adsabs/SciX_UAT_keywords huggingface dataset:
Integral Field Spectroscopy of Fast Outflows in Dwarf Galaxies with AGNs

Feedback likely plays a vital role in the formation of dwarf galaxies. While stellar processes have long been considered the main source of feedback, recent studies have revealed tantalizing signs of active galactic nucleus (AGN) feedback in dwarf galaxies. In this paper, we report the results from an integral field spectroscopic study of a sample of eight dwarf galaxies with known AGNs and suspected outflows. Outflows are detected in seven of them. The outflows are fast, with 50th-percentile (median) velocity of up to ∼240 km s-1 and 80th-percentile line width reaching ∼1200 km s-1, in clear contrast with the more quiescent kinematics of the host gas and stellar components. The outflows are generally spatially extended on a scale of several hundred parsecs to a few kiloparsecs, although our data do not clearly resolve the outflows in three targets. The outflows appear to be primarily photoionized by the AGN rather than shocks or young, massive stars. The kinematics and energetics of these outflows suggest that they are primarily driven by the AGN, although the star formation activity in these objects may also contribute to the energy input. A small but nonnegligible portion of the outflowing material likely escapes the main body of the host galaxy and contributes to the enrichment of the circumgalactic medium. Overall, the impact of these outflows on their host galaxies is similar to those taking place in the more luminous AGNs in the low-redshift universe.

Keywords: agn host galaxies; active galactic nuclei; galaxy winds; dwarf galaxies; extragalactic astronomy; galaxy kinematics; galaxy evolution
Extended Cosmic Ray Decreases with Strong Anisotropy after Passage of Interplanetary Shocks

The passage of an interplanetary shock and/or interplanetary coronal mass ejection often causes a rapid decrease in the Galactic cosmic-ray (GCR) flux, known as a Forbush decrease, followed by a recovery of the flux over some days. These local effects are of short duration and strongly rigidity dependent, with higher-rigidity particles exhibiting much weaker effects. In contrast, we present data for two events in which the cosmic-ray flux gradually decreased for about 1 week after shock passage, then recovering over the following week, with the highest anisotropy levels observed throughout Solar Cycle 24. These extended decreases have a weak rigidity dependence and are much more prominent in observations at higher cutoff rigidity, where the initial Forbush decrease is not clearly detected and other variations are generally weak, as we demonstrate using data from the Princess Sirindhorn Neutron Monitor at Doi Inthanon, Thailand with a cutoff rigidity of about 17 GV. We propose that these extended decrease events were initiated upon the passage of an interplanetary shock that inhibited the inflow of GCRs along the interplanetary magnetic field, possibly due to magnetic mirroring at the shock. We also discuss the general behavior of GCR anisotropy as observed at this high cutoff rigidity.

Keywords: galactic cosmic rays; forbush effect; interplanetary shocks; solar-terrestrial interactions
21cmVAE: A Very Accurate Emulator of the 21 cm Global Signal

Considerable observational efforts are being dedicated to measuring the sky-averaged (global) 21 cm signal of neutral hydrogen from Cosmic Dawn and the Epoch of Reionization. Deriving observational constraints on the astrophysics of this era requires modeling tools that can quickly and accurately generate theoretical signals across the wide astrophysical parameter space. For this purpose artificial neural networks were used to create the only two existing global signal emulators, 21CMGEM and GLOBALEMU. In this paper we introduce 21CMVAE, a neural-network-based global signal emulator, trained on the same data set of ~30,000 global signals as the other two emulators, but with a more direct prediction algorithm that prioritizes accuracy and simplicity. Using neural networks, we compute derivatives of the signals with respect to the astrophysical parameters and establish the most important astrophysical processes that drive the global 21 cm signal at different epochs. 21CMVAE has a relative rms error of only 0.34%-equivalently 0.54 mK-on average, which is a significant improvement compared to the existing emulators, and a run time of 0.04 s per parameter set. The emulator, the code, and the processed data sets are publicly available at https://github.com/christianhbye/21cmVAE and through https://zenodo.org/record/5904939.

Keywords: early universe; cosmology; astronomy software
Turbulent Cosmic Ray-Mediated Shocks in the Hot Ionized Interstellar Medium

The structure of shocks and turbulence are strongly modified during the acceleration of cosmic rays (CRs) at a shock wave. The pressure and the collisionless viscous stress decelerate the incoming thermal gas and thus modify the shock structure. A CR streaming instability ahead of the shock generates the turbulence on which CRs scatter. The turbulent magnetic field in turn determines the CR diffusion coefficient and further affects the CR energy spectrum and pressure distribution. The dissipation of turbulence contributes to heating the thermal gas. Within a multicomponent fluid framework, CRs and thermal gas are treated as fluids and are closely coupled to the turbulence. The system equations comprise the gas dynamic equations, the CR pressure evolution equation, and the turbulence transport equations, and we adopt typical parameters for the hot ionized interstellar medium. It is shown that the shock has no discontinuity but possesses a narrow but smooth transition. The self-generated turbulent magnetic field is much stronger than both the large-scale magnetic field and the preexisting turbulent magnetic field. The resulting CR diffusion coefficient is substantially suppressed and is more than three orders smaller near the shock than it is far upstream. The results are qualitatively consistent with certain observations.

Keywords: cosmic rays; shocks
The Kepler Giant Planet Search. I. A Decade of Kepler Planet-host Radial Velocities from W. M. Keck Observatory

Despite the importance of Jupiter and Saturn to Earth's formation and habitability, there has not yet been a comprehensive observational study of how giant exoplanets correlate with the architectural properties of close-in, sub-Neptune-sized exoplanets. This is largely because transit surveys are particularly insensitive to planets at orbital separations ≳1 au, and so their census of Jupiter-like planets is incomplete, inhibiting our study of the relationship between Jupiter-like planets and the small planets that do transit. To investigate the relationship between close-in, small and distant, giant planets, we conducted the Kepler Giant Planet Survey (KGPS). Using the W. M. Keck Observatory High Resolution Echelle Spectrometer, we spent over a decade collecting 2844 radial velocities (RVs; 2167 of which are presented here for the first time) of 63 Sunlike stars that host 157 transiting planets. We had no prior knowledge of which systems would contain giant planets beyond 1 au, making this survey unbiased with respect to previously detected Jovians. We announce RV-detected companions to 20 stars from our sample. These include 13 Jovians ( $0.3\,{M}_{{\rm{J}}}\lt M\sin i\lt 13\,{M}_{{\rm{J}}}$ , 1 au < a < 10 au), eight nontransiting sub-Saturns, and three stellar-mass companions. We also present updated masses and densities of 84 transiting planets. The KGPS project leverages one of the longest-running and most data-rich collections of RVs of the NASA Kepler systems yet, and it will provide a basis for addressing whether giant planets help or hinder the growth of sub-Neptune-sized and terrestrial planets. Future KGPS papers will examine the relationship between small, transiting planets and their long-period companions.

Keywords: exoplanets; exoplanet catalogs; exoplanet systems; radial velocity; transits; orbital elements; exoplanet detection methods; mini neptunes; super earths; extrasolar rocky planets; binary stars
Galaxy Rotation Curves and Universal Scaling Relations: Comparison between Phenomenological and Fermionic Dark Matter Profiles

Galaxies show different halo scaling relations such as the radial acceleration relation, the mass discrepancy acceleration relation (MDAR), or the dark matter (DM) surface density relation. At difference with traditional studies using phenomenological ΛCDM halos, we analyze the above relations assuming that DM halos are formed through a maximum entropy principle (MEP) in which the fermionic (quantum) nature of the DM particles is dully accounted for. For the first time, a competitive DM model based on first physical principles, such as (quantum) statistical-mechanics and thermodynamics, is tested against a large data set of galactic observables. In particular, we compare the fermionic DM model with empirical DM profiles: the Navarro-Frenk-White (NFW) model, a generalized NFW model accounting for baryonic feedback, the Einasto model, and the Burkert model. For this task, we use a large sample of 120 galaxies taken from the Spitzer Photometry and Accurate Rotation Curves data set, from which we infer the DM content to compare with the models. We find that the radial acceleration relation and MDAR are well explained by all the models with comparable accuracy, while the fits to the individual rotation curves, in contrast, show that cored DM halos are statistically preferred with respect to the cuspy NFW profile. However, very different physical principles justify the flat inner-halo slope in the most-favored DM profiles: while generalized NFW or Einasto models rely on complex baryonic feedback processes, the MEP scenario involves a quasi-thermodynamic equilibrium of the DM particles.

Keywords: galaxy dynamics; galaxy structure; galaxy physics; dark matter; galaxy dark matter halos
The Circumstellar Material around the Type IIP SN 2021yja

The majority of Type II-plateau supernovae (SNe IIP) have light curves that are not compatible with the explosions of stars in a vacuum; instead, the light curves require the progenitors to be embedded in circumstellar matter (CSM). We report on the successful fitting of the well-observed SN IIP 2021yja as a core-collapse explosion of a massive star with an initial mass of ~15 M ⊙ and a pre-explosion radius of 631 R ⊙. To explain the early-time behavior of the broadband light curves, the presence of 0.55 M ⊙ CSM within ~2 × 1014 cm is needed. Like many other SNe IIP, SN 2021yja exhibits an early-time flux excess including ultraviolet wavelengths. This, together with the short rise time (<2 days) in the gri bands, indicates the presence of a compact component in the CSM, essentially adjacent to the progenitor. We discuss the origin of the preexisting CSM, which is most likely a common property of highly convective red supergiant envelopes. We argue that the difficulty in fitting the entire light curve with one spherical distribution indicates that the CSM around the SN 2021yja progenitor was asymmetric.

Keywords: type ii supernovae; circumstellar matter; radiative transfer simulations; massive stars
Exploring the Milky Way Circumgalactic Medium in a Cosmological Context with a Semianalytic Model

We combine the Santa Cruz semianalytic model (SAM) for galaxy formation and evolution with the circumgalactic medium (CGM) model presented in Faerman et al. to explore the CGM properties of L * galaxies. We use the SAM to generate a sample of galaxies with halo masses similar to the Milky Way (MW) halo, M vir ≈ 1012 M ⊙, and find that the CGM mass and mean metallicity in the sample are correlated. We use the CGM masses and metallicities of the SAM galaxies as inputs for the FSM20 model and vary the amount of nonthermal support. The density profiles in our models can be approximated by power-law functions with slopes in the range of 0.75 < a n < 1.25, with higher nonthermal pressure resulting in flatter distributions. We explore how the gas pressure, dispersion measure, O VI-O VIII column densities, and cooling rates behave with the gas distribution and total mass. We show that for CGM masses below ~3 × 1010 M ⊙ photoionization has a significant effect on the column densities of O VI and O VIII. The combination of different MW CGM observations favors models with similar fractions in thermal pressure, magnetic fields/cosmic rays, and turbulent support and with M CGM ~ (3-10) × 1010 M ⊙. The MW O VI column requires t cool/t dyn ~ 4, independent of the gas distribution. The AGN jet-driven heating rates in the SAM are enough to offset the CGM cooling, although exact balance is not required in star-forming galaxies. We provide predictions for the column densities of additional metal ions-N V, Ne VIII, and Mg X.

Keywords: circumgalactic medium; galaxy structure; quasar absorption line spectroscopy; galaxy formation; milky way formation; galactic and extragalactic astronomy; galaxy evolution; milky way evolution
The μ Tau Association: A 60 Myr Old Coeval Group at 150 pc from the Sun

We present an analysis of the newly identified μ Tau Association (MUTA) of young stars at ≃150 pc from the Sun that is part of the large Cas-Tau structure, coeval and comoving with the α Persei cluster. This association is also located in the vicinity of the Taurus-Auriga star-forming region and the Pleiades association, although it is unrelated to them. We identify more than 500 candidate members of MUTA using Gaia DR2 data and the BANYAN Σ tool, and we determine an age of 62 ± 7 Myr for its population based on an empirical comparison of its color-magnitude diagram sequence with those of other nearby young associations. The MUTA association is related to the Theia 160 group of Kounkel & Covey and corresponds to the e Tau group of Liu et al. It is also part of the Cas-Tau group of Blaauw. As part of this analysis, we introduce an iterative method based on spectral templates to perform an accurate correction of interstellar extinction of Gaia DR2 photometry, needed because of its wide photometric bandpasses. We show that the members of MUTA display an expected increased rate of stellar activity and faster rotation rates compared with older stars, and that literature measurements of the lithium equivalent width of nine G0- to K3-type members are consistent with our age determination. We show that the present-day mass function of MUTA is consistent with other known nearby young associations. We identify WD 0340+103 as a hot, massive white dwarf remnant of a B2 member that left its planetary nebula phase only 270,000 yr ago, posing an independent age constraint of ${60}_{-6}^{+8}$ Myr for MUTA, consistent with our isochrone age. This relatively large collection of comoving young stars near the Sun indicates that more work is required to unveil the full kinematic structure of the complex of young stars surrounding α Persei and Cas-Tau.

Keywords: astrometry; stellar associations; proper motions; brown dwarfs; stellar kinematics; low mass stars
Waterworlds May Have Better Climate Buffering Capacities than Their Continental Counterparts

The long-term habitability of a planet is often assumed to be controlled by its ability to cycle carbon between the solid planetary interior and atmosphere. This process allows the planet to respond to external forcings (i.e., changes in insolation, changes in volcanic outgassing rates, etc.) and regulate its surface temperature through negative feedbacks on atmospheric CO2 involved in silicate weathering. Continental weathering and seafloor weathering rates have different, non-linear dependencies on pCO2 and will respond differently to changes in external forcings. Because waterworlds (planets with only seafloor weathering) have a weaker pCO2 dependence than continental worlds (such as modern Earth), we find that waterworlds are better at resisting changes in surface temperature resulting from perturbations in insolation than their continental counterparts, and may be more habitable in this respect.

Keywords: habitable planets; exoplanets; extrasolar rocky planets; ocean planets; carbon dioxide
NuSTAR Survey of Obscured Swift/BAT-selected Active Galactic Nuclei. II. Median High-energy Cutoff in Seyfert II Hard X-Ray Spectra

Broadband X-ray spectroscopy of the X-ray emission produced in the coronae of active galactic nuclei (AGNs) can provide important insights into the physical conditions very close to their central supermassive black holes. The temperature of the Comptonizing plasma that forms the corona is manifested through a high-energy cutoff that has been difficult to directly constrain even in the brightest AGN because it requires high-quality data at energies above 10 keV. In this paper we present a large collection of coronal cutoff constraints for obscured AGNs based on a sample of 130 AGNs selected in the hard X-ray band with Swift/BAT and observed nearly simultaneously with NuSTAR and Swift/XRT. We find that under a reasonable set of assumptions regarding partial constraints the median cutoff is well constrained to 290 ± 20 keV, where the uncertainty is statistical and given at the 68% confidence level. We investigate the sensitivity of this result to our assumptions and find that consideration of various known systematic uncertainties robustly places the median cutoff between 240 and 340 keV. The central 68% of the intrinsic cutoff distribution is found to be between about 140 and 500 keV, with estimated uncertainties of 20 and 100 keV, respectively. In comparison with the literature, we find no clear evidence that the cutoffs in obscured and unobscured AGNs are substantially different. Our analysis highlights the importance of carefully considering partial and potentially degenerate constraints on the coronal high-energy cutoff in AGNs.

Keywords: active galactic nuclei; x-ray active galactic nuclei; seyfert galaxies; high energy astrophysics; x-ray surveys
The IGRINS YSO Survey II: Veiling Spectra of Pre-main-sequence Stars in Taurus-Auriga

We present measurements of the H- and K-band veiling for 141 young stellar objects (YSOs) in the Taurus-Auriga star-forming region using high-resolution spectra from the Immersion Grating Near-Infrared Spectrometer. In addition to providing measurements of rH and rK, we produce low-resolution spectra of the excess emission across the H and K bands. We fit temperatures to the excess spectra of 46 members of our sample and measure near-infrared excess temperatures ranging from 1200-2200 K, with an average of 1575 ± 225 K. We compare the luminosity of the excess continuum emission in Class II and Class III YSOs and find that a number of Class III sources display a significant amount of excess flux in the near-infrared. We conclude that the mid-infrared SED slope, and therefore young stellar object classification, is a poor predictor of the amount of near-infrared veiling. If the veiling arises in thermal emission from dust, its presence implies a significant amount of remaining inner-disk (<1 au) material in these Class III sources. We also discuss the possibility that the veiling effects could result from massive photospheric spots, unresolved binary companions, or accretion emission. Six low-mass members of our sample contain a prominent feature in their H-band excess spectra that is consistent with veiling from cool photospheric spots.

Keywords: young stellar objects; near infrared astronomy; high resolution spectroscopy; protoplanetary disks
Expanded Capability of the Breakthrough Listen Parkes Data Recorder for Observations with the UWL Receiver

The ultra-wideband low (UWL) receiver is a new feed for the Parkes telescope, which covers the combined bandwidth of four previously installed receivers. In order to use the UWL for technosignature observations, several updates and upgrades were made on the Breakthrough Listen Parkes Data Recorder (BLPDR). This Research Note summarizes BLPDR hardware upgrades and new capacity for technosignature observations with the UWL receiver.

Keywords: search for extraterrestrial intelligence; technosignatures; astronomical instrumentation
A Low-velocity Bipolar Outflow from a Deeply Embedded Object in Taurus Revealed by the Atacama Compact Array

The first hydrostatic core, the first quasi-hydrostatic object formed during the star formation process, is still the observational missing link between the prestellar and protostellar phases, mainly due to its short lifetime. Although we have not established a clear method to identify this rare object, recent theoretical studies predict that the first core has millimeter continuum emission and low-velocity outflow with a wide opening angle. An extensive continuum/outflow survey toward a large number of "starless" cores in nearby star-forming regions works as a pathfinder. We observed 32 prestellar cores in Taurus with an average density of ≳105 cm-3 in 1.3 mm continuum and molecular lines using the Atacama Large Millimeter/submillimeter Array-Atacama Compact Array (ALMA-ACA) stand-alone mode. Among the targets, MC35-mm centered at one of the densest "starless" cores in Taurus has blueshifted/redshifted wings in the 12CO (2-1) line, indicating that there is a deeply embedded object driving molecular outflow. The observed velocities and sizes of the possible outflow lobes are 2-4 km s-1 and ∼2 × 103 au, respectively, and the dynamical time is calculated to be ∼103 yr. In addition to this, the core is one of the strongest N2D+ (3-2) emitters in our sample. All of the observed signatures do not conflict with any of the theoretical predictions about the first hydrostatic core so far, and thus MC35-mm is unique as the only first-core candidate in the Taurus molecular cloud.

Keywords: collapsing clouds; protostars; star formation
Comparing Observed Stellar Kinematics and Surface Densities in a Low-latitude Bulge Field to Galactic Population Synthesis Models

We present an analysis of Galactic bulge stars from Hubble Space Telescope Wide Field Camera 3 observations of the Stanek window (l, b = [0.25, -2.15]) from two epochs approximately two years apart. This data set is adjacent to the provisional Wide-field Infrared Survey Telescope (WFIRST) microlensing field. Proper motions are measured for approximately 115,000 stars down to 28th mag in V band and 25th mag in I band, with accuracies of 0.5 mas yr-1 (20 km s-1) at I ≈ 21. A cut on the longitudinal proper motion μl allows us to separate disk and bulge populations and produce bulge-only star counts that are corrected for photometric completeness and efficiency of the proper-motion cut. The kinematic dispersions and surface density in the field are compared to the nearby SWEEPS sight line, finding a marginally larger-than-expected gradient in stellar density. The observed bulge star counts and kinematics are further compared to the Besançon, Galaxia, and GalMod Galactic population synthesis models. We find that most of the models underpredict low-mass bulge stars by ∼33% below the main-sequence turnoff, and upwards of ∼70% at redder J and H wavebands. While considering inaccuracies in the Galactic models, we give implications for the exoplanet yield from the WFIRST microlensing mission.

Keywords: galactic bulge; astronomical models; gravitational microlensing; stellar kinematics; luminosity function; hst photometry