adsabs/SciX_UAT_keywords huggingface dataset:
High-z Universe Probed via Lensing by QSOs (HULQ). I. Number Estimates of QSO-QSO and QSO-Galaxy Lenses

It is unclear how galaxies and their central supermassive black holes coevolve across cosmic time, especially for the nonlocal universe (z ≳ 0.5). The High-z Universe probed via Lensing by QSOs project proposes to utilize quasi-stellar object (QSO) host galaxies acting as gravitational lenses (QSO lenses) to investigate this topic. This paper focuses on the feasibility of this project, that is, whether sufficiently large numbers of QSO lenses are expected to be found in various concurrent and future imaging surveys. We find that ∼440 QSO lenses will reside in the Hyper Suprime-Cam Wide survey (HSC/Wide), which is expected to be the most prolific concurrent survey, with this number being boosted by one to two orders of magnitude (to ∼10,000) with upcoming surveys such as that conducted with the Large Synoptic Survey Telescope (LSST). We discuss several methods of how to study the redshift evolution of the ${M}_{\mathrm{BH}}\mbox{--}{\sigma }_{* }$ relation, which is a standout illustration of the coevolution. In addition, we demonstrate how the intimacy of lensed images to the bright deflector QSO for most systems will affect the detectability of QSO lenses. We estimate that only ∼82 and 900 will be detectable for HSC/Wide and LSST, respectively; the decrease is significant yet still yields an acceptable sample for the main objective. This decrease will be less of a problem for space-based imaging surveys, for their small point-spread function FWHMs will allow detections of lensed images lying relatively close to the deflector QSO, and thus unveil the less massive yet more numerous QSO hosts.

Keywords: galaxy evolution; galaxies; gravitational lensing; active galaxies; agn host galaxies; supermassive black holes; quasars; strong gravitational lensing
The California-Kepler Survey. X. The Radius Gap as a Function of Stellar Mass, Metallicity, and Age

In 2017, the California-Kepler Survey (CKS) published its first data release (DR1) of high-resolution optical spectra of 1305 planet hosts. Refined CKS planet radii revealed that small planets are bifurcated into two distinct populations, super-Earths (smaller than 1.5 R ⊕) and sub-Neptunes (between 2.0 and 4.0 R ⊕), with few planets in between (the "radius gap"). Several theoretical models of the radius gap predict variation with stellar mass, but testing these predictions is challenging with CKS DR1 due to its limited M ⋆ range of 0.8-1.4 M ⊙. Here we present CKS DR2 with 411 additional spectra and derived properties focusing on stars of 0.5-0.8 M ⊙. We found that the radius gap follows R p ∝ P m with m = -0.10 ± 0.03, consistent with predictions of X-ray and ultraviolet- and core-powered mass-loss mechanisms. We found no evidence that m varies with M ⋆. We observed a correlation between the average sub-Neptune size and M ⋆. Over 0.5-1.4 M ⊙, the average sub-Neptune grows from 2.1 to 2.6 R ⊕, following ${R}_{p}\propto {M}_{\star }^{\alpha }$ with α = 0.25 ± 0.03. In contrast, there is no detectable change for super-Earths. These M ⋆-R p trends suggest that protoplanetary disks can efficiently produce cores up to a threshold mass of M c , which grows linearly with stellar mass according to M c ≈ 10 M ⊕(M ⋆/M ⊙). There is no significant correlation between sub-Neptune size and stellar metallicity (over -0.5 to +0.5 dex), suggesting a weak relationship between planet envelope opacity and stellar metallicity. Finally, there is no significant variation in sub-Neptune size with stellar age (over 1-10 Gyr), which suggests that the majority of envelope contraction concludes after ~1 Gyr.

Keywords: exoplanet astronomy; exoplanet formation; transit photometry; exoplanets; super earths; mini neptunes; high resolution spectroscopy
Black Hole Mergers from Star Clusters with Top-heavy Initial Mass Functions

Recent observations of globular clusters (GCs) provide evidence that the stellar initial mass function (IMF) may not be universal, suggesting specifically that the IMF grows increasingly top-heavy with decreasing metallicity and increasing gas density. Noncanonical IMFs can greatly affect the evolution of GCs, mainly because the high end determines how many black holes (BHs) form. Here we compute a new set of GC models, varying the IMF within observational uncertainties. We find that GCs with top-heavy IMFs lose most of their mass within a few gigayears through stellar winds and tidal stripping. Heating of the cluster through BH mass segregation greatly enhances this process. We show that, as they approach complete dissolution, GCs with top-heavy IMFs can evolve into "dark clusters" consisting of mostly BHs by mass. In addition to producing more BHs, GCs with top-heavy IMFs also produce many more binary BH (BBH) mergers. Even though these clusters are short-lived, mergers of ejected BBHs continue at a rate comparable to, or greater than, what is found for long-lived GCs with canonical IMFs. Therefore, these clusters, though they are no longer visible today, could still contribute significantly to the local BBH merger rate detectable by LIGO/Virgo, especially for sources with higher component masses well into the BH mass gap. We also report that one of our GC models with a top-heavy IMF produces dozens of intermediate-mass black holes (IMBHs) with masses $M\gt 100\,{M}_{\odot }$ , including one with $M\gt 500\,{M}_{\odot }$ . Ultimately, additional gravitational wave observations will provide strong constraints on the stellar IMF in old GCs and the formation of IMBHs at high redshift.

Keywords: initial mass function; stellar mass black holes; globular star clusters; stellar dynamics; n-body simulations; gravitational wave sources
Understanding Type Ia Supernova Distance Biases by Simulating Spectral Variations

In the next decade, transient searches from the Vera C. Rubin Observatory and the Nancy Grace Roman Space Telescope will increase the sample of known Type Ia supernovae (SNe Ia) from ∼103 to 105. With this reduction of statistical uncertainties on cosmological measurements, new methods are needed to reduce systematic uncertainties. Characterizing the underlying spectroscopic evolution of SN Ia remains a major systematic uncertainty in current cosmological analyses, motivating a new simulation tool for the next era of SN Ia cosmology: Build Your Own Spectral Energy Distribution (BYOSED). BYOSED is used within the SNANA framework to simulate light curves by applying spectral variations to model SEDs, enabling flexible testing of possible systematic shifts in SN Ia distance measurements. We test the framework by comparing a nominal Roman SN Ia survey simulation using a baseline SED model to simulations using SEDs perturbed with BYOSED, and investigating the impact of ignoring specific SED features in the analysis. These features include semiempirical models of two possible, predicted relationships: between SN ejecta velocity and light-curve observables, and a redshift-dependent relationship between SN Hubble residuals and host-galaxy mass. We analyze each BYOSED simulation using the SALT2 and BEAMS with Bias Corrections framework, and estimate changes in the measured value of the dark-energy equation-of-state parameter, w. We find a difference of Δw = -0.023 for SN velocity and Δw = 0.021 for redshift-evolving host mass when compared to simulations without these features. By using BYOSED for SN Ia cosmology simulations, future analyses (e.g., the Rubin and Roman SN Ia samples) will have greater flexibility to constrain or reduce such SN Ia modeling uncertainties.

Keywords: type ia supernovae; cosmology; astronomical simulations
The TESS Faint-star Search: 1617 TOIs from the TESS Primary Mission

We present the detection of 1617 new transiting-planet candidates, identified in the Transiting Exoplanet Survey Satellite (TESS) full-frame images observed during the Primary Mission (Sectors 1-26). These candidates were initially detected by the Quick-Look Pipeline (QLP), which extracts full-frame image lightcurves for, and searches all stars brighter than, TESS magnitude T = 13.5 mag in each sector. However, QLP heavily relies on manual inspection for the identification of planet candidates, limiting vetting efforts to planet-hosting stars brighter than T = 10.5 mag and leaving millions of potential transit signals unvetted. We describe an independent vetting pipeline applied to QLP transit search results, incorporating both automated vetting tests and manual inspection to identify promising planet candidates around these fainter stars. The new candidates discovered by this ongoing project will allow TESS to significantly improve the statistical power of demographic studies of giant, close-in exoplanets.

Keywords: exoplanets; exoplanet detection methods; transit photometry; time series analysis
Electron Holography Details the Tagish Lake Parent Body and Implies Early Planetary Dynamics of the Solar System

The degree of aqueous alteration of small bodies in the solar system depends on the time of their formation, their size, and collisions with other bodies, among other factors. Therefore, a knowledge of the aqueous alterations recorded in meteorites is crucial to understanding the history of our solar system. The Tagish Lake meteorite, believed to have formed in the cold outer solar system, contains framboidal magnetite, a major product of the aqueous process. By in situ annealing experiments on the magnetic properties of the magnetite by electron holography and by numerical simulations, we show that the interior temperature of the parent body of the Tagish Lake meteorite reached ~250°C as a result of radiogenic heating and an energetic impact. Our nanometer-scale magnetic study suggested that the parent body grew to >160 km in diameter in the Kuiper Belt at ~3 Myr after the first solar system minerals formed and then experienced an energetic impact from a smaller body with a diameter of ~10 km at a speed of ~5 km s-1 about 4-5 Myr after the first minerals. The probability of such a high-impact-velocity event would have increased during travel of the parent body from the Kuiper Belt to the asteroid belt, triggered by the formation and migration of the giant planets. Our results imply the early dynamics of solar system bodies that occurred several million years after the formation of the solar system and a highly efficient formation of the outer bodies of the solar system, including Jupiter.

Keywords: meteorites; planetary dynamics
Migratory Outbursting Quasi-Hilda Object 282P/(323137) 2003 BM80

We report that object 282P/(323137) 2003 BM80 is undergoing a sustained activity outburst, lasting over 15 months thus far. These findings stem in part from our NASA Partner Citizen Science project Active Asteroids (http://activeasteroids.net), which we introduce here. We acquired new observations of 282P via our observing campaign (Vatican Advanced Technology Telescope (VATT), Lowell Discovery Telescope (LDT), and the Gemini South telescope), confirming 282P was active on UT 2022 June 7, some 15 months after 2021 March images showed activity in the 2021-2022 epoch. We classify 282P as a member of the quasi-Hilda objects (QHOs), a group of dynamically unstable objects found in an orbital region similar to, but distinct in their dynamical characteristics to, the Hilda asteroids (objects in 3:2 resonance with Jupiter). Our dynamical simulations show 282P has undergone at least five close encounters with Jupiter and one with Saturn over the last 180 yr. 282P was most likely a Centaur or Jupiter-family comet (JFC) 250 yr ago. In 350 yr, following some 15 strong Jovian interactions, 282P will most likely migrate to become a JFC or, less likely, an outer main-belt asteroid orbit. These migrations highlight a dynamical pathway connecting Centaurs and JFCs with quasi-Hildas and, potentially, active asteroids. Synthesizing these results with our thermodynamical modeling and new activity observations, we find volatile sublimation is the primary activity mechanism. Observations of a quiescent 282P, which we anticipate will be possible in 2023, will help confirm our hypothesis by measuring a rotation period and ascertaining the spectral type. * Based on observations obtained at the international Gemini Observatory, a program of NSF's NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). ** Magellan telescope time was granted by NSF's NOIRLab, through the Telescope System Instrumentation Program (TSIP). TSIP was funded by the National Science Foundation (NSF).

Keywords: hilda group; comet dynamics; comet tails; centaur group; asteroid dynamics
Synthetic Light Curves of Accretion Variability in T Tauri Stars

Photometric observations of accreting, low-mass, pre-main-sequence stars (i.e., Classical T Tauri stars; CTTS) have revealed different categories of variability. Several of these classifications have been linked to changes in $\dot{M}$ . To test how accretion variability conditions lead to different light-curve morphologies, we used 1D hydrodynamic simulations of accretion along a magnetic field line coupled with radiative transfer models and a simple treatment of rotation to generate synthetic light curves. We adopted previously developed metrics in order to classify observations to facilitate comparisons between observations and our models. We found that stellar mass, magnetic field geometry, corotation radius, inclination, and turbulence all play roles in producing the observed light curves and that no single parameter is entirely dominant in controlling the observed variability. While the periodic behavior of the light curve is most strongly affected by the inclination, it is also a function of the magnetic field geometry and inner disk turbulence. Objects with either pure dipole fields, strong aligned octupole components, or high turbulence in the inner disk all tend to display accretion bursts. Objects with anti-aligned octupole components or aligned, weaker octupole components tend to show light curves with slightly fewer bursts. We did not find clear monotonic trends between the stellar mass and empirical classification. This work establishes the groundwork for more detailed characterization of well-studied targets as more light curves of CTTS become available through missions such as the Transiting Exoplanet Survey Satellite (TESS).

Keywords: classical t tauri stars; stellar accretion; hydrodynamical simulations; light curve classification
SDSS-V Algorithms: Fast, Collision-free Trajectory Planning for Heavily Overlapping Robotic Fiber Positioners

Robotic fiber positioner (RFP) arrays are becoming heavily adopted in wide-field massively multiplexed spectroscopic survey instruments. RFP arrays decrease nightly operational overheads through rapid reconfiguration between fields and exposures. In comparison to similar instruments, SDSS-V has selected a very dense RFP packing scheme where any point in a field is typically accessible to three or more robots. This design provides flexibility in target assignment. However, the task of collisionless trajectory planning is especially challenging. We present two multiagent distributed control strategies that are highly efficient and computationally inexpensive for determining collision-free paths for RFPs in heavily overlapping workspaces. We demonstrate that a reconfiguration path between two arbitrary robot configurations can be efficiently found if a "folded" state, in which all robot arms are retracted and aligned in a lattice-like orientation, is inserted between the initial and final states. Although developed for SDSS-V, the approach we describe is generic and thus applicable to a wide range of RFP designs and layouts. Robotic fiber positioner technology continues to advance rapidly, and in the near future ultra-densely packed RFP designs may be feasible. Our algorithms are especially capable in routing paths in very crowded environments, where we see efficient results even in regimes significantly more crowded than the SDSS-V RFP design.

Keywords: astronomy software; open source software; wide-field telescopes; sky surveys; astronomical instrumentation; spectroscopy; algorithms
Evaluating the Thickness and Stratigraphy of Ejecta Materials at the Change-4 Landing Site

The landing site of Chinas Change-4 (CE-4) probe is located on the mare basalts on the floor of the Von Krmn crater on the lunar far side. The Von Krmn crater is inside the ancient and highly cratered South PoleAitken basin, which has experienced complex emplacement sequences of both near and distant ejecta materials. These issues complicated the interpretation of the CE-4 surface in situ measurements of the visible and near-infrared spectrometer and the lunar penetrating radar (LPR) onboard Yutu-2 rover. To evaluate the sources and amounts of all principle foreign materials at the CE-4 landing site, we thoroughly examine the ejecta delivered by crater-forming events that occurred later than the formation of the mare basalts at the CE-4 landing site. We found a total of 16 craters that may have delivered ejecta thicker than 10 cm level superposed on the mare basalts at the CE-4 landing site. Crater Finsen, Von Krmn L, Von Krmn L, and Maksutov are the top four major foreign material sources, and each of them contributed ejecta thicker than 1 m. Our surveys confirm that the ejecta from Finsen crater are the most dominant foreign materials in the uppermost few meters at the CE-4 landing site and the total impact ejecta deposited upon the mare basalts at the landing site is estimated to be thinner than 30 m. We found that the estimations from Pikes model are the most consistent with the Yutu-2 LPR observations.

Keywords: the moon; lunar craters
Meso-scale Instability Triggered by Dust Feedback in Dusty Rings: Origin and Observational Implications

High spatial resolution observations of protoplanetary disks by ALMA have revealed many substructures that are providing interesting constraints on disk physics as well as dust dynamics, both of which are essential for understanding planet formation. We carry out high-resolution, 2D global hydrodynamic simulations, including the effects of dust feedback, to study the stability of dusty rings. When the ring edges are relatively sharp and the dust surface density becomes comparable to the gas surface density, we find that dust feedback enhances the radial gradients of both the azimuthal velocity profile and the potential vorticity profile at the ring edges. This eventually leads to instabilities on meso-scales (spatial scales of several disk scale heights), causing dusty rings to be populated with many compact regions with highly concentrated dust densities. We also produce synthetic dust emission images using our simulation results and discuss the comparison between simulations and observations.

Keywords: planet formation; hydrodynamical simulations; submillimeter astronomy; protoplanetary disks; hydrodynamics; radiative transfer simulations
22Ne Phase Separation as a Solution to the Ultramassive White Dwarf Cooling Anomaly

The precise astrometric measurements of the Gaia Data Release 2 have opened the door to detailed tests of the predictions of white dwarf cooling models. Significant discrepancies between theory and observations have been identified, the most striking affecting ultramassive white dwarfs. Cheng et al. found that a small fraction of white dwarfs on the so-called Q branch must experience an extra cooling delay of ∼8 Gyr not predicted by current models. 22Ne phase separation in a crystallizing C/O white dwarf can lead to a distillation process that efficiently transports 22Ne toward its center, thereby releasing a considerable amount of gravitational energy. Using state-of-the-art Monte Carlo simulations, we show that this mechanism can largely resolve the ultramassive cooling anomaly if the delayed population consists of white dwarfs with moderately above-average 22Ne abundances. We also argue that 22Ne phase separation can account for the smaller cooling delay currently missing for models of white dwarfs with more standard compositions.

Keywords: cosmochronology; degenerate matter; plasma physics; stellar evolution; stellar interiors; white dwarf stars
Nuclear Matter and Neutron Stars from Relativistic Brueckner-Hartree-Fock Theory

The momentum and isospin dependence of the single-particle potential for the in-medium nucleon are the key quantities in the Relativistic Brueckner-Hartree-Fock (RBHF) theory. It depends on how to extract the scalar and the vector components of the single-particle potential inside nuclear matter. In contrast to the RBHF calculations in the Dirac space with the positive-energy states (PESs) only, the single-particle potential can be determined in a unique way by the RBHF theory together with the negative-energy states, i.e., the RBHF theory in the full Dirac space. The saturation properties of symmetric and asymmetric nuclear matter in the full Dirac space are systematically investigated based on the realistic Bonn nucleon-nucleon potentials. In order to further specify the importance of the calculations in the full Dirac space, the neutron star properties are investigated. The direct URCA process in neutron star cooling will happen at density ρ DURCA = 0.43, 0.48, 0.52 fm-3 with proton fractions of Y p,DURCA = 0.13. The radii of a 1.4M ⊙ neutron star are predicated as ${R}_{1.4{M}_{\odot }}=11.97,12.13,12.27$ km, and their tidal deformabilities are ${{\rm{\Lambda }}}_{1.4{M}_{\odot }}=376,405,433$ for potential Bonn A, B, C. Compared with the results obtained in the Dirac space with PESs only, the full-Dirac-space RBHF calculation predicts the softest symmetry energy, which would be more favored by the gravitational wave detection of GW170817. Furthermore, the results from the full-Dirac-space RBHF theory are consistent with the recent astronomical observations of massive neutron stars and simultaneous mass-radius measurement.

Keywords: nuclear physics
Deep Orbital Search for Additional Planets in the HR 8799 System

The HR 8799 system hosts four massive planets orbiting 15 and 80 au. Studies of the system's orbital stability and its outer debris disk open the possibility of additional planets, both interior to and exterior to the known system. Reaching a sufficient sensitivity to search for interior planets is very challenging due to the combination of bright quasi-static speckle noise close to the stellar diffraction core and relatively fast orbital motion. In this work, we present a deep L-band imaging campaign using NIRC2 at Keck comprising 14 observing sequences. We further re-reduce archival data for a total of 16.75 hr, one of the largest uniform data sets of a single direct imaging target. Using a Bayesian modeling technique for detecting planets in images while compensating for plausible orbital motion, we then present deep limits on the existence of additional planets in the HR 8799 system. The final combination shows a tentative candidate, consistent with 4-7 M jup at 4-5 au, detected with an equivalent false-alarm probability better than 3σ. This analysis technique is widely applicable to archival data and to new observations from upcoming missions that revisit targets at multiple epochs.

Keywords: exoplanets; direct imaging