adsabs/SciX_UAT_keywords huggingface dataset:
Circumnuclear Multiphase Gas in the Circinus Galaxy. VI. Detectability of Molecular Inflow and Atomic Outflow

Recent submillimeter observations have revealed signs of parsec-scale molecular inflow and atomic outflow in the nearest Seyfert 2 galaxy, the Circinus galaxy. To verify the gas kinematics suggested by these observations, we performed molecular and atomic line transfer calculations based on a physics-based 3D radiation-hydrodynamic model, which has been compared with multiwavelength observations in this paper series. The major-axis position–velocity diagram (PVD) of CO(3–2) reproduces the observed faint emission at the systemic velocity, and our calculations confirm that this component originates from failed winds falling back to the disk plane. The minor-axis PVD of [C I](3 P 1–3 P 0), when created using only the gas with positive radial velocities, presents a sign of blueshifted and redshifted offset peaks similar to those in the observation, suggesting that the observed peaks indeed originate from the outflow, but that the model may lack outflows as strong as those in the Circinus galaxy. Similar to the observed HCN(3–2), the similar dense-gas tracer HCO+(3–2) can exhibit nuclear spectra with inverse P-Cygni profiles with ∼0.5 pc beams, but the line shape is azimuthally dependent. The corresponding continuum absorbers are inflowing clumps at 5–10 pc from the center. To detect significant absorption with a high probability, the inclination must be fairly edge-on (≳85°), and the beam size must be small (≲1 pc). These results suggest that HCN or HCO+ and [C I] lines are effective for observing parsec-scale inflows and outflows, respectively.

Keywords: active galactic nuclei; seyfert galaxies; interstellar medium; radiative transfer simulations; millimeter astronomy; submillimeter astronomy
Ultra-light Dark Matter Is Incompatible with the Milky Way's Dwarf Satellites

The density profiles of dwarf galaxies are a highly varied set. If the dark matter is an ultra-light particle such as axions, then simulations predict a distinctive and unique profile. If the axion mass is large enough to fit the ultra-faint dwarf (UFD) satellites ( $m\gtrapprox {10}^{-21}$ eV), then the models do not fit the density profile of Fornax and Sculptor and are ruled out by more than $3-\sigma $ confidence. If the axion mass is in the mass range that can fit mass profiles of Fornax and Sculptor dwarf spheroidals, then its extended profile implies enormous masses ( $\approx {10}^{11}\mbox{--}{10}^{12}\,{M}_{\odot }$ ) for the UFDs. These large masses for the UFDS are ruled out by more than $3-\sigma $ confidence by dynamical friction arguments. The tension would increase further considering star formation histories and stellar masses of the UFDs. Unless future ultra-light dark matter (ULDM) simulations with baryonic feedback show a significant change in the density structure of the halos, the current data is incompatible with the ULDM scenario. Relaxing the slope constraint from classical dwarf galaxies would lead to excluding ULDM with mass less than $6\times {10}^{-22}\,{\rm{eV}}$ .

Keywords: dark matter; dwarf galaxies; dwarf spheroidal galaxies; dark matter distribution
Ursa Major III/UNIONS 1: The Darkest Galaxy Ever Discovered?

The recently discovered stellar system Ursa Major III/UNIONS 1 (UMa3/U1) is the faintest known Milky Way satellite to date. With a stellar mass of ${16}_{-5}^{+6}\,{M}_{\odot }$ and a half-light radius of 3 ± 1 pc, it is either the darkest galaxy ever discovered or the faintest self-gravitating star cluster known to orbit the Galaxy. Its line-of-sight velocity dispersion suggests the presence of dark matter, although current measurements are inconclusive because of the unknown contribution to the dispersion of potential binary stars. We use N-body simulations to show that, if self-gravitating, the system could not survive in the Milky Way tidal field for much longer than a single orbit (roughly 0.4 Gyr), which strongly suggests that the system is stabilized by the presence of large amounts of dark matter. If UMa3/U1 formed at the center of a ∼109 M ⊙ cuspy LCDM halo, its velocity dispersion would be predicted to be of order ∼1 km s‑1. This is roughly consistent with the current estimate, which, neglecting binaries, places σ los in the range 1–4 km s‑1. Because of its dense cusp, such a halo should be able to survive the Milky Way tidal field, keeping UMa3/U1 relatively unscathed until the present time. This implies that UMa3/U1 is plausibly the faintest and densest dwarf galaxy satellite of the Milky Way, with important implications for alternative dark matter models and for the minimum halo mass threshold for luminous galaxy formation in the LCDM cosmology. Our results call for multi-epoch high-resolution spectroscopic follow-up to confirm the dark matter content of this extraordinary system.

Keywords: cold dark matter; dwarf spheroidal galaxies; low surface brightness galaxies; n-body simulations; star clusters; tidal disruption
Modeling of the High-velocity Jet Powered by the Massive Star MWC 349A

MWC 349A is a massive star with a well-known circumstellar disk rotating following a Keplerian law, and an ionized wind launched from the disk surface. Recent observations with the Atacama Large Millimeter/submillimeter Array (ALMA) carried out toward this system, however, have revealed an additional high-velocity component in the strong, maser emission of hydrogen radio recombination lines (RRLs), suggesting the presence of a high-velocity ionized jet. In this work, we present 3D non-LTE radiative transfer modeling of the emission of the H30α and H26α maser lines, and of their associated radio continuum emission, toward MWC 349A. By using the MORELI code, we reproduce the spatial distribution and kinematics of the high-velocity emission of the H30α and H26α maser lines with a high-velocity ionized jet expanding at a velocity of ~250 km s-1, surrounded by MWC 349A's wide-angle ionized wind. The bipolar jet, which is launched from MWC 349A's disk, is poorly collimated and slightly misaligned with respect to the disk rotation axis. Thanks to the unprecedented sensitivity and spatial accuracy provided by ALMA, we also find that the already known, wide-angle ionized wind decelerates as it expands radially from the ionized disk. We briefly discuss the implications of our findings for understanding the formation and evolution of massive stars. Our results show the huge potential of RRL masers as powerful probes of the innermost ionized regions around massive stars and of their high-velocity jets.

Keywords: massive stars; circumstellar masers; h ii regions; stellar winds; stellar jets; stellar accretion disks
A Spectroscopic Classification Survey to Search for New ρ Puppis Stars

The ρ Puppis stars are mid-F-type stars that show peculiar chemical-abundance patterns similar to those of the Am stars. Typically they exhibit overabundances of iron-peak elements such as Fe and Ni and s- and r-process elements such as Sr and Eu, and underabundances of certain other elements including He, Ca, and Sc. It has been proposed that these stars are evolving Am stars passing through the short-lived phase that occurs between the re-establishment of convection and the consequent erasure of their chemical peculiarities. In this paper we suggest a second hypothesis: these stars may have acquired their peculiar abundance patterns in a fashion similar to the Barium stars, i.e., they may have gained the s-process element enhancements via mass transfer from a once asymptotic giant-branch companion star, now turned white dwarf. This study will detail our efforts to investigate the ρ Puppis stars with regard to these two hypotheses, with a view to understanding these stars and their significance in terms of stellar evolution. We have performed a spectral classification survey, and a detailed chemical-abundance analysis of selected ρ Puppis stars. This paper gives an overview of the ρ Puppis stars and describes the spectral classification survey which has increased the number of ρ Puppis stars currently known from 6 to 49. A future paper will describe the chemical-abundance analysis which should provide insight into the nature of these stars.

Keywords: barium stars; stellar classification; chemically peculiar stars; am stars
Correcting Stellar Flare Frequency Distributions Detected by TESS and Kepler

The habitability of planets is closely connected with stellar activity, mainly the frequency of flares and the distribution of flare energy. Kepler and TESS find many flaring stars via precise time-domain photometric data, and the frequency and energy distribution of stellar flares on different types of stars are studied statistically. However, the completeness and observational bias of detected flare events from different missions (e.g., Kepler and TESS) vary a lot. We use a unified data processing and detection method for flare events based on the light curves from Kepler and TESS. Then we perform injection and recovery tests in the original light curve of each star for each flare event to correct the completeness and energy of flares. Three samples of flaring stars are selected from Kepler and TESS, with rotation periods from 1 to ~5 days. Adopting a hot-blackbody assumption, our results show that the cumulative flare frequency distributions (FFDs) of the same stars in Kepler and TESS bands tend to be consistent after correction, revealing a more natural flaring frequency and energy distribution. Our results also extend the low-energy limit in cumulative FFD fitting to 1031.5-33 erg on different types of stars. For solar-type stars, the average power-law index of cumulative FFD (α cum) is -0.84, which indicates that low-energy flares contribute less to the total flare energy. With a piecewise correlation between α cum and T eff, α cum first rises from M2 to K1 stars, then slightly decreases for stars hotter than K1.

Keywords: stellar flares; stellar activity; habitable zone; planet hosting stars
Mapping Obscured Star Formation in the Host Galaxy of FRB 20201124A

We present high-resolution 1.5-6 GHz Karl G. Jansky Very Large Array and Hubble Space Telescope (HST) optical and infrared observations of the extremely active repeating fast radio burst (FRB) FRB 20201124A and its barred spiral host galaxy. We constrain the location and morphology of star formation in the host and search for a persistent radio source (PRS) coincident with FRB 20201124A. We resolve the morphology of the radio emission across all frequency bands and measure a star formation rate (SFR) ≈ 8.9 M ⊙ yr-1, approximately ≈2.5-6 times larger than optically inferred SFRs, demonstrating dust-obscured star formation throughout the host. Compared to a sample of all known FRB hosts with radio emission, the host of FRB 20201124A has the most significantly obscured star formation. While HST observations show the FRB to be offset from the bar or spiral arms, the radio emission extends to the FRB location. We propose that the FRB progenitor could have formed in situ (e.g., a magnetar born from a massive star explosion). It is still plausible, although less likely, that the progenitor of FRB 20201124A migrated from the central bar of the host. We further place a limit on the luminosity of a putative PRS at the FRB position of L 6.0GHz ≲ 1.8 ×1027 erg s-1 Hz-1, among the deepest PRS luminosity limits to date. However, this limit is still broadly consistent with both magnetar nebulae and hypernebulae models assuming a constant energy injection rate of the magnetar and an age of ≳105 yr in each model, respectively.

Keywords: magnetars; star formation; radio transient sources
Herschel SPIRE Discovery of Far-infrared Excess Synchrotron Emission from the West Hot Spot of the Radio Galaxy Pictor A

A far-infrared counterpart to the west hot spot of the radio galaxy Pictor A is discovered with the Spectral and Photometric Imaging REceiver (SPIRE) on board Herschel. The color-corrected flux density of the source is measured as 70.0 ± 9.9 mJy at the wavelength of 350 μm. A close investigation into its radio-to-optical spectrum indicates that the mid-infrared excess over the radio synchrotron component, detected with Wide-field Infrared Survey Explorer and Spitzer, significantly contributes to the far-infrared band. Thanks to the SPIRE data, it is revealed that the spectrum of the excess is described by a broken power-law model subjected to a high-energy cutoff. By applying the radiative cooling break under continuous energy injection (Δα = 0.5), the broken power-law model supports an idea that the excess originates in 10 pc scale substructures within the hot spot. From the break frequency, ${\nu }_{{\rm{b}}}={1.6}_{-1.0}^{+3.0}\times {10}^{12}$ Hz, the magnetic field was estimated as B ≃ 1-4 mG. This is higher than the minimum-energy magnetic field of the substructures by a factor of 3-10. Even if the origin of the excess is larger than ∼100 pc, the magnetic field stronger than the minimum-energy field is confirmed. It is proposed that regions with a magnetic field locally boosted via plasma turbulence are observed as the substructures. The derived energy index below the break, α ∼ 0.22 (conservatively <0.42), is difficult to be attributed to the strong-shock acceleration (α = 0.5). Stochastic acceleration and magnetic reconnection are considered as a plausible alternative mechanism.

Keywords: galaxy jets; non-thermal radiation sources; radio hot spots; high energy astrophysics; active galaxies; far infrared astronomy; fanaroff-riley radio galaxies
Evaluating Lyα Emission as a Tracer of the Largest Cosmic Structure at z 2.47

The discovery and spectroscopic confirmation of Hyperion, a protosupercluster at z ~ 2.47, provides an unprecedented opportunity to study distant galaxies in the context of their large-scale environment. We carry out deep narrowband imaging of a ≈1° × 1° region around Hyperion and select 157 Lyα emitters (LAEs). The inferred LAE overdensity is δ g ≈ 40 within an effective volume of 30 × 20 × 15 cMpc3, consistent with the fact that Hyperion is composed of multiple protoclusters and will evolve into a supercluster with a total mass of M tot ≈ 1.4 × 1015 M ⊙ at z = 0. The distribution of LAEs closely mirrors that of known spectroscopic members, tracing the protocluster cores and extended filamentary arms connected to them, suggesting that they trace the same large-scale structure. By cross-correlating the LAE positions with H I tomography data, we find weak evidence that LAEs may be less abundant in the highest H I regions, perhaps because Lyα is suppressed in such regions. The Hyperion region hosts a large population of active galactic nuclei (AGNs) ≈ 12 times more abundant than that in the field. The prevalence of AGNs in protocluster regions hints at the possibility that they may be triggered by physical processes that occur more frequently in dense environments, such as galaxy mergers. Our study demonstrates LAEs as reliable markers of the largest cosmic structures. When combined with ongoing and upcoming imaging and spectroscopic surveys, wide-field narrowband imaging has the potential to advance our knowledge in the formation and evolution of cosmic structures and of their galaxy inhabitants.

Keywords: galaxy evolution; galaxy formation; high-redshift galaxy clusters
Mapping the Supernovae Driven Winds of the Large Magellanic Cloud in Hα Emission I

We present the first spectroscopically resolved Hα emission map of the Large Magellanic Cloud's (LMC) galactic wind. By combining new Wisconsin H-alpha Mapper observations (IHα ≳ 10 mR) with existing H I 21 cm emission observations, we (1) mapped the LMC's nearside galactic wind over a local standard of rest (LSR) velocity range of +50 ≤ vLSR ≤ +250 km s-1, (2) determined its morphology and extent, and (3) estimated its mass, outflow rate, and mass-loading factor. We observe Hα emission from this wind to typically 1° off the LMC's H I disk. Kinematically, we find that the diffuse gas in the warm-ionized phase of this wind persists at both low (≲100 km s-1) and high (≳100 km s-1) velocities, relative to the LMC's H I disk. Furthermore, we find that the high-velocity component spatially aligns with the most intense star-forming region, 30 Doradus. We, therefore, conclude that this high-velocity material traces an active outflow. We estimate the mass of the warm (Te ≈ 104 K) ionized phase of the nearside LMC outflow to be $\mathrm{log}\left({M}_{\mathrm{ionized}}/{M}_{\odot }\right)=7.51\pm 0.15$ for the combined low and high-velocity components. Assuming an ionization fraction of 75% and that the wind is symmetrical about the LMC disk, we estimate that its total (neutral and ionized) mass is $\mathrm{log}\left({M}_{\mathrm{total}}/{M}_{\odot }\right)=7.93$ , its mass-flow rate is ${\dot{M}}_{\mathrm{outflow}}\approx 1.43\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$ , and its mass-loading factor is η ≈ 4.54. Our average mass-loading factor results are roughly a factor of 2.5 larger than previous Hα imaging and UV absorption line studies, suggesting that those studies are missing nearly half the gas in the outflows.

Keywords: dwarf galaxies; galaxy evolution; interstellar medium; large magellanic cloud; circumgalactic medium; high-velocity clouds; galactic winds; stellar feedback
Formation of the Hub-Filament System G33.92+0.11: Local Interplay between Gravity, Velocity, and Magnetic Field

The formation of filaments in molecular clouds is an important process in star formation. Hub-filament systems (HFSs) are a transition stage connecting parsec-scale filaments and protoclusters. Understanding the origin of HFSs is crucial to reveal how star formation proceeds from clouds to cores. Here we report James Clerk Maxwell telescope POL-2 850 μm polarization and IRAM 30 m C18O (2-1) line observations toward the massive HFS G33.92+0.11. The 850 μm continuum map reveals four major filaments converging to the center of G33.92+0.11 with numerous short filaments connecting to the major filaments at local intensity peaks. We estimate the local orientations of filaments, magnetic field, gravity, and velocity gradients from observations, and we examine their correlations based on their local properties. In the high-density areas, our analysis shows that the filaments tend to align with the magnetic field and local gravity. In the low-density areas, we find that the local velocity gradients tend to be perpendicular to both the magnetic field and local gravity, although the filaments still tend to align with local gravity. A global virial analysis suggests that the gravitational energy overall dominates the magnetic and kinematic energy. Combining local and global aspects, we conclude that the formation of G33.92+0.11 is predominantly driven by gravity, dragging and aligning the major filaments and magnetic field on the way to the inner dense center. Traced by local velocity gradients in the outer diffuse areas, ambient gas might be accreted onto the major filaments directly or via the short filaments.

Keywords: collapsing clouds; infrared dark clouds; molecular clouds; interstellar filaments; interstellar magnetic fields; interstellar medium; polarimetry; interstellar dynamics; submillimeter astronomy; young massive clusters
Early Planet Formation in Embedded Disks (eDisk). I. Overview of the Program and First Results

We present an overview of the Large Program, "Early Planet Formation in Embedded Disks (eDisk)," conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The ubiquitous detections of substructures, particularly rings and gaps, in protoplanetary disks around T Tauri stars raise the possibility that at least some planet formation may have already started during the embedded stages of star formation. In order to address exactly how and when planet formation is initiated, the program focuses on searching for substructures in disks around 12 Class 0 and 7 Class I protostars in nearby (<200 pc) star-forming regions through 1.3 mm continuum observations at a resolution of ~7 au (0.″04). The initial results show that the continuum emission, mostly arising from dust disks around the sample protostars, has relatively few distinctive substructures, such as rings and spirals, in marked contrast to Class II disks. The dramatic difference may suggest that substructures quickly develop in disks when the systems evolve from protostars to Class II sources, or alternatively that high optical depth of the continuum emission could obscure internal structures. Kinematic information obtained through CO isotopologue lines and other lines reveals the presence of Keplerian disks around protostars, providing us with crucial physical parameters, in particular, the dynamical mass of the central protostars. We describe the background of the eDisk program, the sample selection and their ALMA observations, and the data reduction, and we also highlight representative first-look results.

Keywords: protoplanetary disks; planetary system formation; protostars; submillimeter astronomy
Fitting the Nonlinear Matter Bispectrum by the Halofit Approach

We provide a new fitting formula of the matter bispectrum in the nonlinear regime calibrated by high-resolution cosmological N-body simulations of 41 cold dark matter (wCDM, w = constant) models around the Planck 2015 best-fit parameters. As the parameterization in our fitting function is similar to that in Halofit, our fitting is named BiHalofit. The simulation volume is sufficiently large ( $\gt 10\,{\mathrm{Gpc}}^{3}$ ) to cover almost all measurable triangle bispectrum configurations in the universe. The function is also calibrated using one-loop perturbation theory at large scales ( $k\lt 0.3\,h\,{\mathrm{Mpc}}^{-1}$ ). Our formula reproduced the matter bispectrum to within 10% (15%) accuracy in the Planck 2015 model at wavenumber $k\lt 3\,(10)\,h\,{\mathrm{Mpc}}^{-1}$ and redshifts z = 0-3. The other 40 wCDM models obtained poorer fits, with accuracy approximating 20% at $k\lt 3\,h\,{\mathrm{Mpc}}^{-1}$ and $z=0\mbox{--}1.5$ (the deviation includes the 10%-level sample variance of the simulations). We also provide a fitting formula that corrects the baryonic effects such as radiative cooling and active galactic nucleus feedback, using the latest hydrodynamical simulation IllustrisTNG. We demonstrate that our new formula more accurately predicts the weak-lensing bispectrum than the existing fitting formulae. This formula will assist current and future weak-lensing surveys and cosmic microwave background lensing experiments. Numerical codes of the formula are available, written in Python (https://toshiyan.github.io/clpdoc/html/basic/basic.html#module-basic.bispec), C, and Fortran (http://cosmo.phys.hirosaki-u.ac.jp/takahasi/codes_e.htm).

Keywords: n-body simulations; weak gravitational lensing; cosmic microwave background radiation; large-scale structure of the universe; cosmological parameters from large-scale structure