adsabs/SciX_UAT_keywords huggingface dataset:
Early High-contrast Imaging Results with Keck/NIRC2-PWFS: The SR 21 Disk

High-contrast imaging of exoplanets and protoplanetary disks depends on wave front sensing and correction made by adaptive optics instruments. Classically, wave front sensing has been conducted at optical wavelengths, which made high-contrast imaging of red targets such as M-type stars or extincted T Tauri stars challenging. Keck/NIRC2 has combined near-infrared (NIR) detector technology with the pyramid wave front sensor (PWFS). With this new module we observed SR 21, a young star that is brighter at NIR wavelengths than at optical wavelengths. Compared with the archival data of SR 21 taken with the optical wave front sensing we achieved ∼20% better Strehl ratio in similar natural seeing conditions. Further post-processing utilizing angular differential imaging and reference-star differential imaging confirmed the spiral feature reported by the Very Large Telescope/Spectro-Polarimetric High-contrast Exoplanet REsearch instrument polarimetric observation, which is the first detection of the SR 21 spiral in total intensity at L' band. We also compared the contrast limit of our result (10-4 at 0"4 and 2 × 10-5 at 1"0) with the archival data that were taken with optical wave front sensing and confirmed the improvement, particularly at ≤0"5. Our observation demonstrates that the NIR PWFS improves AO performance and will provide more opportunities for red targets in the future.

Keywords: coronagraphic imaging; protoplanetary disks
Effects of Modified Theories of Gravity on Neutrino Pair Annihilation Energy Deposition near Neutron Stars

We study the neutrino pair annihilation into electron-positron pairs ( $\nu +\bar{\nu }\to {e}^{-}+{e}^{+}$ ) near the surface of a neutron star. The analysis is performed in the framework of extended theories of gravity. The latter induce a modification of the minimum photon sphere radius (Rph) and the maximum energy deposition rate near Rph, as compared to those of general relativity. These results might lead to an efficient mechanism for generating GRBs.

Keywords: particle astrophysics; high energy astrophysics; black holes; gamma-ray bursts; non-standard theories of gravity; cosmological neutrinos; supernova neutrinos; neutron stars
Gravelamps: Gravitational Wave Lensing Mass Profile Model Selection

We present the package GRAVELAMPS, which is designed to analyze gravitationally lensed gravitational wave signals in order to constrain the mass density profile of the lensing object. GRAVELAMPS does this via parameter estimation using the framework of BILBY, which enables estimation of both the lens and the source parameters. The package can be used to study both microlensing and macrolensing cases, where the lensing mass distribution is described by a point-mass and extended-mass density profile, respectively. It allows the user to easily and freely switch between a full wave optics and approximate geometric optics description. The performance of GRAVELAMPS is demonstrated via simulated analysis of both microlensing and macrolensing events, illustrating its capability for both parameter estimation and model selection in the wave optics and hybrid environments. To further demonstrate the utility of the package, the real gravitational-wave event GW170809 was analyzed using GRAVELAMPS; this event was found to yield no strong evidence supporting the lensing hypothesis, consistent with previously published results.

Keywords: gravitational wave astronomy; astronomy data analysis; astronomy software; gravitational lensing; strong gravitational lensing; gravitational microlensing
A Conditional Autoencoder for Galaxy Photometric Parameter Estimation

Astronomical photometric surveys routinely image billions of galaxies, and traditionally infer the parameters of a parametric model for each galaxy. This approach has served us well, but the computational expense of deriving a full posterior probability distribution function is a challenge for increasingly ambitious surveys. In this paper, we use deep learning methods to characterize galaxy images, training a conditional autoencoder on mock data. The autoencoder can reconstruct and denoise galaxy images via a latent space engineered to include semantically meaningful parameters, such as brightness, location, size, and shape. Our model recovers galaxy fluxes and shapes on mock data with a lower variance than the Hyper Suprime-Cam photometry pipeline, and returns reasonable answers even for inputs outside the range of its training data. When applied to data in the training range, the regression errors on all extracted parameters are nearly unbiased with a variance near the Cramr-Rao bound.

Keywords: photometry; galaxy photometry; galaxy classification systems
Characteristics of Effective Dark Matter in Nonlocal Gravity

Nonlocal gravity (NLG) is a classical nonlocal generalization of Einstein's theory of gravitation that has been constructed in close analogy with the nonlocal electrodynamics of media. According to NLG, what appears as dark matter in astrophysics and cosmology is in reality the nonlocal aspect of the universal gravitational interaction. We focus here on two main features of the effective dark matter in NLG, namely, (a) the density of effective dark matter in NLG is always finite and therefore cusp-free, and (b) there is less effective dark matter in dwarf galaxies than is generally assumed in the standard particle dark matter paradigm. The corresponding astrophysical implications of NLG in connection with three ultra-diffuse galaxies AGC 114905, 242019, and 219533 are discussed.

Keywords: non-standard theories of gravity
Panic! at the Disks: First Rest-frame Optical Observations of Galaxy Structure at z > 3 with JWST in the SMACS 0723 Field

We present early results regarding the morphological and structural properties of galaxies seen with the James Webb Space Telescope (JWST) at z > 3 in the Early Release Observations toward the SMACS 0723 cluster field. Using JWST we investigate, for the first time, the optical morphologies of a significant number of z > 3 galaxies with accurate photometric redshifts in this field to determine the form of galaxy structure in the relatively early universe. We use visual morphologies and MORFOMETRYKA measures to perform quantitative morphology measurements, both parametric with light profile fitting (Sérsic indices) and nonparametric (concentration, asymmetry, and smoothness (CAS) values). Using these, we measure the relative fraction of disk, spheroidal, and peculiar galaxies at 3 < z < 8. We discover the surprising result that at z > 1.5 disk galaxies dominate the overall fraction of morphologies, with a factor of ~10 relative higher number of disk galaxies than seen by the Hubble Space Telescope at these redshifts. Our visual morphological estimates of galaxies align closely with their locations in CAS parameter space and their Sérsic indices.

Keywords: galaxy classification systems
Preliminary Target Selection for the DESI Emission Line Galaxy (ELG) Sample

DESI will precisely constrain cosmic expansion and the growth of structure by collecting ∼35 million redshifts across ∼80% of cosmic history and one third of the sky to study Baryon Acoustic Oscillations (BAO) and Redshift Space Distortions (RSD). We present a preliminary target selection for an Emission Line Galaxy (ELG) sample, which will comprise about half of all DESI tracers. The selection consists of a g-band magnitude cut and a (g - r) versus (r - z) color box, which we validate using HSC/PDR2 photometric redshifts and DEEP2 spectroscopy. The ELG target density should be ∼2400 deg-2, with ∼65% of ELG redshifts reliably within a redshift range of 0.6 < z < 1.6. ELG targeting for DESI will be finalized during a "Survey Validation" phase.

Keywords: large-scale structure of the universe; redshift surveys; emission line galaxies; observational cosmology
Self-interacting Dark Matter Interpretation of Crater II

The satellite galaxy Crater II of the Milky Way is extremely cold and exceptionally diffuse. These unusual properties are challenging to understand in the standard model of cold dark matter. We use controlled N-body simulations to investigate the formation of Crater II in self-interacting dark matter (SIDM), where dark matter particles can scatter and thermalize. Taking the orbit motivated by the measurements from Gaia Early Data Release 3, we show a strong self-interacting cross section per particle mass of 60 cm2 g‑1 is favored for Crater II. The simulated SIDM halo, with a 1 kpc core, leads to both a low stellar velocity dispersion and a large half-light radius for Crater II. These characteristics remain robust regardless of the initial stellar distribution.

Keywords: dark matter; dwarf spheroidal galaxies; galaxy dark matter halos
A Search for TeV Gamma-Ray Emission from Pulsar Tails by VERITAS

We report on the search for very-high-energy gamma-ray emission from the regions around three nearby supersonic pulsars (PSR B0355+54, PSR J0357+3205, and PSR J1740+1000) that exhibit long X-ray tails. To date there is no clear detection of TeV emission from any pulsar tail that is prominent in X-ray or radio. We provide upper limits on the TeV flux, and luminosity, and also compare these limits with other pulsar wind nebulae detected in X-rays and the tail emission model predictions. We find that at least one of the three tails is likely to be detected in observations that are a factor of 2-3 more sensitive. The analysis presented here also has implications for deriving the properties of pulsar tails, for those pulsars whose tails could be detected in TeV.

Keywords: gamma-rays; pulsars
Carbon Stars as Standard Candles: An Empirical Test for the Reddening, Metallicity, and Age Sensitivity of the J-region Asymptotic Giant Branch (JAGB) Method

The J-region Asymptotic Giant Branch (JAGB) method is a standard candle based on the intrinsic luminosities of carbon stars in the near-infrared. We directly constrain the impact of metallicity, age, and reddening on the JAGB method. We assess how the mode, skew, and spread of the JAGB star LF change throughout diverse stellar environments in M31's NE disk from 13 < d < 18 kpc using data from the Panchromatic Hubble Andromeda Treasury (PHAT). As expected, the mode is found to be fainter in higher-reddening regions. To cross-check this result, we also measure a fiducial J-band ground-based JAGB distance using data from the UKIRT/WFCam in M31's outermost disk (18 < d < 40 kpc) where internal reddening is minimal. We find that this J-band distance modulus agrees well with the F110W distance moduli measured in the lowest-reddening regions of the PHAT data, demonstrating the JAGB method is most accurate if measured in the low-reddening outer disks of galaxies. On the other hand, the mode of the JAGB star LF appears empirically to show no dependence on age or metallicity within the range -0.18 < [M/H] < -0.26 dex. In conclusion, the JAGB method proves to be a robust standard candle capable of calibrating the luminosities of Type Ia supernovae and therefore providing a high-accuracy, high-precision measurement of the Hubble constant.

Keywords: observational cosmology; distance indicators; asymptotic giant branch stars; carbon stars; galaxy distances; andromeda galaxy
Star Formation Histories of Massive Red Spiral Galaxies in the Local Universe

We investigate the star formation histories (SFHs) of massive red spiral galaxies with stellar mass M* > 1010.5 M⊙, and make comparisons with blue spirals and red ellipticals of similar masses. We make use of the integral field spectroscopy from the Sloan Digital Sky Survey IV/DR15 MaNGA sample, and estimate spatially resolved SFHs and stellar population properties of each galaxy by applying a Bayesian spectral fitting code to the MaNGA spectra. We find that both red spirals and red ellipticals have experienced only one major star formation episode at early times, and the result is independent of the adopted SFH model. On average, more than half of their stellar masses were formed >10 Gyr ago, and more than 90% were formed >6 Gyr ago. The two types of galaxies show similarly flat profiles in a variety of stellar population parameters: old stellar ages indicated by D4000 (the spectral break at around 4000 Å), high stellar metallicities, large Mgb/Fe ratios indicating fast formation, and little stellar dust attenuation. In contrast, although blue spirals also formed their central regions >10 Gyr ago, both their central regions and outer disks continuously form stars over a long timescale. Our results imply that massive red spirals are likely to share some common processes of formation (and possibly quenching) with massive red ellipticals in the sense that both types were formed at z > 2 through a fast formation process. Possible mechanisms for the formation and quenching of massive red spirals are discussed.

Keywords: galaxy formation; spiral galaxies; galaxy evolution; galaxy stellar content
Chromospheric Magnetic Field: A Comparison of He I 10830 Å Observations with Nonlinear Force-free Field Extrapolation

The nonlinear force-free field (NLFFF) modeling has been extensively used to infer the three-dimensional magnetic field in the solar corona. One of the assumptions in the NLFFF extrapolation is that the plasma beta is low, but this condition is considered to be incorrect in the photosphere. We examine direct measurements of the chromospheric magnetic field in two active regions through spectropolarimetric observations at He I 10830 Å, which are compared with the potential fields and NLFFFs extrapolated from the photosphere. The comparisons allow quantitative estimation of the uncertainty in the NLFFF extrapolation from the photosphere. Our analysis shows that observed chromospheric magnetic field may have larger nonpotentiality compared to the photospheric magnetic field. Moreover, the large nonpotentiality in the chromospheric height may not be reproduced by the NLFFF extrapolation from the photospheric magnetic field. The magnitude of the underestimation of the nonpotentiality at chromospheric heights may reach 30°-40° in shear signed angle in some locations. This deviation may be caused by the non-force-freeness in the photosphere. Our study suggests the importance of the inclusion of measured chromospheric magnetic fields in the NLFFF modeling for the improvement of the coronal extrapolation.

Keywords: solar chromosphere; solar magnetic fields; solar photosphere; solar active regions; spectropolarimetry
The Supersonic Project: The Early Evolutionary Path of Supersonically Induced Gas Objects

Supersonically induced gas objects (SIGOs) are a class of early universe objects that have gained attention as a potential formation route for globular clusters. SIGOs have recently begun to be studied in the context of molecular hydrogen cooling, which is key to characterizing their structure and evolution. Studying the population-level properties of SIGOs with molecular cooling is important for understanding their potential for collapse and star formation, and for addressing whether SIGOs can survive to the present epoch. Here, we investigate the evolution of SIGOs before they form stars, using a combination of numerical and analytical analysis. We study timescales important to the evolution of SIGOs at a population level in the presence of molecular cooling. Revising the previous formulation for the critical density of collapse for SIGOs allows us to show that their prolateness tends to act as an inhibiting factor to collapse. We find that simulated SIGOs are limited by artificial two-body relaxation effects that tend to disperse them. We expect that SIGOs in nature will be longer lived compared to our simulations. Further, the fall-back timescale on which SIGOs fall into nearby dark matter halos, potentially producing a globular-cluster-like system, is frequently longer than their cooling timescale and the collapse timescale on which they shrink through gravity. Therefore, some SIGOs have time to cool and collapse outside of halos despite initially failing to exceed the critical density. From this analysis we conclude that SIGOs should form stars outside of halos in nonnegligible stream velocity patches in the universe.

Keywords: globular star clusters; star formation; giant molecular clouds; high-redshift galaxies; galactic and extragalactic astronomy
Near-infrared Spectroscopy of Ultracompact H II Regions in W51A with NIFS/ALTAIR

W51A is the most active star formation region of the giant H II region W51. It harbors the two massive protoclusters W51e and W51 IRS2, which are very rare in the Galaxy. We aim to identify the newborn massive stars and ultracompact H II regions to derive its distance and age. We performed Integral Field Unit observations with NIFS+ALTAIR of nine targets in the W51A subregion. The distance modulus was obtained using the spectral classification in the K band and a reddening law appropriate to the inner Galactic plane. We derived the distance and the spectral types for five of the targets, ranging from O8 to O9.5, similar to those derived from radio continuum data, except for two sources to which we assigned a somewhat later spectral type. We included another seven objects with precise spectral classification from other works, which allowed us to better constrain the distance estimate. Our spectrophotometric distance d = 4.80 ± 1.27 kpc is in good agreement with those derived from the Galactic rotation model and trigonometric parallaxes, placing the region near the tangent point of the Sagittarius arm. We conclude that the stars studied in this work have an age spread of 1.5-4 Myr, substantially older than thought to date. *Based on observations obtained at the Gemini Observatory (processed using the Gemini IRAF package v1.14), which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), Ministério da Ciência, Tecnologia e Inovação (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea).

Keywords: massive stars; star forming regions; spectroscopy; stellar spectral lines; stellar spectral types; near infrared astronomy; spectrophotometry
Dust Accretion onto Exoplanets

Accretion of interplanetary dust onto gas giant exoplanets is considered. Poynting-Robertson drag causes dust particles from distant reservoirs to slowly inspiral toward the star. Orbital simulations for the three-body system of the star, planet, and dust particle show that a significant fraction of the dust may accrete onto massive planets in close orbits. The deceleration of the supersonic dust in the planet's atmosphere is modeled, including ablation by thermal evaporation and sputtering. The fraction of the accreted dust mass deposited as gas-phase atoms is found to be large for close-in orbits and massive planets. If mass outflow and vertical mixing are sufficiently weak, the accreted dust produces a constant mixing ratio of atoms and remnant dust grains below the stopping layer. When vertical mixing is included along with settling, the solutions interpolate between the mixing ratio due to the meteoric source above the homopause, and that of the well-mixed deeper atmosphere below the homopause. The line opacity from atoms and continuum opacity from remnant dust may be observable in transmission spectra for sufficiently large dust accretion rates, a grain size distribution tilted toward the blowout size, and sufficiently weak vertical mixing. If mixing is strong, the meteoric source may still act to augment heavy elements mixed up from the deep atmosphere as well as provide nucleation sites for the formation of larger particles. The possible role of the Lorentz drag force in limiting the flow speeds and mixing coefficient for pressures ≲1 mbar is discussed.

Keywords: exoplanet atmospheres; interplanetary dust; atmospheric circulation; exozodiacal dust; exoplanet atmospheric composition; meteorite composition; transmission spectroscopy; orbital resonances; atmospheric clouds
LOFAR Search for Radio Emission from Galaxies Hosting Tidal Disruption Events

Radio emission from 23 tidal disruption event host galaxies were searched in the 144 MHz LOFAR-LoTSS2 images. Three host galaxies are detected with diffuse radio emission, which can be interpreted as either galactic synchrotron radio emission or diffuse radio halo in dense galactic environments. Non-detection of (transient) radio emission in majority of galaxies could be due to self-absorption of radio emission associated with the tidal disruption event.

Keywords: galaxy interactions; extragalactic radio sources; tidal disruption
The Dearth of Differences between Central and Satellite Galaxies. III. Environmental Dependencies of Mass-Size and Mass-Structure Relations

As demonstrated in Paper I, the quenching properties of central and satellite galaxies are quite similar as long as both stellar mass and halo mass are controlled. Here, we extend the analysis to the size and bulge-to-total light ratio (B/T) of galaxies. In general, central galaxies have size-stellar mass and B/T-stellar mass relations different from satellites. However, the differences are eliminated when halo mass is controlled. We also study the dependence of size and B/T on halo-centric distance and find a transitional stellar mass ( ${M}_{* ,{\rm{t}}}$ ) at given halo mass (Mh), which is about one-fifth of the mass of the central galaxies in halos of mass Mh. The transitional stellar masses for size, B/T and quenched fraction are similar over the whole halo mass range, suggesting a connection between the quenching of star formation and the structural evolution of galaxies. Our analysis further suggests that the classification based on the transitional stellar mass is more fundamental than the central-satellite dichotomy, and provides a more reliable way to understand the environmental effects on galaxy properties. We compare the observational results with the hydrodynamical simulation, EAGLE, and the semianalytic model, L-GALAXIES. The EAGLE simulation successfully reproduces the similarities of size for centrals, satellites, and even ${M}_{* ,{\rm{t}}}$ , while L-GALAXIES fails to recover the observational results.

Keywords: galaxies; galaxy clusters; galaxy environments; galaxy structure; galaxy bulges