adsabs/SciX_UAT_keywords huggingface dataset:
The Redshift Evolution of the M •–M ⋆ Relation for JWST's Supermassive Black Holes at z > 4

JWST has detected many overmassive galactic systems at z > 4, where the mass of the black hole, M •, is 10–100 times larger than expected from local relations, given the host's stellar mass, M ⋆. This paper presents a model to describe these overmassive systems in the high-z Universe. We suggest that the black hole mass is the main driver of high-z star formation quenching. Supermassive black holes globally impact their high-z galaxies because their hosts are physically small, and the black holes have duty cycles close to unity at z > 4. In this regime, we assume that black hole mass growth is regulated by the quasar's output, while stellar mass growth is quenched by it and uncorrelated to the global properties of the host halo. We find that the ratio M •/M ⋆ controls the average star formation efficiency: if M •/M ⋆ > 8 × 1018(nΛ/ f Edd)[(Ω b M h )/(Ω m M ⋆) ‑ 1], then the galaxy is unable to form stars efficiently. Once this ratio exceeds the threshold, a runaway process brings the originally overmassive system toward the local M •–M ⋆ relation. Furthermore, the M •–M ⋆ relation evolves with redshift as ∝(1 + z)5/2. At z ∼ 5, we find an overmassive factor of ∼55, in excellent agreement with current JWST data and the high-z relation inferred from those. Extending the black hole horizon farther in redshift and lower in mass will test this model and improve our understanding of the early coevolution of black holes and galaxies.

Keywords: active galaxies; supermassive black holes; galaxy evolution; star formation; surveys
MARVEL Analysis of the Measured High-resolution Rovibronic Spectra of the Calcium Monohydroxide Radical (CaOH)

The calcium monohydroxide radical (CaOH) is an important astrophysical molecule relevant to cool stars and rocky exoplanets, among other astronomical environments. Here, we present a consistent set of highly accurate rovibronic (rotation-vibration-electronic) energy levels for the five lowest electronic states ( $\tilde{X}{}^{2}{{\rm{\Sigma }}}^{+}$ , $\tilde{A}{}^{2}{\rm{\Pi }}$ , $\tilde{B}{}^{2}{{\rm{\Sigma }}}^{+}$ , $\tilde{C}{}^{2}{\rm{\Delta }}$ , and $\tilde{D}{}^{2}{{\rm{\Sigma }}}^{+}$ ) of CaOH. A comprehensive analysis of the published spectroscopic literature on this system has allowed 1955 energy levels to be determined from 3204 rovibronic experimental transitions, all with unique quantum number labeling and measurement uncertainties. The data set covers rotational excitation up to J = 62.5 for molecular states below 29,000 cm-1. The analysis was performed using the Measured Active Rotational-Vibrational Energy Levels algorithm, which is a robust procedure based on the theory of spectroscopic networks. The data set provided will significantly aid future interstellar, circumstellar, and atmospheric detections of CaOH, as well as assist in the design of efficient laser cooling schemes in ultracold molecule research and precision tests of fundamental physics.

Keywords: molecular spectroscopy; exoplanet atmospheres; astronomy databases
Can We Estimate the Intensities of Great Geomagnetic Storms (ΔSYM-H ≤ -200 nT) with the Burton Equation or the O'Brien and McPherron Equation?

We input the solar wind parameters responsible for the main phases of 15 great geomagnetic storms (GGSs; ΔSYM-H ≤ -200 nT) into the empirical formulae created by Burton et al. (hereafter the Burton equation) and by OBrien & McPherron (hereafter the OM equation) to evaluate whether these two equations can correctly estimate the intensities of GGSs. The results show that the intensities of most GGSs estimated by the OM equation are much smaller than the observed intensities. The rms error between the intensities estimated by the OM equation and the observed intensities is 203 nT, implying that the estimated storm intensity deviates significantly from the observed one. The rms error between the intensities estimated by the Burton equation and the observed intensities is 130.8 nT. The relative error caused by the Burton equation for storms with intensities ΔSYM-H<-400 nT is larger than 27%, implying that the absolute error will be large for storms with ΔSYM-H < -400 nT. The results indicate that the two equations cannot predict the intensities of GGSs correctly. On the contrary, the intensity of a GGS estimated by the empirical formula created by Wang et al. can approximate observations better if we select the right weight for the solar wind dynamic pressure, proving that solar wind dynamic pressure is an important factor of GGS intensity. This pressure is overlooked by the ring current injection terms of the Burton and OM equations. This is the reason why the two equations do not effectively estimate GGSs.

Keywords: solar wind; space weather; solar-terrestrial interactions
H2 Rovibrational Excitation in Protoplanetary Disks and Its Effects on the Chemistry

The effect of H2 rovibrational excitation on the chemistry of protoplanetary disks is studied using a framework that solves for the disk physical and chemical structure and includes a detailed calculation of H2 level populations. Chemistry with rovibrationally excited H2 is found to be important for the formation of several commonly observed species in disks and this work demonstrates the need to accurately treat photon-dominated-region chemistry in disks if we are to make inferences on the chemical state of the disk during planet formation epochs. This is found to be even more critical for molecules like C2H, CN, or HCN that are commonly used to infer changes in the elemental disk C/O and N/O ratios, with implications for planetesimal formation and the composition of exoplanet atmospheres. Computed vertical column densities with the full H2 population calculation are increased by ~1-2 orders of magnitude for molecules such as CN and HCN/HNC compared to calculations with no treatment of excited H2. For the commonly used pseudo-level approximation, the computed columns of these molecules are overestimated by a factor of ~3-5 when compared to the full model. We further note that the computed abundance for these molecules strongly depends on the strength of the FUV photons at energies that pump H2 (i.e., 11-13.6 eV), which is not well constrained in disks, and that rate constants as a function of H2 rovibrational levels for the key reaction N + H2 → NH are needed for a more accurate assessment of CN/HCN chemistry but are currently unavailable.

Keywords: protoplanetary disks; astrochemistry; star formation; chemical abundances
Analysis of Gaia DR3 Data of Selected High Galactic Latitude Hα Emission Stars

Gaia DR3 data of 52 high galactic latitude Hα emission stars selected from the paper of Stephenson are analyzed. Ten new variable stars and eight new high velocity stars have been found. Details of six post-AGB stars and several other interesting stars are discussed. Many of the stars presented in this paper have Gaia DR3 light curves and spectra. A detailed study of these 52 stars is needed to derive their chemical composition and to further understand their binarity, circumstellar matter and evolutionary status. The astrophysical parameters from the Gaia DR3 data reveal several hot (OBA) and several F and G-type stars in this sample. Some of them are metal-poor stars.

Keywords: h-alpha stars
Evolution of the Density PDF in Star-forming Clouds: The Role of Gravity

We derive an analytical theory of the PDF of density fluctuations in supersonic turbulence in the presence of gravity in star-forming clouds. The theory is based on a rigorous derivation of a combination of the Navier-Stokes continuity equations for the fluid motions and the Poisson equation for the gravity. It extends previous approaches, first by including gravity and second by considering the PDF as a dynamical system, not a stationary one. We derive the transport equations of the density PDF, characterize its evolution, and determine the density threshold above which gravity strongly affects and eventually dominates the dynamics of turbulence. We demonstrate the occurrence of two power-law tails in the PDF, with two characteristic exponents, corresponding to two different stages in the balance between turbulence and gravity. Another important result of this study is to provide a procedure to relate the observed column density PDFs to the corresponding volume density PDFs. This allows us to infer, from the observation of column densities, various physical parameters characterizing molecular clouds, notably the virial parameter. Furthermore, the theory offers the possibility to date the clouds in units of tcoll, the time since a statistically significant fraction of the cloud started to collapse. The theoretical results and diagnostics reproduce very well numerical simulations and observations of star-forming clouds. The theory provides a sound theoretical foundation and quantitative diagnostics to analyze observations or numerical simulations of star-forming regions and to characterize the evolution of the density PDF in various regions of molecular clouds.

Keywords: molecular clouds; star formation; hydrodynamics
Detectability of Axisymmetric Magnetic Fields from the Core to the Surface of Oscillating Post-main-sequence Stars

Magnetic fields in the stellar interiors are key candidates to explain observed core rotation rates inside solar-like stars along their evolution. Recently, asteroseismic estimates of radial magnetic field amplitudes near the hydrogen-burning shell (H-shell) inside about 24 red giants (RGs) have been obtained by measuring frequency splittings from their power spectra. Using general Lorentz-stress (magnetic) kernels, we investigated the potential for detectability of near-surface magnetism in a 1.3 M ⊙ star of supersolar metallicity as it evolves from a mid subgiant to a late subgiant into an RG. Based on these sensitivity kernels, we decompose an RG into three zones—deep core, H-shell, and near-surface. The subgiants instead required decomposition into an inner core, an outer core, and a near-surface layer. Additionally, we find that for a low-frequency g-dominated dipolar mode in the presence of a typical stable magnetic field, ∼25% of the frequency shift comes from the H-shell and the remaining from deeper layers. The ratio of the subsurface tangential field to the radial field in the H-burning shell decides if subsurface fields may be potentially detectable. For p-dominated dipole modes close to , this ratio is around two orders of magnitude smaller in subgiant phases than the corresponding RG. Further, with the availability of magnetic kernels, we propose lower limits of field strengths in crucial layers in our stellar model during its evolutionary phases. The theoretical prescription outlined here provides the first formal way to devise inverse problems for stellar magnetism and can be seamlessly employed for slow rotators.

Keywords: asteroseismology; stellar interiors; stellar magnetic fields; stellar oscillations; red giant stars; subgiant stars; perturbation methods
Anatomy of a Slow Merger: Dissecting Secularly Driven Inspirals of LIGO/Virgo Gravitational Wave Sources

The dozens of compact object mergers detected by LIGO/Virgo raise a key theoretical question: how do initially wide binaries shrink sufficiently quickly that they are able to merge via gravitational wave (GW) radiation within a Hubble time? One promising class of answers involves secular driving of binary eccentricity by some external tidal perturbation. This perturbation can arise due to the presence of a tertiary point mass, in which case the system exhibits Lidov-Kozai (LK) dynamics, or it can stem from the tidal field of the stellar cluster in which the binary orbits. While these secular tide-driven mechanisms have been studied exhaustively in the case of no GW emission, when GWs are included the dynamical behavior is still incompletely understood. In this paper we consider compact object binaries driven to merger via high-eccentricity excitation by (doubly averaged, test-particle quadrupole level) cluster tides-which includes LK-driven mergers as a special case-and include the effects of both general relativistic precession and GW emission. We provide for the first time an analytical understanding of the different evolutionary stages of the binary's semimajor axis, secular oscillation timescale, and phase-space structure all the way to merger. Our results will inform future population synthesis calculations of compact object binary mergers from hierarchical triples and stellar clusters.

Keywords: compact binary stars; relativistic binary stars; gravitational wave sources; celestial mechanics; star clusters; ligo; astrodynamics
Spitzer Mid-infrared Study of Sh 2-208: Evolution of Protoplanetary Disks in Low-metallicity Environments

This study presents sensitive mid-infrared (MIR) photometry obtained with the Spitzer/IRAC for a young cluster in Sh 2-208 (S208) located in one of the lowest-metallicity H II regions in the Galaxy, $[{\rm{O}}/{\rm{H}}]=-0.8$ dex. Previous studies suggested that the cluster is ~0.5 Myr old and has a distance of D = 4 kpc, which is consistent with the astrometric distance from Gaia EDR3. In a ~ $3\buildrel{\,\prime}\over{.} 5\times 4^{\prime} $ field, 96 sources were detected in at least one MIR band at ≥10σ, covering intermediate-mass stars with a ~1.0 ${M}_{\odot }$ mass detection limit. A total of 41 probable cluster members were identified based on the spatial distributions of spectral energy distribution slopes derived from the near-infrared (NIR) KS and IRAC bands and extinctions of the sources. The cumulative distribution of the spectral energy distribution slopes for the S208 cluster was not significantly different from those of other clusters in solar-metallicity environments with approximately the same age for intermediate-mass stars, if one also considers nondetected MIR sources identified as S208 cluster members from NIR observations. This suggests that the degree of dust growth/settling does not significantly change with metallicities as different as ~1 dex. The fraction of stars with MIR disk emissions for the cluster members with ≥1 ${M}_{\odot }$ was 64%-93%, which is comparable to the results in solar-metallicity environments. Although this may suggest that dominant disk dispersal mechanisms for intermediate-mass stars have either no or very weak dependence on metallicity, it can be argued alternatively that this may suggest that the disk dispersal process does not work effectively at this young stage.

Keywords: protoplanetary disks
Inferring the Energy and Distance Distributions of Fast Radio Bursts Using the First CHIME/FRB Catalog

Fast radio bursts (FRBs) are brief, energetic, typically extragalactic flashes of radio emission whose progenitors are largely unknown. Although studying the FRB population is essential for understanding how these astrophysical phenomena occur, such studies have been difficult to conduct without large numbers of FRBs and characterizable observational biases. Using the recently released catalog of 536 FRBs published by the Canadian Hydrogen Intensity Mapping Experiment/Fast Radio Burst (CHIME/FRB) collaboration, we present a study of the FRB population that also calibrates for selection effects. Assuming a Schechter function, we infer a characteristic energy cut-off of ${E}_{\mathrm{char}}={2.38}_{-1.64}^{+5.35}\times {10}^{41}$ erg and a differential power-law index of γ = $-{1.3}_{-0.4}^{+0.7}$ . Simultaneously, we infer a volumetric rate of [ ${7.3}_{-3.8}^{+8.8}$ (stat.) ${}_{-1.8}^{+2.0}(\mathrm{sys}.)]\times {10}^{4}$ Gpc-3 yr-1 above a pivot energy of 1039 erg and below a scattering timescale of 10 ms at 600 MHz, and find we cannot significantly constrain the cosmic evolution of the FRB population with star-formation rate. Modeling the host's dispersion measure (DM) contribution as a log-normal distribution and assuming a total Galactic contribution of 80 pc cm-3, we find a median value of ${\mathrm{DM}}_{\mathrm{host}}={84}_{-49}^{+69}$ pc cm-3, comparable with values typically used in the literature. Proposed models for FRB progenitors should be consistent with the energetics and abundances of the full FRB population predicted by our results. Finally, we infer the redshift distribution of FRBs detected with CHIME, which will be tested with the localizations and redshifts enabled by the upcoming CHIME/FRB Outriggers project.

Keywords: radio transient sources; radio bursts
Star Formation and Morphological Properties of Galaxies in the Pan-STARRS 3π Survey. I. A Machine-learning Approach to Galaxy and Supernova Classification

We present a classification of galaxies in the Pan-STARRS1 (PS1) 3π survey based on their recent star formation history and morphology. Specifically, we train and test two Random Forest (RF) classifiers using photometric features (colors and moments) from the PS1 data release 2. The labels for the morphological classification are taken from Huertas-Company et al., while labels for the star formation fraction (SFF) are from the Blanton et al. catalog. We find that colors provide more predictive accuracy than photometric moments. We morphologically classify galaxies as either early- or late-type, and our RF model achieves a 78% classification accuracy. Our second model classifies galaxies as having either a low-to-moderate or high SFF. This model achieves an 89% classification accuracy. We apply both RF classifiers to the entire PS1 3π dataset, which allows us to assign two scores to each PS1 source: PHSFF, which quantifies the probability of having a high SFF; and Pspiral, which quantifies the probability of having a late-type morphology. Finally, as a proof of concept, we apply our classification framework to supernova (SN) host galaxies from the Zwicky Transient Factory and the Lick Observatory Supernova Search samples. We show that by selecting PHSFF or Pspiral, it is possible to significantly enhance or suppress the fraction of core-collapse SNe (or thermonuclear SNe) in the sample with respect to random guessing. This result demonstrates how contextual information can aid transient classifications at the time of first detection. In the current era of spectroscopically starved time-domain astronomy, prompt automated classification is paramount. Our table is available at 10.5281/zenodo.3990545.

Keywords: classification; supernovae; core-collapse supernovae; type ia supernovae; random forests
Model-based Cross-correlation Search for Gravitational Waves from the Low-mass X-Ray Binary Scorpius X-1 in LIGO O3 Data

We present the results of a model-based search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1 using LIGO detector data from the third observing run of Advanced LIGO and Advanced Virgo. This is a semicoherent search that uses details of the signal model to coherently combine data separated by less than a specified coherence time, which can be adjusted to balance sensitivity with computing cost. The search covered a range of gravitational-wave frequencies from 25 to 1600 Hz, as well as ranges in orbital speed, frequency, and phase determined from observational constraints. No significant detection candidates were found, and upper limits were set as a function of frequency. The most stringent limits, between 100 and 200 Hz, correspond to an amplitude h 0 of about 10-25 when marginalized isotropically over the unknown inclination angle of the neutron star's rotation axis, or less than 4 × 10-26 assuming the optimal orientation. The sensitivity of this search is now probing amplitudes predicted by models of torque balance equilibrium. For the usual conservative model assuming accretion at the surface of the neutron star, our isotropically marginalized upper limits are close to the predicted amplitude from about 70 to 100 Hz; the limits assuming that the neutron star spin is aligned with the most likely orbital angular momentum are below the conservative torque balance predictions from 40 to 200 Hz. Assuming a broader range of accretion models, our direct limits on gravitational-wave amplitude delve into the relevant parameter space over a wide range of frequencies, to 500 Hz or more.

Keywords: gravitational waves; gravitational wave astronomy; low-mass x-ray binary stars; neutron stars
The Period Distribution of Hot Jupiters Is Not Dependent on Host Star Metallicity

The probability that a Sun-like star has a close-orbiting giant planet (period ≲1 yr) increases with stellar metallicity. Previous work provided evidence that the period distribution of close-orbiting giant planets is also linked to metallicity, hinting that there two formation/evolution pathways for such objects, one of which is more probable in high-metallicity environments. Here, we check for differences in the period distribution of hot Jupiters (P < 10 days) as a function of host star metallicity, drawing on a sample of 232 transiting hot Jupiters and homogeneously derived metallicities from Gaia Data Release 3. We found no evidence for any metallicity dependence; the period distributions of hot Jupiters around metal-poor and metal-rich stars are indistinguishable. As a byproduct of this study, we provide transformations between metallicities from the Gaia Radial Velocity Spectrograph and from traditional high-resolution optical spectroscopy of main-sequence FGK stars.

Keywords: exoplanets; hot jupiters
Y Gem: A White Dwarf Symbiotic Star?

In this work we conduct a thorough investigation of the X-ray and ultraviolet (UV) properties of Y Gem based on six archival XMM-Newton and Chandra observations to explore the nature of the system. The results show that Y Gem has strong (1032-34 erg s-1) X-ray emission, including a hard (with a maximum emission temperature of 8-16 keV) and a soft (with emission temperatures of 0.02-0.2 and 0.2-0.9 keV) component. The integrated UV luminosity of Y Gem reaches ~1035 erg s-1. We show that the previous asymptotic giant branch-main-sequence (AGB-MS) Roche-lobe overflow (RLOF) scenario is dynamically unstable and can hardly explain the ~10 keV X-ray emission temperature. We propose Y Gem as a symbiotic star, where a white dwarf (WD) accretes from its AGB companion based on its X-ray and UV properties. We make numerical simulations to examine the evolutionary history of this system. The simulations can produce the observed properties of Y Gem in the wind WRLOF scenario. An ~0.8M ⊙ WD with a ~1.0-1.8M ⊙ companion in a ~2000-32,000 day initial orbit may evolve to a Y Gem-like system. Our finding implies a potential population of symbiotic stars that may have been misclassified as AGB-MS binaries. What is more, their high mass accretion rates may enable mass accumulation to the WD and makes them candidates of Type Ia supernovae progenitors.

Keywords: symbiotic binary stars; white dwarf stars; x-ray sources
PGC 38025: A Star-forming Lenticular Galaxy with an Off-nuclear Star-forming Core

Lenticular galaxies (S0s) were considered mainly as passive evolved spirals due to environmental effects for a long time; however, most S0s in the field cannot fit into this common scenario. In this work, we study one special case, Sloan Digital Sky Survey J120237.07+642235.3 (PGC 38025), a star-forming field S0 galaxy with an off-nuclear blue core. We present optical integral field spectroscopic observation with the 3.5 meter telescope at Calar Alto Observatory, and high-resolution millimeter observation with the NOrthern Extended Millimeter Array. We estimated the star formation rate (SFR = 0.446 M⊙ yr-1) and gaseous metallicity (12 + log(O/H) = 8.42) for PGC 38025, which follows the star formation main sequence and stellar mass-metallicity relation. We found that the ionized gas and cold molecular gas in PGC 38025 show the same spatial distribution and kinematics, while rotating misaligned with stellar component. The off-nuclear blue core is locating at the same redshift as PGC 38025 and its optical spectrum suggest it is H II region. We suggest that the star formation in PGC 38025 is triggered by a gas-rich minor merger, and the off-nuclear blue core might be a local star formation happened during the accretion/merger process.

Keywords: lenticular galaxies; star formation; early-type galaxies; galaxies; galaxy kinematics