adsabs/SciX_UAT_keywords huggingface dataset:
Standard-siren Cosmology Using Gravitational Waves from Binary Black Holes

Gravitational-wave astronomy provides a unique new way to study the expansion history of the universe. In this work, we investigate the impact future gravitational-wave observatories will have on cosmology. Third-generation observatories like the Einstein Telescope and Cosmic Explorer will be sensitive to essentially all of the binary black hole coalescence events in the universe. Recent work by Farr et al. points out that features in the stellar-mass black hole population break the mass-redshift degeneracy, facilitating precise determination of the Hubble parameter without electromagnetic counterparts or host galaxy catalogs. Using a hierarchical Bayesian inference model, we show that with one year of observations by the Einstein Telescope, the Hubble constant will be measured to ≲1%. We also show that this method can be used to perform Bayesian model selection between cosmological models. As an illustrative example, we find that a decisive statement can be made comparing the ΛCDM and RHCT cosmological models using two weeks of data from the Einstein Telescope.

Keywords: gravitational waves; hierarchical models; hubble constant
A LAMOST Spectroscopic Study of T Tauri Stars in the Orion OB1a Subassociation

We present a spectroscopic analysis of T Tauri stars (TTSs) observed with the wide-field multifiber spectrograph LAMOST in the substellar associations Ori OB1a located in the Orion Star-forming Complex. Based on GAIA-DR3 data, we selected stars with proper motions and parallaxes expected for TTSs belonging to the young association. We perform a spectroscopic analysis to obtain the spectral types and measure the equivalent widths of Li I and Hα to confirm the youth of the stars and estimate the accretion status. We also estimate extinctions, masses, and ages for the studied sample. Out of 342 TTSs with spectroscopic and kinematic properties indicating their membership of the subassociation, 2 are reported here for the first time. Finally, we detect four stellar kinematic groups located at different distances, two in the north fields and two in the south field. These groups also show different proper motions. This suggests that the star-forming scenario in this region is more complex than the traditional spatial-temporal scenario, in which a generation of stars triggers the formation of a new spatially differentiated generation of stars.

Keywords: star forming regions; ob associations; hertzsprung russell diagram; pre-main sequence; t tauri stars; stellar spectral types; stellar kinematics; protoplanetary disks
Magnetic Field Extrapolation in Active Region Well Comparable to Observations in Multiple Layers

Magnetic field extrapolation is a fundamental tool to reconstruct the three-dimensional magnetic field above the solar photosphere. However, the prevalently used force-free field model might not be applicable in the lower atmosphere with non-negligible plasma β, where the crucial process of flux rope formation and evolution could happen. In this work, we perform extrapolation in active region 12158, based on a recently developed magnetohydrostatic (MHS) method that takes plasma forces into account. By comparing the results with those from the force-free field extrapolation methods, we find that the overall properties, which are characterized by the magnetic free energy and helicity, are roughly the same. The major differences lie in the magnetic configuration and the twist number of the magnetic flux rope (MFR). Unlike previous works either obtained sheared arcades or one coherent flux rope, the MHS method derives two sets of MFR, which are highly twisted and slightly coupled. Specifically, the result in the present work is more comparable to the high-resolution observations from the chromosphere, through the transition region to the corona, such as the filament fibrils, pre-eruptive braiding characteristics, and the eruptive double-J-shaped hot channel. Overall, our work shows that the newly developed MHS method is more promising to reproduce the magnetic fine structures that can well match the observations at multiple layers, and future data-driven simulation based on such extrapolation will benefit in understanding the critical and precise dynamics of flux rope before eruption.

Keywords: solar magnetic fields; solar active regions; solar extreme ultraviolet emission; solar corona; solar chromosphere; solar photosphere
AESTRA: Deep Learning for Precise Radial Velocity Estimation in the Presence of Stellar Activity

Stellar activity interferes with precise radial velocity measurements and limits our ability to detect and characterize planets, in particular Earth-like planets. We introduce AESTRA (Auto-Encoding STellar Radial-velocity and Activity), a deep-learning method for precise radial velocity measurements. It combines a spectrum autoencoder, which learns to create realistic models of the star's rest-frame spectrum, and a radial-velocity estimator, which learns to identify true Doppler shifts in the presence of spurious shifts due to line-profile variations. Being self-supervised, AESTRA does not need "ground truth" radial velocities for training, making it applicable to exoplanet host stars for which the truth is unknown. In tests involving 1000 simulated spectra, AESTRA can detect planetary signals as low as 0.1 m s-1 even in the presence of 3 m s-1 of activity-induced noise and 0.3 m s-1 of photon noise per spectrum.

Keywords: high resolution spectroscopy; stellar activity; radial velocity
Accurate Distances of Massive Young Stars in the Scutum Spiral Arm

As part of the BeSSeL Survey, we have used the Very Long Baseline Array to measure 16 trigonometric parallaxes and proper motions of molecular masers associated with 14 high-mass star-forming regions in the Scutum arm in the first quadrant of the Milky Way. This increases the number of maser sources with accurate distances in this arm to 42. The Scutum arm can now be traced over a length of ≈8 kpc and spanning ≈100° of Galactic azimuth. We find that the large inward peculiar motions noted by Immer et al. are concentrated near the end of the Galactic bar, while away from the bar modest peculiar motions more typical of spiral arms are seen, strengthening the suggestion that the large motions are induced by the bar.

Keywords: trigonometric parallax
How Negative Energy and Kelvin-Helmholtz Instabilities Grow by Longitudinal Waves in Solar Atmospheric Jets

We model the propagation of slow magnetoacoustic body waves in solar jets in the course of negative energy wave excitation in the context of magnetohydrodynamic theory. Explicit approximate expressions are provided for the dispersion relation of slow body waves, providing insight into the influence of the steady flow speed, radiative cooling, and plasma-β at a glance. Analytic expressions are provided regarding critical speeds in the presence of backward waves, negative energy wave speeds, and instabilities. The buildup of the Kelvin-Helmholtz instability above the negative energy wave instability is expressed through analytic expressions that provide insight into the interplay of equilibrium conditions and dispersive effects as they affect the instability growth rate of slow body waves at various altitudes. As slow magnetoacoustic waves propagate with the same speed in the long-wavelength limit, slow body kink waves experience stronger dispersion than sausage waves. Backward waves are also probable at lower steady flow speeds for medium wavelengths when the jet hosts slow body kink waves that provide greater domains for dissipative processes. Slow body sausage waves grow faster while nearing the long-wavelength limit, while the internal plasma-β decreases the instability growth rate. The seismological aspect is that energy transfer to the external medium is observed on various timescales. The observational aspect is that slow body kink waves may exist at higher altitudes as energy has already been extracted to the external medium due to negative energy unstable slow body sausage waves in earlier stages contributing toward coronal heating.

Keywords: magnetohydrodynamics; solar coronal waves; magnetic fields
Variation of Dust Properties with Cosmic Time Implied by Radiative Torque Disruption

Dust properties within a galaxy are known to change from the diffuse medium to dense clouds due to increased local gas density. However, the question of whether dust properties change with redshift remains elusive. In this paper, using the fact that the mean radiation intensity of the interstellar medium (ISM) of star-forming galaxies increases with redshift, we show that dust properties should change due to increasing efficiency of rotational disruption by radiative torques, an effect named radiative torque disruption (RATD). We first show that because of RATD, the size distribution of interstellar dust varies with redshift, for instance, dust grains become smaller at higher z. We model the extinction curves and find that the curve becomes steeper with increasing redshift. The ratio of total-to-selective extinction, RV, decreases with redshift and achieves low values of RV ∼ 1.5-2.5 for grains having a composite structure. We also find that dust properties change with the local gas density because of RATD, but the change is dominated by the radiation field for the diffuse ISM. The low values of RV implied by RATD of interstellar dust could reproduce anomalous dust extinction observed toward supernovae Ia and Small Magellanic Cloud-like extinction curves with a steep far-UV rise toward high-z galaxies. Fluctuations in RV due to interstellar turbulence and varying radiation intensity may resolve the tension in measurements of the Hubble constant using supernovae Ia. We finally discuss the implications of evolving dust properties for high-z astrophysics.

Keywords: interstellar dust; interstellar dust extinction; interstellar medium; type ia supernovae; high-redshift galaxies
An Ongoing Tidal Capture in the Large Magellanic Cloud: The Low-mass Star Cluster KMK 88-10 Captured by the Massive Globular Cluster NGC 1835?

In the context of a project aimed at characterizing the dynamical evolution of old globular clusters in the Large Magellanic Cloud, we have secured deep HST/WFC3 images of the massive cluster NGC 1835. In the field of view of the acquired images, at a projected angular separation of approximately 2' from the cluster, we detected the small stellar system KMK 88-10. The observations provided the deepest color-magnitude diagram ever obtained for this cluster, revealing that it hosts a young stellar population with an age of 600-1000 Myr. The cluster surface brightness profile is nicely reproduced by a King model with a core radius r c = 4″ (0.97 pc), a half-mass radius r hm = 12″ (2.9 pc), and a concentration parameter c ~ 1.3 corresponding to a truncation radius r t ~ 81″ (19.5 pc). We also derived its integrated absolute magnitude (M V = -0.71) and total mass (M ~ 80-160 M ⊙). The most intriguing feature emerging from this analysis is that KMK 88-10 presents a structure elongated in the direction of NGC 1835, with an intracluster overdensity that suggests the presence of a tidal bridge between the two systems. If confirmed, this would be the first evidence of a tidal capture of a small star cluster by a massive globular. * Based on observations collected at the Hubble Space Telescope under proposal GO16361 (PI: Ferraro).

Keywords: stellar photometry; young star clusters; large magellanic cloud
The Role of Infrared Radiation Pressure in Shaping Dusty Winds in AGNs

The detection of dusty winds dominating the infrared emission of active galactic nuclei (AGNs) on parsec scales has revealed the limitations of traditional radiative transfer models based on a toroidal distribution of dusty gas. A new, more complex, dynamical structure is emerging and the physical origin of such dusty winds has to be critically assessed. We present a semi-analytical model to test the hypothesis of radiatively accelerated dusty winds launched by the AGN and by the heated dust itself. The model consists of an AGN and an infrared radiating dusty disk, the latter being the primary mass reservoir for the outflow. We calculate the trajectories of dusty gas clumps in this environment, accounting for both gravity and the AGN radiation as well as the re-radiation by the hot, dusty gas clouds themselves. We find that the morphology consists of a disk of material that orbits with sub-Keplerian velocities and a hyperboloid polar wind launched at the inner edge of the dusty disk. This is consistent with high-angular resolution infrared and sub-mm observations of some local Seyfert AGN. The strength of the wind and its orientation depend on the Eddington ratio and the column density of the dusty clumps, which is in agreement with proposed radiation regulated obscuration models developed for the X-ray obscuring material around AGNs.

Keywords: active galactic nuclei; seyfert galaxies; infrared galaxies
Massive Black Hole Merger Rates: The Effect of Kiloparsec Separation Wandering and Supernova Feedback

We revisit the predictions for the merger rate of massive black hole binaries detectable by the Laser Interferometer Space Antenna (LISA) and their background signal for pulsar-timing arrays. We focus on the effect of the delays between the merger of galaxies and the final coalescence of black hole binaries, and on supernova feedback on the black hole growth. By utilizing a semianalytic galaxy formation model, not only do we account for the driving of the evolution of binaries at separations ≲1 pc (gas-driven migration, stellar hardening, and triple/quadruple massive black hole systems), but we also improve on previous studies by accounting for the time spent by black hole pairs from kiloparsec down to parsec separation. We also include the effect of supernova feedback, which may eject gas from the nuclear region of low-mass galaxies, thus hampering the growth of black holes via accretion and suppressing their orbital migration in circumbinary disks. Despite including these novel physical effects, we predict that the LISA detection rate should still be $\gtrsim 2{{\rm{yr}}}^{-1}$ , irrespective of the model for the black hole seeds at high redshifts. Scenarios where black holes form from $\sim 100{M}_{\odot }$ seeds are more significantly impacted by supernova feedback. We also find that for detectable events, the merging black holes typically have mass ratios between ∼0.1 and 1. Predictions for the stochastic background in the band of pulsar-timing array experiments are instead rather robust and show only a mild dependence on the model.

Keywords: astrophysical black holes; gravitational waves; galaxy formation; supermassive black holes
Swift Spectroscopy of the Accretion Disk Wind in the Black Hole GRO J1655-40

Chandra obtained two High Energy Transmission Grating spectra of the stellar-mass black hole GRO J1655-40 during its 2005 outburst, revealing a rich and complex disk wind. Soon after its launch, the Neil Gehrels Swift Observatory began monitoring the same outburst. Some X-ray Telescope (XRT) observations were obtained in a mode that makes it impossible to remove strong Mn calibration lines, so the Fe Kα line region in the spectra was previously neglected. However, these lines enable a precise calibration of the energy scale, facilitating studies of the absorption-dominated disk wind and its velocity shifts. Here we present fits to 15 Swift/XRT spectra, revealing variability and evolution in the outflow. The data strongly point to a magnetically driven disk wind: both the higher-velocity (e.g., $V\simeq {10}^{4}\,\mathrm{km}\,{{\rm{s}}}^{-1}$ ) and lower-velocity (e.g., $V\simeq {10}^{3}\,\mathrm{km}\,{{\rm{s}}}^{-1}$ ) wind components are typically much faster than is possible for thermally driven outflows ( $V\leqslant 200\,\mathrm{km}\,{{\rm{s}}}^{-1}$ ), and photoionization modeling yields absorption radii that are two orders of magnitude below the Compton radius that defines the typical inner extent of thermal winds. Moreover, correlations between key wind parameters yield an average absorption measure distribution that is consistent with magnetohydrodynamic wind models. We discuss our results in terms of recent observational and theoretical studies of black hole accretion disks and outflows, as well as future prospects.

Keywords: black holes; compact objects; stellar accretion disks
Formation and Evolution of Transient Jets and Their Cavities in Black Hole X-Ray Binaries

We propose a model explaining the origin of transient/episodic jets in black hole X-ray binaries, in which they are caused by transitions from a collimated, strongly magnetized jet to a wide, uncollimated outflow. The change occurs when the accretion flow leaves the magnetically choked state due to an increase of the accretion rate for a weakly varying magnetic flux. The formed powerful jet then detaches from its base, and propagates as a discrete ejection. The uncollimated outflow then produces a relativistic plasma that fills the surroundings of the black hole, contributing to the formation of a low-density cavity. While the pressure in the cavity is in equilibrium with the surrounding interstellar medium (ISM), its inertia is orders of magnitude lower than that of the ISM. This implies that the plasma cannot efficiently decelerate the ejecta, explaining most of the observations. The modest deceleration within the cavities observed in some cases can then be due to the presence of clouds and/or filaments, forming a wide transition zone between the cavity and the ISM.

Keywords: relativistic jets; x-ray binary stars; accretion; galactic radio sources
The Origin of Neptune's Unusual Satellites from a Planetary Encounter

The Neptunian satellite system is unusual, comprising Triton, a large (∼2700 km) moon on a close-in, circular, yet retrograde orbit, flanked by Nereid, the largest irregular satellite (∼300 km) on a highly eccentric orbit. Capture origins have been previously suggested for both moons. Here we explore an alternative in situ formation model where the two satellites accreted in the circum-Neptunian disk and are imparted irregular and eccentric orbits by a deep planetary encounter with an ice giant (IG), like that predicted in the Nice scenario of early solar system development. We use N-body simulations of an IG approaching Neptune to 20 Neptunian radii (RNep), through a belt of circular prograde regular satellites at 10-30 RNep. We find that half of these primordial satellites remain bound to Neptune and that 0.4%-3% are scattered directly onto wide and eccentric orbits resembling that of Nereid. With better matches to the observed orbit, our model has a success rate comparable to or higher than capture of large Nereid-sized irregular satellites from heliocentric orbit. At the same time, the IG encounter injects a large primordial moon onto a retrograde orbit with specific angular momentum similar to Triton's in 0.3%-3% of our runs. While less efficient than capture scenarios, our model does indicate that an in situ origin for Triton is dynamically possible. We also simulate the post-encounter collisional and tidal orbital evolution of Triton analog satellites and find they are decoupled from Nereid on timescales of ∼104 yr, in agreement with Cuk & Gladman.

Keywords: natural satellite formation; neptunian satellites; irregular satellites; close encounters; celestial mechanics
A New Implementation of the Schwarzchild Method for Constructing Observationally Driven Dynamical Models of Galaxies of All Morphological Types

We present Forstand, a new code for constructing dynamical models of galaxies with the Schwarzschild orbit-superposition method. These models are constrained by line-of-sight kinematic observations and applicable to galaxies of all morphological types, including disks and triaxial rotating bars. Our implementation has several novel and improved features, is computationally efficient, and has been made publicly available. Using mock data sets taken from N-body simulations, we demonstrate that the pattern speed of a bar can be recovered with an accuracy of 10-20%, regardless of orientation, if the 3D shape of the galaxy is known or inferred correctly.

Keywords: galaxy dynamics; galaxy structure
The Near Infrared Imager and Slitless Spectrograph for JWST. V. Kernel Phase Imaging and Data Analysis

Kernel phase imaging (KPI) enables the direct detection of substellar companions and circumstellar dust close to and below the classical (Rayleigh) diffraction limit. The high-Strehl full pupil images provided by the James Webb Space Telescope (JWST) are ideal for application of the KPI technique. We present a kernel phase analysis of JWST NIRISS full pupil images taken during the instrument commissioning and compare the performance to closely related NIRISS aperture masking interferometry (AMI) observations. For this purpose, we develop and make publicly available the custom Kpi3Pipeline data reduction pipeline enabling the extraction of kernel phase observables from JWST images. The extracted observables are saved into a new and versatile kernel phase FITS file data exchange format. Furthermore, we present our new and publicly available fouriever toolkit which can be used to search for companions and derive detection limits from KPI, AMI, and long-baseline interferometry observations while accounting for correlated uncertainties in the model fitting process. Among the four KPI targets that were observed during NIRISS instrument commissioning, we discover a low-contrast (~1:5) close-in (~1 λ/D) companion candidate around CPD-66 562 and a new high-contrast (~1:170) detection separated by ~1.5 λ/D from 2MASS J062802.01-663738.0. The 5σ companion detection limits around the other two targets reach ~6.5 mag at ~200 mas and ~7 mag at ~400 mas. Comparing these limits to those obtained from the NIRISS AMI commissioning observations, we find that KPI and AMI perform similar in the same amount of observing time. Due to its 5.6 times higher throughput if compared to AMI, KPI is beneficial for observing faint targets and superior to AMI at separations ≳325 mas. At very small separations (≲100 mas) and between ~250 and 325 mas, AMI slightly outperforms KPI which suffers from increased photon noise from the core and the first Airy ring of the point-spread function.

Keywords: high angular resolution; interferometry; direct imaging; astronomy data reduction
Can LISA Resolve Black Hole Binaries in the M87 Globular Clusters?

As stellar black holes (BHs) interact with one another in globular clusters, BH binaries form, inspiral, and merge via gravitational wave emission. These dynamically formed BH binaries may account for a fraction of the sources observed by LIGO/Virgo and, earlier in their inspirals, may be detected at millihertz frequencies by LISA in nearby galaxies. M87, known to contain over 104 globular clusters, is a promising candidate for such millihertz sources. Utilizing N-body cluster simulations, we investigate the binary BH population in M87 clusters. Although thousands of sources in LISA's frequency range (10-5-1 Hz) are expected in M87's clusters, we predict none are resolvable with sufficiently high signal-to-noise ratios. We predict the nearest globular clusters in the Milky Way and clusters found in distant galaxies (d ≳ 100 Mpc) near LISA's detection horizon for stellar BH binaries are more promising hosts of resolvable LISA sources.

Keywords: globular star clusters; gravitational wave sources; stellar mass black holes; n-body simulations