adsabs/SciX_UAT_keywords huggingface dataset:
Indefinitely Flat Circular Velocities and the Baryonic Tully–Fisher Relation from Weak Lensing

We use a new deprojection formula to infer the gravitational potential around isolated galaxies from weak gravitational lensing. The results imply circular velocity curves that remain flat for hundreds of kiloparsecs, greatly extending the classic result from 21 cm observations. Indeed, there is no clear hint of a decline out to 1 Mpc, well beyond the expected virial radii of dark matter halos. Binning the data by mass reveals a correlation with the flat circular speed that closely agrees with the baryonic Tully–Fisher relation known from kinematic data. These results apply to both early- and late-type galaxies, indicating a common universal behavior.

Keywords: scaling relations; galaxy rotation curves; weak gravitational lensing
Phase-modulated X-Ray Emission from Cepheids due to Pulsation-driven Shocks

Cepheids are pulsating variable stars with a periodic chromospheric response at UV wavelengths close to their minimum radius phase. Recently, an X-ray variable signature was captured in observations during the maximum radius phase. This X-ray emission came as a surprise and is not understood. In this work, we use the modern astrophysical code PLUTO to investigate the effects of pulsations on Cepheid X-ray emission. We run a number of hydrodynamic numerical simulations with a variety of initial and boundary conditions in order to explore the capability of shocks to produce the observed phase-dependent X-ray behavior. Finally, we use the Simulated Observations of X-ray Sources (SOXS) package to create synthetic spectra for each simulation case and link our simulations to observables. We show that, for certain conditions, we can reproduce observed X-ray fluxes at phases 0.4-0.8 when the Cepheid is at maximum radius. Our results span a wide range of mass-loss rates, 2 × 10-13 M⊙ yr-1 to 3 × 10-8 M⊙ yr-1, and peak X-ray luminosities, 5 × 10-17 erg cm-2 s-1 to 1.4 × 10-12 erg cm-2 s-1. We conclude that Cepheids exhibit two-component emission with (a) shock waves being responsible for the phase-dependent variable emission (phases 0.2-0.6) and (b) a separate quiescent mechanism being the dominant emission mechanism for the remaining phases.

Keywords: pulsating variable stars; delta cepheid variable stars; stellar flares; late-type stars; stellar atmospheres; stellar coronae; magnetohydrodynamical simulations; plasma astrophysics; high energy astrophysics; shocks; stellar physics
MINDS. The Detection of 13CO2 with JWST-MIRI Indicates Abundant CO2 in a Protoplanetary Disk

We present JWST-MIRI Medium Resolution Spectrometer (MRS) spectra of the protoplanetary disk around the low-mass T Tauri star GW Lup from the MIRI mid-INfrared Disk Survey Guaranteed Time Observations program. Emission from 12CO2, 13CO2, H2O, HCN, C2H2, and OH is identified with 13CO2 being detected for the first time in a protoplanetary disk. We characterize the chemical and physical conditions in the inner few astronomical units of the GW Lup disk using these molecules as probes. The spectral resolution of JWST-MIRI MRS paired with high signal-to-noise data is essential to identify these species and determine their column densities and temperatures. The Q branches of these molecules, including those of hot bands, are particularly sensitive to temperature and column density. We find that the 12CO2 emission in the GW Lup disk is coming from optically thick emission at a temperature of ~400 K. 13CO2 is optically thinner and based on a lower temperature of ~325 K, and thus may be tracing deeper into the disk and/or a larger emitting radius than 12CO2. The derived ${N}_{{\mathrm{CO}}_{2}}$ / ${N}_{{{\rm{H}}}_{2}{\rm{O}}}$ ratio is orders of magnitude higher than previously derived for GW Lup and other targets based on Spitzer-InfraRed-Spectrograph data. This high column density ratio may be due to an inner cavity with a radius in between the H2O and CO2 snowlines and/or an overall lower disk temperature. This paper demonstrates the unique ability of JWST to probe inner disk structures and chemistry through weak, previously unseen molecular features.

Keywords: protoplanetary disks; planet formation
Swift J0503.7-2819: a Short-period Asynchronous Polar or Stream-fed Intermediate Polar

We analyze a 7.4 hr XMM-Newton light curve of the cataclysmic variable Swift J0503.7-2819, previously classified using optical periods as an intermediate polar (IP) with an orbital period of 0.0567 days. A photometric signal at 975 s, previously suggested to be the spin period, is not present in X-rays and is readily understood as a quasiperiodic oscillation. The X-ray light curve instead shows clear behavior of a highly asynchronous polar or stream-fed IP. It can be described by either of two scenarios: one that switches between one-pole and two-pole accretion, and another in which accretion alternates fully between two poles. The spin periods in these two models are 0.0455 days and 0.0505 days, respectively. The spin frequency ω is thus either 24% faster or 12% faster than the orbital frequency Ω, and the corresponding beat period between spin and orbit is 0.231 days or 0.462 days. Brief absorption events seen in the light curve are spaced in a way that may favor the longer spin and beat periods. These periods are confirmed and refined using data from the Transiting Exoplanet Survey Satellite and the Asteroid Terrestrial-impact Last Alert System. The short beat cycle of Swift J0503.7-2819 makes it well-suited to resolving this common dilemma, which amounts to deciding whether the main signal in the power spectrum is ω or 2ω - Ω.

Keywords: cataclysmic variable stars; dq herculis stars; am herculis stars
Hydrogen Isotopic Composition of Hydrous Minerals in Asteroid Ryugu

Rock fragments of the Cb-type asteroid Ryugu returned to Earth by the JAXA Hayabusa2 mission share mineralogical, chemical, and isotopic properties with the Ivuna-type (CI) carbonaceous chondrites. Similar to CI chondrites, these fragments underwent extensive aqueous alteration and consist predominantly of hydrous minerals likely formed in the presence of liquid water on the Ryugu parent asteroid. Here we present an in situ analytical survey performed by secondary ion mass spectrometry from which we have estimated the D/H ratio of Ryugu's hydrous minerals, D/HRyugu, to be [165 ± 19] × 10-6, which corresponds to δDRyugu = +59 ± 121‰ (2σ). The hydrous mineral D/HRyugu's values for the two sampling sites on Ryugu are similar; they are also similar to the estimated D/H ratio of hydrous minerals in the CI chondrites Orgueil and Alais. This result reinforces a link between Ryugu and CI chondrites and an inference that Ryugu's samples, which avoided terrestrial contamination, are our best proxy to estimate the composition of water at the origin of hydrous minerals in CI-like material. Based on this data and recent literature studies, the contribution of CI chondrites to the hydrogen of Earth's surficial reservoirs is evaluated to be ~3%. We conclude that the water responsible for the alteration of Ryugu's rocks was derived from water ice precursors inherited from the interstellar medium; the ice partially re-equilibrated its hydrogen with the nebular H2 before being accreted on the Ryugu's parent asteroid.

Keywords: carbonaceous chondrites; earth (planet); asteroids; ice composition; solar system; small solar system bodies; planetary science; chondrites; meteorites; meteorite composition
Stringent Search for Precursor Emission in Short GRBs from Fermi/GBM Data and Physical Implications

We perform a stringent search for precursor emission of short gamma-ray bursts (SGRBs) from the Fermi/GBM data and find 16 precursor events with ≳4.5σ significance. We find that the durations of the main SGRB emission ( ${T}_{\mathrm{GRB}}$ ) and the precursor emission ( ${T}_{\mathrm{pre}}$ ), as well as the waiting time ( ${T}_{\mathrm{wt}}$ ) in between, are roughly comparable to each other, with ${T}_{\mathrm{wt}}$ ≈ 2.8 ${T}_{\mathrm{GRB}}$ 1.2 approximately satisfied for most cases except one significant outlier. We also perform spectral analyses to the precursors and SGRBs, and find that the spectra of precursor emission can be fitted with the blackbody, nonthermal cutoff power law and/or power-law models. We consider several possible models for precursor emission in SGRBs and find that the luminosity and spectral shape may be explained by the the shock breakout or the photospheric radiation of a fireball launched after the merger for thermal precursors, or magnetospheric interaction between two neutron stars prior to the merger for nonthermal precursors. For the fireball photospheric model, a matter-dominated jet is preferred and a constraint on the fireball Lorentz factor can be placed as Γ ∼ 30. For the magnetospheric interaction model, the jet launching mechanism may be constrained. In particular, those events with ${T}_{\mathrm{wt}}$ / ${T}_{\mathrm{GRB}}$ ≫ 1 (e.g., GRB191221802) require the formation of a supramassive or stable neutron star after the merger, with the delay time defined by the timescale for an initially baryon-loaded jet to become magnetically dominated and relativistic.

Keywords: gamma-ray bursts; neutron stars; gravitational waves; astrostatistics
Comparing Turbulent Cascades and Heating versus Spectral Anisotropy in Solar Wind via Direct Simulations

In a previous work (MGV18), we showed numerically that the turbulent cascade generated by quasi-2D structures (with wavevectors mostly perpendicular to the mean magnetic field) is able to generate a temperature profile close to the one observed in solar wind (≃1/R) in the range 0.2 ≤ R ≤ 1 au. Theory, observations, and numerical simulations point to another robust structure, the radial slab, with dominant wavevectors along the radial: we study here the efficiency of the radial-slab cascade in building the 1/R temperature profile. As in MGV18, we solve the three-dimensional magnetohydrodynamic equations including expansion to simulate the turbulent evolution. We find that an isotropic distribution of wavevectors with large cross-helicity at 0.2 au, along with a large wind expansion rate, lead again to a temperature decay rate close to 1/R but with a radial-slab anisotropy at 1 au. Surprisingly, the turbulent cascade concentrates in the plane transverse to the radial direction, displaying 1D spectra with scalings close to k-5/3 in this plane. This supports both the idea of turbulent heating of the solar wind, and the existence of two different turbulent cascades, associated to quasi-2D and radial-slab geometries. We conclude that sampling the radial spectrum in the solar wind may give poor information on the real cascade regime and rate when the radial slab is a non-negligible part of turbulence.

Keywords: magnetohydrodynamics; solar wind; heliosphere; interplanetary turbulence
Poking Holes: Looking for Gaps in LIGO/Virgo's Black Hole Population

Stellar evolution models predict the existence of a gap in the black hole mass spectrum from ∼55 M⊙-120 M⊙ due to pair-instability supernovae (PISNe). We investigate the possible existence of such an "upper" mass gap in the second gravitational-wave transient catalog (GWTC-2) by hierarchically modeling the astrophysical distribution of black hole masses. We extend the TRUNCATED and POWERLAW+PEAK mass distribution families to allow for an explicit gap in the mass distribution, and apply the extended models to GWTC-2. We find that with the TRUNCATED model there is mild evidence favoring an upper mass gap with log Bayes Factor $\mathrm{ln}{ \mathcal B }=2.79$ , inferring the lower and upper bounds at ${56.12}_{-4.38}^{+7.54}\,{M}_{\odot }$ and ${103.74}_{-6.32}^{+17.01}\,{M}_{\odot }$ respectively. When using the POWERLAW+PEAK model, we find no preference for the gap. When imposing tighter priors on the gap bounds centered on the expected PISNe gap bounds, the log Bayes factors in favor of a gap mildly increase. These results are however contingent on the parameter inference for the most massive binary, GW190521, for which follow-up analyses showed the source may be an intermediate mass ratio merger that has component masses straddling the gap. Using the GW190521 posterior samples from the analysis in Nitz & Capano (2021), we find an increase in Bayes factors in favor of the gap. However, the overall conclusions are unchanged: there is no preference for a gap when using the POWERLAW+PEAK model. This work paves the way for constraining the physics of pair-instability and pulsational pair-instability supernovae and high-mass black hole formation.

Keywords: gravitational wave astronomy; gravitational wave sources; gravitational waves; black holes; astrophysical black holes; stellar mass black holes; supernova remnants
Black Hole–Halo Mass Relation from UNIONS Weak Lensing

This Letter presents, for the first time, direct constraints on the black hole–halo mass relation using weak gravitational-lensing measurements. We construct type I and type II active galactic nucleus (AGN) samples from the Sloan Digital Sky Survey, with a mean redshift of 0.4 (0.1) for type I (type II) AGNs. This sample is cross correlated with weak-lensing shear from the Ultraviolet Near Infrared Optical Northern Survey. We compute the excess surface mass density of the halos associated with 36,181 AGNs from 94,308,561 lensed galaxies and fit the halo mass in bins of black hole mass. We find that more massive AGNs reside in more massive halos. The relation between halo mass and black hole mass is well described by a power law of slope 0.6 for both type I and type II samples, in agreement with models that link black hole growth to baryon feedback. We see no dependence on AGN type or redshift in the black hole–halo mass relation below a black hole mass of 108.5 M ⊙. Above that mass, we find more massive halos for the low-z type II sample compared to the high-z type I sample, but this difference may be interpreted as systematic error in the black hole mass measurements. Our results are consistent with previous measurements for non-AGN galaxies. At a fixed black hole mass, our weak-lensing halo masses are consistent with galaxy rotation curves but significantly lower than galaxy-clustering measurements. Finally, our results are broadly consistent with state-of-the-art hydrodynamical cosmological simulations, providing a new constraint for black hole masses in simulations.

Keywords: galaxy dark matter halos; gravitational lensing; active galactic nuclei; supermassive black holes; galaxies
BASS. XXIX. The Near-infrared View of the Broad-line Region (BLR): The Effects of Obscuration in BLR Characterization

Virial black hole (BH) mass (M BH) determination directly involves knowing the broad-line region (BLR) clouds' velocity distribution, their distance from the central supermassive BH (R BLR), and the virial factor (f). Understanding whether biases arise in M BH estimation with increasing obscuration is possible only by studying a large (N > 100) statistical sample of obscuration-unbiased (hard) X-ray-selected active galactic nuclei (AGNs) in the rest-frame near-infrared (0.8–2.5 μm) since it penetrates deeper into the BLR than the optical. We present a detailed analysis of 65 local Burst Alert Telescope (BAT) selected Seyfert galaxies observed with Magellan/FIRE. Adding these to the near-infrared BAT AGN spectroscopic survey database, we study a total of 314 unique near-infrared spectra. While the FWHMs of Hα and near-infrared broad lines (He I, Paβ, Paα) remain unbiased to either BLR extinction or X-ray obscuration, the Hα broad-line luminosity is suppressed when N H ≳ 1021 cm‑2, systematically underestimating M BH by 0.23–0.46 dex. Near-infrared line luminosities should be preferred to Hα until N H < 1022 cm‑2, while at higher obscuration a less-biased R BLR proxy should be adopted. We estimate f for Seyfert 1 and 2 using two obscuration-unbiased M BH measurements, i.e., the stellar velocity dispersion and a BH mass prescription based on near-infrared and X-ray, and find that the virial factors do not depend on the redshift or obscuration, but some broad lines show a mild anticorrelation with M BH. Our results show the critical impact obscuration can have on BLR characterization and the importance of the near-infrared and X-rays for a less-biased view of the BLR. *This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Keywords: active galactic nuclei; high energy astrophysics; x-ray active galactic nuclei; active galaxies
On the Fate of Slow Boulders Ejected after DART Impact on Dimorphos

On 2022 September 26 23:14 UT, the NASA Double Asteroid Redirection Test spacecraft successfully impacted Dimorphos, the secondary component of the binary (65803) Didymos system, demonstrating asteroid orbit deflection for the first time. A large amount of debris, consisting of a wide size–frequency distribution of particulates (from micron-sized dust to meter-sized boulders), was released, and a long-lasting tail has been observed over more than 9 months since impact. An important fraction of the ejecta mass has been ejected as individual meter-sized boulders, as have been found in images obtained by the Light Italian CubeSat for Imaging of Asteroid (LICIACube), as well as from the Hubble Space Telescope (HST). While the boulders observed by LICIACube had projected speeds of several tens of m s–1, those seen by the HST were about 100 times slower. In this paper, we analyze the long-term orbital evolution of those slow boulders using different dynamical codes, providing constraints on the fate of such large particles, and giving insight on the possibility of observing some of those boulders that might remain in orbit at the time of the ESA/Hera mission arrival to the binary system in late 2026.

Keywords: asteroid dynamics
Empirical Assessment of Aperiodic and Periodic Radio Bursts from Young Precessing Magnetars

We analyze the slow periodicities identified in burst sequences from FRB 121102 and FRB 180916 with periods of about 16 and 160 days, respectively, while also addressing the absence of any fast periodicity that might be associated with the spin of an underlying compact object. Both phenomena can be accounted for by a young, highly magnetized, precessing neutron star that emits beamed radiation with significant imposed phase jitter. Sporadic narrow-beam emission into an overall wide solid angle can account for the necessary phase jitter, but the slow periodicities with 25%-55% duty cycles constrain beam traversals to be significantly smaller. Instead, phase jitter may result from variable emission altitudes that yield large retardation and aberration delays. A detailed arrival time analysis for triaxial precession includes wobble of the radio beam and the likely larger, cyclical torque resulting from the changes in the spin-magnetic moment angle. These effects will confound identification of the fast periodicity in sparse data sets longer than about a quarter of a precession cycle unless fitted for and removed as with orbital fitting. Stochastic spin noise, likely to be much larger than in radio pulsars, may hinder detection of any fast periodicity in data spans longer than a few days. These decoherence effects will dissipate as sources of fast radio bursts age, so they may evolve into objects with properties similar to Galactic magnetars.

Keywords: neutron stars; magnetars; pulsars; pulsar timing method; red noise; time series analysis
Structural Parameters and Possible Association of the Ultra-faint Dwarfs Pegasus III and Pisces II from Deep Hubble Space Telescope Photometry

We present deep Hubble Space Telescope (HST) photometry of the ultra-faint dwarf (UFD) galaxies Pegasus III (Peg III) and Pisces II (Psc II), two of the most distant satellites in the halo of the Milky Way (MW). We measure the structure of both galaxies, derive mass-to-light ratios with newly determined absolute magnitudes, and compare our findings to expectations from UFD-mass simulations. For Peg III, we find an elliptical half-light radius of ${a}_{h}=1\buildrel{\,\prime}\over{.} {88}_{-0.33}^{+0.42}$ ( ${118}_{-30}^{+31}$ pc) and ${M}_{V}=-{4.17}_{-0.22}^{+0.19};$ for Psc II, we measure ${a}_{h}=1\buildrel{\,\prime}\over{.} {31}_{-0.09}^{+0.10}$ (69 ± 8 pc) and ${M}_{V}=-{4.28}_{-0.16}^{+0.19}$ . We do not find any morphological features that indicate a significant interaction between the two has occurred, despite their close separation of only ~40 kpc. Using proper motions (PMs) from Gaia early Data Release 3, we investigate the possibility of any past association by integrating orbits for the two UFDs in an MW-only and a combined MW and Large Magellanic Cloud (LMC) potential. We find that including the gravitational influence of the LMC is crucial, even for these outer-halo satellites, and that a possible orbital history exists where Peg III and Psc II experienced a close (~10-20 kpc) passage about each other just over ~1 Gyr ago, followed by a collective passage around the LMC (~30-60 kpc) just under ~1 Gyr ago. Considering the large uncertainties on the PMs and the restrictive priors imposed to derive them, improved PM measurements for Peg III and Psc II will be necessary to clarify their relationship. This would add to the rare findings of confirmed pairs of satellites within the Local Group.

Keywords: dwarf galaxies; local group; galaxy structure
CO Excitation, Molecular Gas Density, and Interstellar Radiation Field in Local and High-redshift Galaxies

We study the carbon monoxide (CO) excitation, mean molecular gas density, and interstellar radiation field (ISRF) intensity in a comprehensive sample of 76 galaxies from local to high redshift (z ∼ 0-6), selected based on detections of their CO transitions J = 2 → 1 and 5 → 4 and their optical/infrared/(sub)millimeter spectral energy distributions (SEDs). We confirm the existence of a tight correlation between CO excitation as traced by the CO (5-4)/(2-1) line ratio R52 and the mean ISRF intensity $\left\langle U\right\rangle $ as derived from infrared SED fitting using dust SED templates. By modeling the molecular gas density probability distribution function (PDF) in galaxies and predicting CO line ratios with large velocity gradient radiative transfer calculations, we present a framework linking global CO line ratios to the mean molecular hydrogen gas density $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $ and kinetic temperature Tkin. Mapping in this way observed R52 ratios to $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $ and Tkin probability distributions, we obtain positive $\left\langle U\right\rangle $ - $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $ and $\left\langle U\right\rangle $ -Tkin correlations, which imply a scenario in which the ISRF in galaxies is mainly regulated by Tkin and (nonlinearly) by $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $ . A small fraction of starburst galaxies showing enhanced $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $ could be due to merger-driven compaction. Our work demonstrates that ISRF and CO excitation are tightly coupled and that density-PDF modeling is a promising tool for probing detailed ISM properties inside galaxies.

Keywords: interstellar medium; star formation; molecular gas; starburst galaxies; spiral galaxies