adsabs/SciX_UAT_keywords huggingface dataset:
Osaka Feedback Model. II. Modeling Supernova Feedback Based on High-resolution Simulations

Feedback from supernovae (SNe) is an essential mechanism that self-regulates the growth of galaxies, and a better model of SN feedback is still needed in galaxy-formation simulations. In the first part of this paper, using an Eulerian hydrodynamic code ATHENA++, we find the universal scaling relations for the time evolution of momentum and radius for a superbubble, when the momentum and time are scaled by those at the shell-formation time. In the second part of this paper, we develop a SN feedback model based on the ATHENA++ simulation results utilizing Voronoi tessellation around each star particle, and implement it into the GADGET3-OSAKA smoothed particle hydrodynamic code. Our feedback model was demonstrated to be isotropic and conservative in terms of energy and momentum. We examined the mass/energy/metal loading factors and find that our stochastic thermal feedback model produced galactic outflow that carries metals high above the galactic plane but with weak suppression of star formation. Additional mechanical feedback further suppressed star formation and brought the simulation results into better agreement with the observations of the Kennicutt-Schmidt relation, with all the results being within the uncertainties of observed data. We argue that both thermal and mechanical feedback are necessary for the SN feedback model of galaxy evolution when an individual SN bubble is unresolved.

Keywords: galaxies; hydrodynamical simulations; star formation; supernovae; stellar feedback; galaxy formation; galactic winds; superbubbles; interstellar medium
Interplanetary Shock Candidates Observed at Venus's Orbit

The measurements from the Venus Express spacecraft are analyzed for the basic properties of fast forward interplanetary shocks at Venus's orbit (∼0.72 au). A total of 143 fast forward interplanetary shock candidates during 2006-2014 are identified. The shock angle ΘBn, defined as the angle between the shock normal and the upstream magnetic field, and the magnetic compression ratio rB, defined as the ratio of the magnetic field strength downstream to that upstream, of these shocks are determined based on the magnetic coplanarity method. The shock occurrence at Venus shows a correlated variation with the solar activity level measured by the number of sunspots, while the shock angle and magnetic compression ratio do not show such a correspondence. The shock angle spreads almost uniformly between 10° and 80° with its mean value at about 45°, and the magnetic compression ratio shows a unimodal distribution between 1.0 and 4.5 with a mean value of 2.1. In addition, we also analyze the properties of fast forward shocks driven by interplanetary coronal mass ejections (ICMEs). We found that interplanetary shocks with and without detected ICMEs showed no significant differences in terms of the shock strength and the shock angle. Further comparison with previous observational results at 1 au shows that fast forward shocks at 1 au are generally weaker than those at 0.72 au, and the shock angle ΘBn is more perpendicular at 1 au.

Keywords: venus; solar system terrestrial planets; interplanetary shocks
Comet 21P/Giacobini-Zinner: Narrowband Photometry of the Prototype of Carbon-chain Depleted Comets at Multiple Apparitions

We obtained extensive narrowband photoelectric photometry of Comet 21P/Giacobini-Zinner with observations spanning 33 yr. The original data from 1985 were re-reduced and are presented along with data from three additional apparitions, including 2018/19. The original conclusion regarding Giacobini-Zinner's chemical composition remains unchanged, with it having a 4-6× depletion in the carbon-chain molecules C2 and C3 and in NH, as compared with both OH and CN. The comet continues to exhibit a large asymmetry in production rates as a function of time and heliocentric distance, with production reaching a peak 3-5 weeks prior to perihelion. All species, including dust, follow the same general production rate curve each apparition, and the carbon-bearing species are always very similar to one another. However, OH and NH each differ in detail from the carbon-bearing species, implying somewhat varied composition between source regions. Longer term, there are only small secular changes among the apparitions before and near perihelion, but larger changes are evident as the comet recedes from the Sun, suggestive of a progressive precession of the rotation axis.

Keywords: comets; short period comets; comet nuclei; comae; comet volatiles; near-earth objects
A High-resolution View of Fast Radio Burst Host Environments

We present Hubble Space Telescope ultraviolet and infrared observations of eight fast radio burst (FRB) host galaxies with subarcsecond localizations, including the hosts of three known repeating FRBs. We quantify their spatial distributions and locations with respect to their host galaxy light distributions, finding that they occur at moderate host-normalized offsets of 1.4re ([0.6, 2.1]re; 68% interval) and on fainter regions of their hosts in terms of IR light but overall trace the radial distribution of IR light in their galaxies. The FRBs in our tested distribution do not clearly trace the distributions of any other transient population with known progenitors and are statistically distinct from the locations of LGRBs, H-poor SLSNe, SGRBs, and Ca-rich transients. We further find that most FRBs are not in regions of elevated local star formation rates and stellar mass surface densities in comparison to the mean global values of their hosts. We also place upper limits on the IR flux at the FRB positions of mIR ≳ 24.8-27.6 AB mag, constraining both satellite and background galaxies to luminosities well below the host luminosity of FRB 121102. We find that 5/8 FRB hosts exhibit clear spiral arm features in IR light, and that the positions of all well-localized FRBs located in such hosts are consistent with their spiral arms, although not on their brightest regions. Our results do not strongly support the primary progenitor channel of FRBs being connected with either the most massive (stripped-envelope) stars or events that require kicks and long delay times (neutron star mergers).

Keywords: galaxies; radio transient sources; transient sources; radio bursts; hst photometry
The Cepheid Distance to the Narrow-line Seyfert 1 Galaxy NGC 4051

We derive a distance of D = 16.6 ± 0.3 Mpc (μ = 31.10 ± 0.04 mag) to the archetypal narrow-line Seyfert 1 galaxy NGC 4051 based on Cepheid period-luminosity relations and new Hubble Space Telescope multiband imaging. We identify 419 Cepheid candidates and estimate the distance at both optical and near-infrared wavelengths using subsamples of precisely photometered variables (123 and 47 in the optical and near-infrared subsamples, respectively). We compare our independent photometric procedures and distance-estimation methods to those used by the Supernovae, H0, for the Equation of State team and find agreement to 0.01 mag. The distance we obtain suggests an Eddington ratio of $\dot{m}\approx 0.2$ for NGC 4051, typical of narrow-line Seyfert 1 galaxies, unlike the seemingly odd value implied by previous distance estimates. We derive a peculiar velocity of -490 ± 34 km s-1 for NGC 4051, consistent with the overall motion of the Ursa Major Cluster in which it resides. We also revisit the energetics of the NGC 4051 nucleus, including its outflow and mass accretion rates.

Keywords: distance measure; cepheid distance; agn host galaxies; hubble space telescope; hst photometry; time series analysis; near infrared astronomy; distance indicators; galaxy distances
Red Supergiants in M31 and M33. I. The Complete Sample

The aim of this paper is to establish a complete sample of red supergiants (RSGs) in M31 and M33. The member stars of the two galaxies are selected from the near-infrared (NIR) point sources after removing the foreground dwarfs from their obvious branch in the J - H/H - K diagram with the archival photometric data taken by the UKIRT/WFCAM. This separation by NIR colors of dwarfs from giants is confirmed by the optical/infrared color-color diagrams (r - z/z - H and B - V/V - R) and the Gaia measurement of parallax and proper motion. The RSGs are then identified by their outstanding location in the members' J - K/K diagram due to high luminosity and low effective temperature. The resultant sample has 5498 and 3055 RSGs in M31 and M33 respectively, which should be complete because the lower limiting K magnitude of RSGs in both cases is brighter than the complete magnitude of the UKIRT photometry. Analysis of the control fields finds that the pollution rate in the RSG sample is less than 1%. The by-product is the complete sample of oxygen-rich asymptotic giant branch stars (AGBs), carbon-rich AGBs, thermally pulsing AGBs, and extreme AGBs. In addition, the tip-RGB is determined together with its implication on the distance modulus to M31 and M33.

Keywords: massive stars; red supergiant stars; andromeda galaxy; triangulum galaxy
Espresso and Stochastic Acceleration of Ultra-high-energy Cosmic Rays in Relativistic Jets

In the espresso scenario, ultra-high-energy (UHE) cosmic rays (CRs) are produced via a one-shot reacceleration of galactic-like CRs in the relativistic jets of active galactic nuclei, independently of the scattering rate dictated by magnetic fluctuations. In Mbarek & Caprioli (2019) we traced test-particle CRs in high-resolution magnetohyrodynamic (MHD) jet simulations and found that the associated spectral slope, chemical composition, and anisotropy are consistent with UHECR phenomenology. In this work, we extend such an analysis by including subgrid pitch-angle scattering to model small-scale magnetic turbulence that cannot be resolved by MHD simulations. We find that a large scattering rate unlocks stochastic acceleration and fosters the energization of lower-energy CRs, which eventually leads to harder UHECR spectra. Yet, the particles that achieve the highest energies (up to the Hillas limit) are invariably produced by espresso acceleration and their spectrum is independent of the assumed subgrid scattering rate.

Keywords: ultra-high-energy cosmic radiation; active galactic nuclei; cosmic rays; magnetohydrodynamical simulations
In Situ Observations of Interplanetary Dust Variability in the Inner Heliosphere

This work examines the variation of interplanetary dust count rates and directionality during the first three solar encounters made by the Parker Solar Probe spacecraft, covering distances between 0.65 au (∼140 solar radii, RS) and 0.16 au (∼35 RS). Dust detections are made by the FIELDS instrument via plasma clouds, produced by impact ionization of dust grains on spacecraft surfaces and resultant spacecraft potential perturbations. Dust count rates and inferred densities are found to vary by ∼50% between the three solar encounters (∼5 months per orbit), with most of the variation concentrated below 0.23 au (∼50RS). Dust count rates and directionality, as well as the encounter-to-encounter variability in both quantities are found to be consistent with β-meteoroids: dust grains exiting the solar system on hyperbolic trajectories. Interpretation of the the dust count rate data and the dust directionality data independently suggest (I) that the β-meteoroid source region is more complex than preliminary models suggest, and (II) that the primary β-meteoroid source region is approximately located between 10 and 30 solar radii from the Sun. These data offer important clues as to the location and geometry of the β-meteoroid source region, and consequently clues about the collisional and sublimation processing of interplanetary dust grains near the Sun.

Keywords: interplanetary dust; zodiacal cloud; heliosphere
Laboratory Measurement of CH2DOH Line Intensities in the Millimeter-wave Region

Deuterium fractionation in molecules is known as one of the most powerful tools to study chemical processes during star and planet formation. Among various interstellar molecules, methanol often shows very high deuterium fractionation. It is the most abundant saturated organic molecule and is known as a parent species to form more complex organic molecules. However, deriving the abundance of deuterated methanol suffers from the uncertainty in the intrinsic line intensities (S μ 2) of CH3OH isotopologues. Due to their floppy nature, theoretical evaluation of the S μ 2 values is not straightforward, particularly for asymmetric-top asymmetric-frame isotopologues such as CH2DOH. In this study, we have measured the line frequencies and their intensities for CH2DOH in the millimeter-wave region from 216 to 264 GHz by using an emission-type millimeter and submillimeter-wave spectrometer. For the a-type J = 5 - 4 transition, the derived S μ 2 values are 13%-27% larger than those theoretically calculated, except for the transitions of K a = 2 for e 0 and K a = 1 for e 1 affected by avoided level crossing. For b-type transitions, significant systematic differences are found between theoretical and experimental S μ 2 values. The results of the present study enable us to accurately derive from observations the CH2DOH abundances, which are essential for understanding deuterium fractionation in various sources.

Keywords: molecular spectroscopy; line positions; line intensities; astrochemistry
Dissipative Capture of Planets into First-order Mean-motion Resonances

The emergence of orbital resonances among planets is a natural consequence of the early dynamical evolution of planetary systems. While it is well established that convergent migration is necessary for mean-motion commensurabilities to emerge, recent numerical experiments have shown that the existing adiabatic theory of resonant capture provides an incomplete description of the relevant physics, leading to an erroneous mass scaling in the regime of strong dissipation. In this work, we develop a new model for resonance capture that self-consistently accounts for migration and circularization of planetary orbits, and derive an analytic criterion based upon stability analysis that describes the conditions necessary for the formation of mean-motion resonances. We subsequently test our results against numerical simulations and find satisfactory agreement. Our results elucidate the critical role played by adiabaticity and resonant stability in shaping the orbital architectures of planetary systems during the nebular epoch, and provide a valuable tool for understanding their primordial dynamical evolution.

Keywords: orbital resonances; perturbation methods
First Comet Observations with NIRSPEC-2 at Keck: Outgassing Sources of Parent Volatiles and Abundances Based on Alternative Taxonomic Compositional Baselines in 46P/Wirtanen

A major upgrade to the NIRSPEC instrument at the Keck II telescope was successfully completed in time for near-infrared spectroscopic observations of comet 46P/Wirtanen during its exceptionally close flyby of Earth in 2018 December. These studies determined the abundances of several volatiles, including C2H2, C2H6, CH3OH, NH3, HCN, H2CO, and H2O. Long-slit spatial distributions of gas rotational temperature and column density are diagnostic for the presence of icy grains in the coma and understanding if different volatiles are associated with common or distinct outgassing sources. These spatial distributions suggest that C2H2, C2H6, and HCN have a common outgassing source, whereas H2O and CH3OH have additional, more extended sources. The synergy of these findings with observations by space missions (Rosetta and EPOXI) motivates continuing studies to address whether or not C2H6, C2H2, and HCN have a common source of release (plausibly associated with CO2) in a larger sample of comets and whether systematic differences exist in the release of these species compared to H2O and CH3OH. Abundances of volatiles are reported relative to H2O, as traditionally done, as well as C2H6. While not unique, the choice of C2H6 demonstrates the value of extending the chemical taxonomy of parent volatiles in comets toward additional compositional "baselines" and, importantly, closer integration between coma abundances and the underlying volatile associations as revealed by spatial distributions. Our findings on composition and sources of outgassing include information relevant to future evaluations of 46P/Wirtanen as a prospective spacecraft target.

Keywords: solar system; small solar system bodies; comets; short period comets; comae
The Interstellar Medium Scaling Relations Using Inner H I and an Application of Estimating Dust Mass

We select a disk-like galaxy sample with observations of the H I, H2, and dust from the Herschel Reference Survey, and derive inner H I masses within the optical radius. We find that the inner gas-to-dust ratio is almost independent of gas-phase metallicity, and confirm that the inner gas mass (H I+H2) shows a tighter relation with dust mass and monochromatic 500 μm luminosity than the integral gas mass. It supports that dust is more closely associated with cospatial cold gas than the overall cold gas. Based on the newly calibrated relationship between inner gas mass and dust mass, we predict dust masses for disk-dominated galaxies from the xCOLD GASS sample. The predicted dust masses show scaling relations consistent with fiducial ones in the literature, supporting their robustness. Additionally, we find that at a given dust mass and star formation rate (SFR), the galactic Wide-field Infrared Explorer W3 luminosities show a significant dependence on the [N II] luminosity and the stellar mass surface density. Such dependence highlights the caveat of using the W3 luminosity as an integral SFR indicator, and is consistent with findings of studies that target star-forming regions in more nearby galaxies and accurately derive dust masses based on mapping-mode spectroscopy.

Keywords: interstellar medium; late-type galaxies; star formation; gas-to-dust ratio; polycyclic aromatic hydrocarbons
Absorption and Self-absorption of [C II] and [O I] Far Infrared Lines toward a Bright Bubble in the Nessie Infrared Dark Cloud

Using the upGREAT instrument on board the Stratospheric Observatory for Infrared Astronomy, we imaged [C II] 157.74 and [O I] 63.18 μm line emission from a bright photodissociation region (PDR) associated with an ionized bubble located in the Nessie Nebula, a filamentary infrared dark cloud. A comparison with Australia Telescope Compact Array data reveals a classic photodissociation region (PDR) structure, with a uniform progression from ionized gas, to photodissociated gas, and to molecular gas from the bubble's interior to its exterior. [O I] line emission from the bubble's PDR reveals self-absorption features. Toward a far-IR bright protostar, both [O I] and [C II] show an absorption feature at a velocity of ‑18 km s‑1, the same velocity as an unrelated foreground molecular cloud. Since the gas density in typical molecular clouds is well below the [O I] and [C II] critical densities, the excitation temperatures for both lines are low (∼20 K). The Meudon models demonstrate that the surface of a molecular cloud, externally illuminated by a standard G 0 = 1 interstellar radiation field, can produce absorption features in both transitions. Thus, the commonly observed [O I] and [C II] self-absorption and absorption features plausibly arise from the subthermally excited, externally illuminated photodissociated envelopes of molecular clouds. The luminous young stellar object AGAL337.916-00.477, located precisely where the expanding bubble strikes the Nessie filament, is associated with two shock tracers: NH3 (3,3) maser emission and SiO 2‑1 emission, indicating an interaction between the bubble and the filament. The interaction of the expanding bubble with its parental dense filament has triggered star formation.

Keywords: photodissociation regions; interstellar medium; star formation; h ii regions; interstellar line absorption
Thermal Structure and Millimeter Emission from a Protoplanetary Disk with Embedded Protoplanets from Radiative Transfer Modeling

The discovery of protoplanets and circumplanetary disks provides a unique opportunity to characterize planet formation through observations. Massive protoplanets shape the physical and chemical structure of their host circumstellar disk by accretion, localized emission, and disk depletion. In this work, we study the thermal changes induced within the disk by protoplanet accretion and synthetic predictions through hydrodynamical simulations with postprocessed radiative transfer with an emphasis on radio millimeter emission. We explored distinct growth conditions and varied both planetary accretion rates and the local dust-to-gas mass ratios for a protoplanet at 1200 K. The radiative transfer models show that beyond the effect of disk gaps, in most cases, the circumplanetary disk (CPD) and the planet's emission locally increase the disk temperature. Moreover, depending on the local dust-to-gas depletion and accretion rate, the presence of the CPD may have detectable signatures in millimeter emission. It also has the power to generate azimuthal asymmetries that are important for continuum subtraction. Thus, if other means of detection of protoplanets are proven, the lack of corresponding evidence at other wavelengths can set limits on their growth timescales through a combined analysis of the local dust-to-gas ratio and the accretion rate.

Keywords: protoplanetary disks; submillimeter astronomy; planetary-disk interactions
Milliarcsecond X-Ray Astrometry to Resolve Inner Regions of AGN at z > 1 Using Gravitational Lensing

We report the localization of the X-ray emission from two strongly lensed AGN, CLASS B0712+472 (z = 1.34) and CLASS B1608+656 (z = 1.394). We obtain milliarcsecond X-ray astrometry by developing a novel method that combines parametric lens modeling with a Bayesian analysis. We spatially locate the X-ray sources in CLASS B0712+472 and CLASS B1608+656 within 11 mas and 9 mas from the radio source, respectively. For CLASS B0712+472, we find that the X-ray emission is cospatial with the radio and optical emission. On the other hand, for CLASS B1608+656, the X-ray emission is cospatial with radio but displaced with respect to the optical emission at the 1σ level, which positions this source as an offset AGN candidate. This high astrometric precision improves on the limitations of existing X-ray instruments by two orders of magnitude. The demonstrated method opens a path to search for offset and binary AGN at z > 1, and to directly test supermassive black hole formation models in a redshift range that has been mostly underconstrained to date.

Keywords: strong gravitational lensing; black hole physics; supermassive black holes; active galaxies; active galactic nuclei; astrometry; x-ray quasars