adsabs/SciX_UAT_keywords huggingface dataset:
Searching for C II Emission from the First Sample of z ∼ 6 O I Absorption-associated Galaxies with the Atacama Large Millimeter/submillimeter Array

We report the first statistical analyses of [C II] and dust continuum observations in six strong O I absorber fields at the end of the reionization epoch obtained by the Atacama Large Millimeter/submillimeter Array (ALMA). Combined with one [C II] emitter reported in Wu et al., we detect one O I-associated [C II] emitter in six fields. At redshifts of O I absorbers in nondetection fields, no emitters are brighter than our detection limit within impact parameters of 50 kpc and velocity offsets between ±200 km s-1. The averaged [C II]-detection upper limit is <0.06 Jy km s-1(3σ), corresponding to the [C II] luminosity of L [C II]< 5.8 × 107 L ⊙ and the [C II]-based star formation rate of SFR[C II]<5.5 M ⊙ yr-1. Cosmological simulations suggest that only ~10-2.5 [C II] emitters around O I absorbers have comparable SFR to our detection limit. Although the detection in one out of six fields is reported, an order of magnitude number excess of emitters obtained from our ALMA observations supports that the contribution of massive galaxies that caused the metal enrichment cannot be ignored. Further, we also found 14 tentative galaxy candidates with a signal-to-noise ratio of ≈4.3 at large impact parameters (>50 kpc) and having larger outflow velocities within ±600 km s-1. If these detections are confirmed in the future, then the mechanism of pushing metals at larger distances with higher velocities needs to be further explored from the theoretical side.

Keywords: high-redshift galaxies; quasars
The Green Bank North Celestial Cap Survey. IX. Timing Follow-up for 128 Pulsars

The Green Bank North Celestial Cap survey is one of the largest and most sensitive searches for pulsars and transient radio objects. Observations for the survey have finished; priorities have shifted toward long-term monitoring of its discoveries. In this study, we have developed a pipeline to handle large data sets of archival observations and connect them to recent, high-cadence observations taken using the Canadian Hydrogen Intensity Mapping Experiment telescope. This pipeline handles data for 128 pulsars and has produced measurements of spin, positional, and orbital parameters that connect data over observation gaps as large as 2000 days. We have also measured glitches in the timing residuals for five of the pulsars included and proper motion for 19 sources (13 new). We include updates to orbital parameters for 19 pulsars, including nine previously unpublished binaries. For two of these binaries, we provide updated measurements of post-Keplerian binary parameters, which result in much more precise estimates of the total masses of both systems. For PSR J0509+3801, the much improved measurement of the Einstein delay yields much improved mass measurements for the pulsar and its companion, 1.399(6) M ⊙ and 1.412(6) M ⊙, respectively. For this system, we have also obtained a measurement of the orbital decay due to the emission of gravitational waves, ${\dot{P}}_{{\rm{B}}}=-1.37(7)\times {10}^{-12}$ , which is in agreement with the rate predicted by general relativity for these masses.

Keywords: radio pulsars; binary pulsars
Particle-in-cell Simulations of Mildly Relativistic Outflows in Kilonova Emissions

The electromagnetic emission from neutron star mergers is comprised of multiple components. Synchrotron emission from the disk-powered jet and thermal emission from the merger ejecta (powered by a variety of sources) are among the most studied sources. The low masses and high velocities of the merger ejecta quickly develop conditions where emission from collisionless shocks becomes critical and synchrotron emission from the merger ejecta constitutes a third component to the observed signal. The aim of this project is to examine shock development, magnetic field generation, and particle acceleration in the case of mildly relativistic shocks, which are expected when the tidal ejecta of neutron star mergers drive a shock into the external medium. Using LANL's vector particle-in-cell (VPIC) code, we have run simulations of such mildly relativistic, collisionless, weakly magnetized plasmas and computed the resultant magnetic fields and particle energy spectra. We show the effects of varying plasma conditions, as well as explore the validity of using different proton-to-electron mass ratios in VPIC. Our results have implications for observing late-time electromagnetic counterparts to gravitational wave detections of neutron star mergers.

Keywords: plasma astrophysics; shocks; stellar winds
Evidence for Low-power Radio Jet-ISM Interaction at 10 pc in the Dwarf AGN Host NGC 4395

Black-hole-driven outflows in galaxies hosting active galactic nuclei (AGN) may interact with their interstellar medium (ISM) affecting star formation (SF). Such feedback processes, reminiscent of those seen in massive galaxies, have been reported recently in some dwarf galaxies. However, such studies have usually been on kiloparsec and larger scales and our knowledge of the smallest spatial scales to which these feedback processes can operate is unclear. Here we demonstrate radio jet-ISM interaction on the scale of an asymmetric triple radio structure of ~10 pc size in NGC 4395. This triple radio structure is seen in the 15 GHz continuum image and the two asymmetric jet-like structures are situated on either side of the radio core that coincides with the optical Gaia position. The high-resolution radio image and the extended [O III]λ5007 emission, indicative of an outflow, are spatially coincident and are consistent with the interpretation of a low-power radio jet interacting with the ISM. Modelling of the spectral lines using MAPPINGS, and estimation of temperature using optical integral field spectroscopic data suggest shock ionization of the gas. The continuum emission at 237 GHz, though weak, was found to spatially coincide with the AGN. However, the CO(2-1) line emission was found to be displaced by around 20 pc northward of the AGN core. The spatial coincidence of molecular H2 λ2.4085 along the jet direction, the morphology of ionized [O III]λ5007, and displacement of the CO(2-1) emission argues for conditions less favorable for SF in the central ~10 pc region.

Keywords: dwarf galaxies; active galactic nuclei; radio jets; agn host galaxies
The Origin of the [C II] Deficit in a Simulated Dwarf Galaxy Merger-driven Starburst

We present [C II] synthetic observations of smoothed particle hydrodynamics (SPH) simulations of a dwarf galaxy merger. The merging process varies the star formation rate (SFR) by more than three orders of magnitude. Several star clusters are formed, the feedback of which disperses and unbinds the dense gas through expanding H II regions and supernova (SN) explosions. For galaxies with properties similar to the modeled ones, we find that the [C II] emission remains optically thin throughout the merging process. We identify the warm neutral medium ( $3\lt \mathrm{log}{T}_{\mathrm{gas}}\lt 4$ with χ HI > 2χ H2) to be the primary source of [C II] emission (~58% contribution), although at stages when the H II regions are young and dense (during star cluster formation or SNe in the form of ionized bubbles), they can contribute ≳50% to the total [C II] emission. We find that the [C II]/far-IR (FIR) ratio decreases owing to thermal saturation of the [C II] emission caused by strong far-UV radiation fields emitted by the massive star clusters, leading to a [C II] deficit medium. We investigate the [C II]-SFR relation and find an approximately linear correlation that agrees well with observations, particularly those from the Dwarf Galaxy Survey. Our simulation reproduces the observed trends of [C II]/FIR versus ΣSFR and ΣFIR, and it agrees well with the Kennicutt relation of SFR-FIR luminosity. We propose that local peaks of [C II] in resolved observations may provide evidence for ongoing massive cluster formation.

Keywords: interstellar medium; photodissociation regions; radiative transfer simulations
Abnormal Dawn-Dusk Asymmetry of Protonated Ions in the Martian Ionosphere

Normally, the Martian ionosphere displays a dusk enhancement due to continuous depletion of plasma via recombination during day-to-night transport. Using the extensive measurements made by the Neutral Gas and Ion Mass Spectrometer on board the Mars Atmosphere and Volatile Evolution spacecraft, we show that several species, including ${{\rm{H}}}_{2}^{+}$ , OH+, H2O+, and NH+, present instead an abnormal dawn enhancement above the exobase where they are mainly produced by ion-neutral reactions involving H2. Such a peculiarity is indicative of a dawn bulge of H2 present in the Martian upper atmosphere and corona, which is driven by subsidence in regions of horizontal wind convergence and the subsequent buildup of minor atmospheric species with large vertical scale heights. A similar dynamical process is also known to occur in the upper atmospheres of other solar system bodies such as the Earth, Venus, and Titan. Interestingly, despite that the diurnal variations of O and N are subject to the same dynamical effect, a dawn enhancement is not seen for O+ and N+, possibly due to the nonthermal production of their parent atoms in the ambient atmosphere via processes such as photodissociation and dissociative recombination. The H2 distribution inferred in this study is important for a thorough understanding of hydrogen escape and climate evolution on Mars.

Keywords: solar system astronomy; solar system planets; solar system; solar system terrestrial planets; mars; atmospheric variability; atmospheric composition; upper atmosphere; aeronomy; atmospheric science; planetary science; planetary atmospheres
The Near-stellar Environment of Class 0 Protostars: A First Look with Near-infrared Spectroscopy

We present near-infrared K-band spectra for a sample of seven Class 0 protostars in the Perseus and Orion star-forming regions. We detect Brγ, CO overtone, and H2 emission, features that probe the near-circumstellar environment of the protostar and reveal evidence of magnetospheric accretion, a hot inner disk atmosphere, and outflows, respectively. Comparing the properties of these features with those of Class I sources from the literature, we find that their Brγ emission and CO emission are generally consistent in strength and velocity width. The Brγ line profiles are broad and centrally peaked, with FWHMs of ~200 km s-1 and wings extending to ~300 km s-1. The line ratios of our H2 emission features, which are spatially extended for some sources, are consistent with shock excitation and indicate the presence of strong jets or a disk wind. Within our small sample, the frequency of CO band emission (~67%) is high relative to that of Class I samples (~15%), indicating that Class 0 sources have high inner disk accretion rates, similar to those of the most actively accreting Class I sources. Collectively, our results suggest that Class 0 sources have similar accretion mechanisms to the more evolved classes, with strong organized stellar magnetic fields established at the earliest observable stage of evolution.

Keywords: protostars; stellar accretion disks; near infrared astronomy
Exploring the Hadronic Origin of LHAASO J1908+0621

Recent observations by the Large High Altitude Air Shower Observatory (LHAASO) have paved the way for the observational detection of PeVatrons in the Milky Way, thus revolutionizing the field of γ-ray astrophysics. In this paper, we study one such detected source, LHAASO J1908+0621, and explore the origin of multi-TeV γ-ray emission from this source. A middle-aged radio supernova remnant SNR G40.5-0.5 and a GeV pulsar PSR J1907+0602 are cospatial with LHAASO J1908+0621. Dense molecular clouds are also found to be associated with SNR G40.5-0.5. We explain the multi-TeV γ-ray emission observed from the direction of LHAASO J1908+0621, by the hadronic interaction between accelerated protons that escaped from the SNR shock front and cold protons present inside the dense molecular clouds, and the leptonic emission from the pulsar wind nebula (PWN) associated with the pulsar J1907+0602. Moreover, we explain lower energy γ-ray emission by considering the radiative cooling of the electrons that escaped from SNR G40.5-0.5. Finally, the combined lepto-hadronic scenario was used to explain the multiwavelength spectral energy distribution of LHAASO J1908+0621. Although not yet significant, an IceCube hotspot of neutrino emission is spatially associated with LHAASO J1908+0621, indicating a possible hadronic contribution. In this paper, we show that if a hadronic component is present in LHAASO J1908+0621, then the second-generation IceCube observatory will detect neutrinos from this source.

Keywords: high energy astrophysics; gamma-ray sources; gamma-rays; supernova remnants; molecular clouds
Dark Matter Constraints from a Unified Analysis of Strong Gravitational Lenses and Milky Way Satellite Galaxies

Joint analyses of small-scale cosmological structure probes are relatively unexplored and promise to advance measurements of microphysical dark matter properties using heterogeneous data. Here, we present a multidimensional analysis of dark matter substructure using strong gravitational lenses and the Milky Way (MW) satellite galaxy population, accounting for degeneracies in model predictions and using covariances in the constraining power of these individual probes for the first time. We simultaneously infer the projected subhalo number density and the half-mode mass describing the suppression of the subhalo mass function in thermal relic warm dark matter (WDM), Mhm, using the semianalytic model Galacticus to connect the subhalo population inferred from MW satellite observations to the strong lensing host halo mass and redshift regime. Combining MW satellite and strong lensing posteriors in this parameter space yields Mhm < 107.0 M⊙ (WDM particle mass mWDM > 9.7 keV) at 95% confidence and disfavors Mhm = 107.4 M⊙ (mWDM = 7.4 keV) with a 20:1 marginal likelihood ratio, improving limits on mWDM set by the two methods independently by ~30%. These results are marginalized over the line-of-sight contribution to the strong lensing signal, the mass of the MW host halo, and the efficiency of subhalo disruption due to baryons and are robust to differences in the disruption efficiency between the MW and strong lensing regimes at the ~10% level. This work paves the way for unified analyses of next-generation small-scale structure measurements covering a wide range of scales and redshifts.

Keywords: dark matter; strong gravitational lensing; milky way dark matter halo; galaxy abundances
Luminosity Models and Density Profiles for Nuclear Star Clusters for a Nearby Volume-limited Sample of 29 Galaxies

Nuclear star clusters (NSCs) are dense stellar clusters that are found at the centers of a majority of galaxies. In this paper, we study the density profiles for 29 galaxies in a volume-limited survey within 10 Mpc to characterize their NSCs. These galaxies span a 3 × 108-8 × 1010 M⊙ and a wide range of Hubble types. We use high-resolution Hubble Space Telescope archival data to create luminosity models for the galaxies using Sérsic profiles to parameterize the NSCs. We also provide estimates for photometric masses of NSCs and their host galaxies using color-M/L relationships and examine their correlation. We use the multi-Gaussian expansion to derive the NSC densities and their 3D mass-density profiles. The 3D density profiles characterize the NSC densities on scales as small as ∼1 pc, approaching the likely spheres of influence for BHs in these objects. We find that these densities correlate with galaxy mass, with NSC density profiles becoming both denser and flatter at higher galaxy masses. Most galaxy NSCs are denser than typical globular clusters. We parameterize the 3D NSC density profiles and their scatter and slope as a function of galaxy stellar mass to enable the construction of realistic nuclear mass profiles. Our fitted profiles and the derived relations are useful in predicting the rate of tidal disruption events in galaxies. We will verify the results of this paper in a follow-up paper that presents the dynamical modeling of the same sample of NSCs.

Keywords: galaxy nuclei; globular star clusters; young star clusters; tidal disruption; late-type galaxies; early-type galaxies
The Carnegie-Irvine Galaxy Survey. IX. Classification of Bulge Types and Statistical Properties of Pseudo Bulges

We study the statistical properties of 320 bulges of disk galaxies in the Carnegie-Irvine Galaxy Survey, using robust structural parameters of galaxies derived from image fitting. We apply the Kormendy relation to classify classical and pseudo bulges and characterize the bulge dichotomy with respect to the structural properties of the bulges and the physical properties of the host galaxies. We confirm previous findings that pseudo bulges on average have smaller Sérsic indices, lower bulge-to-total ratios, and fainter surface brightnesses than classical bulges. Our sizable sample statistically shows that pseudo bulges are more intrinsically flattened than classical bulges. Pseudo bulges are most frequent (incidence ≳80%) in late-type spirals (later than Sc). Our measurements support the picture in which pseudo bulges arose from star formation induced by inflowing gas, while classical bulges were born out of violent processes such as mergers and coalescence of clumps. We reveal differences with the literature that warrant attention: (1) the bimodal distribution of Sérsic indices presented by previous studies is not reproduced in our study; (2) classical and pseudo bulges have similar relative bulge sizes; and (3) the pseudo bulge fraction is considerably smaller in early-type disks than reported in previous studies based on one-dimensional surface brightness profile fitting. We attribute these differences to our improved image quality, more robust bulge-to-disk decomposition technique, and to the different classification criteria that we applied. Moreover, we find that barred galaxies do not host more pseudo bulges or more prominent pseudo bulges than unbarred galaxies. Various implications of these findings are discussed.

Keywords: galaxy bulges; galaxy structure; galaxy photometry; disk galaxies; elliptical galaxies; galaxy evolution
The Classification of Galaxy Morphology in the H Band of the COSMOS-DASH Field: A Combination-based Machine-learning Clustering Model

By applying our previously developed two-step scheme for galaxy morphology classification, we present a catalog of galaxy morphology for H-band-selected massive galaxies in the COSMOS-DASH field, which includes 17,292 galaxies with stellar mass M ⋆ > 1010 M ⊙ at 0.5 < z < 2.5. The classification scheme is designed to provide a complete morphology classification for galaxies via a combination of two machine-learning steps. We first use an unsupervised machine-learning method (i.e., bagging-based multiclustering) to cluster galaxies into five categories: spherical (SPH), early-type disk, late-type disk, irregular (IRR), and unclassified. About 48% of the galaxies (8258/17,292) are successfully clustered during this step. For the remaining sample, we adopt a supervised machine-learning method (i.e., GoogLeNet) to classify them, during which galaxies that are well classified in the previous step are taken as our training set. Consequently, we obtain a morphology classification result for the full sample. The t-SNE test shows that galaxies in our sample can be well aggregated. We also measure the parametric and nonparametric morphologies of these galaxies. We find that the Sérsic index increases from IRR to SPH and the effective radius decreases from IRR to SPH, consistent with the corresponding definitions. Galaxies from different categories are separately distributed in the G-M 20 space. Such consistencies with other characteristic descriptions of galaxy morphology demonstrate the reliability of our classification result, ensuring that it can be used as a basic catalog for further galaxy studies.

Keywords: galaxy structure; astrostatistics techniques; astronomy data analysis
Misaligned Spinning Binary Black Hole Mergers in Hot Magnetized Plasma

We present general relativistic magnetohydrodynamical simulations of equal-mass spinning black hole binary mergers embedded in a magnetized gas cloud. We focus on the effect of the spin orientation relative to the orbital angular momentum on the flow dynamics, mass accretion rate, and Poynting luminosity. We find that, across the inspiral, the gas accreting onto the individual black holes concentrates into disklike overdensities whose angular momenta are oriented toward the spin axes and that persist until merger. We identify quasiperiodic modulations occurring in the mass accretion rate at the level of ~1%-20%, evolving in parallel with the gravitational-wave chirp. The similarity between the accretion rate time series and the gravitational strain is a consequence of the interplay between strong, dynamical gravitational fields and magnetic fields in the vicinity of the inspiraling black holes. This result suggests that quasiperiodicity in the premerger accretion rate of massive binaries is not exclusive of environments in which the black holes are embedded in a circumbinary accretion disk and could provide an additional useful signature of electromagnetic emission concurrent to low-frequency gravitational-wave detection.

Keywords: general relativity; gravitational waves; supermassive black holes; black hole physics; gravitational wave sources; magnetohydrodynamical simulations; rotating black holes
The R-Process Alliance: Fourth Data Release from the Search for R-process-enhanced Stars in the Galactic Halo

This compilation is the fourth data release from the R-Process Alliance (RPA) search for r-process-enhanced stars and the second release based on "snapshot" high-resolution (R ∼ 30,000) spectra collected with the du Pont 2.5 m Telescope. In this data release, we propose a new delineation between the r-I and r-II stellar classes at $[\mathrm{Eu}/\mathrm{Fe}]=+0.7$ , instead of the empirically chosen $[\mathrm{Eu}/\mathrm{Fe}]=+1.0$ level previously in use, based on statistical tests of the complete set of RPA data released to date. We also statistically justify the minimum level of [Eu/Fe] for definition of the r-I stars, [Eu/Fe] > +0.3. Redefining the separation between r-I and r-II stars will aid in the analysis of the possible progenitors of these two classes of stars and determine whether these signatures arise from separate astrophysical sources at all. Applying this redefinition to previous RPA data, the number of identified r-II and r-I stars changes to 51 and 121, respectively, from the initial set of data releases published thus far. In this data release, we identify 21 new r-II, 111 new r-I (plus 3 re-identified), and 7 new (plus 1 re-identified) limited-r stars out of a total of 232 target stars, resulting in a total sample of 72 new r-II stars, 232 new r-I stars, and 42 new limited-r stars identified by the RPA to date. * This paper includes data gathered with the 2.5 m du Pont telescope located at Las Campanas Observatory, Chile.

Keywords: r-process; nucleosynthesis; metallicity; stellar abundances; population ii stars; stellar atmospheres