adsabs/SciX_UAT_keywords huggingface dataset:
Detection of the Mass-dependent Dual Type Transition of Galaxy Spins in IllustrisTNG Simulations

A numerical detection of the mass-dependent spin transition of the galaxies is presented. Analyzing a sample of the galaxies with stellar masses in the range of 109 < (M⋆/M⊙) ≤ 1011 from the IllustrisTNG300-1 simulations, we explore the alignment tendency between the galaxy baryon spins and the three eigenvectors of the linearly reconstructed tidal field as a function of M⋆ and its evolution in the redshift range of 0 ≤ z ≤ 1.5. Detecting a significant signal of the occurrence of the mass-dependent transition of the galaxy spins, we show that the centrals differ from the satellites in their spin transition type. As M⋆ increases beyond a certain threshold mass, the preferred directions of the central galaxy spins transit from the minor to the intermediate tidal eigenvectors (type two) at z = 0.5 and 1, while those of the satellites transit from the minor to the major tidal eigenvectors (type one) at z = 1 and 1.5. It is also shown that the mass range and type of the spin transition depend on the galaxy morphology, the degree of the alignments between the baryon and total spin vectors, and the environmental density. Meanwhile, the stellar spins of the galaxies are found to yield a weak signal of the T1 transitions at z = 0, whose strength and trend depend on the degree of the alignments between the stellar and baryon spins. The possible mechanisms responsible for the T1 and T2 spin transitions are discussed.

Keywords: large-scale structure of the universe; galaxy formation
Broadband Electrostatic Waves near the Lower-hybrid Frequency in the Near-Sun Solar Wind Observed by the Parker Solar Probe

Using Parker Solar Probe observations, this Letter reports for the first time the existence of broadband electrostatic waves below the electron cyclotron frequency in the near-Sun solar wind and even in the extended solar corona. These waves have enhanced power spectral densities of the electric fields near the lower-hybrid frequency f LH, and their peak frequencies can be below or exceed f LH. The perturbed electric fields are distributed between about 0.1 and 50 mV m-1. Accompanying broadband electrostatic waves, strong electrostatic solitary structures can arise, and their peak amplitudes approach nearly 500 mV m-1. Due to the appearance of considerable electric field fluctuations perpendicular to the background magnetic field, the observed waves would propagate obliquely. Moreover, this Letter conjectures the wavenumber and frequency information for the candidate of the wave mode nature being the oblique slow mode wave, the ion Bernstein wave, or the oblique fast-magnetosonic whistler wave. One important consequence of the observed waves is that they may regulate the electron heat flux in the near-Sun solar wind and in the solar corona.

Keywords: solar wind; plasma physics; space plasmas
Tidal Disruptions of Main-sequence Stars. II. Simulation Methodology and Stellar Mass Dependence of the Character of Full Tidal Disruptions

This is the second in a series of papers presenting the results of fully general relativistic simulations of stellar tidal disruptions in which the stars' initial states are realistic main-sequence models. In the first paper, we gave an overview of this program and discussed the principal observational implications of our work. Here we describe our calculational method, which includes a new method for calculating fully relativistic stellar self-gravity, and provide details about the outcomes of full disruptions, focusing on the stellar mass dependence of the outcomes for a black hole of mass 106 M⊙. We consider eight different stellar masses, from 0.15 M⊙ to 10 M⊙. We find that, relative to the traditional order-of-magnitude estimate rt, the physical tidal radius of low-mass stars (M⋆ ≲ 0.7 M⊙) is larger by tens of percent, while for high-mass stars (M⋆ ≳ 1 M⊙) it is smaller by a factor of 2-2.5. The traditional estimate of the range of energies found in the debris is ≈1.4× too large for low-mass stars, but is a factor of ∼2 too small for high-mass stars; in addition, the energy distribution for high-mass stars has significant wings. For all stars undergoing tidal encounters, we find that mass loss continues for many stellar vibration times because the black hole's tidal gravity competes with the instantaneous stellar gravity at the star's surface until the star has reached a distance from the black hole ∼O(10)rt.

Keywords: black hole physics; gravitation; general relativity; hydrodynamics; galaxy nuclei; stellar dynamics; supermassive black holes
Mapping the Planetary Wake in HD 163296 with Kinematics

We map the planetary wake associated with the embedded protoplanet creating the CO kink in the disk of HD 163296. We show that the wake can be traced by a series of correlated perturbations in the peak velocity map. The sign change of the perturbations across the disk's major axis confirms that the wake induces predominantly radial motion, as predicted by models of planet-disk interaction. These results provide the first direct confirmation of planet wakes generated by Lindblad resonances. Mapping the wake provides a constraint on the disk aspect ratio, which is required to measure the mass of the planet.

Keywords: planet formation; protoplanetary disks; hydrodynamical simulations; radiative transfer
The Evolutionary Pathways of Disk-, Bulge-, and Halo-dominated Galaxies

To break the degeneracy among galactic stellar components, we extract kinematic structures using the framework that was described in Du et al. For example, the concept of stellar halos is generalized to weakly rotating structures that are composed of loosely bound stars, which can hence be associated to both disk and elliptical type morphologies. By applying this method to central galaxies with stellar mass 1010-11.5 M⊙ from the TNG50 simulation, we identify three broadly-defined types of galaxies: galaxies dominated by disk, by bulge, or by stellar halo structures. We then use the simulation to infer the underlying connection between the growth of structures and physical processes over cosmic time. By tracing galaxies back in time, we recognize three fundamental regimes: an early phase of evolution (z ≳ 2), and internal and external (mainly mergers) processes that act at later times. We find that disk- and bulge-dominated galaxies are not significantly affected by mergers since z ~ 2. The difference in their present-day structures originates from two distinct evolutionary pathways-extended versus compact-that are likely to be determined by their parent dark matter halos (i.e., nature). In contrast, slow rotator elliptical galaxies are typically halo-dominated, forming by external processes (e.g., mergers) in the later phase (i.e., nurture). This picture challenges the general idea that elliptical galaxies are the same objects as classical bulges. In observations, both bulge- and halo-dominated galaxies are likely to be classified as early-type galaxies with compact morphology and quiescent star formation. However, here we find them to have very different evolutionary histories.

Keywords: galaxy structure; galaxy evolution; galaxy formation; galaxy bulges; spiral galaxies; star formation
SOAR TESS Survey. I. Sculpting of TESS Planetary Systems by Stellar Companions

The Transiting Exoplanet Survey Satellite (TESS) is finding transiting planet candidates around bright, nearby stars across the entire sky. The large field of view, however, results in low spatial resolution; therefore, multiple stars contribute to almost every TESS light curve. High angular resolution imaging can detect the previously unknown companions to planetary candidate hosts that dilute the transit depths, lead to host star ambiguity, and, in some cases, are the source of false-positive transit signals. We use speckle imaging on the Southern Astrophysical Research (SOAR) telescope to search for companions to 542 TESS planet candidate hosts in the southern sky. We provide correction factors for the 117 systems with resolved companions due to photometric contamination. The contamination in TESS due to close binaries is similar to that found in surveys of Kepler planet candidates. For the solar-type population, we find a deep deficit of close binary systems with projected stellar separations less than 100 au among planet candidate hosts (44 observed binaries compared to 124 expected based on field binary statistics). The close binary suppression among TESS planet candidate hosts is similar to that seen for the more distant Kepler population. We also find a large surplus of TESS planet candidates in wide binary systems detected in both SOAR and Gaia DR2 (119 observed binaries compared to 77 expected). These wide binaries almost exclusively host giant planets, however, suggesting that orbital migration caused by perturbations from the stellar companion may lead to planet-planet scattering and suppress the population of small planets in wide binaries. Both trends are also apparent in the M dwarf planet candidate hosts.

Keywords: exoplanets; exoplanet formation; binary stars; close binary stars; speckle interferometry
Neutron Star Radius-to-mass Ratio from Partial Accretion Disk Occultation as Measured through Fe Kα Line Profiles

We present a new method to measure the radius-to-mass ratio (R/M) of weakly magnetic, disk-accreting neutron stars by exploiting the occultation of parts of the inner disk by the star itself. This occultation imprints characteristic features on the X-ray line profile that are unique and are expected to be present in low-mass X-ray binary systems seen under inclinations higher than ∼65°. We analyze a Nuclear Spectroscopic Telescope Array observation of a good candidate system, 4U 1636-53, and find that X-ray spectra from current instrumentation are unlikely to single out the occultation features owing to insufficient signal-to-noise. Based on an extensive set of simulations we show that large-area X-ray detectors of the future generation could measure R/M to ∼ $2\div3$ % precision over a range of inclinations. Such is the precision in radius determination required to derive tight constraints on the equation of state of ultradense matter and it represents the goal that other methods also aim to achieve in the future.

Keywords: neutron stars; low-mass x-ray binary stars; stellar accretion disks; general relativity; x-ray sources
Mechanical Energy Deposition in Cool Star Atmospheres: Resonant Coupling to Coronal Loops in M Dwarfs

The efficiency of coronal heating ɛ(cor) in a star can be quantified by L X/L bol, i.e., the ratio of X-ray luminosity to bolometric luminosity. The efficiency of chromospheric heating in the same star ɛ(chr) is typically assumed to be proportional to L(Hα)/L bol or L(Ca K)/L bol where the lines Hα and Ca K are often the two strongest emission lines in the visible spectrum: the constant of proportionality (η = ɛ(chr)/[L(Hα)/L bol] > 1) includes contributions from many other lines emitted by the chromosphere. In the case of the quiet Sun, it has been known for decades that, in the Sun, the efficiency of chromospheric heating is larger by a factor of ɛ(chr)/ɛ(cor) > 10 than the efficiency of coronal heating. Over the intervening years, data pertaining to ɛ(cor) and ɛ(chr) have been estimated for an increasingly large sample of main-sequence stars with spectral types later than the Sun. These data suggest that among M dwarfs, the efficiency ratio ɛ(chr)/ɛ(cor) may in some stars become smaller than in the solar case. The effect of this is such that the value of ɛ(cor) may become comparable to the value of ɛ(chr). Here, we seek to understand why coronal heating may be >10 times more efficient (relative to chromospheric heating) in certain M dwarfs than in the Sun. Using data on coronal loop properties in flaring stars, we examine the hypothesis that in M dwarfs, the enhanced efficiency of coronal heating may be related to resonant coupling between coronal loops and the source of mechanical energy in the convection zone.

Keywords: late-type dwarf stars; stellar coronae; solar coronal heating
COOL-LAMPS. Discovery of COOL J0335-1927, a Gravitationally Lensed Quasar at z = 3.27 with an Image Separation of 23.″3

We report the discovery of COOL J0335-1927, a quasar at z = 3.27 lensed into three images with a maximum separation of 23.″3 by a galaxy cluster at z = 0.4178. To date, this is the highest redshift wide-separation lensed quasar known. In addition, COOL J0335-1927 shows several strong intervening absorbers visible in the spectra of all three quasar images with varying equivalent widths. The quasar also shows mini-broad line absorption. We construct a parametric strong gravitational lens model using ground-based imaging, constrained by the redshift and positions of the quasar images as well as the positions of three other multiply imaged background galaxies. Using our best-fit lens model, we calculate the predicted time delays between the three quasar images to be Δt AB = ${499}_{-146}^{+141}$ (stat) and Δt AC = $-{127}_{-17}^{+83}$ (stat) days. Folding in systematic uncertainties, the model-predicted time delays are within the ranges 240 < Δt AB < 700 and -300 < Δt AC < -30. We also present g-band photometry from archival Dark Energy Camera Legacy Survey and Pan-STARRS imaging, and new multi-epoch observations obtained between 2022 September 18 UT and 2023 February 22 UT, which demonstrate significant variability in the quasar and will eventually enable the measurement of the time delay between the three quasar images. The currently available light curves are consistent with the model-predicted time delays. This is the fifth paper from the COOL-LAMPS collaboration.

Keywords: strong gravitational lensing; quasars; galaxy clusters
Quantifying the Bayesian Evidence for a Planet in Radial Velocity Data

We present results from a data challenge posed to the radial velocity (RV) community: namely, to quantify the Bayesian "evidence" for n = {0, 1, 2, 3} planets in a set of synthetically generated RV data sets containing a range of planet signals. Participating teams were provided the same likelihood function and set of priors to use in their analysis. They applied a variety of methods to estimate $\widehat{{ \mathcal Z }}$ , the marginal likelihood for each n-planet model, including cross-validation, the Laplace approximation, importance sampling, and nested sampling. We found the dispersion in $\widehat{{ \mathcal Z }}$ across different methods grew with increasing n-planet models: ∼3 for zero planets, ∼10 for one planet, ∼102-103 for two planets, and >104 for three planets. Most internal estimates of uncertainty in $\widehat{{ \mathcal Z }}$ for individual methods significantly underestimated the observed dispersion across all methods. Methods that adopted a Monte Carlo approach by comparing estimates from multiple runs yielded plausible uncertainties. Finally, two classes of numerical algorithms (those based on importance and nested samplers) arrived at similar conclusions regarding the ratio of $\widehat{{ \mathcal Z }}{\rm{s}}$ for n- and (n + 1)-planet models. One analytic method (the Laplace approximation) demonstrated comparable performance. We express both optimism and caution: we demonstrate that it is practical to perform rigorous Bayesian model comparison for models of ≤3 planets, yet robust planet discoveries require researchers to better understand the uncertainty in $\widehat{{ \mathcal Z }}$ and its connections to model selection.

Keywords: exoplanet detection methods; radial velocity; astrostatistics techniques; model selection; time series analysis; algorithms; bayes factor; nested sampling; importance sampling
How Does Magnetic Reconnection Drive the Early-stage Evolution of Coronal Mass Ejections?

Theoretically, coronal mass ejection (CME) kinematics are related to magnetic reconnection processes in the solar corona. However, the current quantitative understanding of this relationship is based on the analysis of only a handful of events. Here we report a statistical study of 60 CME-flare events from 2010 August to 2013 December. We investigate kinematic properties of CMEs and magnetic reconnection in the low corona during the early phase of the eruptions, by combining limb observations from STEREO with simultaneous on-disk views from SDO. For a subset of 42 events with reconnection rate evaluated by the magnetic fluxes swept by the flare ribbons on the solar disk observed from SDO, we find a strong correlation between the peak CME acceleration and the peak reconnection rate. Also, the maximum velocities of relatively fast CMEs (≳600 km s-1) are positively correlated with the reconnection flux, but no such correlation is found for slow CMEs. A time-lagged correlation analysis suggests that the distribution of the time lag of CME acceleration relative to reconnection rate exhibits three peaks, approximately 10 minutes apart, and on average, acceleration-led events have smaller reconnection rates. We further compare the CME total mechanical energy with the estimated energy in the current sheet. The comparison suggests that, for small-flare events, reconnection in the current sheet alone is insufficient to fuel CMEs. Results from this study suggest that flare reconnection may dominate the acceleration of fast CMEs, but for events of slow CMEs and weak reconnection, other mechanisms may be more important.

Keywords: solar flares; coronagraphic imaging; solar coronal mass ejections; solar magnetic reconnection
A Cross-internal Linear Combination Approach to Probe the Secondary CMB Anisotropies: Kinematic Sunyaev-Zel'dovich Effect and CMB Lensing

We propose a cross-internal linear combination (cross-ILC) approach to measure the small-scale cosmic microwave background (CMB) anisotropies robustly against the contamination from astrophysical signals. In particular, we focus on the mitigation of systematics from cosmic infrared background (CIB) and thermal Sunyaev-Zel'dovich (tSZ) signals in kinematic Sunyaev-Zel'dovich (kSZ) power spectrum and CMB lensing. We show the cross-spectrum measurement between two CMB maps created by nulling the contributions from CIB (CIB-free map) and tSZ (tSZ-free map) to be robust for kSZ, as the approach significantly suppresses the total contribution of CIB and tSZ signals. Similarly, for CMB lensing, we use the approach introduced by Madhavacheril & Hill but with a slight modification by using the tSZ-free and CIB-free maps in the two legs of the quadratic estimator. By cross-correlating the CMB lensing map created using this technique with galaxy surveys, we show that the biases from both CIB and tSZ are negligible. We also compute the impact of unmodeled CIB/tSZ residuals on kSZ and cosmological parameters, finding the kSZ measured using the standard ILC to be significantly biased. The kSZ estimate from the cross-ILC remains less affected by CIB/tSZ, making it crucial for current and upcoming CMB surveys such as the South Pole Telescope (SPT), Simons Observatory (SO), and CMB-S4. With the cross-ILC approach, we find that the total kSZ power spectrum can be measured at very high significance in the coming years: 35σ by SPT, 22σ by SO, and 80σ by CMB-S4. Finally, we forecast constraints on the epoch of reionization using the kSZ power spectrum and find that the duration of reionization, currently unconstrained by Planck, can be constrained to $\sigma ({\rm{\Delta }}{z}_{\mathrm{re}})$ = 1.5 or 0.5 depending on the choice of the prior on the optical depth to reionization. The data products and the associated codes can be downloaded from this link (https://github.com/sriniraghunathan/cross_ilc_methods_paper).

Keywords: cosmic microwave background radiation; sunyaev-zeldovich effect; gravitational lensing
On the Origin of Stochastic, Low-Frequency Photometric Variability in Massive Stars

High-precision photometric observations have revealed ubiquitous stochastic low-frequency photometric variability in early-type stars. It has been suggested that this variability arises due to either subsurface convection or internal gravity waves launched by the convective core. Here we show that relevant properties of convection in subsurface convective layers correlate very well with the timescale and amplitude of stochastic low-frequency photometric variability, as well as with the amplitude of macroturbulence. We suggest that low-frequency, stochastic photometric variability and surface turbulence in massive stars are caused by the presence of subsurface convection. We show that an explanation for the observed surface photometric variability and macroturbulence relying on convective core driven internal gravity waves encounters a number of difficulties and seems unlikely to be able to explain the observed trends.

Keywords: asteroseismology; stellar structures; stellar evolution; stellar convection envelopes; stellar convective zones; surface variability; stellar magnetic fields; internal waves; non-radial pulsations; stellar pulsations; massive stars
REQUIEM-2D: A Diversity of Formation Pathways in a Sample of Spatially Resolved Massive Quiescent Galaxies at z 2

REQUIEM-2D (Resolving Quiescent Magnified Galaxies with 2D Grism Spectroscopy) comprises a sample of eight massive ( ${\rm{log}}({M}_{\ast }/{M}_{\odot })\gt 10.6$ ) strongly lensed quiescent galaxies at z ~ 2. REQUIEM-2D combines the natural magnification from strong gravitational lensing with the high-spatial-resolution grism spectroscopy of the Hubble Space Telescope through a spectrophotometric fit to study spatially resolved stellar populations. We show that quiescent galaxies in the REQUIEM-2D survey have diverse formation histories with age gradients at the 1σ-3σ level, including examples of (1) a younger central region supporting outside-in formation, (2) flat age gradients that show evidence for both spatially uniform early formation and inside-out quenching, and (3) regions at a fixed radial distance having different ages (such asymmetries cannot be recovered when averaging stellar population measurements azimuthally). The typical dust attenuation curve for the REQUIEM-2D galaxies is constrained to be steeper than Calzetti's law in the UV and generally consistent with A V < 1. Combined together and accounting for the different physical radial distances and formation timescales, we find that the REQUIEM-2D galaxies that formed earlier in the universe exhibit slow and uniform growth in their inner core, whereas the galaxies that formed later have rapid inner growth in their inner core with younger ages than the outskirts. These results challenge the currently accepted paradigm of how massive quiescent galaxies form, where the earliest galaxies are thought to form most rapidly. Significantly larger samples close to the epoch of formation with similar data quality and higher spectral resolution are required to validate this finding.

Keywords: galaxy formation; extragalactic astronomy; observational astronomy
A Microlensing Accretion Disk Size Measurement in the Lensed Quasar WFI 2026-4536

We use 13 seasons of R-band photometry from the 1.2 m Leonard Euler Swiss Telescope at La Silla to examine microlensing variability in the quadruply imaged lensed quasar WFI 2026-4536. The lightcurves exhibit ∼0.2 mag of uncorrelated variability across all epochs and a prominent single feature of ∼0.1 mag within a single season. We analyze this variability to constrain the size of the quasar's accretion disk. Adopting a nominal inclination of 60°, we find an accretion disk scale radius of $\mathrm{log}({r}_{s}/\mathrm{cm})={15.74}_{-0.29}^{+0.34}$ at a rest-frame wavelength of 2043 Å, and we estimate a black hole mass of $\mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })={9.18}_{-0.34}^{+0.39}$ , based on the C IV line in VLT spectra. This size measurement is fully consistent with the quasar accretion disk size—black hole mass relation, providing another system in which the accretion disk is larger than predicted by thin-disk theory.

Keywords: quasar microlensing; gravitational microlensing; strong gravitational lensing; reverberation mapping