adsabs/SciX_UAT_keywords huggingface dataset:
Planes of Satellites around Simulated Disk Galaxies. I. Finding High-quality Planar Configurations from Positional Information and Their Comparison to MW/M31 Data

We address the "plane of satellites problem" by studying planar configurations around two disk galaxies with no late major mergers, formed in zoom-in hydro-simulations. Due to the current lack of good-quality kinematic data for M31 satellites, we use only positional information. So far, positional analyses of simulations are unable to find planes as thin and populated as the observed ones. We follow a novel systematic and detailed plane searching technique to study the properties and quality of planes of satellites, in both simulations or real data. In particular, (I) we extend the four-galaxy-normal density plot method (Pawlowski et al. 2013) in a way designed to efficiently identify high-quality planes (I.e., thin and populated) without imposing extra constraints on their properties, and (II), we apply it for the first time to simulations. Using zoom-in simulations allows us to mimic Milky Way/M31-like systems regarding the number of satellites involved as well as galactic disk effects. In both simulations, we find satellite planar configurations that are compatible, along given time intervals, with all of the spatial characteristics of observed planes identified using the same methodology. During most of these periods, planes are approximately perpendicular to the galactic disk. However, the fraction of co-orbiting satellites within them is, in general, low, suggesting time-varying satellite membership. We conclude that high-quality positional planes of satellites could be not infrequent in ΛCDM-formed disk galaxies with a quiet assembly history. Detecting kinematically coherent, time-persistent planes demands considering the full six-dimensional phase-space information of satellites.

Keywords: dwarf galaxies; local group; galaxy planes; galaxy dynamics; galaxy kinematics
The GMRT High Resolution Southern Sky Survey for Pulsars and Transients. III. Searching for Long-period Pulsars

Searching for periodic non-accelerated signals in the presence of ideal white noise using the fully phase-coherent fast-folding algorithm (FFA) is theoretically established as a more sensitive search method than the fast Fourier transform (FFT) search with incoherent harmonic summing. In this paper, we present a comparison of the performance of an FFA search implementation using RIPTIDE and an FFT search implementation using PRESTO, over a range of signal parameters with white noise and with real telescope noise from the Giant Meterwave Radio Telescope (GMRT) High Resolution Southern Sky (GHRSS) survey with the upgraded GMRT (uGMRT). We find that the FFA search with appropriate de-reddening of the time series performs better than the FFT search with spectral whitening for long-period pulsars under real GHRSS noise conditions. We describe an FFA-search pipeline implemented for the GHRSS survey looking for pulsars over a period of 0.1-100 s and up to a dispersion measure of 500 pc cm-3. We processed GHRSS survey data covering ~1500 deg2 of the sky with this pipeline. We re-detected 43 known pulsars with a better signal-to-noise ratio in the FFA search than in the FFT search. We also report the discovery of two new pulsars, including a long-period pulsar with a short duty cycle, using this FFA-search pipeline. A population of long-period pulsars with periods of several seconds or higher could help constrain the pulsar death line.

Keywords: pulsars; radio pulsars; astronomical techniques; observational astronomy
Impact of PREX-II and Combined Radio/NICER/XMM-Newton's Mass-radius Measurement of PSR J0740+6620 on the Dense-matter Equation of State

In this paper, we discuss the impact of the following laboratory experiments and astrophysical observation of neutron stars (NSs) on their equation of state (EoS): (a) the new measurement of neutron skin thickness of 208Pb, ${R}_{\mathrm{skin}}^{208}=0.29\pm 0.07$ fm by the PREX-II experiment; (b) the mass measurement of PSR J0740+6620 has been slightly revised down by including additional ~1.5 yr of pulsar timing data. As well as the radius measurement of PSR J0740+6620 by joint NICER/XMM-Newton collaboration, which has a similar size to PSR J0030+0451. We combine this information using Bayesian statistics along with the previous LIGO/Virgo and NICER observations of NS using a hybrid nuclear+piecewise-polytrope EoS parameterization. Our findings are as follows. (a). Adding PREX-II result yields the value of empirical parameter $L={69}_{-19}^{+21}$ MeV, ${R}_{\mathrm{skin}}^{208}={0.20}_{-0.05}^{+0.05}$ fm, and radius of a 1.4 M⊙ ( ${R}_{1.4})={12.75}_{-0.54}^{+0.42}$ km at 1σ confidence interval. We find these inferred values are mostly dominated by the combined astrophysical observations as the measurement uncertainty in ${R}_{\mathrm{skin}}^{208}$ by PREX-II is much broader. Also, a better measurement of ${R}_{\mathrm{skin}}^{208}$ might have a small effect on the radius of low-mass NSs but, for the high masses, there will be almost no effect. (b) After adding the revised mass and radius measurement of PSR J0740+6620, we find the inferred radii of NSs are slightly pushed toward the larger values and the uncertainty on the radius of a 2.08 M⊙ NS is moderately improved.

Keywords: neutron stars; gravitational wave astronomy; nuclear astrophysics; pulsars
The Massive and Distant Clusters of WISE Survey. VIII. Radio Activity in Massive Galaxy Clusters

We present a study of the central radio activity of galaxy clusters at high redshift. Using a large sample of galaxy clusters at 0.7 < z < 1.5 from the Massive and Distant Clusters of Wide-field Infrared Survey Explorer Survey and the Faint Images of the Radio Sky at Twenty-Centimeters 1.4 GHz catalog, we measure the fraction of clusters containing a radio source within the central 500 kpc, which we term the cluster radio-active fraction, and the fraction of cluster galaxies within the central 500 kpc exhibiting radio emission. We find tentative (2.25σ) evidence that the cluster radio-active fraction increases with cluster richness, while the fraction of cluster galaxies that are radioluminous ( ${L}_{1.4\mathrm{GHz}}\geqslant {10}^{25}$ W Hz-1) does not correlate with richness at a statistically significant level. Compared to that calculated at 0 < z < 0.6, the cluster radio-active fraction at 0 < z < 1.5 increases by a factor of 10. This fraction is also dependent on the radio luminosity. Clusters at higher redshift are much more likely to host a radio source of luminosity ${L}_{1.4\mathrm{GHz}}\gtrsim {10}^{26}$ W Hz-1 than are lower-redshift clusters. We compare the fraction of radioluminous cluster galaxies to the fraction measured in a field environment. For 0.7 < z < 1.5, we find that both the cluster and field radioluminous galaxy fraction increases with stellar mass, regardless of environment, though at fixed stellar mass, cluster galaxies are roughly 2 times more likely to be radioluminous than field galaxies.

Keywords: active galactic nuclei; extragalactic radio sources; high-redshift galaxy clusters; galaxy clusters; galaxy evolution
Formation History of HD 106906 and the Vertical Warping of Debris Disks by an External Inclined Companion

HD 106906 is a planetary system that hosts a wide-orbit companion, as well as an eccentric and flat debris disk, which hold important constraints on its formation and subsequent evolution. The recent observations of the companion constrain its orbit to be eccentric and inclined relative to the plane of the debris disk. Here, we show that, in the presence of the inclined companion, the debris disk quickly (≲5 Myr) becomes warped and puffy. This suggests that the current configuration of the system is relatively recent. We explore the possibility that a recent close encounter with a free-floating planet could produce a companion with orbital parameters that agree with observations of HD 106906 b. We find that this scenario is able to recreate the structure of the debris disk while producing a companion in agreement with observation.

Keywords: exoplanets; debris disks; orbits; planetary dynamics
The Intriguing Behavior of Ultraviolet Photodesorption and Color Temperature of Astrophysical CO Ice Analogs: A Possible Indication of Molecular Disorder

Ejection of molecules from ice-covered dust exposed to ultraviolet photons, known as photodesorption, is summoned to account for gas abundances in cold regions. Carbon monoxide (CO) is the second most abundant ice component in interstellar clouds. Photon energy transfer between CO molecules can eventually excite molecules on the ice surface, allowing desorption. CO photodesorption drops linearly by a factor of 4 for increasing ice deposition temperature between 7 and 20 K. Because translation of molecules leading to crystallization occurs above 20 K, amorphous CO ice must hold another property that depends on deposition temperature and has an impact on photodesorption. CO ice molecules act as tiny dipoles weakly bonded to each other. We used colorimetry to trace variations of the relative orientations between CO molecules, a process not observed using other techniques. Color variations seen by eye at different deposition temperatures range from brown to translucent, or transparent when CO ice is deposited above 20 K and is nearly crystalline. As expected, apolar N2 ice did not display a visual color. Color temperature measurements allowed quantification of this phenomenon. The behavior of color temperature matches the photodesorption, allowing a better understanding of this process, and provides a method to monitor structural changes in molecular solids. An implication in astrophysics is that the albedo of icy bodies can be low in CO patches. A brownish color is not only indicative of organic matter, as it may be due to disordered solid CO, and allows to determine the build-up temperature of CO ice.

Keywords: dense interstellar clouds; interstellar dust processes; interstellar molecules
High-contrast JWST-MIRI Spectroscopy of Planet-forming Disks for the JDISC Survey

The JWST Disk Infrared Spectral Chemistry Survey (JDISCS) aims to understand the evolution of the chemistry of inner protoplanetary disks using the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST). With a growing sample of >30 disks, the survey implements a custom method to calibrate the MIRI Medium Resolution Spectrometer (MRS) to contrasts of better than 1:300 across its 4.9–28 μm spectral range. This is achieved using observations of Themis family asteroids as precise empirical reference sources. The high spectral contrast enables precise retrievals of physical parameters, searches for rare molecular species and isotopologues, and constraints on the inventories of carbon- and nitrogen-bearing species. JDISCS also offers significant improvements to the MRS wavelength and resolving power calibration. We describe the JDISCS calibrated data and demonstrate their quality using observations of the disk around the solar-mass young star FZ Tau. The FZ Tau MIRI spectrum is dominated by strong emission from warm water vapor. We show that the water and CO line emission originates from the disk surface and traces a range of gas temperatures of ∼500–1500 K. We retrieve parameters for the observed CO and H2O lines and show that they are consistent with a radial distribution represented by two temperature components. A high water abundance of n(H2O) ∼ 10‑4 fills the disk surface at least out to the 350 K isotherm at 1.5 au. We search the FZ Tau environs for extended emission, detecting a large (radius of ∼300 au) ring of emission from H2 gas surrounding FZ Tau, and discuss its origin.

Keywords: protoplanetary disks; james webb space telescope; water vapor; infrared spectroscopy; astronomy data reduction; astrochemistry
Evolution of Nonparametric Morphology of Galaxies in the JWST CEERS Field at z ≃ 0.8-3.0

Galaxy morphology is one of the most fundamental ways to describe galaxy properties, but the morphology we observe may be affected by wavelength and spatial resolution, which may introduce systematic bias when comparing galaxies at different redshift. Taking advantage of the broad wavelength coverage from optical to near-IR and the high-resolution NIRCam instrument of the JWST, we measure the nonparametric morphological parameters of a total of 1376 galaxies at z ≃ 0.8-3.0 in the CEERS field through an optimized code called statmorph_csst. We divide our sample into three redshift intervals and investigate the wavelength and redshift dependence of the morphological parameters. We also explore how the widely used galaxy type classification methods based on the morphological parameters depend on wavelength and spatial resolution. We find that there are variations in all morphological parameters with rest-frame wavelength (λ rf), especially at the short-wavelength end, and that λ rf mainly affects the classification between late- and early-type galaxies. As λ rf increases, the galaxies on the G-M 20 diagram move to the upper left with a slope of -0.23 ± 0.03 on average. We find that spatial resolution mainly affects the merger identification. The merger fraction in F200W resolution can be ≳2 times larger than that in F444W resolution. Furthermore, we compare the morphological parameter evolution of galaxies with different stellar masses. We find that there are differences in the morphological evolution of high- and low-mass (log M * ≥ 10 and 9 < log M * < 10) galaxies in the studied redshift range, which may be caused by their different evolutionary paths.

Keywords: galaxy classification systems; galaxy structure; high-redshift galaxies; galaxy evolution
Very Long Baseline Array Astrometry of Cassini: The Final Epochs and an Improved Orbit of Saturn

We report results from multi-epoch radio astrometry of the Cassini spacecraft with the Very Long Baseline Array (VLBA). These observations are part of a program to determine a series of accurate positions for the Saturn system barycenter in the inertial International Celestial Reference Frame (ICRF) and to use these position measurements to improve our knowledge of Saturn's orbit in the planetary ephemeris. Our VLBA observations cover the full duration of the orbital phase of the Cassini mission, from Saturn orbit insertion in 2004 to the end of mission in 2017. This period covers more than one-third of Saturn's orbital period, allowing us to obtain good orbit constraints for Saturn, particularly on the inclination and ascending node longitude. During the early years of Cassini's orbital mission our VLBA data dominated the determination of orbit orientation, while later in the mission range measurements become more significant. The orientation of Saturn's orbit is now known to approximately 0.25 milli-arcseconds (1.25 nrad), an order of magnitude improvement since the start of Cassini observations. Continuing improvements in the ICRF position accuracy for our phase reference sources, and possible improvements in the final orbit solutions for Cassini, may lead to a still better Saturn orbit over the coming years.

Keywords: radio astrometry; ephemerides; saturn
The Evolution of Protostellar Outflow Cavities, Kinematics, and Angular Distribution of Momentum and Energy in Orion A: Evidence for Dynamical Cores

We present Atacama Large Millimeter/submillimeter Array observations of the ~10,000 au environment surrounding 21 protostars in the Orion A molecular cloud tracing outflows. Our sample is composed of Class 0 to flat-spectrum protostars, spanning the full ~1 Myr lifetime. We derive the angular distribution of outflow momentum and energy profiles and obtain the first two-dimensional instantaneous mass, momentum, and energy ejection rate maps using our new approach: the pixel flux-tracing technique. Our results indicate that by the end of the protostellar phase, outflows will remove ~2-4 M ⊙ from the surrounding ~1 M ⊙ low-mass core. These high values indicate that outflows remove a significant amount of gas from their parent cores and continuous core accretion from larger scales is needed to replenish core material for star formation. This poses serious challenges to the concept of cores as well-defined mass reservoirs, and hence to the simplified core-to-star conversion prescriptions. Furthermore, we show that cavity opening angles, and momentum and energy distributions all increase with protostar evolutionary stage. This is clear evidence that even garden-variety protostellar outflows: (a) effectively inject energy and momentum into their environments on 10,000 au scales, and (b) significantly disrupt their natal cores, ejecting a large fraction of the mass that would have otherwise fed the nascent star. Our results support the conclusion that protostellar outflows have a direct impact on how stars get their mass, and that the natal sites of individual low-mass star formation are far more dynamic than commonly accepted theoretical paradigms.

Keywords: star formation; protostars; stellar feedback; giant molecular clouds; stellar-interstellar interactions; stellar winds; stellar jets; star forming regions; observational astronomy; radio interferometry; circumstellar envelopes; circumstellar matter
Calculation and Uncertainty of Fast Radio Burst Structure Based on Smoothed Data

Studies of the time-domain structure of fast radio bursts (FRBs) require an accurate estimate of the FRB dispersion measure in order to recover the intrinsic burst shape. Furthermore, the exact dispersion measure is itself of interest when studying the time evolution of the medium through which multiple bursts from repeating FRBs propagate. A commonly used approach to obtain the dispersion measure is to take the value that maximizes the FRB structure in the time domain. However, various authors use differing methods to obtain this structure parameter and do not document the smoothing method used. Furthermore, there are no quantitative estimates of the error in this procedure in the FRB literature. In this article, we present a smoothing filter based on the discrete cosine transform, and show that computing the structure parameter by summing the squares of the derivatives and taking the square root (that is, the 2-norm, $\sqrt{{\rm{\Sigma }}{(d/{dt})}^{2}}$ ) immediately lends itself to the calculation of the uncertainty of the structure parameter. We illustrate this with FRB 20181112A and FRB 20210117A data, which were detected by the Australian Square Kilometre Array Pathfinder, and for which high-time-resolution data are available.

Keywords: radio transient sources
Identification of Hot Gas around Low-mass Protostars

The low carbon content of Earth and primitive meteorites compared to the Sun and interstellar grains suggests that carbon-rich grains were destroyed in the inner few astronomical units of the young solar system. A promising mechanism to selectively destroy carbonaceous grains is thermal sublimation within the soot line at ≳300 K. To address whether such hot conditions are common among low-mass protostars, we observe CH3CN transitions at 1, 2, and 3 mm with the NOrthern Extended Millimeter Array toward seven low-mass and one intermediate-mass protostar (L bol ∼ 2–300L ⊙), as CH3CN is an excellent temperature tracer. We find >300 K gas toward all sources, indicating that hot gas may be prevalent. Moreover, the excitation temperature for CH3OH obtained with the same observations is always lower (∼135–250 K), suggesting that CH3CN and CH3OH have a different spatial distribution. A comparison of the column densities at 1 and 3 mm shows a stronger increase at 3 mm for CH3CN than for CH3OH. Since the dust opacity is lower at longer wavelengths, this indicates that CH3CN is enhanced in the hot gas compared to CH3OH. If this CH3CN enhancement is the result of carbon-grain sublimation, these results suggest that Earth's initial formation conditions may not be rare.

Keywords: astrochemistry; protostars
First Detection of Orbital Motion for HD 106906 b: A Wide-separation Exoplanet on a Planet Nine-like Orbit

HD 106906 is a 15 Myr old short-period (49 days) spectroscopic binary that hosts a wide-separation (737 au) planetary-mass ( $\sim 11\,{M}_{\mathrm{Jup}}$ ) common proper motion companion, HD 106906 b. Additionally, a circumbinary debris disk is resolved at optical and near-infrared wavelengths that exhibits a significant asymmetry at wide separations that may be driven by gravitational perturbations from the planet. In this study we present the first detection of orbital motion of HD 106906 b using Hubble Space Telescope images spanning a 14 yr period. We achieve high astrometric precision by cross-registering the locations of background stars with the Gaia astrometric catalog, providing the subpixel location of HD 106906 that is either saturated or obscured by coronagraphic optical elements. We measure a statistically significant 31.8 ± 7.0 mas eastward motion of the planet between the two most constraining measurements taken in 2004 and 2017. This motion enables a measurement of the inclination between the orbit of the planet and the inner debris disk of either ${36}_{-14}^{+27}$ deg or ${44}_{-14}^{+27}$ deg, depending on the true orientation of the orbit of the planet. There is a strong negative correlation between periastron and mutual inclination; orbits with smaller periastra are more misaligned with the disk plane. With a periastron of ${510}_{-320}^{+480}$ au, HD 106906 b is likely detached from the planetary region within 100 au radius, showing that a Planet Nine-like architecture can be established very early in the evolution of a planetary system.

Keywords: exoplanets; extrasolar gaseous giant planets; astrometry; orbit determination; debris disks
A New Scenario of Solar Modulation Model during the Polarity Reversing

When entering the heliosphere, galactic cosmic rays (GCRs) will encounter the solar wind plasma, reducing their intensity. This solar modulation effect is strongly affected by the structure of the solar wind and the heliospheric magnetic field (HMF). To address the effect during the solar maximum of cycle 24, we study the solar modulation under a scenario in which the weights for A = ±1 are determined by the structure of HMF, and the traveling time of GCRs simulated by SOLARPROP is taken into account. We then fit the cosmic-ray proton data provided by AMS-02 and Voyager in the energy range 4 MeV-30 GeV, and confirm that the modulation time lag in this model is about 9 months, which is consistent with the previous studies. This model incorporates a more realistic description of the polarity reversing and provides a more reliable estimation of the solar modulation effect during the maximum activity period.

Keywords: heliosphere; solar system; galactic cosmic rays
Detecting Preheating in Protoclusters with Lyα Forest Tomography

Studies of low-redshift galaxy clusters suggest the intracluster medium (ICM) has experienced nongravitational heating during the formation phase of the clusters. Using simple phenomenological heating prescriptions, we simulate the effect of this preheating of the nascent ICM in galaxy protoclusters and examine its effect on Lyα forest tomographic maps. We analyze a series of cosmological zoom-in simulations of protoclusters within the framework of the Lyα transmission-dark matter (DM) density distribution. We find that the more energy is injected into the proto-ICM at z = 3, the more the distribution at high DM density tilts toward higher Lyα transmission. This effect has been confirmed in both low-resolution simulations adopting a preheating scheme based on entropy floors, as well as in higher-resolution simulations with another scheme based on energy floors. The evolution of the slope of this distribution is shown to vary with redshift. The methodology developed here can be applied to current and upcoming Lyα forest tomographic survey data to help constrain feedback models in galaxy protoclusters.

Keywords: galaxy clusters; intracluster medium; lyman alpha forest