with one of the bright ionized cores of the cometary H II region that shows broad radio recombination line emission. We discuss a scenario where the OH absorption is tracing the remnants of a pole-on molecular outflow that is being ionized inside-out by the ultracompact H II region.

Keywords: H II regions, Interstellar medium
The Subtle Effects of Mergers on Star Formation in Nearby Galaxies. Interactions and mergers play an important role in regulating the physical properties of galaxies, such as their morphology, gas content, and star formation rate (SFR). Controversy exists as to the degree to which these events, even gas-rich major mergers, enhance star formation activity. We study merger pairs selected from a sample of massive (M * ≥ 1010 M ⊙), low-redshift (z = 0.01-0.11) galaxies located in the Stripe 82 region of the Sloan Digital Sky Survey, using stellar masses, SFRs, and total dust masses derived from a new set of uniformly measured panchromatic photometry and spectral energy distribution analysis. The dust masses, when converted to equivalent total atomic and molecular hydrogen, probe gas masses as low as ~108.5 M ⊙. Our measurements delineate a bimodal distribution on the M gas-M * plane: the gas-rich, star-forming galaxies that trace the well-studied gas mass main sequence, and passive galaxies that occupy a distinct, gas-poor regime. These two populations, in turn, map into a bimodal distribution on the relation between SFR and gas mass surface density. Among low-redshift galaxies, galaxy mergers, including those that involve gas-rich and nearly equal-mass galaxies, exert a minimal impact on their SFR, specific SFR, or star formation efficiency. Starbursts are rare. The star formation efficiency of gas-rich, minor mergers even appears suppressed. This study stresses the multiple, complex factors that influence the evolution of the gas and its ability to form stars in mergers.

Keywords: Starburst galaxies, Galaxy interactions, Galaxy evolution, Interstellar medium
Observed Polarized Scattered Light Phase Functions of Planet-forming Disks. Dust particles are the building blocks from which planetary bodies are made. A major goal of studies of planet-forming disks is to constrain the properties of dust particles and aggregates in order to trace their origin, structure, and the associated growth and mixing processes in the disk. Observations of the scattering and/or emission of dust in a location of the disk often lead to degenerate information about the kinds of particles involved, such as the size, porosity, or fractal dimensions of aggregates. Progress can be made by deriving the full (polarizing) scattering phase function of such particles at multiple wavelengths. This has now become possible by careful extraction from scattered light images. Such an extraction requires knowledge about the shape of the scattering surface in the disk, and we discuss how to obtain such knowledge as well as the associated uncertainties. We use a sample of disk images from observations with the Very Large Telescope/SPHERE to, for the first time, extract the phase functions of a whole sample of disks with broad phase-angle coverage. We find that polarized phase functions come in two categories. Comparing the extracted functions with theoretical predictions from rigorous T-Matrix computations of aggregates, we show that one category can be linked back to fractal, porous aggregates, while the other is consistent with more compact, less porous aggregates. We speculate that the more compact particles become visible in disks where embedded planets trigger enhanced vertical mixing.

Keywords: High contrast techniques, Exoplanets, Direct imaging, Protoplanetary disks, Circumstellar disks, Polarimetry, Planet formation
Observational Properties of a Bright Type lax SN 2018cni and a Faint Type Iax SN 2020kyg. We present the optical photometric and spectroscopic analysis of two Type Iax supernovae (SNe), 2018cni and 2020kyg. SN 2018cni is a bright Type Iax SN (M  V,peak = -17.81 ± 0.21 mag), whereas SN 2020kyg (M  V,peak = -14.52 ± 0.21 mag) is a faint one. We derive 56Ni mass of 0.07 and 0.002 M ☉ and ejecta mass of 0.48 and 0.14 M ☉ for SNe 2018cni and 2020kyg, respectively. A combined study of the bright and faint Type Iax SNe in R/r-band reveals that the brighter objects tend to have a longer rise time. However, the correlation between the peak luminosity and decline rate shows that bright and faint Type Iax SNe exhibit distinct behavior. Comparison with standard deflagration models suggests that SN 2018cni is consistent with the deflagration of a CO white dwarf, whereas the properties of SN 2020kyg can be better explained by the deflagration of a hybrid CONe white dwarf. The spectral features of both the SNe point to the presence of similar chemical species but with different mass fractions. Our spectral modeling indicates stratification at the outer layers and mixed inner ejecta for both of the SNe.

Keywords: Supernovae
Formation of the Injection Function of Solar Energetic Particles in Gradual Events. We present a model for solar energetic particle injection into interplanetary space in gradual events, in which particle acceleration occurs in a limited region of the solar atmosphere. The distribution function of particles accelerated by the diffusion mechanism is calculated. The flux of injected solar energetic particles is determined as a function of time and energy. We provide an explanation of the characteristic properties of the injection function and their dependence on the particle energy. Comparing the calculation results with ground-based measurements in the 2001 April 15 event shows a rough agreement with the particle density as a function of time and good agreement with the spectrum of maximum intensity values.

Keywords: Solar energetic particles, Solar coronal mass ejection shocks, Solar particle emission
Fermi-LAT Detection of a New Starburst Galaxy Candidate: IRAS 13052-5711. A likely starburst galaxy (SBG), IRAS 13052-5711, which is the most distant SBG candidates discovered to date, was found by analyzing 14.4 yr of data from the Fermi large-area telescope. This SBG's significance level is approximately 6.55σ in the 0.1-500 GeV band. Its spatial position is close to that of 4FGL J1308.9-5730, determined from the Fermi large telescope fourth-source Catalog (4FGL). Its power-law spectral index is approximately 2.1, and its light curve for 14.4 yr has no significant variability. These characteristics are highly similar to those of SBGs found in the past. We calculate the SBG's star formation rate (SFR) to be 29.38 M ⊙ yr-1, which is within the SFR range of SBGs found to date. Therefore, IRAS 13052-5711 is considered to be a likely SBG. In addition, its 0.1-500 GeV luminosity is (3.28 ± 0.67) × 1042 erg s-1, which deviates from the empirical relationship of the γ-ray luminosity and the total infrared luminosity. We considered a hadronic model to explain the GeV spectrum of IRAS 13052-5711.

Keywords: Starburst galaxies, Gamma-ray astronomy
Porous Dust Particles in Protoplanetary Disks: Application to the HL Tau Disk. Dust particle sizes constrained from dust continuum and polarization observations by radio interferometry are inconsistent by at least an order of magnitude. Motivated by porous dust observed in small solar system bodies (e.g., from the Rosetta mission), we explore how the dust particle's porosity affects the estimated particle sizes from these two methods. Porous particles have lower refractive indices, which affect both opacity and polarization fraction. With weaker Mie interference patterns, the porous particles have lower opacity at millimeter wavelengths than the compact particles if the particle size exceeds several hundred microns. Consequently, the inferred dust mass using porous particles can be up to a factor of six higher. The most significant difference between compact and porous particles is their scattering properties. The porous particles have a wider range of particle sizes with high linear polarization from dust self-scattering, allowing millimeter- to centimeter-sized particles to explain polarization observations. With a Bayesian approach, we use porous particles to fit HL Tau disk's multiwavelength continuum and millimeter-polarization observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Array (VLA). The moderately porous particles with sizes from 1 mm-1 m can explain both continuum and polarization observations, especially in the region between 20 and 60 au. If the particles in HL Tau are porous, the porosity should be from 70%-97% from current polarization observations. We also predict that future observations of the self-scattering linear polarization at longer wavelengths (e.g., ALMA B1 and ngVLA) have the potential to further constrain the particle's porosity and size.

Keywords: Dust composition, Millimeter astronomy, Interstellar dust extinction, Polarimetry, Astrophysical dust processes, Dust continuum emission, Protoplanetary disks, Submillimeter astronomy, Spectral index, Radio astronomy, Planet formation, Optical constants (Dust)
Quantifying the Impact of the Dust Torque on the Migration of Low-mass Planets. Disk solids are critical in many planet formation processes; however, their effect on planet migration remains largely unexplored. Here we assess this important issue for the first time by building on the systematic measurements of dust torques on an embedded planet by Benitez-Llambay &amp; Pessah. Adopting standard models for the gaseous disk and its solid content, we quantify the impact of the dust torque for a wide range of conditions describing the disk/planet system. We show that the total torque can be positive and reverse inward planet migration for planetary cores with M p ≲ 10 M ⊕. We compute formation tracks for low-mass embryos for conditions usually invoked when modeling planet formation processes. Our most important conclusion is that dust torques can have a significant impact on the migration and formation history of planetary embryos. The most important implications of our findings are as follows. (i) For nominal dust-to-gas mass ratios ϵ ≃ 0.01, low-mass planets migrate outwards beyond the water ice-line if most of the mass in the solids is in particles with Stokes numbers St ≃0.1. (ii) For ϵ ≳ 0.02-0.05, solids with small Stokes numbers, St ≃ 0.01, can play a dominant role if most of the mass is in those particles. (iii) Dust torques have the potential to enable low-mass planetary cores formed in the inner disk to migrate outwards and act as the seed for massive planets at distances of tens of au.

Keywords: Planetary migration, Planetary-disk interactions, Protoplanetary disks, Planet formation
Tomographic Alcock-Paczyński Test with Redshift-space Correlation Function: Evidence for the Dark Energy Equation-of-state Parameter w &gt; -1. The apparent shape of galaxy clustering depends on the adopted cosmology used to convert observed redshift to comoving distance, the r(z) relation, as it changes the line elements along and across the line of sight differently. The Alcock-Paczyński (AP) test exploits this property to constrain the expansion history of the universe. We present an extensive review of past studies on the AP test. We adopt an extended AP test method introduced by Park et al., which uses the full shape of redshift-space two-point correlation function (CF) as the standard shape, and apply it to the Sloan Digital Sky Survey DR7, BOSS, and eBOSS LRG samples covering the redshift range up to z = 0.8. We calibrate the test against the nonlinear cosmology-dependent systematic evolution of the CF shape using Multiverse simulations. We focus on examining whether or not the flat Lambda cold dark matter (ΛCDM) concordance model is consistent with observation. We constrain the flat wCDM model to have $w=-{0.892}_{-0.050}^{+0.045}$ and ${{\rm{\Omega }}}_{m}={0.282}_{-0.023}^{+0.024}$ from our AP test alone, which is significantly tighter than the constraints from the BAO or SNe Ia methods by a factor of 3-6. When the AP test result is combined with the recent BAO and SNe Ia results, we obtain $w=-{0.903}_{-0.023}^{+0.023}$ and ${{\rm{\Omega }}}_{m}={0.285}_{-0.009}^{+0.014}$ . This puts a strong tension with the flat ΛCDM model with w = -1 at the 4.2σ level. Consistency with w = -1 is obtained only when the Planck cosmic microwave background (CMB) observation is combined. It remains to be seen whether this tension between observations of galaxy distribution at low redshifts and CMB anisotropy at the decoupling epoch becomes greater in future studies and leads us to a new paradigm of cosmology.

Keywords: Large-scale structure of the universe, Cosmology, Dark energy
Subhalo Spreading of Thin Tidal Star Streams. Dark matter subhalos that pass a thin tidal star stream change the velocities of the stars near the point of closest encounter. Subsequent orbital evolution increases the stream width and spreads the changes along the stream. We measure the average widths and velocity dispersions of stream populations in three Milky Way-like cold dark matter cosmology simulations containing star particle globular clusters and galactic disks of 0, 1, and 2 times a baseline model. Power-law fits to the velocity dispersion with stream longitude, ϕ, for the overlaid streams in the 10-60 kpc range find σ ≃ 5-15 ϕ 0.2-0.5 km s-1, with the coefficients depending on the subhalo numbers, as well as the stream measurement details. The velocity distributions summed along the entire length of the streams do not require the progenitor location. They also rise with subhalo number and are significantly non-Gaussian, with the ratios of the 6σ to the 3σ clipped velocity dispersions being ~1.5 ± 0.3 and ~2.5 ± 1 for measurements within 1° and 5° of the streams, respectively. Streams longer than 50° have an average radial velocity dispersion of 2.1 km s-1 with a disk and 4.2 km s-1 without a disk. However, a few similar thin, low-velocity dispersion streams are present in all three simulations. Statistically reliable conclusions require velocity data extending several degrees from the stream centerline for a set of streams.

Keywords: Milky Way dark matter halo, Stellar streams, N-body simulations
The Nature of γ-Ray Emission from HESS J1912+101. Since the discovery of HESS J1912+101 at teraelectronvolt energies, its nature has been extensively studied. Due to the absence of X-ray and radio counterparts, whether its γ-ray emission is produced by relativistic electrons or ions is still a matter of debate. We reanalyze its megaelectronvolt to gigaelectronvolt γ-ray emission using 14 yr of Pass 8 data of the Fermi-LAT, and find that the gigaelectronvolt γ-ray emission is more extended than the teraelectronvolt shell detected by H. E. S. S. and flux above 10 GeV from the northern half is much higher than that from the southern half, where there is evident interaction between shocks and molecular clouds. As a consequence, the gigaelectronvolt spectrum of the northern half (with an index of 2.19 ± 0.12) is much harder than that in the south (with an index of 2.72 ± 0.08), and the overall gigaelectronvolt spectrum shows a concave shape, which is distinct from most γ-ray supernova remnants (SNRs). In combination with the teraelectronvolt spectrum, the overall γ-ray spectrum can be fitted with a broken power-law model for trapped ions and a low energy component due to escaping ions. The diffusion coefficient for escaping ions however needs to be proportional to the energy, implying that the low energy component may also be attributed to ions accelerated via recent shock-cloud interactions. A hadronic origin for the γ-ray emission is therefore favored and the overall emission properties are consistent with ion acceleration by SNR shocks. On the other hand, it is still undeniable that stellar cluster or PWN may have some contribution in some parts of this extended source.

Keywords: Supernova remnants, Molecular clouds, High energy astrophysics
Modulation of Cosmic-Ray Antiprotons in the Heliosphere: Simulations for a Solar Cycle. The precision measurements of galactic cosmic-ray protons from the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics and the Alpha Magnetic Spectrometer are reproduced using a well-established three-dimensional numerical model for the period 2006 July-2019 November. The resulting modulation parameters are applied to simulate the modulation for cosmic antiprotons over the same period, which includes the times of minimum modulation before and after 2009, the maximum modulation from 2012 to 2015, including the reversal of the Sun's magnetic field polarity, and the approach to new minimum modulation in 2020. Apart from their local interstellar spectra, the modulation of protons and antiprotons differ in their charge sign and consequent drift pattern. The lowest proton flux was in 2014 February-March, but the lowest simulated antiproton flux is found to have been in 2015 March-April. These simulated fluxes are used to predict the proton-to-antiproton ratios as a function of rigidity. The trends in these ratios contribute to clarifying, to a large extent, the phenomenon of charge-sign dependence of heliospheric modulation during vastly different phases of the solar activity cycle. This is reiterated and emphasized by displaying so-called hysteresis loops. It is also illustrated how the values of the parallel and perpendicular mean free paths, as well as the drift scale, vary with rigidity over this extensive period. The drift scale is found to be at its lowest level during the polarity reversal period, while the lowest level of the mean free paths is found to be in 2015 March-April.

Keywords: Solar cycle, Quiet sun, Heliosphere, Cosmic rays
The First Weak-lensing Analysis with the James Webb Space Telescope: SMACS J0723.3-7327. Utilizing the James Webb Space Telescope Early Release NIRCam Observations, we perform a weak-lensing analysis of the massive galaxy cluster SMACS J0723.3-7327 (z = 0.39). We investigate the spatial variation of the point-spread function (PSF) from the stars in the mosaic image. Our measurements show that the PSF for both modules has very small spatial and temporal variation with average complex ellipticity components of e 1 = 0.007 ± 0.001 and e 2 = 0.029 ± 0.001 in the observed north-up reference frame. We create PSF models through a principal component analysis of the stars and show that they properly account for the ellipticity of the PSF with residual shapes of e 1 = (0.3 ± 3.5) × 10-4 and e 2 = (1.8 ± 4.0) × 10-4. We select background galaxies by their photometric redshift and measure galaxy shapes by model fitting. Our weak-lensing source catalog achieves ~215 galaxies arcmin-2. We map the convergence field of SMACSJ0723 and detect the cluster with a peak significance of 12.2σ. The mass distribution is found to elongate in the east-west direction with an extension to the northeast edge of the field of view where a candidate substructure is found in the Chandra X-ray imaging. We fit the tangential shear with a Navarro-Frenk-White model and estimate the mass of the cluster to be M 500 = 7.9 ± 1.1 × 1014 M ⊙ (M 200 = 11.4 ± 1.5 × 1014 M ⊙), which agrees with existing mass estimates. Combining the multiwavelength evidence from literature with our weak-lensing analysis, we hypothesize that SMACSJ0723 is observed near first pericenter passage and we identify candidate radio relics.

Keywords: Weak gravitational lensing, Hubble Space Telescope, James Webb Space Telescope, Galaxy clusters