Sazuna/UAT_keywords huggingface dataset:
Bye-bye, Local-in-matter-density Bias: The Statistics of the Halo Field Are Poorly Determined by the Local Mass Density. Bias models relating the dark matter field to the spatial distribution of halos are widely used in current cosmological analyses. Many models predict halos purely from the local Eulerian matter density, yet bias models in perturbation theory require other local properties. We assess the validity of assuming that only the local dark matter density can be used to predict the number density of halos in a model-independent way and in the nonperturbative regime. Utilizing N-body simulations, we study the properties of the halo counts field after spatial voxels with near-equal dark matter density have been permuted. If local-in-matter-density (LIMD) biasing were valid, the statistical properties of the permuted and unpermuted fields would be indistinguishable since both represent equally fair draws of the stochastic biasing model. If the Lagrangian radius is greater than approximately half the voxel size and for halos less massive than ∼1015 h‑1 M☉, we find the permuted halo field has a scale-dependent bias with greater than 25% more power on scales relevant for current surveys. These bias models remove small-scale power by not modeling correlations between neighboring voxels, which substantially boosts large-scale power to conserve the field's total variance. This conclusion is robust to the choice of initial conditions and cosmology. Assuming LIMD halo biasing cannot, therefore, reproduce the distribution of halos across a large range of scales and halo masses, no matter how complex the model. One must either allow the biasing to be a function of other quantities and/or remove the assumption that neighboring voxels are statistically independent.

Keywords: Cosmology, Dark matter distribution, Large-scale structure of the universe
Be Careful in Multimessenger Inference of the Hubble Constant: A Path Forward for Robust Inference. Multimessenger observations of coalescing binary neutron stars (BNSs) using gravitational-wave (GW) and electromagnetic- (EM) wave signals are a direct probe of the expansion history of the Universe and carry the potential to shed light on the disparity between low- and high-redshift measurements of the Hubble constant H 0. To measure the value of H 0 with such observations requires pristine inference of the luminosity distance and the true source redshift with minimal impact from systematics. In this analysis, we carry out joint inference on mock GW signals and their EM afterglows from BNS coalescences and find that the inclination angle inferred from the afterglow light curve and apparent superluminal motion can be precise but need not be accurate and is subject to a systematic uncertainty that could be as large as 1.5σ. This produces a disparity between the EM and GW inferred inclination angles, which if not carefully treated when combining observations can bias the inferred value of H 0. We also find that already small misalignments of 3°–6° between the inherent system inclinations for the GW and EM emission can bias the inference by   if not taken into account. As multimessenger BNS observations are rare, we must make the most out of a small number of events and harness the increased precision while avoiding a reduced accuracy. We demonstrate how to mitigate these potential sources of bias by jointly inferring the mismatch between the GW- and EM-based inclination angles and H 0.

Keywords: Cosmology, Relativistic jets, Hubble constant, Gravitational wave astronomy
[C II] Properties and Far-infrared Variability of a z = 7 Blazar. We present millimeter observations of the host galaxy of the most distant blazar known, VLASS J041009.05−013919.88 (hereafter J0410─0139) at z = 7, using Atacama Large Millimeter/submillimeter Array (ALMA) and NOrthern Extended Millimeter Array (NOEMA) observations. The ALMA data reveal a (2.02 ± 0.36) × 1042 erg s−1 [C II] 158 μm emission line at z = 6.9964 with a [C II]-inferred star formation rate (SFR) of 58 ± 9 M ⊙ yr−1. We estimate a dynamical mass of M dyn,[C II] = (4.6 ± 2.0) × 109 M ⊙, implying a black hole mass to host a dynamical mass ratio of  . The 238 GHz continuum (rest-frame IR) decreased by ∼33% from the NOEMA to the ALMA observations taken ∼10 months apart. The Very Large Array 3─10 GHz radio flux densities showed a ∼37% decrease in a similar time frame, suggesting a causal connection. At face value, J0410─0139 would have the lowest [C II]-to-IR luminosity ratio of a z &gt; 5.7 quasar reported to date (∼10−4). However, if only &lt;20% of the measured IR luminosity was due to thermal emission from dust, the [C II]-to-IR luminosity ratio would be typical of (U)LIRGs, and the SFRs derived from [C II] and IR luminosities would be consistent. These results provide further evidence that synchrotron emission significantly contributes to the observed rest-frame IR emission of J0410─0139, similar to what has been reported in some radio-loud active galactic nuclei at z &lt; 1.

Keywords: Radio loud quasars, Quasars
PDS 70b Shows Stellar-like Carbon-to-oxygen Ratio. The ~5 Myr PDS 70 is the only known system with protoplanets residing in the cavity of the circumstellar disk from which they formed, ideal for studying exoplanet formation and evolution within its natal environment. Here, we report the first spin constraint and C/O measurement of PDS 70b from Keck/KPIC high-resolution spectroscopy. We detected CO (3.8σ) and H2O (3.5σ) molecules in the PDS 70b atmosphere via cross correlation, with a combined CO and H2O template detection significance of 4.2σ. Our forward-model fits, using BT-Settl model grids, provide an upper limit for the spin rate of PDS 70b (&lt;29 km s‑1). The atmospheric retrievals constrain the PDS 70b C/O ratio to   (&lt;0.63 under 95% confidence level) and a metallicity [C/H] of   dex, consistent with that of its host star. The following scenarios can explain our measured C/O of PDS 70b in contrast with that of the gas-rich outer disk (for which C/O ≳ 1). First, the bulk composition of PDS 70b might be dominated by dust+ice aggregates rather than disk gas. Another possible explanation is that the disk became carbon enriched after PDS 70b was formed, as predicted in models of disk chemical evolution and as observed in both very low-mass stars and older disk systems with JWST/MIRI. Because PDS 70b continues to accrete and its chemical evolution is not yet complete, more sophisticated modeling of the planet and the disk, and higher-quality observations of PDS 70b (and possibly PDS 70c), are necessary to validate these scenarios.

Keywords: High resolution spectroscopy, Exoplanet formation, High angular resolution, Exoplanet atmospheres
The Newly Discovered Nova Super-remnant Surrounding Recurrent Nova T Coronae Borealis: Will it Light Up during the Coming Eruption?. A century or less separates the thermonuclear-powered eruptions of recurrent novae (RNe) in the hydrogen-rich envelopes of massive white dwarfs. The colliding ejecta of successive RN events are predicted to always generate very large (tens of parsecs) super-remnants; only two examples are currently known. T CrB offers an excellent opportunity to test this prediction. As it will almost certainly undergo its next, once in ∼80 yr RN event between 2024 and 2026, we carried out very deep narrowband and continuum imaging to search for the predicted, piled-up ejecta of the past millennia. While nothing is detected in continuum or narrowband [O III] images, a ∼30 pc diameter, faint nebulosity surrounding T CrB is clearly present in deep Hα, [N II], and [S II] narrowband Condor Array Telescope imagery. We predict that these newly detected nebulosities, as well as the recent ejecta that have not yet reached the super-remnant, are far too optically thin to capture all but a tiny fraction of the photons emitted by RN flashes. We thus predict that fluorescent light echoes will not be detectable following the imminent nova flash of T CrB. Dust may be released by the T CrB red giant wind in preeruption outbursts, but we have no reliable estimates of its quantity or geometrical distribution. While we cannot predict the morphology or intensity of dust-induced continuum light echoes following the coming flash, we encourage multiepoch Hubble Space Telescope optical imaging as well as James Webb Space Telescope infrared imaging of T CrB during the year after it erupts.

Keywords: Recurrent novae, Novae
Protosolar D-to-H Abundance and One Part per Billion PH<SUB>3</SUB> in the Coldest Brown Dwarf. The coldest Y spectral type brown dwarfs are similar in mass and temperature to cool and warm (∼200–400 K) giant exoplanets. We can therefore use their atmospheres as proxies for planetary atmospheres, testing our understanding of physics and chemistry for these complex, cool worlds. At these cold temperatures, their atmospheres are cold enough for water clouds to form, and chemical timescales increase, increasing the likelihood of disequilibrium chemistry compared to warmer classes of planets. JWST observations are revolutionizing the characterization of these worlds with high signal-to-noise, moderate-resolution near- and mid-infrared spectra. The spectra have been used to measure the abundances of prominent species, like water, methane, and ammonia; species that trace chemical reactions, like carbon monoxide; and even isotopologues of carbon monoxide and ammonia. Here, we present atmospheric retrieval results using both published fixed-slit (Guaranteed Time Observation program 1230) and new averaged time series observations (GO program 2327) of the coldest known Y dwarf, WISE 0855–0714 (using NIRSpec G395M spectra), which has an effective temperature of ∼264 K. We present a detection of deuterium in an atmosphere outside of the solar system via a relative measurement of deuterated methane (CH3D) and standard methane. From this, we infer the D/H ratio of a substellar object outside the solar system for the first time. We also present a well-constrained part-per-billion abundance of phosphine (PH3). We discuss our interpretation of these results and the implications for brown dwarf and giant exoplanet formation and evolution.

Keywords: Exoplanet atmospheric composition , Brown dwarfs, Planetary atmospheres, Y dwarfs, Exoplanet atmospheres
Constraining the Progenitor of the Nearby Type II-P SN 2024ggi with Environmental Analysis. The progenitors of Type II-P supernovae (SN) have been confirmed to be red supergiants. However, the upper mass limit of the directly probed progenitors is much lower than that predicted by current theories, and the accurate determination of the progenitor masses is key to understand the final fate of massive stars. Located at a distance of only 6.72 Mpc, the Type II-P SN 2024ggi is one of the closest SNe in the last decade. Previous studies have analyzed its progenitor by direct detection, but the derived progenitor mass may be influenced by the very uncertain circumstellar extinction and pulsational brightness variability. In this work, we try to constrain the progenitor mass with an environmental analysis based on images from the Hubble Space Telescope. We found that stars in the progenitor environment have a uniform spatial distribution without significant clumpiness, and we derived the star formation history of the environment with a hierarchical Bayesian method. The progenitor is associated with the youngest population in the SN environment with an age of log(t/yr) = 7.41 (i.e., 25.7 Myr), which corresponds to an initial mass of   M⊙. Our work provides an independent measurement of the progenitor mass, which is not affected by circumstellar extinction and pulsational brightness variability.

Keywords: Supernovae
Volatile-rich Sub-Neptunes as Hydrothermal Worlds: The Case of K2-18 b. Temperate exoplanets between the sizes of Earth and Neptune, known as "sub-Neptunes," have emerged as intriguing targets for astrobiology. It is unknown whether these planets resemble Earth-like terrestrial worlds with a habitable surface, Neptune-like giant planets with deep atmospheres and no habitable surface, or something exotic in between. Recent JWST transmission spectroscopy observations of the canonical sub-Neptune, K2-18 b, revealed ~1% CH4, ~1% CO2, and a nondetection of CO in the atmosphere. While previous studies proposed that the observed atmospheric composition could help constrain the lower atmosphere's conditions and determine the interior structure of sub-Neptunes like K2-18 b, the possible interactions between the atmosphere and a hot, supercritical water ocean at its base remain unexplored. In this work, we investigate whether a global supercritical water ocean, resembling a planetary-scale hydrothermal system, can explain these observations on K2-18 b─like sub-Neptunes through equilibrium aqueous geochemical calculations. We find that the observed atmospheric CH4/CO2 ratio implies a minimum ocean temperature of ~710 K, whereas the corresponding CO/CO2 ratio allows ocean temperatures up to ~1070 K. These results indicate that a global supercritical water ocean on K2-18 b is plausible. While life cannot survive in such an ocean, this work represents the first step toward understanding how a global supercritical water ocean may influence observable atmospheric characteristics on volatile-rich sub-Neptunes. Future observations with better-constrained CO and NH3 mixing ratios could further help distinguish between possible interior compositions of K2-18 b.

Keywords: Ocean planets, Exoplanets, Planetary atmospheres, James Webb Space Telescope, Astrobiology, Exoplanet surfaces, Extrasolar gaseous planets, Exoplanet atmospheres, Exoplanet atmospheric structure
The Classification and Formation Rate of Swift/BAT Gamma-Ray Bursts. Gamma-ray bursts (GRBs) are usually classified into long/short categories according to their durations, but controversy still exists in this aspect. Here we reexamine the long/short classification of GRBs and further compare the cosmological distribution and evolution of each potential subclass. A large number of Swift Burst Alert Telescope (BAT) GRBs are analyzed in this study. The Gaussian mixture model is used to fit the duration distribution as well as the joint distribution of duration and hardness ratio, and the Akaike and Bayesian information criteria are adopted to assess the goodness of fit. It is found that three Gaussian components can better fit both the univariate and bivariate distributions, indicating that there are three subclasses in the Swift/BAT GRBs, namely, short, intermediate, and long subclasses. The nonparametric Efron–Petrosian and Lynden-Bell's c‑ methods are used to derive the luminosity function and formation rate from the truncated data of bursts with known redshift in each subclass. It is found that the luminosity distributions and birth rates of the three subclasses are different, further supporting the existence of the intermediate subclass in the Swift/BAT GRBs.

Keywords: Luminosity function, Gamma-ray bursts, Classification, Astrostatistics, Star formation
The California Legacy Survey. IV. Lonely, Poor, and Eccentric: A Comparison between Solitary and Neighborly Gas Giants. We compare systems with single giant planets to systems with multiple giant planets using a catalog of planets from a high-precision radial velocity survey of FGKM stars. Our comparison focuses on orbital properties, planet masses, and host-star properties. We use hierarchical methods to model the orbital eccentricity distributions of giant singles and giant multiples, and find that the distributions are distinct. The multiple giant planets typically have moderate eccentricities and their eccentricity distribution extends to e = 0.47 (90th percentile), while the single giant planets have a pileup of nearly circular orbits and a long tail that extends to e = 0.77. We determine that the stellar hosts of multiple giants are distinctly more metal rich than the hosts of solitary giants, with respective mean metallicities of 0.228 ± 0.027 versus 0.129 ± 0.019 dex. We measure the distinct occurrence distributions of single and multiple giants with respect to orbital separation, and find that single gas giants have a ~2.3σ significant hot Jupiter (a &lt; 0.06) pileup not seen among multigiant systems. We find that the median mass ( $M\sin i$ ) of giants in multiples is nearly double that of single giants (1.71 M J versus 0.92 M J). We find that giant planets in the same system have correlated masses, analogous to the "peas in a pod" effect seen among less-massive planets.

Keywords: Exoplanets
Experimental Phase Function and Degree of Linear Polarization of Light Scattered by Hydrogenated Amorphous Carbon Circumstellar Dust Analogs. Astronomical observations of the polarized intensity of scattered visible light have revealed the presence of dust envelopes around different types of evolved stars. These observations have helped determine the diameter and width of dust shells around stars with unprecedented accuracy. Simple geometric particle models are used in order to retrieve dust properties from these observations. In this work, we have synthesized and characterized a particulate sample of hydrogenated amorphous carbon (HAC), which is considered to be a realistic carbonaceous interstellar dust analog based on infrared absorption spectroscopy, and we have measured its phase function and degree of linear polarization curves at 514 nm using the CODULAB apparatus at IAA-CSIC. The experimental light-scattering data has been examined in order to explore possible improvements in the interpretation of astronomical observations of circumstellar dust from the point of view of the retrieval of dust properties, including size and porosity. Our results suggest that circumstellar dust observations of linearly polarized scattered light, which are commonly attributed to a population of spherical grains with a radius of ∼0.1 μm, are consistent with larger porous aggregates composed of nanometer-sized grains. In addition, an internal 50wt% mixture of HAC and ultrafine forsterite powder has been generated to study the effect of the mixing of these two components on the light-scattering behavior of dust in cometary environments and protoplanetary disks. In this case, the HAC component, which is not very absorbent, has a very small effect, and the mixture scatters light similarly to the forsterite sample.

Keywords: Interstellar dust, Dust physics, Experimental data, Laboratory astrophysics, Astrophysical dust processes, Interstellar scattering, Dust shells, Circumstellar dust, Optical constants (Dust)
Calibration of the Timing Performance of GECAM-C. As a new member of the Gravitational-wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) after GECAM-A and GECAM-B, GECAM-C (originally called HEBS), which was launched on board the SATech-01 satellite on 2022 July 27, aims to monitor and localize X-ray and gamma-ray transients from ~6 keV to 6 MeV. GECAM-C utilizes a similar design to GECAM but operates in a more complex orbital environment. In this work, we utilize the secondary particles simultaneously produced by the cosmic-ray events on orbit and recorded by multiple detectors to calibrate the relative timing accuracy between all detectors of GECAM-C. We find the result is 0.1 μs, which is the highest time resolution among all GRB detectors ever flown and very helpful in timing analyses such as minimum variable timescale and spectral lags, as well as in time delay localization. Besides this, we calibrate the absolute time accuracy using the one-year Crab Pulsar data observed by GECAM-C and Fermi's Gamma-ray Burst Monitor, as well as GECAM-C and GECAM-B. The results are 2.02 ± 2.26 μs and 5.82 ± 3.59 μs, respectively. Finally, we investigate the spectral lag between the different energy bands of the Crab Pulsar observed by GECAM and the Gamma-ray Burst Monitor, which is ~ -0.2 μs keV-1.

Keywords: Astronomical instrumentation
Coronal Loop Detection Using Multiscale Convolutional Neural Networks. Solar magnetic fields play an important role in many solar activities, such as the solar wind, coronal mass ejections, and coronal oscillation. Coronal loops are curvilinear structures in the solar atmosphere and are closely related to coronal magnetic fields, so the study of their structure is very important. However, it is difficult to identify coronal loops accurately because of the complexity of their features. Therefore, we propose a two-stage detection method, using multiscale convolutional neural networks, to identify coronal loops. The regions including initial coronal loops are first marked by a improved Res-UNet model. The loop structures in the region are then detected using a improved dense extreme inception network for edge detection model. We selected the coronal images observed by the Transition and Coronal Explorer and the Atmospheric Imaging Assembly of the Solar Dynamics Observatory in the 171 Å channel to illustrate the detection processing. Meanwhile, we also compared the accuracy of our method to others. The results demonstrate that our proposed method has a high recognition rate and good robustness over previous identification methods and can be used to study the physical characteristics of coronal loops.

Keywords: Solar coronal loops
Stellar Neutrino Emission across the Mass-Metallicity Plane. We explore neutrino emission from nonrotating, single-star models across six initial metallicities and 70 initial masses from the zero-age main sequence to the final fate. Overall, across the mass spectrum, we find metal-poor stellar models tend to have denser, hotter, and more massive cores with lower envelope opacities, larger surface luminosities, and larger effective temperatures than their metal-rich counterparts. Across the mass-metallicity plane we identify the sequence (initial CNO → 14N → 22Ne → 25Mg → 26Al → 26Mg → 30P → 30Si) as making primary contributions to the neutrino luminosity at different phases of evolution. For the low-mass models we find neutrino emission from the nitrogen flash and thermal pulse phases of evolution depend strongly on the initial metallicity. For the high-mass models, neutrino emission at He-core ignition and He-shell burning depends strongly on the initial metallicity. Antineutrino emission during C, Ne, and O burning shows a strong metallicity dependence with 22Ne(α, n)25Mg providing much of the neutron excess available for inverse-β decays. We integrate the stellar tracks over an initial mass function and time to investigate the neutrino emission from a simple stellar population. We find average neutrino emission from simple stellar populations to be 0.5-1.2 MeV electron neutrinos. Lower metallicity stellar populations produce slightly larger neutrino luminosities and average β decay energies. This study can provide targets for neutrino detectors from individual stars and stellar populations. We provide convenient fitting formulae and open access to the photon and neutrino tracks for more sophisticated population synthesis models.

Keywords: High energy astrophysics, Neutrino astronomy, Stellar physics, Nuclear astrophysics, Stellar evolutionary tracks