adsabs/SciX_UAT_keywords huggingface dataset:
CEERS: Spatially Resolved UV and Mid-infrared Star Formation in Galaxies at 0.2 < z < 2.5: The Picture from the Hubble and James Webb Space Telescopes

We present the mid-infrared (MIR) morphologies for 64 star-forming galaxies (SFGs) at 0.2 < z < 2.5 with stellar mass M * > 109 M ⊙ using James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) observations from the Cosmic Evolution Early Release Science survey. The MIRI bands span the MIR (7.7-21 μm), enabling us to measure the effective radii (R eff) and Sérsic indexes of these SFGs at rest-frame 6.2 and 7.7 μm, which contains strong emission from Polycyclic aromatic hydrocarbon (PAH) features, a well-established tracer of star formation in galaxies. We define a "PAH band" as the MIRI bandpass that contains these features at the redshift of the galaxy. We then compare the galaxy morphologies in the PAH bands to those in the rest-frame near-ultraviolet (NUV) using Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)/F435W or ACS/F606W and optical/near-IR using HST WFC3/F160W imaging from UVCANDELS and CANDELS. The R eff of galaxies in the PAH band are slightly smaller (~10%) than those in F160W for galaxies with M * ≳ 109.5 M ⊙ at z ≤ 1.2, but the PAH band and F160W have similar fractions of light within 1 kpc. In contrast, the R eff of galaxies in the NUV band are larger, with lower fractions of light within 1 kpc compared to F160W for galaxies at z ≤ 1.2. Using the MIRI data to estimate the SFRIR surface density, we find that the correlation between the SFRIR surface density and stellar mass has a steeper slope than that of the SFRUV surface density and stellar mass, suggesting more massive galaxies having increasing amounts of obscured fraction of star formation in their inner regions. This paper demonstrates how the high-angular resolution data from JWST/MIRI can reveal new information about the morphology of obscured star formation.

Keywords: high-redshift galaxies; star formation; galaxy stellar content; galaxy evolution
CHIMERA Occultation Constraints on the Abundance of Kilometer-scale Kuiper Belt Objects

Occultations provide indirect sensitivity to the number density of small Kuiper Belt objects (KBOs) too faint to directly detect telescopically. We present results from the Caltech HI-speed Multicolor camERA (CHIMERA) survey with the Palomar Hale Telescope, which monitored stars over the central $5^{\prime} \times 5^{\prime} $ of the M22 globular cluster along the ecliptic plane for serendipitous occultations by kilometer-scale KBOs over 63 hr across 24 nights at a 33 Hz frame rate simultaneously in $i^{\prime} $ and $g^{\prime} $ . We adapted dense-field photometry and occultation template fitting techniques to this data set, finding a 95% confidence upper limit on the occultation rate, corresponding to an ecliptic sky density of ≲107 deg-2 of >1 km diameter classical KBOs. We discuss a few of the occultation-like light curve signatures at the edge of the sensitivity limit responsible for setting the upper bounds, and their likely nonviability as true occultations.

Keywords: kuiper belt; multi-color photometry; stellar occultation
Characterizing the Discovery of a New Trans-Neptunian Object Binary in a Trailed Point-spread Function Search

The Latitude Density Search utilized the Hyper Suprime-Cam on the Subaru Telescope to discover 60 moving objects in the outer solar system, 54 of which have semimajor axes beyond 30 au. The images were acquired in exceptional seeing (0"4) and reached a detection limit of mr ≃ 25.2. The two night arcs were used to calculate orbits that are poorly constrained; however, the distance and inclination are the parameters best constrained by short arcs, and a reasonable determination can be made of which objects are cold classical trans-Neptunian objects (TNOs) and which are dynamically excited. We identify 10 objects as likely cold classical objects. We searched all of the detections for binary sources using a trailed point-spread function (PSF) subtraction method and identified one binary object with a separation of 0"34 and a secondary with 17% the brightness of the primary (2.0 magnitudes fainter). This is the brightest TNO in the sample, the previously known object (471165) 2010 HE79, which has a dynamically excited orbit. Because of the excellent seeing, this search was sensitive to secondaries with 0"34 separation and a brightness of ≥50% the primary brightness for seven objects, including one cold classical. This gives an intrinsic binary fraction of ${17}_{-10}^{+19}$ % (one of six) for the dynamically excited objects within our detection limits. The trailed PSF subtraction method used in the Latitude Density Search to identify binaries, fit the two components, and determine the sensitivity limits is a useful tool that could be more broadly applied to identify binary TNOs and track known binary TNO orbits.

Keywords: trans-neptunian objects; kuiper belt; classical kuiper belt objects
Future Prospects for Constraining Black Hole Spacetime: Horizon-scale Variability of Astrophysical Jets

The Event Horizon Telescope (EHT) Collaboration has recently published the first horizon-scale images of the supermassive black holes M87* and Sgr A* and provided some first information on the physical conditions in their vicinity. The comparison between the observations and the three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations has enabled the EHT to set initial constraints on the properties of these black hole spacetimes. However, accurately distinguishing the properties of the accretion flow from those of the spacetime, most notably, the black hole mass and spin, remains challenging because of the degeneracies the emitted radiation suffers when varying the properties of the plasma and those of the spacetime. The next-generation EHT (ngEHT) observations are expected to remove some of these degeneracies by exploring the complex interplay between the disk-jet dynamics, which represents one of the most promising tools for extracting information on the black hole spin. By using GRMHD simulations of magnetically arrested disks and general relativistic radiative transfer (GRRT) calculations of the emitted radiation, we have studied the properties of the jet and the accretion disk dynamics on spatial scales that are comparable with the horizon. In this way, we are able to highlight that the radial and azimuthal dynamics of the jet are well correlated with the black hole spin. Based on the resolution and image reconstruction capabilities of the ngEHT observations of M87*, we can assess the detectability and associated uncertainty of this correlation. Overall, our results serve to assess the prospects for constraining the black hole spin with future EHT observations.

Keywords: black hole physics; galaxies; relativistic jets; high angular resolution; astronomy image processing; magnetohydrodynamics; radiative transfer
Finding Strong Gravitational Lenses in the DESI DECam Legacy Survey

We perform a semi-automated search for strong gravitational lensing systems in the 9000 deg2 Dark Energy Camera Legacy Survey (DECaLS), part of the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys. The combination of the depth and breadth of these surveys are unparalleled at this time, making them particularly suitable for discovering new strong gravitational lensing systems. We adopt the deep residual neural network architecture developed by Lanusse et al. for the purpose of finding strong lenses in photometric surveys. We compile a training sample that consists of known lensing systems in the Legacy Surveys and the Dark Energy Survey as well as non-lenses in the footprint of DECaLS. In this paper we show the results of applying our trained neural network to the cutout images centered on galaxies typed as ellipticals in DECaLS. The images that receive the highest scores (probabilities) are visually inspected and ranked. Here we present 335 candidate strong lensing systems, identified for the first time.

Keywords: strong gravitational lensing; high-redshift galaxies; galaxies; galaxy clusters; galaxy groups
Residual Entropy as a Diagnostic and Stopping Metric for CLEAN

We propose the use of entropy, measured from the spatial and flux distribution of pixels in the residual image, as a potential diagnostic and stopping metric for the CLEAN algorithm. Despite its broad success as the standard deconvolution approach in radio interferometry, finding the optimum stopping point for the iterative CLEAN algorithm is still a challenge. We show that the entropy of the residual image, measured during the final stages of CLEAN, can be computed without prior knowledge of the source structure or expected noise levels, and that finding the point of maximum entropy as a measure of randomness in the residual image serves as a robust stopping criterion. We also find that, when compared to the expected thermal noise in the image, the maximum entropy of the residuals is a useful diagnostic that can reveal the presence of data editing, calibration, or deconvolution issues that may limit the fidelity of the final CLEAN map.

Keywords: interferometry; deconvolution; radio astronomy
Dating Granites Using CODEX, with Application to In Situ Dating on the Moon

We have measured 87Rb-87Sr isochron ages for two granites, using the breadboard version of our Chemistry, Organics, and Dating EXperiment (CODEX), a laser-ablation resonance-ionization mass spectrometer designed for in situ geochronology on the Moon or Mars. These measurements extend the demonstrated analytical capabilities of CODEX, and indicate the value of incorporating a flight-ready version of CODEX, now under construction, into a future mission payload. We used CODEX to obtain accurate ages for the 1700 Ma Boulder Creek Granite, with 1σ statistical precision of 110 Myr, and for the 1100 Ma Pikes Peak Granite, with 1σ statistical precision of 160 Myr. To provide an end-to-end illustration of how CODEX analysis of granites can address critical lunar science questions regarding rock age and composition in situ, we describe an example mission to the lunar Gruithuisen Domes. Gruithuisen Domes appear to be volcanic edifices of granitic composition. Orbital remote sensing suggests that granitic rocks represent only a small fraction of the lunar surface, and the mere fact of their existence on the Moon is a puzzle. CODEX determination of the timing and process of their formation, both presently ill-understood, would provide important constraints on the thermal and geochemical evolution of the lunar interior.

Keywords: the moon; lunar geochronology; space vehicle instruments; lunar evolution
Stellar Populations in the Central 0.5 pc of Our Galaxy. III. The Dynamical Substructures

We measure the 3D kinematic structures of the young stars within the central 0.5 pc of our Galactic Center using the 10 m telescopes of the W. M. Keck Observatory over a time span of 25 yr. Using high-precision measurements of positions on the sky and proper motions and radial velocities from new observations and the literature, we constrain the orbital parameters for each young star. Our results show two statistically significant substructures: a clockwise stellar disk with 18 candidate stars, as has been proposed before, but with an improved disk membership; and a second, almost edge-on plane of 10 candidate stars oriented east-west on the sky that includes at least one IRS 13 star. We estimate the eccentricity distribution of each substructure and find that the clockwise disk has <e> = 0.39 and the edge-on plane has <e> = 0.68. We also perform simulations of each disk/plane with incompleteness and spatially variable extinction to search for asymmetry. Our results show that the clockwise stellar disk is consistent with a uniform azimuthal distribution within the disk. The edge-on plane has an asymmetry that cannot be explained by variable extinction or incompleteness in the field. The orientation, asymmetric stellar distribution, and high eccentricity of the edge-on plane members suggest that this structure may be a stream associated with the IRS 13 group. The complex dynamical structure of the young nuclear cluster indicates that the star formation process involved complex gas structures and dynamics and is inconsistent with a single massive gaseous disk.

Keywords: astrometry; galactic center; infrared observatories; high angular resolution
Electron Energization and Energy Dissipation in Microscale Electromagnetic Environments

Particle energization and energy dissipation in electromagnetic environments are longstanding topics of intensive research in space, laboratory, and astrophysical plasmas. One challenge is to understand these conversion processes at smaller and smaller spatial/temporal scales. In this Letter, with very high cadence measurements of particle distributions from the Magnetospheric Multiscale spacecraft, we report evidence of evolution of an identified microscale (i.e., electron gyro-scale) magnetic cavity structure and reveal within it a unique energization process that does not adhere to prevailing adiabatic invariance theory. Our finding indicates that this process is largely energy dependent, and can accelerate/decelerate charged particles inside the trapping region during their gyromotion, clearly altering the particle distribution.

Keywords: space plasmas
Origin and Properties of the Near-subsonic Solar Wind Observed by Parker Solar Probe

We identify and examine the solar wind intervals near the sonic critical point (i.e., M S ∼ 1) observed by the Parker Solar Probe. The near-subsonic wind intervals show similar properties: a low density, an extremely low velocity, a low proton temperature, and essentially no magnetic field deflections compared with the surrounding solar wind. The extremely low velocity is the primary contributor to the near crossing of the sonic critical point rather than the sound speed, which is roughly constant in these intervals. Source tracing with a potential-field source-surface model suggests that the near subsonic intervals all connect to the boundaries inside coronal holes. Heliospheric current sheet (HCS) and partial HCS crossings around the near subsonic intervals indicate that the near subsonic wind is a transition layer between the slow and fast winds. The above scenario is consistent with the nature of the near-subsonic wind as a low-Mach-number boundary layer, which facilitates the crossing of the sonic critical point at 15–20 R S . Moreover, we find a dependence of the amplitude of switchbacks on the radial sonic Mach number. Magnetic field deflections essentially disappear near the sonic critical point, which suggests that switchbacks originate from above the sonic critical point.

Keywords: solar wind; solar corona; alfven waves; solar coronal holes
Ultrafaint Dwarfs in a Milky Way Context: Introducing the Mint Condition DC Justice League Simulations

We present results from the "Mint" resolution DC Justice League suite of Milky Way-like zoom-in cosmological simulations, which extend our study of nearby galaxies down into the ultrafaint dwarf (UFD) regime for the first time. The mass resolution of these simulations is the highest ever published for cosmological Milky Way zoom-in simulations run to z = 0, with initial star (dark matter) particle masses of 994 (17900) M⊙, and a force resolution of 87 pc. We study the surrounding dwarfs and UFDs, and find that the simulations match the observed dynamical properties of galaxies with -3 > MV > -19, and reproduce the scatter seen in the size-luminosity plane for rh ≳ 200 pc. We predict the vast majority of nearby galaxies will be observable by the Vera Rubin Observatory's coadded Legacy Survey of Space and Time. We additionally show that faint dwarfs with velocity dispersions ≲5 km s-1 result from severe tidal stripping of the host halo. We investigate the quenching of UFDs in a hydrodynamical Milky Way context and find that the majority of UFDs are quenched prior to interactions with the Milky Way, though some of the quenched UFDs retain their gas until infall. Additionally, these simulations yield some unique dwarfs that are the first of their kind to be simulated, e.g., an H I-rich field UFD, a late-forming UFD that has structural properties similar to Crater 2, as well as a compact dwarf satellite that has no dark matter at z = 0.

Keywords: dwarf galaxies; galaxy evolution; hydrodynamical simulations; galaxy quenching
Disentangling the Cosmic Web toward FRB 190608

Fast radio burst (FRB) 190608 was detected by the Australian Square Kilometre Array Pathfinder (ASKAP) and localized to a spiral galaxy at ${z}_{\mathrm{host}}=0.11778$ in the Sloan Digital Sky Survey (SDSS) footprint. The burst has a large dispersion measure ( ${\mathrm{DM}}_{\mathrm{FRB}}=339.8\,\mathrm{pc}\,{\mathrm{cm}}^{-3}$ ) compared to the expected cosmic average at its redshift. It also has a large rotation measure ( ${\mathrm{RM}}_{\mathrm{FRB}}=353\,\mathrm{rad}\,{{\rm{m}}}^{-2}$ ) and scattering timescale (τ = 3.3 ms at 1.28 GHz). Chittidi et al. perform a detailed analysis of the ultraviolet and optical emission of the host galaxy and estimate the host DM contribution to be $110\pm 37\,{\rm{p}}{\rm{c}}\,{{\rm{c}}{\rm{m}}}^{-3}$ . This work complements theirs and reports the analysis of the optical data of galaxies in the foreground of FRB 190608 in order to explore their contributions to the FRB signal. Together, the two studies delineate an observationally driven, end-to-end study of matter distribution along an FRB sightline, the first study of its kind. Combining our Keck Cosmic Web Imager (KCWI) observations and public SDSS data, we estimate the expected cosmic dispersion measure ${\mathrm{DM}}_{\mathrm{cosmic}}$ along the sightline to FRB 190608. We first estimate the contribution of hot, ionized gas in intervening virialized halos ( ${\mathrm{DM}}_{\mathrm{halos}}\approx 7\mbox{--}28\,\mathrm{pc}\,{\mathrm{cm}}^{-3}$ ). Then, using the Monte Carlo Physarum Machine methodology, we produce a 3D map of ionized gas in cosmic web filaments and compute the DM contribution from matter outside halos ( ${\mathrm{DM}}_{\mathrm{IGM}}\approx 91\mbox{--}126\,\mathrm{pc}\,{\mathrm{cm}}^{-3}$ ). This implies that a greater fraction of ionized gas along this sightline is extant outside virialized halos. We also investigate whether the intervening halos can account for the large FRB rotation measure and pulse width and conclude that it is implausible. Both the pulse broadening and the large Faraday rotation likely arise from the progenitor environment or the host galaxy.

Keywords: galaxy dark matter halos; quasar absorption line spectroscopy; galaxy evolution; intergalactic medium; radio transient sources
MAGIC: Microlensing Analysis Guided by Intelligent Computation

The modeling of binary microlensing light curves via the standard sampling-based method can be challenging, because of the time-consuming light-curve computation and the pathological likelihood landscape in the high-dimensional parameter space. In this work, we present MAGIC, which is a machine-learning framework to efficiently and accurately infer the microlensing parameters of binary events with realistic data quality. In MAGIC, binary microlensing parameters are divided into two groups and inferred separately with different neural networks. The key feature of MAGIC is the introduction of a neural controlled differential equation, which provides the capability to handle light curves with irregular sampling and large data gaps. Based on simulated light curves, we show that MAGIC can achieve fractional uncertainties of a few percent on the binary mass ratio and separation. We also test MAGIC on a real microlensing event. MAGIC is able to locate degenerate solutions even when large data gaps are introduced. As irregular samplings are common in astronomical surveys, our method also has implications for other studies that involve time series.

Keywords: neural networks; time series analysis; gravitational microlensing exoplanet detection; binary lens microlensing
An Information Theory Approach on Deciding Spectroscopic Follow-ups

Classification and characterization of variable phenomena and transient phenomena are critical for astrophysics and cosmology. These objects are commonly studied using photometric time series or spectroscopic data. Given that many ongoing and future surveys are conducted in a time domain, and given that adding spectra provides further insights but requires more observational resources, it would be valuable to know which objects we should prioritize to have a spectrum in addition to a time series. We propose a methodology in a probabilistic setting that determines a priori which objects are worth taking a spectrum of to obtain better insights, where we focus on the insight of the type of the object (classification). Objects for which we query their spectrum are reclassified using their full spectral information. We first train two classifiers, one that uses photometric data and another that uses photometric and spectroscopic data together. Then for each photometric object we estimate the probability of each possible spectrum outcome. We combine these models in various probabilistic frameworks (strategies), which are used to guide the selection of follow-up observations. The best strategy depends on the intended use, whether it is obtaining more confidence or accuracy. For a given number of candidate objects (127, equal to 5% of the data set) for taking spectra, we improve the class prediction accuracy by 37% as opposed to 20% of a non-naive (non-random) best-baseline strategy. Our approach provides a general framework for follow-up strategies and can be extended beyond classification to include other forms of follow-ups beyond spectroscopy.

Keywords: computational methods; astronomy data analysis; astrostatistics tools; variable stars
Striped Jets in Post-Neutron Star Merger Systems

Models invoking magnetic reconnection as the particle acceleration mechanism within relativistic jets often adopt a gradual energy dissipation profile within the jet. However, such a profile has yet to be reproduced in first-principles simulations. Here we perform a suite of 3D general relativistic magnetohydrodynamic simulations of post-neutron star merger disks with an initially purely toroidal magnetic field. We explore the variations in both the microphysics (e.g., nuclear recombination, neutrino emission) and system parameters (e.g, disk mass). In all of our simulations, we find the formation of magnetically striped jets. The stripes result from the reversals in the poloidal magnetic flux polarity generated in the accretion disk. The simulations display large variations in the distributions of stripe duration, τ, and power, <P Φ>. We find that more massive disks produce more powerful stripes, the most powerful of which reaches <P Φ> ~ 1049 erg s-1 at τ ~ 20 ms. The power and variability that result from the magnetic reconnection of the stripes agree with those inferred in short-duration gamma-ray bursts. We find that the dissipation profile of the cumulative energy is roughly a power law in both radial distance, z, and τ, with a slope in the range of ~1.7-3; more massive disks display larger slopes.

Keywords: jets; gamma-ray bursts; magnetohydrodynamical simulations