adsabs/SciX_UAT_keywords huggingface dataset:
The High-Redshift Gas-Phase Mass–Metallicity Relation in FIRE-2

The unprecedented infrared spectroscopic capabilities of JWST have provided high-quality interstellar medium metallicity measurements and enabled characterization of the gas-phase mass–metallicity relation (MZR) for galaxies at z ≳ 5 for the first time. We analyze the gas-phase MZR and its evolution in a high-redshift suite of FIRE-2 cosmological zoom-in simulations at z = 5–12 and for stellar masses M * ∼ 106–1010 M ⊙. These simulations implement a multichannel stellar feedback model and produce broadly realistic galaxy properties, including when evolved to z = 0. The simulations predict very weak redshift evolution of the MZR over the redshift range studied, with the normalization of the MZR increasing by less than 0.01 dex as redshift decreases from z = 12 to z = 5. The median MZR in the simulations is well approximated as a constant power-law relation across this redshift range given by . We find good agreement between our best-fit model and recent observations made by JWST at high redshift. The weak evolution of the MZR at z > 5 contrasts with the evolution at z ≲ 3, where increasing normalization of the MZR with decreasing redshift is observed and predicted by most models. The FIRE-2 simulations predict increasing scatter in the gas-phase MZR with decreasing stellar mass, in qualitative agreement with some observations.

Keywords: galaxies; high-redshift galaxies; metallicity; chemical abundances; galaxy chemical evolution; galaxy abundances; interstellar medium; james webb space telescope; galaxy formation; astronomical simulations; early universe
A Multi-Observing Technique Study of the Dynamical Evolution of the Viscous Disk around the Be Star ω CMa

The observed emission lines of Be stars originate from a circumstellar Keplerian disk, which is generally well explained by the viscous decretion disk model. In an earlier work we performed modeling of the full light curve of the bright Be star ω CMa with the 1D time-dependent hydrodynamic code SINGLEBE and the Monte Carlo radiative transfer code HDUST. We used a V-band light curve that probes the inner disk through four disk formation and dissipation cycles. This new study compares predictions of the same set of model parameters with time-resolved photometry from the near-UV through the mid-IR, comprehensive series of optical spectra, and optical broadband polarimetry, which overall represent a larger volume of the disk. Qualitatively, the models reproduce the trends in the observed data due to the growth and decay of the disk. However, quantitative differences exist, e.g., an overprediction of flux increasing with wavelength, too slow decreases in Balmer emission line strength during disk dissipation, and a discrepancy between the range of polarimetric data and the model. We find that a larger value of the viscosity parameter alone or a disk truncated by a companion star reduces these discrepancies by increasing the dissipation rate in the outer regions of the disk.

Keywords: be stars; massive stars; stellar rotation; circumstellar matter; variable stars; starlight polarization; spectroscopy; emission line stars
Magnetohydrodynamic Instabilities of Double Magnetic Bands in a Shallow-water Tachocline Model. I. Cross-equatorial Interactions of Bands

Along with a butterfly diagram of sunspots, combined observational studies of ephemeral active regions, X-ray and EUV bright points, plage, filaments, faculae, and prominences demonstrate a pattern, which is known as the Extended Solar Cycle. This pattern indicates that the wings of the sunspot butterfly could be extended to much higher latitudes (up to ~60°), to an earlier time than the start of a sunspot cycle, hence yielding a strong overlap between cycles. Thus, during the ongoing cycle's activity near 30° latitude in each hemisphere, the next cycle kicks off at around 60°. By representing these epochs of overlaps by oppositely directed double magnetic bands in each hemisphere, we compute the unstable eigenmodes for MHD Rossby waves at the base of the convection zone and study how the properties of these energetically active Rossby waves change as these band pairs migrate equatorward. We find that in each hemisphere the low-latitude band interacts with the high-latitude band and drives the MHD instability as the solar activity progresses from 35°-15° latitude, which is essentially the rising phase. When the activity proceeds further equatorward from 15°, the interaction between low- and high-latitude bands weakens, and the cross-equatorial interaction between two low-latitude bands in each hemisphere starts. The eigenmodes in the latitude-longitude plane also reflect such changes in their pattern as the bend of the active cycle moves below 15° latitude.

Keywords: solar magnetic fields; solar activity; magnetohydrodynamics; solar rotation
The CHARA Array Interferometric Program on the Multiplicity of Classical Be Stars: New Detections and Orbits of Stripped Subdwarf Companions

Rapid rotation and nonradial pulsations enable Be stars to build decretion disks, where the characteristic line emission forms. A major but unconstrained fraction of Be stars owe their rapid rotation to mass and angular momentum transfer in a binary. The faint, stripped companions can be helium-burning subdwarf OB-type stars (sdOBs), white dwarfs (WDs), or neutron stars. We present optical/near-infrared Center for High Angular Resolution Astronomy (CHARA) interferometry of 37 Be stars selected for spectroscopic indications of low-mass companions. From multiepoch H- and/or K-band interferometry plus radial velocities and parallaxes collected elsewhere, we constructed 3D orbits and derived flux ratios and absolute dynamical masses of both components for six objects, quadrupling the number of anchor points for evolutionary models. In addition, a new wider companion was identified for the known Be + sdO binary 59 Cyg, while auxiliary Very Large Telescope Interferometer/GRAVITY spectrointerferometry confirmed circumstellar matter around the sdO companion to HR 2142. On the other hand, we failed to detect any companion to the six Be stars with γ Cas–like X-ray emission, with sdOB and main-sequence companions of the expected spectroscopic mass being ruled out for the X-ray-prototypical stars γ Cas and π Aqr, leaving elusive WDs as the most likely companions, as well as a likely explanation of the X-rays. No low-mass main-sequence close companions were identified for the other stars.

Keywords: be stars; o subdwarf stars; binary stars; orbit determination; optical interferometry; multiple star evolution
Systematically Measuring Ultra-diffuse Galaxies (SMUDGes). VI. Nuclear Star Clusters

We present our photometric search for potential nuclear star clusters (NSCs) in ultra-diffuse galaxies (UDGs) as an extension of the SMUDGes catalog. We identify 325 SMUDGes galaxies with NSCs and, from the 144 with existing distance estimates, identify 33 NSC hosts as UDGs (μ 0,g ≥ 24 mag arcsec-2, r e ≥ 1.5 kpc). The SMUDGes with NSCs lie on the galaxy red sequence, satisfy the relationship between NSC and host galaxy stellar masses, have a mean NSC stellar mass fraction of 0.02 but reach as high as 0.1, have NSCs that are displaced from the host center with a standard deviation of 0.10r e , and weakly favor higher-density environments. All of these properties are consistent with previous results from higher surface brightness galaxy samples, allowing for at most a relatively weak dependence of NSC behavior on host galaxy surface brightness.

Keywords: low surface brightness galaxies; galaxy properties; galaxy structure; galaxy nuclei; star clusters
ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Deriving Inclination Angle and Velocity of the Protostellar Jets from Their SiO Knots

We have selected six sources (G209.55-19.68S2, G205.46-14.56S1-A, G203.21-11.20W2, G191.90-11.21S, G205.46-14.56S3, and G206.93-16.61W2) from the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps (ALMASOP), in which these sources have been mapped in the CO (J = 2-1), SiO (J = 5-4), and C18O (J = 2-1) lines. These sources have high-velocity SiO jets surrounded by low-velocity CO outflows. The SiO jets consist of a chain of knots. These knots have been thought to be produced by semiperiodic variations in jet velocity. Therefore, we adopt a shock-forming model, which uses such variations to estimate the inclination angle and velocity of the jets. We also derive the inclination angle of the CO outflows using the wide-angle wind-driven shell model and find it to be broadly consistent with that of the associated SiO jets. In addition, we apply this shock-forming model to another three protostellar sources with SiO jets in the literature-HH 211, HH 212, and L1448C(N)-and find that their inclination angle and jet velocity are consistent with those previously estimated from proper-motion and radial-velocity studies.

Keywords: shocks; star formation; stellar jets; stellar winds; young stellar objects
The (Black Hole Mass)-(Spheroid Stellar Density) Relations: M BH-μ (and M BH-Σ) and M BH-ρ

This paper is the fourth in a series presenting (galaxy morphology, and thus galaxy formation)-dependent black hole (BH) mass, M BH, scaling relations. We have used a sample of 119 galaxies with directly measured M BH and host spheroid parameters obtained from multicomponent decomposition of, primarily, 3.6 μm Spitzer images. Here, we investigate the correlations between M BH and the projected (apparent) luminosity density μ, the projected stellar mass density Σ, and the de-projected (internal) stellar mass density ρ, for various spheroid radii. We discover the predicted M BH-μ 0,sph relation and present the first M BH-μ e,sph and M BH-ρ e,int,sph diagrams displaying slightly different (possibly curved) trends for early- and late-type galaxies (ETGs and LTGs, respectively) and an offset between ETGs with (fast-rotators, ES/S0) and without (slow-rotators, E) a disk. The scatter about various M BH-<Σ>R,sph (and <ρ> r,sph) relations is shown to systematically decrease as the enclosing aperture (and volume) increases, dropping from 0.69 dex when using the spheroid "compactness," <Σ>1kpc,sph, to 0.59 dex when using <Σ>5kpc,sph. We also reveal that M BH correlates with the internal density, ρ soi,sph, at the BH's sphere-of-influence radius, such that core-Sérsic (high Sérsic index, n) and (low-n) Sérsic galaxies define different relations with total rms scatters 0.21 dex and 0.77 dex, respectively. The M BH-<ρ>soi,sph relations will help with direct estimation of tidal disruption event rates, binary BH lifetimes, and together with other BH scaling relations, improve the characteristic strain estimates for long-wavelength gravitational waves pursued with pulsar timing arrays and space-based interferometers.

Keywords: early-type galaxies; galaxy evolution; late-type galaxies; scaling relations; supermassive black holes; galaxy spheroids
Quantification of High-dimensional Non-Gaussianities and Its Implication to Fisher Analysis in Cosmology

It is well known that the power spectrum is not able to fully characterize the statistical properties of non-Gaussian density fields. Recently, many different statistics have been proposed to extract information from non-Gaussian cosmological fields that perform better than the power spectrum. The Fisher matrix formalism is commonly used to quantify the accuracy with which a given statistic can constrain the value of the cosmological parameters. However, these calculations typically rely on the assumption that the sampling distribution of the considered statistic follows a multivariate Gaussian distribution. In this work, we follow Sellentin & Heavens and use two different statistical tests to identify non-Gaussianities in different statistics such as the power spectrum, bispectrum, marked power spectrum, and wavelet scattering transform (WST). We remove the non-Gaussian components of the different statistics and perform Fisher matrix calculations with the Gaussianized statistics using Quijote simulations. We show that constraints on the parameters can change by a factor of ~2 in some cases. We show with simple examples how statistics that do not follow a multivariate Gaussian distribution can achieve artificially tight bounds on the cosmological parameters when using the Fisher matrix formalism. We think that the non-Gaussian tests used in this work represent a powerful tool to quantify the robustness of Fisher matrix calculations and their underlying assumptions. We release the code used to compute the power spectra, bispectra, and WST that can be run on both CPUs and GPUs.

Keywords: astrostatistics distributions; normal distribution; astrostatistics strategies; cosmology; large-scale structure of the universe; cosmological parameters from large-scale structure
Hubble Constant Measurement from Three Large-separation Quasars Strongly Lensed by Galaxy Clusters

Tension between cosmic microwave background-based and distance ladder-based determinations of the Hubble constant H 0 motivates the pursuit of independent methods that are not subject to the same systematic effects. A promising alternative, proposed by Refsdal in 1964, relies on the inverse scaling of H 0 with the delay between the arrival times of at least two images of a strongly lensed variable source such as a quasar. To date, Refsdal's method has mostly been applied to quasars lensed by individual galaxies rather than by galaxy clusters. Using the three quasars strongly lensed by galaxy clusters (SDSS J1004+4112, SDSS J1029+2623, and SDSS J2222+2745) that have both multiband Hubble Space Telescope data and published time delay measurements, we derive H 0, accounting for the systematic and statistical sources of uncertainty. While a single time delay measurement does not yield a well-constrained H 0 value, analyzing the systems together tightens the constraint. Combining the six time delays measured in the three cluster-lensed quasars gives H 0 = 74.1 ± 8.0 km s-1 Mpc-1. To reach 1% uncertainty in H 0, we estimate that a sample size of order of 620 time delay measurements of similar quality as those from SDSS J1004+4112, SDSS J1029+2623, and SDSS J2222+2745 would be needed. Improving the lens modeling uncertainties by a factor of two and a half may reduce the needed sample size to 100 time delays, potentially reachable in the next decade.

Keywords: gravitational lensing; cosmology; hubble constant; quasars; galaxy clusters
X-Ray Observation of the Roche-lobe-filling White Dwarf plus Hot Subdwarf System ZTF J213056.71+442046.5

ZTF J213056.71+442046.5 is the prototype of a small class of recently discovered compact binaries composed of a white dwarf and a hot subdwarf that fills its Roche lobe. Its orbital period of only 39 minutes is the shortest known for the objects in this class. Evidence for a high orbital inclination (i = 86°) and for the presence of an accretion disk has been inferred from a detailed modeling of its optical photometric and spectroscopic data. We report the results of an XMM-Newton observation carried out on 2021 January 7. ZTF J213056.71+442046.5 was clearly detected by the Optical Monitor, which showed a periodic variability in the UV band (200-400 nm), with a light curve similar to that seen at longer wavelengths. Despite accretion on the white dwarf at an estimated rate of the order of 10-9 M ⊙ yr-1, no X-rays were detected with the EPIC instrument, with a limit of ~1030 erg s-1 on the 0.2-12 keV luminosity. We discuss possible explanations for the lack of a strong X-ray emission from this system.

Keywords: white dwarf stars; stellar accretion; b subdwarf stars; compact binary stars
Zonal Winds of Uranus and Neptune: Gravitational Harmonics, Dynamic Self-gravity, Shape, and Rotation

Uranus and Neptune exhibit fast surface zonal winds that can reach up to a few hundred meters per second. Previous studies on zonal gravitational harmonics and ohmic dissipation constraints suggest that the wind speeds diminish rapidly in relatively shallow depths within the planets. Through a case-by-case comparison between the missing dynamical gravitational harmonic ${J}_{4}^{{\prime} }$ from structure models, and with that expected from fluid perturbations, we put constraints on zonal wind decay in Uranus and Neptune. To this end, we generate polytropic empirical structure models of Uranus and Neptune using fourth-order theory of figures that leave hydrostatic J 4 as an open parameter. Allotting the missing dynamical contribution to density perturbations caused by zonal winds (and their dynamic self-gravity), we find that the maximum scale height of zonal winds are ~2%-3% of the planetary radii for both planets. Allowing the models to have J 2 solutions in the ±5 × 10-6 range around the observed value has similar implications. The effect of self-gravity on ${J}_{4}^{{\prime} }$ is roughly a factor of ten lower than that of zonal winds, as expected. The decay scale heights are virtually insensitive to the proposed modifications to the bulk rotation periods of Uranus and Neptune in the literature. Additionally, we find that the dynamical density perturbations due to zonal winds have a measurable impact on the shape of the planet, and could potentially be used to infer wind decay and bulk rotation period via future observations.

Keywords: planetary interior; planetary dynamics; uranus; neptune
The Spectral Reclassification of Nearby (z < 0.02) Type IIn Supernovae

Type IIn supernovae (SNe IIn) are an enigmatic subclass of SNe that show heterogeneity in their photometric and spectroscopic properties. Complex, multi-component Balmer line profiles are a defining property of SNe IIn. Perhaps owing to the heterogeneity in the SN IIn class, online databases often conflict and hold outdated or erroneous classifications. This is compounded by SN "impostors" and H II region contamination. We outline a classification scheme based on multi-component Hα profiles and apply it to a sample of 115 nearby (redshift z < 0.02) SNe that have held a SN IIn classification on the Open Supernova Catalogue (OSC). We find that 25 of our transients were misclassified as SNe IIn. We also note that there is disagreement between OSC and the Transient Name Server for 51 of the transients.

Keywords: core-collapse supernovae; supernovae; type ii supernovae; spectroscopy
A High-level Ab Initio Study of the Destruction of Methanimine under UV Radiation

The photodecomposition of methanimine (CH2NH) in the interstellar medium through several possible pathways is investigated by means of high-level multireference configuration interaction ab initio calculations. Among these pathways are photodissociation pathways involving hydrogen-atom elimination from both the CH2 and NH groups, and fragmentation into CH2 and NH. Potential-energy curves for the ground and several excited electronic states, as well as nonadiabatic couplings between them, are calculated. Possible dissociation mechanisms are discussed for the different pathways. It is found that the minimum excitation energy required for methanimine dissociation is above 7 eV. By using a two-dimensional representation of methanimine, CH2NH → CHNH2 isomerization is explored as an additional methanimine decomposition pathway. Hydrogen-atom elimination from the CH2 group is also investigated along the isomerization pathway. The results show that the isomerization proceeds by overcoming a transition state that in the first two excited states would require excitation energies similar to or somewhat lower than the typical minimum energies needed for breaking the molecule through the fragmentation pathways. Therefore, CH2NH → CHNH2 isomerization can effectively contribute to methanimine decomposition, competing efficiently with the photodissociation pathways. The radiation content present in the interstellar medium makes possible the occurrence of all the pathways studied.

Keywords: complex organic molecules; photodissociation reactions
Vetting of 384 TESS Objects of Interest with TRICERATOPS and Statistical Validation of 12 Planet Candidates

We present TRICERATOPS, a new Bayesian tool that can be used to vet and validate TESS Objects of Interest (TOIs). We test the tool on 68 TOIs that have been previously confirmed as planets or rejected as astrophysical false positives. By looking in the false-positive probability (FPP)-nearby false-positive probability (NFPP) plane, we define criteria that TOIs must meet to be classified as validated planets (FPP < 0.015 and NFPP < 10-3), likely planets (FPP < 0.5 and NFPP < 10-3), and likely nearby false positives (NFPP > 10-1). We apply this procedure on 384 unclassified TOIs and statistically validate 12, classify 125 as likely planets, and classify 52 as likely nearby false positives. Of the 12 statistically validated planets, 9 are newly validated. TRICERATOPS is currently the only TESS vetting and validation tool that models transits from nearby contaminant stars in addition to the target star. We therefore encourage use of this tool to prioritize follow-up observations that confirm bona fide planets and identify false positives originating from nearby stars.

Keywords: exoplanet astronomy; astrostatistics; planet hosting stars; exoplanets
Do Central Compact Objects have Carbon Atmospheres?

Only three of the dozen central compact objects (CCOs) in supernova remnants (SNRs) show thermal X-ray pulsations due to nonuniform surface temperature (hot spots). The absence of X-ray pulsations from several unpulsed CCOs has motivated suggestions that they have uniform-temperature carbon atmospheres (UTCAs), which adequately fit their spectra with appropriate neutron star (NS) surface areas. This is in contrast to the two-temperature blackbody or hydrogen atmospheres that also fit well. Here we investigate the applicability of UTCAs to CCOs. We show the following: (i) The phase-averaged spectra of the three pulsed CCOs can also be fitted with a UTCA of the appropriate NS area, despite pulsed CCOs manifestly having nonuniform surface temperature. A good spectral fit is therefore not strong support for the UTCA model of unpulsed CCOs. (ii) An improved spectrum of one unpulsed CCO, previously analyzed with a UTCA, does not allow an acceptable fit. (iii) For two unpulsed CCOs, the UTCA does not allow a distance compatible with the SNR distance. These results imply that, in general, CCOs must have hot, localized regions on the NS surface. We derive new X-ray pulse modulation upper limits on the unpulsed CCOs, and constrain their hot spot sizes and locations. We develop an alternative model that accounts for both the pulsed and unpulsed CCOs: a range of angles between hot spot and rotation axes consistent with an exponential distribution with scale factor λ ~ 20°. We discuss the physical mechanisms that could produce such small angles and small hot spots.

Keywords: x-ray sources; neutron stars; supernova remnants