adsabs/SciX_UAT_keywords huggingface dataset:
Constraining the Regolith Composition of Asteroid (16) Psyche via Laboratory Visible Near-infrared Spectroscopy

(16) Psyche is the largest M-type asteroid in the main belt and the target of the NASA Discovery-class Psyche mission. Despite gaining considerable interest in the scientific community, Psyche's composition and formation remain unconstrained. Originally, Psyche was considered to be almost entirely composed of metal due to its high radar albedo and spectral similarities to iron meteorites. More recent telescopic observations suggest the additional presence of low-Fe pyroxene and exogenic carbonaceous chondrites on the asteroid's surface. To better understand the abundances of these additional materials, we investigated visible near-infrared (0.35-2.5 μm) spectral properties of three-component laboratory mixtures of metal, low-Fe pyroxene, and carbonaceous chondrite. We compared the band depths and spectral slopes of these mixtures to the telescopic spectrum of (16) Psyche to constrain material abundances. We find that the best matching mixture to Psyche consists of 82.5% metal, 7% low-Fe pyroxene, and 10.5% carbonaceous chondrite by weight, suggesting that the asteroid is less metallic than originally estimated (∼94%). The relatively high abundance of carbonaceous chondrite material estimated from our laboratory experiments implies the delivery of this exogenic material through low velocity collisions to Psyche's surface. Assuming that Psyche's surface is representative of its bulk material content, our results suggest a porosity of 35% to match recent density estimates.

Keywords: spectroscopy; asteroid surfaces; asteroids; infrared astronomy; iron meteorites; meteorites; carbonaceous chondrites
Gravitational-wave Memory from a Propagating Relativistic Jet: A Probe of the Interior of Gamma-Ray Burst Progenitors

It is believed that the relativistic jets of gamma-ray bursts (GRBs) should initially propagate through a heavy envelope of the massive progenitor stars or through merger ejecta formed from compact binary mergers. The interaction of a jet with a stellar envelope or merger ejecta can lead to the deceleration of the head material of the jet and simultaneously the formation of a hot cocoon. However, this jet-envelope/ejecta interaction is actually undetectable with electromagnetic radiation and can only be inferred indirectly by the structure of the breakout jet. Therefore, as a solution to this phenomenon, we suggest the jet-envelope/ejecta interaction can produce a gravitational-wave (GW) memory of an amplitude of $h\sim {10}^{-26}\mbox{--}{10}^{-23}$ , which could be detected with some future GW detectors sensitive in the frequency range from sub-Hertz to several tens of Hertz. This provides a potential direct way to probe the jet propagation and then the interior of the GRB progenitors.

Keywords: relativistic jets; gamma-ray bursts; gravitational waves; shocks
On Measuring the 21 cm Global Spectrum of the Cosmic Dawn with an Interferometer Array

We theoretically investigate the recovery of the global spectrum (monopole) from visibilities (cross-correlation only) measured by an interferometer array and the feasibility of extracting the 21 cm signal of the cosmic dawn. In our approach, the global spectrum is obtained by solving the monopole and higher-order components simultaneously from visibilities measured with up to thousands of baselines. Using this algorithm, the monopole of both the foreground and the 21 cm signal can be correctly recovered in a broad range of conditions. We find that a 3D baseline distribution can have much better performance than a 2D (planar) baseline distribution, particularly when there is a lack of shorter baselines. We simulate for ground-based 2D and 3D array configurations, and a cross-shaped space array located at the Sun-Earth L2 point that can form 3D baselines through orbital precession. In all simulations we obtain a good recovered global spectrum, and successfully extract the 21 cm signal from it, with a reasonable number of antennas and observation time.

Keywords: reionization; population iii stars; radio interferometers; radio continuum emission
Recipe for Inferring Subsurface Solar Magnetism via Local Mode Coupling Using Slepian Basis Functions

Direct seismic imaging of subsurface flow, sound speed, and magnetic field is crucial for predicting flux-tube emergence on the solar surface, an important ingredient for space weather. The sensitivity of helioseismic mode-amplitude cross-correlation to p- and f-mode oscillations enables formal inversion of such subphotospheric perturbations. It is well known that such problems are written in the form of an integral equation that connects the perturbations to the observations via sensitivity kernels. While the sensitivity kernels for flow and sound speed have been known for decades and have been used extensively, formulating kernels for general magnetic perturbations had been elusive. A recent study proposed sensitivity kernels for Lorentz stresses corresponding to global magnetic fields of general geometry. The present study is devoted to proposing kernels for inferring Lorentz stresses as well as the solenoidal magnetic field in a local patch on the Sun via Cartesian mode coupling. Moreover, for the first time in solar physics, Slepian functions are employed to parameterize perturbations in the horizontal dimension. This is shown to increase the number of data constraints in the inverse problem, implying an increase in the precision of inferred parameters. This paves the path to reliably imaging subsurface solar magnetic features in, e.g., supergranules and (emerging) active regions.

Keywords: helioseismology; solar oscillations; helioseismic pulsations; solar physics; solar interior; magnetohydrodynamics; sunspots; solar active regions; solar magnetic fields
The Effect of Dense Cluster Environments on Galactic Properties

Galaxy clusters are extremely over dense regions of the universe and are therefore ideal for testing how galaxy properties vary with environment. We analyze a sample of >3000 galaxy spectra from 100 galaxy cluster fields, and examine trends in redshift, Dn4000, and a formulated in-fall proxy for member and non-member galaxies. The 4000 Å break (Dn4000) reveals information about the age of each galaxy, and the product of the normalized peculiar velocity and the normalized projected radius of each cluster galaxy serves as a proxy for in-fall time, or how recently each galaxy became gravitationally bound to its cluster. We see a relationship between Dn4000 and the in-fall proxy, with more recently in-fallen galaxies being systematically younger; we interpret this trend as the effect of environmental quenching of cluster galaxies. Furthermore, we see a trend in which all cluster galaxies become older with decreasing redshift, independent of in-fall proxy.

Keywords: galaxy clusters; galaxy evolution; galaxy quenching; high-redshift galaxy clusters
A Shallow Dark Matter Halo in Ultra-diffuse Galaxy AGC 242019: Are UDGs Structurally Similar to Low-surface-brightness Galaxies?

A central question regarding ultra-diffuse galaxies (UDGs) is whether they are in a separate category from low-surface-brightness (LSB) galaxies, or just their natural continuation toward low stellar masses. In this Letter, we show that the rotation curve of the gas rich UDG AGC 242019 is well fit by a dark matter halo with an inner slope that asymptotes to ~-0.54, and that such a fit provides a concentration parameter that matches theoretical expectations. This finding, together with previous works in which shallow inner profiles are derived for UDGs, shows that the structural properties of these galaxies are like other observed LSBs. UDGs show slowly rising rotation curves and this favors formation scenarios in which internal processes, such as supernova-driven gas outflows, are acting to modify UDG profiles.

Keywords: low surface brightness galaxies; dark matter distribution; dark matter density
In Search of the Edge: A Bayesian Exploration of the Detectability of Red Edges in Exoplanet Reflection Spectra

Reflection spectroscopy holds great promise for characterizing the atmospheres and surfaces of potentially habitable terrestrial exoplanets. The surface of the modern Earth exhibits a sharp albedo change near 750 nm caused by vegetation-the red edge-which would leave a strong spectral signature if present on an exoplanet. However, the retrieval of wavelength-dependent surface properties from reflection spectra has seen relatively little study. Here, we propose a new surface albedo parameterization capable of retrieving the wavelength location of a priori unknown "edge-like" features. We demonstrate that a wavelength-dependent surface albedo model achieves higher accuracy in retrieving atmospheric composition than a uniform albedo model. Wavelength-dependent surfaces are also generally preferred over a uniform albedo model when retrieving simulated reflection spectra for a modern Earth analog, even for moderate signal-to-noise ratios (S/N = 10) and Earth-like clouds. Further, the location of the modern Earth's red edge can be robustly and precisely constrained (within 70 nm for S/N = 10). Our results suggest that future space-based direct-imaging missions have the potential to infer surface compositions for rocky exoplanets, including spectral edges similar to those caused by life on the modern Earth.

Keywords: exoplanet atmospheric composition; extrasolar rocky planets; bayesian statistics; exoplanet surface composition; direct imaging; spectroscopy
The Mass Relations between Supermassive Black Holes and Their Host Galaxies at 1 < z < 2 HST-WFC3

Correlations between the mass of a supermassive black hole (SMBH) and the properties of its host galaxy (e.g., total stellar mass M *, luminosity L host) suggest an evolutionary connection. A powerful test of a coevolution scenario is to measure the relations {{ \mathcal M }}BH}-L host and {{ \mathcal M }}BH}-M * at high redshift and compare with local estimates. For this purpose, we acquired Hubble Space Telescope (HST) imaging with WFC3 of 32 X-ray-selected broad-line (type 1) active galactic nuclei at 1.2 < z < 1.7 in deep survey fields. By applying state-of-the-art tools to decompose the HST images including available ACS data, we measured the host galaxy luminosity and stellar mass along with other properties through the two-dimensional model fitting. The black hole mass ({{ \mathcal M }}BH}) was determined using the broad Hα line, detected in the near-infrared with the Subaru Fiber Multi-Object Spectrograph, which potentially minimizes systematic effects using other indicators. We find that the observed ratio of {{ \mathcal M }}BH} to total M * is 2.7× larger at z ∼ 1.5 than in the local universe, while the scatter is equivalent between the two epochs. A nonevolving mass ratio is consistent with the data at the 2σ-3σ confidence level when accounting for selection effects (estimated using two independent and complementary methods) and their uncertainties. The relationship between {{ \mathcal M }}BH} and host galaxy total luminosity paints a similar picture. Therefore, our results cannot distinguish whether SMBHs and their total host stellar mass and luminosity proceed in lockstep or whether the growth of the former somewhat overshoots the latter, given the uncertainties. Based on a statistical estimate of the bulge-to-total mass fraction, the ratio {{ \mathcal M }}BH}/M *,bulge is offset from the local value by a factor of ∼7, which is significant even accounting for selection effects. Taken together, these observations are consistent with a scenario in which stellar mass is subsequently transferred from an angular momentum-supported component of the galaxy to a pressure-supported one through secular processes or minor mergers at a faster rate than mass accretion onto the SMBH.

Keywords: galaxy evolution; active galaxies
Fast Radio Bursts: Electromagnetic Counterparts to Extreme Mass-ratio Inspirals

Recent observations discovered that some repeating fast radio bursts (FRBs) show a large value and complex variations of Faraday rotation measures (RMs). The binary systems containing a supermassive black hole and a neutron star can be used to explain such RM variations. Meanwhile, such systems produce low-frequency gravitational-wave (GW) signals, which are one of the primary interests of three proposed space-based GW detectors: the Laser Interferometer Space Antenna (LISA), Tianqin, and Taiji. These signals are known as extreme mass-ratio inspirals (EMRIs). Therefore, FRBs can serve as candidates of electromagnetic counterparts for EMRI signals. In this Letter, we study the EMRI signals in this binary system, which can be detected up to z ~ 0.04 by LISA and Tianqin for the most optimistic case. Assuming the cosmic comb model for FRB production, the total event rate can be as high as ~1 Gpc-3 yr-1. EMRI signals associated with FRBs can be used to reveal the progenitor of FRBs. It is also a new type of standard siren, which can be used as an independent cosmological probe.

Keywords: radio transient sources; magnetars; gravitational wave sources
DPNNet-2.0. I. Finding Hidden Planets from Simulated Images of Protoplanetary Disk Gaps

The observed substructures, like annular gaps, in dust emissions from protoplanetary disks are often interpreted as signatures of embedded planets. Fitting a model of planetary gaps to these observed features using customized simulations or empirical relations can reveal the characteristics of the hidden planets. However, customized fitting is often impractical owing to the increasing sample size and the complexity of disk-planet interaction. In this paper we introduce the architecture of DPNNet-2.0, second in the series after DPNNet, designed using a convolutional neural network (CNN, specifically ResNet50 here) for predicting exoplanet masses directly from simulated images of protoplanetary disks hosting a single planet. DPNNet-2.0 additionally consists of a multi-input framework that uses both a CNN and multilayer perceptron (a class of artificial neural network) for processing image and disk parameters simultaneously. This enables DPNNet-2.0 to be trained using images directly, with the added option of considering disk parameters (disk viscosities, disk temperatures, disk surface-density profiles, dust abundances, and particle Stokes numbers) generated from disk-planet hydrodynamic simulations as inputs. This work provides the required framework and is the first step toward the use of computer vision (implementing CNNs) to directly extract the mass of an exoplanet from planetary gaps observed in dust surface-density maps by telescopes such as the Atacama Large Millimeter/submillimeter Array.

Keywords: exoplanet detection methods; convolutional neural networks; neural networks; protoplanetary disks
Star Formation Variability as a Probe for the Baryon Cycle within Galaxies

We investigate the connection between the regulation of star formation and the cycling of baryons both within and in and out of galaxies. We use idealized numerical simulations of Milky Way-mass galaxies, in which we vary the galaxy morphology and stellar feedback strength. By following individual gas parcels through the disk, spiral arms, and massive star-forming clumps, we quantify how gas moves through the different phases of the interstellar medium (ISM) and forms stars. We show that the residence time of gas in the dense ISM phase (τ SF), the nature of spiral arms, and the clump properties depend on both the galaxy morphology and stellar feedback. We quantify signatures of the baryon cycle within galaxies using the temporal and spatial power spectrum density (PSD) of the star formation rate (SFR). Stronger stellar feedback leads to more bursty star formation while the correlation timescale of the SFH is longer, because stronger feedback dissolves the dense ISM phase, leading to a more homogeneous ISM and a decrease in τ SF. The bulge strength has a similar effect: the deep gravitational potential in a bulge-dominant galaxy imposes a strong shear force that breaks apart gas clumps in the ISM; this subsequently inhibits the fragmentation of gas and therefore the star formation in the disk, leading to a decrease in the spatial power on scales of ~1 kpc. We conclude that measurements of the temporal and spatial PSD of the SFR can provide constraints on the baryon cycle and the star formation process.

Keywords: galaxy dynamics; galaxy evolution; milky way galaxy; interstellar magnetic fields; stellar physics; interstellar phases; interstellar medium; stellar feedback
Lunar Surface Composition Constraints from Maturity-corrected Far-ultraviolet Reflectance Maps

Far-ultraviolet (FUV) observations by the Lunar Reconnaissance Orbiter Lyman Alpha Mapping Project (LAMP) have shown that the lunar surface reflectance in the ultraviolet is sensitive to changes in both composition and maturity at wavelengths >170 nm. This can lead to uncertainties in the interpretation of features that appear in maps created using LAMP data from this wavelength range. Here we utilize a correction based on the optical maturity parameter to remove large-scale immaturity features from LAMP spectral slope and band ratio maps. After performing the correction, the LAMP maps more accurately represent the FUV lunar surface in the context of composition. Corrected LAMP maps show good correlation with lunar FeO, plagioclase, and bulk silicate abundance maps for moderate- to high-iron regions, indicating a sensitivity in the LAMP data to differences in mineral composition in those regions. These maps represent a unique view into a relatively unexplored region of the spectrum and showcase the ability to perform compositional mapping and mineral identification using FUV remote-sensing measurements.

Keywords: the moon; lunar composition; lunar science
Verification of Gaia Data Release 3 Single-lined Spectroscopic Binary Solutions With Three Transiting Low-mass Secondaries

While secondary mass inferences based on single-lined spectroscopic binary (SB1) solutions are subject to $\sin i$ degeneracies, this degeneracy can be lifted through the observations of eclipses. We combine the subset of Gaia Data Release 3 SB1 solutions consistent with brown dwarf-mass secondaries with the Transiting Exoplanet Survey Satellite (TESS) Object of Interest (TOI) list to identify three candidate transiting brown dwarf systems. Ground-based precision radial velocity follow-up observations confirm that TOI-2533.01 is a transiting brown dwarf with $M={72}_{-3}^{+3}\,{M}_{\mathrm{Jup}}={0.069}_{-0.003}^{+0.003}\,{M}_{\odot }$ orbiting TYC 2010-124-1 and that TOI-5427.01 is a transiting very low-mass star with $M={93}_{-2}^{+2}\,{M}_{\mathrm{Jup}}={0.088}_{-0.002}^{+0.002}\,{M}_{\odot }$ orbiting UCAC4 515-012898. We validate TOI-1712.01 as a very low-mass star with $M={82}_{-7}^{+7}\,{M}_{\mathrm{Jup}}={0.079}_{-0.007}^{+0.007}\,{M}_{\odot }$ transiting the primary in the hierarchical triple system BD+45 1593. Even after accounting for third light, TOI-1712.01 has a radius nearly a factor of 2 larger than predicted for isolated stars with similar properties. We propose that the intense instellation experienced by TOI-1712.01 diminishes the temperature gradient near its surface, suppresses convection, and leads to its inflated radius. Our analyses verify Gaia DR3 SB1 solutions in the low Doppler semiamplitude limit, thereby providing the foundation for future joint analyses of Gaia radial velocities and Kepler, K2, TESS, and PLAnetary Transits and Oscillations light curves for the characterization of transiting massive brown dwarfs and very low-mass stars.

Keywords: brown dwarfs; eclipsing binary stars; substellar companion stars; spectroscopic binary stars; stellar radii; trinary stars; low mass stars
Fast Sausage Oscillations in Coronal Loops with Fine Structures

Fast sausage modes (FSMs) in flare loops have long been invoked to account for rapid quasi-periodic pulsations (QPPs) with periods of order seconds in flare lightcurves. However, most theories of FSMs in solar coronal cylinders assume a perfectly axisymmetric equilibrium, an idealized configuration apparently far from reality. In particular, it remains to be examined whether FSMs exist in coronal cylinders with fine structures. Working in the framework of ideal magnetohydrodynamics (MHD), we numerically follow the response to an axisymmetric perturbation of a coronal cylinder for which a considerable number of randomly distributed fine structures are superposed on an axisymmetric background. The parameters for the background component are largely motivated by the recent IRIS identification of a candidate FSM in Fe XXI 1354 Å observations. We find that the composite cylinder rapidly settles to an oscillatory behavior largely compatible with a canonical trapped FSM. This happens despite that kink-like motions develop in the fine structures. We further synthesize the Fe XXI 1354 Å emissions, finding that the transverse Alfvén time characterizes the periodicities in the intensity, Doppler shift, and Doppler width signals. Distinct from the case without fine structuring, a nonvanishing Doppler shift is seen even at the apex. We conclude that density-enhanced equilibria need not be strictly axisymmetric to host FSM-like motions in general, and FSMs remain a candidate interpretation for rapid QPPs in solar flares.

Keywords: solar corona; magnetohydrodynamics
The Impact of the Mass Spectrum of Lenses in Quasar Microlensing Studies. Constraints on a Mixed Population of Primordial Black Holes and Stars

We show that quasar microlensing magnification statistics induced by a population of point microlenses distributed according to a mass spectrum can be very well approximated by that of a single-mass, monochromatic, population. When the spatial resolution (physically defined by the source size) is small compared with the Einstein radius, the mass of the monochromatic population matches the geometric mean (GM) of the mass spectrum. Otherwise, the best-fit mass can be larger. Taking into account the degeneracy with the GM, the interpretation of quasar microlensing observations under the hypothesis of a mixed population of primordial black holes and stars makes the existence of a significant population of intermediate mass black holes (∼100M⊙) unlikely but allows, within a 2σ confidence interval, the presence of a large population (≳40% of the total mass) of substellar black holes (∼0.01M⊙).

Keywords: gravitational microlensing; black hole physics
Phase-dependent Evolution within the Large Luminosity Range of 1A 0535+262 Observed by Insight-HXMT during 2020 Giant Outburst

We have performed phase-resolved spectral analysis of the accreting pulsar 1A 0535+262 based on observations of Insight-HXMT during the 2020 type II outburst of the source. We focus on the two-dimensional dependence of the cyclotron resonance scattering features (CRSFs) along the outburst time and at different phases. The fundamental CRSF line (f-CRSF) shows different time- and phase-dependent behaviors. At higher luminosity, the phase profile of the f-CRSF energy changes from a single peak to double peaks, with the transition occurring at MJD 59185. On the contrary, the first harmonic CRSF (first CRSF) at ~100 keV is only detected within a narrow phase range (0.8-1.0) accompanied by a shallow f-CRSF line. Based on these results, we speculate that when the source enters the supercritical regime, the higher accretion column height can significantly enhance the harmonic line at a narrow phase through an "anti-pencil" beam at a higher energy band. At the same time, it will also affect the behavior of the fundamental line.

Keywords: binary pulsars; high mass x-ray binary stars; accretion; magnetic fields