adsabs/SciX_UAT_keywords huggingface dataset:
Mapping Outflowing Gas in the Fermi Bubbles: A UV Absorption Survey of the Galactic Nuclear Wind

Using new ultraviolet (UV) spectra of five background quasars from the Cosmic Origins Spectrograph on the Hubble Space Telescope, we analyze the low-latitude ( $| b| =20^\circ \mbox{--}30^\circ $ ) regions of the Fermi Bubbles, the giant gamma-ray-emitting lobes at the Galactic Center. We combine these data with previous UV and atomic hydrogen (H I) data sets to build a comprehensive picture of the kinematics and metal column densities of the cool outflowing clouds entrained in the Fermi Bubbles. We find that the number of UV absorption components per sight line decreases as a function of increasing latitude, suggesting that the outflowing clouds become less common with increasing latitude. The Fermi Bubble H I clouds are accelerated up to b ∼ 7°, whereas when we model the UV Fermi Bubbles clouds' deprojected flow velocities, we find that they are flat or even accelerating with distance from the Galactic center. This trend, which holds in both the northern and southern hemispheres, indicates that the nuclear outflow accelerates clouds throughout the Fermi Bubbles or has an acceleration phase followed by a coasting phase. Finally, we note the existence of several blueshifted high-velocity clouds at latitudes exceeding ∼30°, whose velocities cannot be explained by gas clouds confined to the inside of the gamma-ray-defined Fermi Bubbles. These anomalous-velocity clouds are likely in front of the Fermi Bubbles and could be remnants from past nuclear outflows. Overall, these observations form a valuable set of empirical data on the properties of cool gas in nuclear winds from star-forming galaxies. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program 15339.

Keywords: milky way galaxy; milky way evolution; high-velocity clouds; galactic center
Powerful Radio Sources in the Southern Sky. I. Optical Identifications

Since the early sixties, our view of radio galaxies and quasars has been drastically shaped by discoveries made thanks to observations of radio sources listed in the Third Cambridge Catalog and its revised version (3CR). However, the largest fraction of data collected to date on 3CR sources was performed with relatively old instruments, rarely repeated and/or updated. Importantly, the 3CR contains only objects located in the Northern Hemisphere, thus having limited access to new and innovative astronomical facilities. To mitigate these limitations, we present a new catalog of powerful radio sources visible from the Southern Hemisphere, extracted from the GLEAM 4 Jy (G4Jy) catalog and based on equivalent selection criteria as the 3CR. This new catalog, named G4Jy-3CRE, where the E stands for "equivalent," lists a total of 264 sources at decl. below -5° and with 9 Jy limiting sensitivity at ~178 MHz. We explored archival radio maps obtained with different surveys and compared them with optical images available in the Pan-STARRS, DES, and DSS databases to search for optical counterparts of their radio cores. We compared mid-infrared counterparts, originally associated in the G4Jy, with the optical ones identified here, and we present results of a vast literature search carried out to collect redshift estimates for all G4Jy-3CRE sources resulting in a total of 145 reliable z measurements.

Keywords: extragalactic radio sources
The Viability of the 3 + 1 Neutrino Model in the Supernova Neutrino Process

Adopting the 3 + 1 neutrino mixing parameters by the IceCube and short baseline experiments, we investigate the sterile-active neutrino oscillation effects on the supernova neutrino process. For the sterile neutrino (νs), we study two different luminosity models. First, we presume that the νs does not interact with other particles through the standard interactions apart from the oscillation with the active neutrinos. Second, we consider the νs directly produced by νe scattering with the matter. In both cases, we find that the pattern of neutrino oscillations drastically impacts on the νs in supernova environments. In particular multiple resonances occur, and consequently affect thermal neutrino-induced reaction rates. As a result, 7Li, 7Be, 11B, 11C, 92Nb, 98Tc, and 138La yields in the ν-process change. Among those nuclei, we constrain the 7Li and 11B yields using the analysis of observed SiC X grains. Based on the meteoritic data, we conclude that the second model can be allowed, while the first model is excluded. The viability of the second model depends on the sterile neutrino temperature and the neutrino mass hierarchy.

Keywords: nucleosynthesis; supernova neutrinos; neutrino oscillations; nuclear astrophysics
A Living Catalog of Parker Solar Probe IS⊙IS Energetic Particle Enhancements

Energetic charged particles are pervasive throughout the heliosphere with contributions from solar energetic particle events, stream and corotating interaction regions, galactic cosmic rays, anomalous cosmic rays, and suprathermal ions. The Integrated Science Investigation of the Sun (IS⊙IS) on board the Parker Solar Probe is a suite of energetic particle detectors covering the energy range ~20 keV-200 MeV nuc-1. IS⊙IS measures energetic particles closer to the Sun than any instrument suite in history, providing a singular view of the energetic particle population in a previously unexplored region. To enable the global research community to efficiently use IS⊙IS data, we have developed an online living catalog of energetic particle enhancements observed by the IS⊙IS instruments. Event identification methodology, information on accessing the catalog, highlights of several events, and a summary of the overall trends are presented. Also included is a summary Event Catalog showing many of the key event parameters for IS⊙IS events to the time of writing.

Keywords: solar flares; solar energetic particles; interplanetary physics; solar particle emission; solar coronal mass ejection shocks
Siena Galaxy Atlas 2020

We present the 2020 version of the Siena Galaxy Atlas (SGA-2020), a multiwavelength optical and infrared imaging atlas of 383,620 nearby galaxies. The SGA-2020 uses optical grz imaging over ≈20,000 deg2 from the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys Data Release 9 and infrared imaging in four bands (spanning 3.4-22 μm) from the 6 year unWISE coadds; it is more than 95% complete for galaxies larger than R(26) ≈ 25″ and r < 18 measured at the 26 mag arcsec-2 isophote in the r band. The atlas delivers precise coordinates, multiwavelength mosaics, azimuthally averaged optical surface-brightness profiles, model images and photometry, and additional ancillary metadata for the full sample. Coupled with existing and forthcoming optical spectroscopy from the DESI, the SGA-2020 will facilitate new detailed studies of the star formation and mass assembly histories of nearby galaxies; enable precise measurements of the local velocity field via the Tully-Fisher and fundamental plane relations; serve as a reference sample of lasting legacy value for time-domain and multimessenger astronomical events; and more.

Keywords: galaxy photometry; celestial objects catalogs
Kilonova Detectability with Wide-field Instruments

Kilonovae are ultraviolet, optical, and infrared transients powered by the radioactive decay of heavy elements following a neutron star merger. Joint observations of kilonovae and gravitational waves can offer key constraints on the source of Galactic r-process enrichment, among other astrophysical topics. However, robust constraints on heavy element production require rapid kilonova detection (within ~1 day of merger) as well as multiwavelength observations across multiple epochs. In this study, we quantify the ability of 13 wide-field-of-view instruments to detect kilonovae, leveraging a large grid of over 900 radiative transfer simulations with 54 viewing angles per simulation. We consider both current and upcoming instruments, collectively spanning the full kilonova spectrum. The Roman Space Telescope has the highest redshift reach of any instrument in the study, observing kilonovae out to z ~ 1 within the first day post-merger. We demonstrate that BlackGEM, DECam, GOTO, the Vera C. Rubin Observatory's LSST, ULTRASAT, VISTA, and WINTER can observe some kilonovae out to z ~ 0.1 (~475 Mpc), while DDOTI, MeerLICHT, PRIME, Swift/UVOT, and ZTF are confined to more nearby observations. Furthermore, we provide a framework to infer kilonova ejecta properties following nondetections and explore variation in detectability with these ejecta parameters.

Keywords: gravitational wave astronomy; neutron stars; transient detection; radiative transfer simulations
Cloud Properties of Brown Dwarf Binaries across the L/T Transition

We present a new suite of atmosphere models with flexible cloud parameters to investigate the effects of clouds on brown dwarfs across the L/T transition. We fit these models to a sample of 13 objects with well-known masses, distances, and spectral types spanning L3-T5. Our modeling is guided by spatially resolved photometry from the Hubble Space Telescope and the W. M. Keck Telescopes covering visible to near-infrared wavelengths. We find that, with appropriate cloud parameters, the data can be fit well by atmospheric models with temperature and surface gravity in agreement with the predictions of evolutionary models. We see a clear trend in the cloud parameters with spectral type, with earlier-type objects exhibiting higher-altitude clouds with smaller grains (0.25-0.50 μm) and later-type objects being better fit with deeper clouds and larger grains (≥1 μm). Our results confirm previous work that suggests L dwarfs are dominated by submicron particles, whereas T dwarfs have larger particle sizes.

Keywords: brown dwarfs; stellar evolutionary models; stellar atmospheres; atmospheric clouds; l dwarfs; t dwarfs; hst photometry; infrared photometry
New Time-resolved, Multi-band Flares in the GJ 65 System with gPhoton

Characterizing the distribution of flare properties and occurrence rates is important for understanding habitability of M-dwarf exoplanets. The Galaxy Evolution Explorer (GALEX) space telescope observed the GJ 65 system, composed of the active, flaring M stars BL Cet and UV Cet, for 15,900 s (~4.4 hr) in two ultraviolet (UV) bands. The contrast in flux between flares and the photospheres of cool stars is maximized at UV wavelengths, and GJ 65 is the brightest and nearest flaring M-dwarf system with significant GALEX coverage. It therefore represents the best opportunity to measure low-energy flares with GALEX. We construct high-cadence lightcurves from calibrated photon events and find 13 new flare events with near-UV (NUV) energies ranging from 1028.5-1029.5 erg and recover one previously reported flare with an energy of 1031 erg. The newly reported flares are among the smallest M-dwarf flares observed in the UV with sufficient time resolution to discern lightcurve morphology. The estimated flare frequency at these low energies is consistent with extrapolation from the distributions of higher-energy flares on active M dwarfs measured by other surveys. The largest flare in our sample is bright enough to exceed the local nonlinearity threshold of the GALEX detectors, which precludes color analysis. However, we detect quasi-periodic pulsations during this flare in both the far-UV and NUV bands at a period of ~50 s, which we interpret as a modulation of the flare's chromospheric thermal emission through periodic triggering of reconnection by external MHD oscillations in the corona.

Keywords: flare stars; m dwarf stars; stellar flares; near ultraviolet astronomy
Photochemistry of Venus-like Planets Orbiting K- and M-dwarf Stars

Compared to the diversity seen in exoplanets, Venus is a veritable astrophysical twin of the Earth; however, its global cloud layer truncates features in transmission spectroscopy, masking its non-Earth-like nature. Observational indicators that can distinguish an exo-Venus from an exo-Earth must therefore survive above the cloud layer. The above-cloud atmosphere is dominated by photochemistry, which depends on the spectrum of the host star and therefore changes between stellar systems. We explore the systematic changes in photochemistry above the clouds of Venus-like exoplanets orbiting K-dwarf or M-dwarf host stars, using a recently validated model of the full Venus atmosphere (0-115 km) and stellar spectra from the Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems (MUSCLES) Treasury survey. SO2, OCS, and H2S are key gas species in Venus-like planets that are not present in Earth-like planets, and could therefore act as observational discriminants if their atmospheric abundances are high enough to be detected. We find that SO2, OCS, and H2S all survive above the cloud layer when irradiated by the coolest K dwarf and all seven M dwarfs, whereas these species are heavily photochemically depleted above the clouds of Venus. The production of sulfuric acid molecules that form the cloud layer decreases for decreasing stellar effective temperature. Less steady-state photochemical oxygen and ozone forms with decreasing stellar effective temperature, and the effect of chlorine-catalyzed reaction cycles diminish in favor of HOx and SOx catalyzed cycles. We conclude that trace sulfur gases will be prime observational indicators of Venus-like exoplanets around M-dwarf host stars, potentially capable of distinguishing an exo-Venus from an exo-Earth.

Keywords: venus; planetary atmospheres; exoplanet atmospheres; exoplanet astronomy; extrasolar rocky planets; m dwarf stars; k dwarf stars
Keeping It Cool: Much Orbit Migration, yet Little Heating, in the Galactic Disk

A star in the Milky Way's disk can now be at a Galactocentric radius quite distant from its birth radius for two reasons: either its orbit has become eccentric through radial heating, which increases its radial action JR ("blurring"), or merely its angular momentum Lz has changed and thereby its guiding radius ("churning"). We know that radial orbit migration is strong in the Galactic low-α disk and set out to quantify the relative importance of these two effects, by devising and applying a parameterized model ( ${{\boldsymbol{p}}}_{{\boldsymbol{m}}}$ ) for the distribution $p({L}_{z},{J}_{R},\tau ,\left[\mathrm{Fe}/{\rm{H}}\right]| {{\boldsymbol{p}}}_{{\boldsymbol{m}}})$ in the stellar disk. This model describes the orbit evolution for stars of age τ and metallicity $\left[\mathrm{Fe}/{\rm{H}}\right]$ , presuming that coeval stars were initially born on (near-)circular orbits, and with a unique $\left[\mathrm{Fe}/{\rm{H}}\right]$ at a given birth angular momentum and age. We fit this model to APOGEE red clump stars, accounting for the complex selection function of the survey. The best-fit model implies changes of angular momentum of $\sqrt{\langle {\rm{\Delta }}{L}_{z}{\rangle }^{2}}\approx 619\,\mathrm{kpc}\,\mathrm{km}\,{{\rm{s}}}^{-1}\ {(\tau /6\mathrm{Gyr})}^{0.5}$ and changes of radial action as $\sqrt{\langle {\rm{\Delta }}{J}_{R}{\rangle }^{2}}\approx 63\,\mathrm{kpc}\,\mathrm{km}\,{{\rm{s}}}^{-1}{(\tau /6\mathrm{Gyr})}^{0.6}$ at 8 kpc. This suggests that the secular orbit evolution of the disk is dominated by diffusion in angular momentum, with radial heating being an order of magnitude lower.

Keywords: galaxy abundances; galaxy stellar disks; milky way galaxy; milky way disk; milky way evolution; milky way dynamics; galaxy dynamics
Testing the Isotropy of the Dark Energy Survey's Extreme Trans-Neptunian Objects

We test whether the population of "extreme" trans-Neptunian objects (eTNOs) detected in the first four years of the Dark Energy Survey (DES Y4) data exhibit azimuthal asymmetries that might be evidence of gravitational perturbations from an unseen super-Earth in a distant orbit. By rotating the orbits of the detected eTNOs, we construct a synthetic population that, when subject to the DES selection function, reproduces the detected distribution of eTNOs in the orbital elements a, e, and i as well as absolute magnitude H, but has uniform distributions in mean anomaly ${ \mathcal M }$ , longitude of ascending node Ω, and argument of perihelion ω. We then compare the detected distributions in each of Ω, ω, and the longitude of perihelion $\varpi \equiv {\rm{\Omega }}+\omega $ to those expected from the isotropic population, using Kuiper's variant of the Kolmogorov-Smirnov test. The three angles are tested for each of four definitions of the eTNO population, choosing among a > (150, 250) au and perihelion q > (30, 37) au. These choices yield 3-7 eTNOs in the DES Y4 sample. Among the 12 total tests, two have the likelihood of drawing the observed angles from the isotropic population at p < 0.03. The three detections at a > 250 and q > 37 au and the four detections at a > 250 and q > 30 au have a Ω distribution with p ≈ 0.03 coming from the isotropic construction, but this is not strong evidence of anisotropy given the 12 different tests. The DES data taken on their own are thus consistent with azimuthal isotropy and do not require a "Planet 9" hypothesis. The limited sky coverage and object count mean, however, that the DES data by no means falsify this hypothesis.

Keywords: trans-neptunian objects; kuiper belt
DESI Observations of the Andromeda Galaxy: Revealing the Immigration History of Our Nearest Neighbor

We present Dark Energy Spectroscopic Instrument (DESI) observations of the inner halo of M31, which reveal the kinematics of a recent merger-a galactic immigration event-in exquisite detail. Of the 11,416 sources studied in 3.75 hr of on-sky exposure time, 7438 are M31 sources with well-measured radial velocities. The observations reveal intricate coherent kinematic structure in the positions and velocities of individual stars: streams, wedges, and chevrons. While hints of coherent structures have been previously detected in M31, this is the first time they have been seen with such detail and clarity in a galaxy beyond the Milky Way. We find clear kinematic evidence for shell structures in the Giant Stellar Stream, the Northeast Shelf, and Western Shelf regions. The kinematics are remarkably similar to the predictions of dynamical models constructed to explain the spatial morphology of the inner halo. The results are consistent with the interpretation that much of the substructure in the inner halo of M31 is produced by a single galactic immigration event 1-2 Gyr ago. Significant numbers of metal-rich stars ([Fe/H] > - 0.5) are present in all of the detected substructures, suggesting that the immigrating galaxy had an extended star formation history. We also investigate the ability of the shells and Giant Stellar Stream to constrain the gravitational potential of M31, and estimate the mass within a projected radius of 125 kpc to be ${\mathrm{log}}_{10}\,{M}_{\mathrm{NFW}}(\lt 125\,\mathrm{kpc})/{M}_{\odot }={11.80}_{-0.10}^{+0.12}$ . The results herald a new era in our ability to study stars on a galactic scale and the immigration histories of galaxies.

Keywords: andromeda galaxy; galaxy mergers; galaxy evolution; galaxy dynamics; stellar kinematics; redshift surveys; radial velocity; astrographic catalogs; catalogs
A Dual-band Radio Observation of FRB 121102 with the Deep Space Network and the Detection of Multiple Bursts

The spectra of repeating fast radio bursts (FRBs) are complex and time-variable, sometimes peaking within the observing band and showing a fractional emission bandwidth of about 10%-30%. These spectral features may provide insight into the emission mechanism of repeating FRBs, or they could possibly be explained by extrinsic propagation effects in the local environment. Broadband observations can better quantify this behavior and help to distinguish between intrinsic and extrinsic effects. We present results from a simultaneous 2.25 and 8.36 GHz observation of the repeating FRB 121102 using the 70 m Deep Space Network radio telescope, DSS-43. During the 5.7 hr continuous observing session, we detected six bursts from FRB 121102, which were visible in the 2.25 GHz frequency band. However, none of these bursts were detected in the 8.36 GHz band, despite the larger bandwidth and greater sensitivity in the higher-frequency band. This effect is not explainable by Galactic scintillation and, along with previous multi-band experiments, clearly demonstrates that apparent burst activity depends strongly on the radio frequency band that is being observed.

Keywords: radio transient sources
The Solar System as an Exosystem: Planet Confusion

Future, large-scale, exoplanet direct-imaging missions will be capable of discovering and characterizing Earth-like exoplanets and star systems like our solar system. However, a telescope capable of detecting Earth-like exoplanets would also be sensitive to a myriad of non-Earth-like exoplanets in the exoplanet population with the same instantaneous planet-star separation (s) and planet-star difference in magnitude (Δmag). Here, we consider the solar system as a previously unexplored exosystem, viewed by an external direct-imaging observer for the first time. We find that an external observer could see as many as six (s, Δmag)-coincidence locations between the Earth and other solar system planets. We determine locations of (s, Δmag)-coincidence of solar system planets using realistic planet phase functions and planet properties. By varying system inclinations, we found 36%-69% of inner planet orbits and 1%-4% of outer planet orbits share at least one (s, Δmag)-coincidence with the Earth.

Keywords: direct imaging; exoplanet astronomy; exoplanet systems; solar system
Simulation of Solar Wind Turbulence near Corotating Interaction Regions: Superposed Epoch Analysis of Simulations and Observations

The effect of the turbulence that is associated with solar wind corotating interaction regions (CIRs) on transport of galactic cosmic rays remains an outstanding problem in space science. Observations show that the intensities of the plasma and magnetic fluctuations are enhanced within a CIR. The velocity shear layer between the slow and fast wind embedded in a CIR is thought to be responsible for this enhancement in turbulent energy. We perform physics-based magnetohydrodynamic simulations of the plasma background and turbulent fluctuations in the solar wind dominated by CIRs for radial distances between 0.3 and 5 au. A simple but effective approach is used to incorporate the inner boundary conditions for the solar wind and magnetic field for the periods 2007-2008 and 2017-2018. Legendre coefficients at the source surface obtained from the Wilcox Solar Observatory library are utilized for dynamic reconstructions of the current sheet and the fast and slow streams at the inner boundary. The dynamic inner boundary enables our simulations to generate CIRs that are reasonably comparable with observations near Earth. While the magnetic field structure is reasonably well reproduced, the enhancements in the turbulent energy at the stream interfaces are smaller than observed. A superposed epoch analysis is performed over several CIRs from the simulation and compared to the superposed epoch analysis of the observed CIRs. The results for the turbulent energy and correlation length are used to estimate the diffusion tensor of galactic cosmic rays. The derived diffusion coefficients could be used for more realistic modeling of cosmic rays in a dynamically evolving inner heliosphere.

Keywords: solar wind; interplanetary turbulence; corotating streams