adsabs/SciX_UAT_keywords huggingface dataset:
Performance of NIRCam on JWST in Flight

The Near Infrared Camera for the James Webb Space Telescope (JWST) is delivering the imagery that astronomers have hoped for ever since JWST was proposed back in the 1990s. In the Commissioning Period that extended from right after launch to early 2022 July, NIRCam has been subjected to a number of performance tests and operational checks. The camera is exceeding prelaunch expectations in virtually all areas, with very few surprises discovered in flight. NIRCam also delivered the imagery needed by the Wavefront Sensing Team for use in aligning the telescope mirror segments.

Keywords: infrared telescopes; space observatories; space telescopes
An XMM-Newton EPIC X-Ray View of the Symbiotic Star R Aquarii

We present the analysis of archival XMM-Newton European Photon Imaging Camera (EPIC) X-ray observations of the symbiotic star R Aquarii. We used the Extended Source Analysis Software package to disclose diffuse soft X-ray emission extending up to 2.'2 (≈0.27 pc) from this binary system. The depth of these XMM-Newton EPIC observations reveals in unprecedented detail the spatial distribution of this diffuse emission, with a bipolar morphology spatially correlated with the optical nebula. The extended X-ray emission shares the same dominant soft X-ray-emitting temperature as the clumps in the jet-like feature resolved by Chandra in the vicinity of the binary system. The harder component in the jet might suggest that the gas cools down; however, the possible presence of nonthermal emission produced by the presence of a magnetic field collimating the mass ejection cannot be discarded. We propose that the ongoing precessing jet creates bipolar cavities filled with X-ray-emitting hot gas that feeds the more extended X-ray bubble as they get disrupted. These EPIC observations demonstrate that the jet feedback mechanism produced by an accreting disk around an evolved, low-mass star can blow hot bubbles, similar to those produced by jets arising from the nuclei of active galaxies.

Keywords: symbiotic binary stars; stellar jets; stellar winds; x-ray sources
H-alpha and Ca II Infrared Triplet Variations During a Transit of the 23 Myr Planet V1298 Tau c

Young transiting exoplanets (<100 Myr) provide crucial insight into atmospheric evolution via photoevaporation. However, transmission spectroscopy measurements to determine atmospheric composition and mass loss are challenging due to the activity and prominent stellar disk inhomogeneities present on young stars. We observed a full transit of V1298 Tau c, a 23 Myr, 5.59 R⊕ planet orbiting a young K0-K1.5 solar analog with GRACES on Gemini North. We were able to measure the Doppler tomographic signal of V1298 Tau c using the Ca II infrared triplet (IRT) and find a projected obliquity of λ = 5° ± 15°. The tomographic signal is only seen in the chromospherically driven core of the Ca II IRT, which may be the result of star-planet interactions. Additionally, we find that excess absorption of the Hα line decreases smoothly during the transit. While this could be a tentative detection of hot gas escaping the planet, we find this variation is consistent with similar timescale observations of other young stars that lack transiting planets over similar timescales. We show this variation can also be explained by the presence of starspots with surrounding facular regions. More observations both in and out of the transits of V1298 Tau c are required to determine the nature of the Ca II IRT and Hα line variations.

Keywords: exoplanet astronomy; exoplanet atmospheres; transmission spectroscopy; stellar activity
Energetic Neutral Atoms Detected in the 2022 February 15 Solar Energetic Particle Event

Energetic neutral atoms (ENAs) are expected to be produced near the Sun during large solar energetic particle (SEP) events. However, their detection by SEP instruments near 1 au has been limited. The clearest reported measurement has been from the Solar Terrestrial Relations Observatory (STEREO) during the 2006 December 5 SEP event. Additional evidence of ENAs has been found through reanalysis of observations by the Solar Anomalous and Magnetospheric Particle Explorer obtained near the equator in low Earth orbit and associated with several large X-ray flares and fast coronal mass ejections (CMEs). Here we describe another detection of ENAs from the STEREO Low Energy Telescope associated with the large 2022 February 15 SEP event. Given the timing and spectrum of the ENAs and the location of the source region (behind the east limb from STEREO's viewpoint), these ENAs are most likely a result of acceleration by a CME-driven shock when the CME was at approximately 2–3 R S. The possibility of a postflare loop origin is considered unlikely.

Keywords: solar energetic particles; solar activity; solar coronal mass ejections
TESS Hunt for Young and Maturing Exoplanets (THYME). IV. Three Small Planets Orbiting a 120 Myr Old Star in the Pisces-Eridanus Stream

Young exoplanets can offer insight into the evolution of planetary atmospheres, compositions, and architectures. We present the discovery of the young planetary system TOI 451 (TIC 257605131, Gaia DR2 4844691297067063424). TOI 451 is a member of the 120 Myr old Pisces-Eridanus stream (Psc-Eri). We confirm membership in the stream with its kinematics, its lithium abundance, and the rotation and UV excesses of both TOI 451 and its wide-binary companion, TOI 451 B (itself likely an M-dwarf binary). We identified three candidate planets transiting in the Transiting Exoplanet Survey Satellite data and followed up the signals with photometry from Spitzer and ground-based telescopes. The system comprises three validated planets at periods of 1.9, 9.2, and 16 days, with radii of 1.9, 3.1, and 4.1 R⨂, respectively. The host star is near-solar mass with V = 11.0 and H = 9.3 and displays an infrared excess indicative of a debris disk. The planets offer excellent prospects for transmission spectroscopy with the Hubble Space Telescope and the James Webb Space Telescope, providing the opportunity to study planetary atmospheres that may still be in the process of evolving. * Sometimes called Meingast-1.

Keywords: exoplanet astronomy; exoplanet evolution; exoplanet systems; young star clusters; stellar activity
Reevaluating LSST's Capability for Time Delay Measurements in Quasar Accretion Disks

The Legacy Survey of Space and Time at the Vera C. Rubin Observatory is poised to observe thousands of quasars using the Deep Drilling Fields (DDF) across six broadband filters over a decade. Understanding quasar accretion disk (AD) time delays is pivotal for probing the physics of these distant objects. Pozo Nuñez et al. has recently demonstrated the feasibility of recovering AD time delays with accuracies ranging from 5% to 20%, depending on the quasar's redshift and time sampling intervals. Here we reassess the potential for measuring AD time delays under the current DDF observing cadence, which is placeholder until a final cadence is decided. We find that contrary to prior expectations, achieving reliable AD time delay measurements for quasars is significantly more challenging, if not unfeasible, due to the limitations imposed by the current observational strategies.

Keywords: extragalactic astronomy; quasars; astrophysical black holes
APOGEE Net: An Expanded Spectral Model of Both Low-mass and High-mass Stars

We train a convolutional neural network, APOGEE Net, to predict T eff, $\mathrm{log}g$ , and, for some stars, [Fe/H], based on the APOGEE spectra. This is the first pipeline adapted for these data that is capable of estimating these parameters in a self-consistent manner not only for low-mass stars, (such as main-sequence dwarfs, pre-main-sequence stars, and red giants), but also high-mass stars with T eff in excess of 50,000 K, including hot dwarfs and blue supergiants. The catalog of ~650,000 stars presented in this paper allows for a detailed investigation of the star-forming history of not just the Milky Way, but also of the Magellanic clouds, as different type of objects tracing different parts of these galaxies can be more cleanly selected through their distinct placement in T eff- $\mathrm{log}g$ parameter space than in previous APOGEE catalogs produced through different pipelines.

Keywords: astroinformatics; computational methods; stellar classification; massive stars; magellanic clouds; young stellar objects
Long-term Evolution of Supercritical Black Hole Accretion with Outflows: A Subgrid Feedback Model for Cosmological Simulations

We study the long-term evolution of the global structure of axisymmetric accretion flows onto a black hole (BH) at rates substantially higher than the Eddington value ( ${\dot{M}}_{\mathrm{Edd}}$ ), performing 2D hydrodynamical simulations with and without radiative diffusion. In the high-accretion optically thick limit, where the radiation energy is efficiently trapped within the inflow, the accretion flow becomes adiabatic and comprises turbulent gas in the equatorial region and strong bipolar outflows. As a result, the mass inflow rate decreases toward the center as ${\dot{M}}_{\mathrm{in}}\propto {r}^{p}$ with p ~ 0.5-0.7 and a small fraction of the inflowing gas feeds the nuclear BH. Thus, super-Eddington accretion is sustained only when a larger amount of gas is supplied from larger radii at ≳100-1000 $\,{\dot{M}}_{\mathrm{Edd}}$ . The global structure of the flow settles down to a quasi-steady state in millions of the orbital timescale at the BH event horizon, which is ≳10-100 times longer than that addressed in previous (magneto-)RHD simulation studies. Energy transport via radiative diffusion accelerates the outflow near the poles in the inner region but does not change the overall properties of the accretion flow compared to the cases without diffusion. Based on our simulation results, we provide a mechanical feedback model for super-Eddington accreting BHs. This can be applied as a subgrid model in large-scale cosmological simulations that do not sufficiently resolve galactic nuclei, and to the formation of the heaviest gravitational-wave sources via accretion in dense environments.

Keywords: supermassive black holes; quasars; high-redshift galaxies
Change of Rotation Measure during the Eclipse of a Black Widow PSR J2051-0827

Black widows are millisecond pulsars ablating their companions. The material blown from the companion blocks the radio emission, resulting in radio eclipses. The properties of the eclipse medium are poorly understood. Here, we present direct evidence of the existence of magnetic fields in the eclipse medium of the black widow PSR J2051-0827 using observations made with the Five-hundred-meter Aperture Spherical radio Telescope. We detect a regular decrease in rotation measure (RM) in the egress of the eclipse, changing from 60 to -28.7 rad m-2. The RM gradually changes back to normal when the line of sight moves away from the eclipse. The estimated line-of-sight magnetic field strength in the eclipse medium is ~0.1 G. The RM reversal could be caused by a change in the magnetic field strength along the line of sight due to binary orbital motion. The RM reversal phenomenon has also been observed in some repeating fast radio bursts (FRBs), and the study of spider pulsars may provide additional information about the origin of FRBs.

Keywords: radio pulsars; millisecond pulsars; eclipsing binary stars
The HST See Change Program. I. Survey Design, Pipeline, and Supernova Discoveries

The See Change survey was designed to make z > 1 cosmological measurements by efficiently discovering high-redshift Type Ia supernovae (SNe Ia) and improving cluster mass measurements through weak lensing. This survey observed twelve galaxy clusters with the Hubble Space Telescope (HST) spanning the redshift range z = 1.13-1.75, discovering 57 likely transients and 27 likely SNe Ia at z ∼ 0.8-2.3. As in similar previous surveys, this proved to be a highly efficient use of HST for supernova observations; the See Change survey additionally tested the feasibility of maintaining, or further increasing, the efficiency at yet higher redshifts, where we have less detailed information on the expected cluster masses and star formation rates. We find that the resulting number of SNe Ia per orbit is a factor of ∼8 higher than for a field search, and 45% of our orbits contained an active SN Ia within 22 rest-frame days of peak, with one of the clusters by itself yielding 6 of the SNe Ia. We present the survey design, pipeline, and supernova discoveries. Novel features include fully blinded supernova searches, the first random forest candidate classifier for undersampled IR data (with a 50% detection threshold within 0.05 mag of human searchers), real-time forward-modeling photometry of candidates, and semi-automated photometric classifications and follow-up forecasts. We also describe the spectroscopic follow-up, instrumental in measuring host galaxy redshifts. The cosmology analysis of our sample will be presented in a companion paper. * Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555, under programs 13677, 14327.

Keywords: observational cosmology; type ia supernovae
CGM2 + CASBaH: The Mass Dependence of H I Lyα-Galaxy Clustering and the Extent of the CGM

We combine data sets from the CGM2 and CASBaH surveys to model a transition point, R cross, between circumgalactic and intergalactic media (CGM and IGM, respectively). In total, our data consist of 7244 galaxies at z < 0.5 with precisely measured spectroscopic redshifts, all having impact parameters of 0.01-20 comoving Mpc from 28 QSO sightlines with high-resolution UV spectra that cover H I Lyα. Our best-fitting model is a two-component model that combines a 3D absorber-galaxy cross-correlation function with a simple Gaussian profile at inner radii to represent the CGM. By design, this model gives rise to a determination of R cross as a function of galaxy stellar mass, which can be interpreted as the boundary between the CGM and IGM. For galaxies with 108 ≤ M ⋆/M ⊙ ≤ 1010.5, we find that R cross(M ⋆) ≈ 2.0 ± 0.6R vir. Additionally, we find excellent agreement between R cross(M ⋆) and the theoretically determined splashback radius for galaxies in this mass range. Overall, our results favor models of galaxy evolution at z < 0.5 that distribute T ≈ 104K gas to distances beyond the virial radius.

Keywords: galaxy evolution; circumgalactic medium; surveys; quasar absorption line spectroscopy; galactic and extragalactic astronomy; galaxies; galaxy photometry; galaxy spectroscopy; astronomy data modeling; astronomical models; bayesian statistics
Combining Transit and Radial Velocity: A Synthesized Population Model

We present a framework for estimating exoplanet occurrence rates by synthesizing constraints from radial velocity and transit surveys simultaneously. We employ approximate Bayesian computation and various mass-radius (M-R) relations to explore the population models describing these surveys, both separately and in a joint fit. Using this approach, we fit a planet distribution function of the form ${d}^{2}N/d\mathrm{log}{Pd}\mathrm{log}M\propto {P}^{\beta }{M}^{\alpha }$ , with a break in the power law in mass at Mb, to planets orbiting FGK stars with periods $P=[25,200]$ days and masses $M=[2,50]{M}_{\oplus }$ . We find that the M-R relation from Otegi et al. (2020), which lets rocky and volatile-rich populations overlap in mass, allows us to find a model that is consistent with both types of surveys. Our joint fit gives ${M}_{b}={21.6}_{-3.2}^{+2.5}{M}_{\oplus }$ (errors reflect 68.3% credible interval). This is nearly a factor of three higher than the break from transit-only considerations and an M-R relation without such an overlap. The corresponding planet-star mass ratio break ${q}_{b}\sim 7\times {10}^{-5}$ may be consistent with microlensing studies ( ${q}_{b}\sim 6\times {10}^{-5}-2\times {10}^{-4}$ ). The joint fit also requires that a fraction of ${F}_{\mathrm{rocky}}={0.63}_{-0.04}^{+0.04}$ planets in the overlap region belong to the rocky population. Our results strongly suggest that future M-R relations should account for a mixture of distinct types of planets in order to describe the observed planet population.

Keywords: exoplanet astronomy; exoplanet catalogs; exoplanet detection methods; exoplanets; radial velocity; transit photometry; bayesian statistics
The Space Density of Intermediate-redshift, Extremely Compact, Massive Starburst Galaxies

We present a measurement of the intrinsic space density of intermediate-redshift (z ~ 0.5), massive (M * ~ 1011 M ⊙), compact (R e ~ 100 pc) starburst (ΣSFR ~ 1000 M ⊙ yr-1 kpc-1) galaxies with tidal features indicative of them having undergone recent major mergers. A subset of them host kiloparsec-scale, > 1000 km s-1 outflows and have little indication of AGN activity, suggesting that extreme star formation can be a primary driver of large-scale feedback. The aim for this paper is to calculate their space density so we can place them in a better cosmological context. We do this by empirically modeling the stellar populations of massive, compact starburst galaxies. We determine the average timescale on which galaxies that have recently undergone an extreme nuclear starburst would be targeted and included in our spectroscopically selected sample. We find that massive, compact starburst galaxies targeted by our criteria would be selectable for $\sim {148}_{-24}^{+27}$ Myr and have an intrinsic space density ${n}_{\mathrm{CS}}\sim ({1.1}_{-0.3}^{+0.5})\times {10}^{-6}\,{\mathrm{Mpc}}^{-3}$ . This space density is broadly consistent with our z ~ 0.5 compact starbursts being the most extremely compact and star-forming low-redshift analogs of the compact star-forming galaxies in the early universe, as well as them being the progenitors to a fraction of intermediate-redshift, post-starburst, and compact quiescent galaxies.

Keywords: compact galaxies; starburst galaxies; post-starburst galaxies; galaxy evolution
Enhanced Subkiloparsec-scale Star Formation: Results from a JWST Size Analysis of 341 Galaxies at 5 < z < 14

We present a comprehensive search and analysis of high-redshift galaxies in a suite of nine public JWST extragalactic fields taken in Cycle 1, covering a total effective search area of $\sim 358\,{\mathrm{arcmin}}^{2}$ . Through conservative (8σ) photometric selection, we identify 341 galaxies at 5 < z < 14, with 109 having spectroscopic redshift measurements from the literature, including recent JWST NIRSpec observations. Our regression analysis reveals that the rest-frame UV size–stellar mass relation follows ${R}_{\mathrm{eff}}\propto {M}_{* }^{0.19\pm 0.03}$ , similar to that of star-forming galaxies at z ∼ 3, but scaled down in size by ∼0.7 dex. We find a much slower rate for the average size evolution over the redshift range, R eff ∝ (1 + z)‑0.4±0.2, than that derived in the literature. A fraction (∼13%) of our sample galaxies are marginally resolved even in the NIRCam imaging (≲100 pc), located at ≳1.5σ below the derived size–mass slope. These compact sources exhibit a high star formation surface density ΣSFR > 10 M ⊙ yr‑1 kpc‑2, a range in which only <0.01% of the local star-forming galaxy sample is found. For those with available NIRSpec data, no evidence of ongoing supermassive black hole accretion is observed. A potential explanation for the observed high [O III]-to-Hβ ratios could be high shock velocities, likely originating within intense star-forming regions characterized by high ΣSFR. Lastly, we find that the rest-frame UV and optical sizes of our sample are comparable. Our results are consistent with these early galaxies building up their structures inside out and being yet to exhibit the strong color gradient seen at lower redshift.

Keywords: galaxy structure; high-redshift galaxies; star formation
High-harmonic Plasma Emission Induced by Electron Beams in Weakly Magnetized Plasmas

Electromagnetic radiation at higher harmonics of the plasma frequency (ω ~ n ω pe, n > 2) has been occasionally observed in type II and type III solar radio bursts, yet the underlying mechanism remains undetermined. Here we present two-dimensional fully kinetic electromagnetic particle-in-cell simulations with high spectral resolution to investigate the beam-driven plasma emission process in weakly magnetized plasmas of typical coronal conditions. We focused on the generation mechanisms of high-harmonic emission. We found that a larger beam velocity (u d ) favors the generation of the higher-harmonic emission. The emissions grow later for higher harmonics and decrease in intensity by ~2 orders of magnitude for each jump of the harmonic number. The second and third harmonic (H2 and H3) emissions get closer in intensity with larger u d . We also show that (1) the H3 emission is mainly generated via the coalescence of the H2 emission with the Langmuir waves, i.e., H2 + L → H3, wherein the coalescence with the forward-propagating beam-Langmuir wave leads to the forward-propagating H3, and coalescence with the backward-propagating Langmuir wave leads to the backward-propagating H3; and (2) the H4 emission mainly arises from the coalescence of the H3 emission with the forward- (backward-)propagating Langmuir wave, in terms of H3 + L → H4.

Keywords: solar electromagnetic emission; space plasmas; solar coronal radio emission; plasma astrophysics; radio bursts; solar radio emission
Estimation of the Full-sky Power Spectrum between Intermediate and Large Angular Scales from Partial-sky CMB Anisotropies Using an Artificial Neural Network

Reliable extraction of cosmological information from observed cosmic microwave background (CMB) maps may require removal of strongly foreground-contaminated regions from the analysis. In this paper, we employ an artificial neural network (ANN) to predict the full-sky CMB angular power spectrum between intermediate and large angular scales from the partial-sky spectrum obtained from a masked CMB temperature anisotropy map. We use a simple ANN architecture with one hidden layer containing 895 neurons. Using 1.2 × 105 training samples of full-sky and corresponding partial-sky CMB angular power spectra at HEALPix pixel resolution parameter N side = 256, we show that the spectrum predicted by our ANN agrees well with the target spectrum at each realization for the multipole range 2 ≤ l ≤ 512. The predicted spectra are statistically unbiased, and they preserve the cosmic variance accurately. Statistically, the differences between the mean predicted and underlying theoretical spectra are within approximately 3σ. Moreover, the probability densities obtained from predicted angular power spectra agree very well with those obtained from "actual" full-sky CMB angular power spectra for each multipole. Interestingly, our work shows that the significant correlations in input cut-sky spectra due to mode-mode coupling introduced on the partial sky are effectively removed, since the ANN learns the hidden pattern between the partial- and full-sky spectra preserving all of the statistical properties. The excellent agreement of statistical properties between the predicted and the ground truth demonstrates the importance of using artificial intelligence systems in cosmological analysis more widely.

Keywords: cosmic microwave background radiation; observational cosmology; astronomy data analysis