adsabs/SciX_UAT_keywords huggingface dataset:
X-Ray Constraints on the Hot Gaseous Corona of Edge-on Late-type Galaxies in Virgo

We present a systematic study of the putative hot gas corona around late-type galaxies (LTGs) residing in the Virgo cluster, based on archival Chandra observations. Our sample consists of 21 nearly edge-on galaxies representing a range of star formation rate (SFR) of 0.2–3 M ⊙ yr‑1 and a range of stellar mass (M *) of (0.2–10) × 1010 M ⊙, the majority of which have not been explored with high-sensitivity X-ray observations so far. Significant extraplanar diffuse X-ray (0.5–2 keV) emission is detected in only three LTGs, which are also the three galaxies with the highest SFR. A stacking analysis is performed for the remaining galaxies without individual detection, dividing the whole sample into two subsets based on SFR, stellar mass, or specific SFR. Only the high-SFR bin yields a significant detection, which has a value of L X ∼ 3 × 1038 erg s‑1 per galaxy. The stacked extraplanar X-ray signals of the Virgo LTGs are consistent with the empirical L X–SFR and L X–M * relations found among highly inclined disk galaxies in the field, but appear to be systematically lower than those of a comparison sample of simulated star-forming galaxies in clusters identified from the Illustris-TNG100 simulation. The apparent paucity of hot gas coronae in the sampled Virgo LTGs might be understood as the net outcome of the long-lasting effect of ram pressure stripping exerted by the hot intracluster medium and in-disk star-forming activity acting on shorter timescales. A better understanding of the roles of environmental effects in regulating the hot gas content of cluster galaxies invites sensitive X-ray observations for a large sample of galaxies.

Keywords: virgo cluster; x-ray astronomy; late-type galaxies; disk galaxies; circumgalactic medium
Primordial Giant Planet Obliquity Driven by a Circumplanetary Disk

Detached circumplanetary disks are unstable to tilting as a result of the stellar tidal potential. We examine how a tilted circumplanetary disk affects the evolution of the spin axis of an oblate planet. The disk is evolved using time-dependent equations for linear wave-like warp evolution, including terms representing the effect of the tidal potential and planetary oblateness. For a disk with a sufficiently large mass, we find that the planet spin quickly aligns to the misaligned disk. The tilt of the planetary spin axis then increases on the same timescale as the disk. This can be an efficient mechanism for generating primordial obliquity in giant planets. We suggest that directly imaged exoplanets at large orbital radii, where the disk mass criterion is more likely to be satisfied, could have significant obliquities due to the tilt instability of their circumplanetary disks.

Keywords: exoplanet formation; planet formation; protoplanetary disks; planetary-disk interactions; star-planet interactions; exoplanet evolution; extrasolar gaseous giant planets; planetary alignment; planetary theory; solar system gas giant planets; hydrodynamics; pre-main sequence stars
PHANGS-JWST First Results: Duration of the Early Phase of Massive Star Formation in NGC 628

The earliest stages of star formation, when young stars are still deeply embedded in their natal clouds, represent a critical phase in the matter cycle between gas clouds and young stellar regions. Until now, the high-resolution infrared observations required for characterizing this heavily obscured phase (during which massive stars have formed, but optical emission is not detected) could only be obtained for a handful of the most nearby galaxies. One of the main hurdles has been the limited angular resolution of the Spitzer Space Telescope. With the revolutionary capabilities of the James Webb Space Telescope (JWST), it is now possible to investigate the matter cycle during the earliest phases of star formation as a function of the galactic environment. In this Letter, we demonstrate this by measuring the duration of the embedded phase of star formation and the implied time over which molecular clouds remain inert in the galaxy NGC 628 at a distance of 9.8 Mpc, demonstrating that the cosmic volume where this measurement can be made has increased by a factor of >100 compared to Spitzer. We show that young massive stars remain embedded for ${5.1}_{-1.4}^{+2.7}$ Myr ( ${2.3}_{-1.4}^{+2.7}$ Myr of which being heavily obscured), representing ~20% of the total cloud lifetime. These values are in broad agreement with previous measurements in five nearby (D < 3.5 Mpc) galaxies and constitute a proof of concept for the systematic characterization of the early phase of star formation across the nearby galaxy population with the PHANGS-JWST survey.

Keywords: star formation; galaxies; giant molecular clouds; interstellar medium
X-Ray Spectroscopy of the Highly Magnetized Pulsar PSR J1846-0258, Its Wind Nebula, and Hosting Supernova Remnant Kes 75

We present broadband X-ray spectroscopy of the energetic components that make up the supernova remnant (SNR) Kesteven 75 using concurrent 2017 August 17-20 XMM-Newton and NuSTAR observations, during which the pulsar PSR J1846-0258 is found to be in the quiescent state. The young remnant hosts a bright pulsar wind nebula powered by the highly energetic ( $\dot{E}=8.1\times {10}^{36}$ erg s-1) isolated, rotation-powered pulsar, with a spin-down age of only $P/2\dot{P}\sim 728\,\mathrm{yr}$ . Its inferred magnetic field (Bs = 4.9 × 1013 G) is the largest known for these objects, and is likely responsible for intervals of flare and burst activity, suggesting a transition between/to a magnetar state. The pulsed emission from PSR J1846-0258 is well-characterized in the 2-50 keV range by a power-law model with photon index ΓPSR = 1.24 ± 0.09 and a 2-10 keV unabsorbed flux of (2.3 ± 0.4) × 10-12 erg s-1 cm-2. We find no evidence for an additional non-thermal component above 10 keV in the current state, as would be typical for a magnetar. Compared to the Chandra pulsar spectrum, the intrinsic pulsed fraction is 71 ± 16% in 2-10 keV band. A power-law spectrum for the pulsar wind nebulae (PWN) yields ΓPWN = 2.03 ± 0.02 in the 1-55 keV band, with no evidence of curvature in this range, and a 2-10 keV unabsorbed flux (2.13 ± 0.02) × 10-11 erg s-1 cm-2. The NuSTAR data reveal evidence for a hard X-ray component dominating the SNR spectrum above 10 keV that we attribute to a dust-scattered PWN component. We model the dynamical and radiative evolution of the Kes 75 system to estimate the birth properties of the neutron star, the energetics of its progenitor, and properties of the PWN. This suggests that the progenitor of Kes 75 was originally in a binary system which transferred most of its mass to a companion before exploding.

Keywords: neutron stars; rotation powered pulsars; pulsars; magnetars; supernova remnants
Interstellar Polarization Survey. II. General Interstellar Medium

Magnetic fields permeate the entire Galaxy and are essential to, for example, the regulation of several stages of the star formation process and cosmic-ray transportation. Unraveling their properties, such as intensity and topology, is an observational challenge that requires combining different and complementary techniques. The polarization of starlight due to the absorption by field-aligned nonspherical dust grains provides a unique source of information about the interstellar magnetic field in the optical band. This work introduces a first analysis of a new catalog of optical observations of linearly polarized starlight in the diffuse interstellar medium (ISM), the Interstellar Polarization Survey-General ISM (IPS-GI). We used data from the IPS-GI, focusing on 38 fields sampling lines of sight in the diffuse medium. The fields are about 0.°3 × 0.°3 in size, and each of them contains ~1000 stars, on average. The IPS-GI catalog has polarimetric measurements of over 40,000 stars, over 18,000 of which have P/σ P > 5. We added distances and other parameters from auxiliary catalogs to over 36,000 of these stars. We analyzed parameter distributions and correlations between parameters of a high-quality subsample of 10,516 stars (i.e., ~275 stars per field). As expected, the degree of polarization tends to increase with the extinction, producing higher values of polarization at greater distances or lower absolute Galactic latitudes. Furthermore, we find evidence for a large-scale ordered Galactic magnetic field.

Keywords: optical astronomy; starlight polarization; interstellar medium; polarimetry; interstellar magnetic fields
Comparing the Counter-beaming and Temperature Anisotropy Driven Aperiodic Electron Firehose Instabilities in Collisionless Plasma Environments

The electron firehose instabilities are among the most studied kinetic instabilities, especially in the context of space plasmas, whose dynamics is mainly controlled by collisionless wave-particle interactions. This paper undertakes a comparative analysis of the aperiodic electron firehose instabilities excited either by the anisotropic temperature or by the electron counter-beaming populations. Two symmetric counter-beams provide an effective kinetic anisotropy similar to the temperature anisotropy of a single (nondrifting) population, with the temperature along the magnetic field direction larger than that in the perpendicular direction. Therefore, the counter-beaming plasma is susceptible to firehose-like instabilities (FIs), parallel and oblique branches. Here we focus on the oblique beaming FI, which is also aperiodic when the free energy is provided by symmetric counter-beams. Our results show that, for relative small drifts or beaming speeds (U), not exceeding the thermal speed (α), the aperiodic FIs exist in the same interval of wavenumbers and the same range of oblique angles (with respect to the magnetic field direction), but the growth rates of counter-beaming FI (CBFI) are always higher than those of temperature anisotropy FI (TAFI). For U/α > 1, however, another electrostatic two-stream instability is also predicted, which may have growth rates higher than those of CBFI, and may dominate in that case the dynamics.

Keywords: space plasmas; plasma astrophysics
Helium-rich Superluminous Supernovae from the Zwicky Transient Facility

Helium is expected to be present in the massive ejecta of some hydrogen-poor superluminous supernovae (SLSN-I). However, until now only one event has been identified with He features in its photospheric spectra (PTF10hgi). We present the discovery of a new He-rich SLSN-I, ZTF19aawfbtg (SN2019hge), at z = 0.0866. This event has more than 10 optical spectra at phases from -41 to +103 days relative to the peak, most of which match well with that of PTF10hgi. Confirmation comes from a near-IR spectrum taken at +34 days, revealing He I features with P-Cygni profiles at 1.083 and 2.058 μm. Using the optical spectra of PTF10hgi and SN2019hge as templates, we examined 70 other SLSNe-I discovered by Zwicky Transient Facility in the first two years of operation and found five additional SLSNe-I with distinct He-features. The excitation of He I atoms in normal core-collapse supernovae requires nonthermal radiation, as proposed by previous studies. These He-rich events cannot be explained by the traditional 56Ni mixing model because of their blue spectra, high peak luminosities, and long rise timescales. Magnetar models offer a possible solution since pulsar winds naturally generate high-energy particles, potential sources of nonthermal excitation. An alternative model is the interaction between the ejecta and dense H-poor circumstellar material, which may be supported by observed undulations in the light curves. These six SLSNe-Ib have relatively low-peak luminosities (rest frame Mg = -20.06 ± 0.16).

Keywords: supernovae; type ib supernovae
Limits on the Detection of Planet Nine in the Dark Energy Survey

Studies of the clustering of the most distant Kuiper Belt objects in the outer solar system have hinted at the possible existence of a planet beyond Neptune referred to as Planet Nine (P9). Recent efforts have constrained the parameter space of the orbital elements of P9, allowing for the creation of a synthetic catalog of hypothetical P9s. By examining the potential recovery of such a catalog within numerous sky surveys, it is possible to further constrain the parameter space for P9, providing direction for a more targeted search. We examine the ability of the full six years of the Dark Energy Survey (DES) to recover a synthetic Planet Nine population presented in Brown & Batygin. We find that out of 100,000 simulated objects, 11,709 cross the wide DES survey footprint of which 10,187 (87.0%) are recovered. This rules out an additional 5% of the parameter space after accounting for Planets Nine that would have been detected by both the Zwicky Transient Facility and DES.

Keywords: planetary science; solar system planets
Turbulence and Accretion: A High-resolution Study of the B5 Filaments

High-resolution observations of the Perseus B5 "core" have previously revealed that this subsonic region actually consists of several filaments that are likely in the process of forming a quadruple stellar system. Since subsonic filaments are thought to be produced at the ~0.1 pc sonic scale by turbulent compression, a detailed kinematic study is crucial to test such a scenario in the context of core and star formation. Here we present a detailed kinematic follow-up study of the B5 filaments at a 0.009 pc resolution using the VLA and GBT combined observations fitted with multicomponent spectral models. Using precisely identified filament spines, we find a remarkable resemblance between the averaged width profiles of each filament and Plummer-like functions, with filaments possessing FWHM widths of ~0.03 pc. The velocity dispersion profiles of the filaments also show decreasing trends toward the filament spines. Moreover, the velocity gradient field in B5 appears to be locally well ordered (~0.04 pc) but globally complex, with kinematic behaviors suggestive of inhomogeneous turbulent accretion onto filaments and longitudinal flows toward a local overdensity along one of the filaments.

Keywords: star formation; star forming regions; molecular clouds; interstellar filaments; dense interstellar clouds; interstellar clouds; interstellar line emission; interstellar medium
Effects of Planetesimal Scattering: Explaining the Observed Offsets from Period Ratios 3:2 and 2:1

The observed deficit and excess of adjacent planet pairs with period ratios narrow and wide of 3:2 and 2:1, the nominal values for the corresponding mean-motion resonances (MMRs), have intrigued many. Previously, using a suite of simulations, Chatterjee & Ford showed that the excess above the 2:1 MMR can be naturally explained if planet pairs, initially trapped in the 2:1 MMR, dynamically interact with nearby planetesimals in a disk. We build on this work by (a) updating the census of discovered planet pairs, (b) extending the study to initially nonresonant as well as resonant planet pairs, (c) using initial planet and orbital properties directly guided by those observed, and (d) extending the initial period ratios to include both 2:1 and 3:2. We find that (1) interactions with planetesimals typically increase the period ratios of both initially resonant and nonresonant planet pairs; (2) starting from an initially flat period ratio distribution for systems across 3:2 and 2:1, these interactions can naturally create the deficits observed narrow of these period ratios; (3) a contribution from initially resonant planet pairs is needed to explain the observed levels of excess wide of 3:2; and (4) a mixture model where about 25% (1%) of planet pairs were initially trapped into 3:2 (2:1) MMRs is favored to explain both the observed deficit and excess of systems across these period ratios. However, up to a few percent of planet pairs are expected to remain in MMR today.

Keywords: exoplanet dynamics; exoplanet migration; exoplanets; orbital resonances
Pure Spectroscopic Constraints on UV Luminosity Functions and Cosmic Star Formation History from 25 Galaxies at z spec = 8.61-13.20 Confirmed with JWST/NIRSpec

We present pure spectroscopic constraints on the UV luminosity functions and cosmic star formation rate (SFR) densities from 25 galaxies at z spec = 8.61-13.20. By reducing the JWST/NIRSpec spectra taken in multiple programs of Early Release Observation, Early Release Science, General Observer, and Director's Discretionary Time observations with our analysis technique, we independently confirm 16 galaxies at z spec = 8.61-11.40, including new redshift determinations, and a bright interloper at z spec = 4.91 that was claimed as a photometric candidate at z ~ 16. In conjunction with nine galaxies at redshifts up to z spec = 13.20 in the literature, we make a sample of 25 spectroscopically confirmed galaxies in total and carefully derive the best estimates and lower limits of the UV luminosity functions. These UV luminosity function constraints are consistent with the previous photometric estimates within the uncertainties and indicate mild redshift evolution toward z ~ 12, showing tensions with some theoretical models of rapid evolution. With these spectroscopic constraints, we obtain firm lower limits of the cosmic SFR densities and spectroscopically confirm a high SFR density at z ~ 12 beyond the constant star formation efficiency models, which supports earlier claims from the photometric studies. While there are no spectroscopically confirmed galaxies with very large stellar masses violating the ΛCDM model due to the removal of the bright interloper, we confirm star-forming galaxies at z spec = 11-13 with stellar masses much higher than model predictions. Our results indicate possibilities of high star formation efficiency (>5%), a hidden active galactic nucleus, a top-heavy initial mass function (possibly with Population III), and large scatter/variance. Having these successful and unsuccessful spectroscopy results, we suggest observational strategies for efficiently removing low-redshift interlopers for future JWST programs.

Keywords: galaxy evolution; galaxy formation; high-redshift galaxies
JWST Imaging of Edge-on Protoplanetary Disks. II. Appearance of Edge-on Disks with a Tilted Inner Region: Case Study of IRAS04302+2247

We present James Webb Space Telescope imaging from 2 to 21 μm of the edge-on protoplanetary disk around the embedded young star IRAS04302+2247. The structure of the source shows two reflection nebulae separated by a dark lane. The source extent is dominated by the extended filamentary envelope at ~4.4 μm and shorter wavelengths, transitioning at 7.7 μm and longer wavelengths to more compact lobes of scattered light from the disk itself. The dark lane thickness does not vary significantly with wavelength, which we interpret as an indication for intermediate-sized (~10 μm) grains in the upper layers of the disk. Intriguingly, we find that the brightest nebula of IRAS40302 switches side between 12.8 and 21 μm. We explore the effect of a tilted inner region on the general appearance of edge-on disks. We find that radiative transfer models of a disk including a tilted inner region can reproduce an inversion in the brightest nebula. In addition, for specific orientations, the model predicts strong lateral asymmetries, which can occur for more than half possible viewing azimuths. A large number of edge-on protoplanetary disks observed in scattered light show such lateral asymmetries (15/20), which suggests that a large fraction of protoplanetary disks might host a tilted inner region. Stellar spots may also induce lateral asymmetries, which are expected to vary over a significantly shorter timescale. Variability studies of edge-on disks would allow us to test the dominant scenario for the origin of these asymmetries.

Keywords: protoplanetary disks; planet formation; radiative transfer; dust continuum emission
The White Dwarf Mass versus X-Ray Temperature Relationship of Dwarf Novae, Revisited

Most methods used to determine the white dwarf mass in non-magnetic cataclysmic variables are subject to large systematic errors. X-ray spectroscopy has the potential to enable mass estimation with a good accuracy, when calibrated against accurate and reliable values. This is now possible thanks to the work of Pala et al., who estimated the white dwarf masses for 43 cataclysmic variables relying in part on Gaia distances. In this research note we provide a brief update on the X-ray temperature versus white dwarf mass relationship using the X-ray spectroscopy results of Byckling et al. compared against the results of Pala et al., thereby putting the X-ray spectroscopy method on a securer footing.

Keywords: cataclysmic variable stars
Follow-up Ground-based Observations of the Dwarf Nova KZ Gem

We present spectroscopy of stars in the immediate vicinity of the dwarf nova (DN) KZ Gem to confirm its identification, which is ambiguous in the literature. Analysis of 73 radial velocities spanning from 2014 to 2019 provides a high-precision orbital period of 0.2224628(2) days (∼5.34 hr) and shows KZ Gem to be a double-lined DN. Time series photometry taken from 2016 to 2018 shows a variable double-hump modulation with a full amplitude of ∼0.3 mag, along with five Gaussian-like transient events lasting ∼30 minutes or more. Using the light-curve code XRBinary and nonlinear fitting code NMfit, we obtain an optimized binary model of the dwarf nova (DN) KZ Gem, from time series photometry, consisting of a Roche-lobe-filling K-type dwarf with a mass transfer rate of (2.7-7.9) × 10-10 M⊙ yr-1 to a large, cool, and thick disk surrounding a white dwarf, in an orbit with an inclination of 51°6(±1°4). Two hotspots on the disk are demonstrated to cause the observed variations in the ellipsoidal modulations from the secondary star. This physical model is compatible with the Gaia distance of KZ Gem.

Keywords: close binary stars; interacting binary stars; semi-detached binary stars; cataclysmic variable stars; novae; dwarf novae
The Spectroscopic Follow-up of the QUBRICS Bright Quasar Survey

We present the results of the spectroscopic follow-up of the QUasars as BRIght beacons for Cosmology in the Southern Hemisphere (QUBRICS; Calderone et al. 2019) survey. The selection method is based on a machine-learning approach applied to photometric catalogs, covering an area of ∼12,400 deg2 in the Southern Hemisphere. The spectroscopic observations started in 2018 and identified 55 new, high-redshift (z ≥ 2.5), bright (i ≤ 18) quasi-stellar objects (QSOs), with the catalog published in late 2019. Here we report the current status of the survey, bringing the total number of bright QSOs at z ≥ 2.5 identified by QUBRICS to 224. The success rate of the QUBRICS selection method, in its most recent training, is estimated to be 68%. The predominant contaminant turns out to be lower-z QSOs at z < 2.5. This survey provides a unique sample of bright QSOs at high z available for a number of cosmological investigations. In particular, carrying out the redshift drift measurements (Sandage Test) in the Southern Hemisphere, using the High Resolution Spectrograph at the 39 m Extremely Large Telescope appears to be possible with less than 2500 hr of observations spread over 30 targets in 25 yr.

Keywords: cosmology; quasars; catalogs; redshift surveys; surveys; active galaxies