adsabs/SciX_UAT_keywords huggingface dataset:
The Spiderweb Protocluster is Being Magnetized by Its Central Radio Jet

We present deep broadband radio polarization observations of the Spiderweb radio galaxy (J1140-2629) in a galaxy protocluster at z = 2.16. These yield the most detailed polarimetric maps yet made of a high-redshift radio galaxy. The intrinsic polarization angles and Faraday rotation measures (RMs) reveal coherent magnetic fields spanning the ~60 kpc length of the jets, while ~50% fractional polarizations indicate these fields are well ordered. Source-frame ∣RM∣ values of ~1000 rad m-2 are typical, and values up to ~11,100 rad m-2 are observed. The Faraday-rotating gas cannot be well mixed with the synchrotron-emitting gas, or stronger-than-observed depolarization would occur. Nevertheless, an observed spatial coincidence between a localized ∣RM∣ enhancement of ~1100 rad m-2 , a bright knot of Lyα emission, and a deviation of the radio jet provide direct evidence for vigorous jet-gas interaction. We detect a large-scale RM gradient totaling ~1000 s rad m-2 across the width of the jet, suggesting a net clockwise (as viewed from the active galactic nuclei) toroidal magnetic field component exists at tens-of-kiloparsec scales, which we speculate may be associated with the operation of a Poynting-Robertson cosmic battery. We conclude the RMs are mainly generated in a sheath of hot gas around the radio jet, rather than the ambient foreground protocluster gas. The estimated magnetic field strength decreases by successive orders of magnitude going from the jet hotspots (~90 μG) to the jet sheath (~10 μG) to the ambient intracluster medium (~1 μG). Synthesizing our results, we propose that the Spiderweb radio galaxy is actively magnetizing its surrounding protocluster environment, with possible implications for theories of the origin and evolution of cosmic magnetic fields.

Keywords: extragalactic magnetic fields; high-redshift galaxy clusters; radio galaxies; polarimetry; protoclusters
Observations with the Differential Speckle Survey Instrument. X. Preliminary Orbits of K-dwarf Binaries and Other Stars

This paper details speckle observations of binary stars taken at the Lowell Discovery Telescope, the WIYN telescope, and the Gemini telescopes between 2016 January and 2019 September. The observations taken at Gemini and Lowell were done with the Differential Speckle Survey Instrument (DSSI), and those done at WIYN were taken with the successor instrument to DSSI at that site, the NN-EXPLORE Exoplanet Star and Speckle Imager (NESSI). In total, we present 378 observations of 178 systems, and we show that the uncertainty in the measurement precision for the combined data set is ∼2 mas in separation, ∼1°-2° in position angle depending on the separation, and ∼0.1 mag in magnitude difference. Together with data already in the literature, these new results permit 25 visual orbits and one spectroscopic-visual orbit to be calculated for the first time. In the case of the spectroscopic-visual analysis, which is done on the ternary star HD 173093, we calculate masses with a precision of better than 1% for all three stars in that system. Twenty-one of the visual orbits calculated have a K dwarf as the primary star; we add these to the known orbits of K-dwarf primary stars and discuss the basic orbital properties of these stars at this stage. Although incomplete, the data that exist so far indicate that binaries with K-dwarf primaries tend not to have low-eccentricity orbits at separations of one to a few tens of astronomical units, that is, on solar system scales.

Keywords: visual binary stars; spectroscopic binary stars; interferometric binary stars; speckle interferometry; k dwarf stars
A Rare, Strong Shock Front in the Merging Cluster SPT-CLJ 2031-4037

We present our findings from the new deep Chandra observations (256 ks) of the merging galaxy cluster SPT-CLJ 2031-4037 at z = 0.34. Our observations reveal intricate structures seen in a major merger akin to the Bullet Cluster. The X-ray data confirm the existence of two shock fronts, one to the northwest and one to the southeast, by directly measuring the temperature jump of gas across the surface brightness edges. The stronger shock front in the northwest has a density jump of 3.16 ± 0.34 across the sharp surface brightness edge and Mach number , which makes this cluster one of the rare merging systems with a Mach number M > 2. We use the northwestern shock to compare two models for shock heating—the instant heating model and the Coulomb collisional heating model—and we determine that the temperatures across the shock front agree with the Coulomb collisional model of heating. For the shock front in the southeastern region, we find a density jump of 1.53 ± 0.14 and a Mach number of .

Keywords: galaxy clusters; shocks; x-ray astronomy; intracluster medium
TrExoLiSTS: Transiting Exoplanets List of Space Telescope Spectroscopy

We present the Space Telescope Science Institute Wide Field Camera 3 (WFC3) project webpage, Transiting Exoplanets List of Space Telescope Spectroscopy, TrExoLiSTS. It tabulates existing observations of transiting exoplanet atmospheres, available in the MAST archive made with Hubble Space Telescope (HST) WFC3 using the stare or spatial scan mode. A parallel page is available for all instruments aboard James Webb Space Telescope (JWST) using the spectral Time Series Observation mode. The webpages include observations obtained during primary transits, secondary eclipses and phase curves. TREXOLISTS facilitates proposal preparation for programs that are highly complementary to existing programs in terms of targets, wavelength coverage, as well as reduces duplication and redundant effort. Reference for the quality of the HST WFC3 visits taken more than 1.5 yr ago are made available via including diagrams of the direct image, white light curve and drift of the spectral time series across the detector. Future improvements to the webpage will include: Expanding program query to other HST instruments and reference for the quality of JWST visits.

Keywords: catalogs; exoplanet catalogs; exoplanet atmospheres; observational astronomy
Spectral Energy Distributions for 258 Local Volume Galaxies

We present model spectral energy distribution (SED) fits to ultraviolet/optical/infrared observations for the 258 nearby galaxies in the Local Volume Legacy survey, a sample dominated by lower-luminosity dwarf irregular systems. The data for each galaxy include up to 26 spatially-integrated broadband and narrowband fluxes from the Galaxy Evolution Explorer, Spitzer Space Telescope, and Infrared Astronomical Satellite space-based platforms, and from the Sloan Digital Sky Survey, Two Micron All Sky Survey, and other ground-based efforts. The CIGALE SED fitting package is employed using a delayed star-formation history with an optional late burst or quenching episode to constrain 11 different free parameters that characterize the properties of each galaxy's stellar and dust emission, with the overriding constraint that the ultraviolet/optical emission absorbed by interstellar dust grains is emitted in equal energy portions at infrared wavelengths. The main results are: (i) 94% of the SED fits yield reduced χ 2 values less than 3; (ii) the modeled stellar masses agree with those derived from 3.6 μm-based measures with a scatter of 0.07 dex; (iii) for a typical galaxy in the sample the SED-derived star-formation rate averaged over the past 100 Myr is about 88% of the value derived from standard hybrid indicators on similar timescales; and (iv) there is a statistically significant inverse relation between the stellar mass fraction appearing in the late burst and the total stellar mass. These results build upon prior SED modeling efforts in the local volume and lay the groundwork for future studies of more distant low-metallicity galaxies with JWST.

Keywords: galaxies; spectral energy distribution
Pure Rotational Spectrum of CCL+

The pure rotational spectrum of the CCl+ (X1Σ+) cation has been observed for the first time using a cryogenic ion trap apparatus and applying an action spectroscopy scheme. The major isotopic species 12C35Cl+ was observed up to the J = 4 ← 3 transition around 191 GHz and 12C37Cl+ was observed up to J = 3 ← 2. All transitions exhibit (partially) resolved hyperfine structure from the presence of the chlorine nuclei (both I = 3/2). This study provides the data needed for future sensitive radio astronomical searches for CCl+ in space.

Keywords: high resolution spectroscopy; molecular spectroscopy; millimeter astronomy; astrochemistry
The Role of Gravitational Recoil in the Assembly of Massive Black Hole Seeds

When two black holes merge, the asymmetric emission of gravitational waves provides an impulse to the merged system; this gravitational-wave recoil velocity can be up to 4000 km s-1, easily fast enough for the black hole to escape its host galaxy. We combine semianalytic modeling with cosmological zoom-in simulations of a Milky Way-type galaxy to investigate the role of black hole spin and gravitational recoil in the epoch of massive black hole (MBH) seeding. We sample four different spin distributions (random, aligned, antialigned, and zero spin), and compare the resulting merger rates, occupation fractions, and MBH-host relations with what is expected by excluding the effect of recoil. The inclusion of gravitational recoil and MBH spin in the assembly of MBH seeds can reduce the final z = 5 MBH mass by up to an order of magnitude. The MBH occupation fraction, however, remains effectively unaltered due to episodes of black hole formation following a recoil event. While electromagnetic detections of these events are unlikely, the Laser Interferometer Space Antenna is ideally suited to detect gravitational-wave signals from such events.

Keywords: high-redshift galaxies; black hole physics; n-body simulations; galaxy formation
Examining Dust Directionality with the Parker Solar Probe FIELDS Instrument

Parker Solar Probe's (PSP's) FIELDS instrument provides a measure of the dust impact rate on the spacecraft with a full-coverage summary of the voltages recorded by the spacecraft's antennas. From consecutively sampled periods throughout PSP's orbit, FIELDS stores the maximum amplitude measured by each active antenna. The occurrence of a dust impact during a given period can be identified by these amplitudes exceeding a few tens of millivolts, and a dust grain's impact location can be approximated using the differential amplitudes between antennas. The impact locations indicated in the data are inspected for compatibility with the incident directions of prograde, retrograde, and β-meteoroid orbits in the ecliptic. Important features in the data are consistent with the incidence of β-meteoroids, but others are better explained by the incidence of grains on prograde or retrograde orbits.

Keywords: interplanetary dust; circumstellar dust; the sun
Fluctuation Amplitudes of Magnetic-field Directional Turnings and Magnetic-velocity Alignment Structures in the Solar Wind

Magnetic-field directional turning (MFDT) and magnetic-velocity alignment structure (MVAS) are two typical types of structures in the solar wind. However, their fluctuation amplitudes in different turbulence states have not been studied before. Here, we present the amplitude distributions of MFDTs and MVASs in the ${C}_{{vb}}^{{\prime} }-{\sigma }_{r}$ plane, where ${C}_{{vb}}^{{\prime} }$ is the correlation coefficient between magnetic-field and velocity fluctuations multiplied by the sign of the x component of the mean field in geocentric solar ecliptic coordinates, and σr is normalized residual energy. Measurements from the WIND spacecraft in the slow solar wind during 2005-2009 are used for the analysis. The data are cut into intervals with duration of 6 minutes, and the intervals that are nearly incompressible are selected for analysis. We find that for the fluctuations with $| {C}_{{vb}}^{{\prime} }| \lt 0.55$ and -1 < σr < -0.6, which are considered to be associated with MFDTs, the level contours of the pixel average amplitude of magnetic-field fluctuations in the plane show a horizontal-stripe feature with approximately $10| {\sigma }_{r}| $ km s-1 in Alfvén units. For the fluctuations with $| {C}_{{vb}}^{{\prime} }| \gt 0.85$ and -0.9 < σr < -0.2, which are considered to be associated with MVASs, the level contours of the pixel average amplitude of velocity fluctuations show a vertical stripe feature with approximately $58.6| {C}_{{vb}}^{{\prime} }| \,-47.5$ km s-1. Consequently, the level contours of the pixel average amplitudes of Elsässer variables ${{\boldsymbol{z}}}^{\pm }$ show "U" and "W" shapes, respectively. These results will help us to understand the nature of the fluctuations in the solar wind.

Keywords: solar wind; interplanetary turbulence
Dwindling Surface Cooling of a Rotating Jovian Planet Leads to a Convection Zone That Grows to a Finite Depth

Recent measurements of Jupiter's gravitational field (by Juno) and seismology of Saturn's rings (by Cassini) strongly suggest that both planets have a stably stratified core that still possesses a primordial gradient in the concentration of heavy elements. The existence of such a "diffusely" stratified core has been a surprise as it was long expected that the Jovian planets should be fully convective and hence fully mixed. A vigorous zone of convection, driven by surface cooling, forms at the surface and deepens through entrainment of fluid from underneath. In fact, it was believed that this convection zone should grow so rapidly that the entire planet would be consumed in less than a million years. Here we suggest that two processes, acting in concert, present a solution to this puzzle. All of the giant planets are rapidly rotating and have a cooling rate that declines with time. Both of these effects reduce the rate of fluid entrainment into the convection zone. Through the use of an analytic prescription of entrainment in giant planets, we demonstrate that these two effects, rotation and dwindling surface cooling, result in a convection zone that initially grows but eventually stalls. The depth to which the convective interface asymptotes depends on the rotation rate and on the stratification of the stable interior. Conversely, in a nonrotating planet, or in a planet that maintains a higher level of cooling than current models suggest, the convection zone deepens forever, eventually spanning the entire planet.

Keywords: hydrodynamics; astrophysical fluid dynamics; planetary cores; planetary interior; planetary thermal histories; solar system gas giant planets; jupiter
Active Galactic Nucleus Ghosts: A Systematic Search for Faded Nuclei

Physical processes such as reignition, enhancement, and fading of active galactic nuclei (AGN) are not entirely understood because the timeline of these events is expected to last many years. However, it is well known that the differences in the energy budget between AGN components, like the optical ionizing region and the mid-infrared (MIR) dust echoes, can be interpreted as a hint of AGN evolution. Here we present a catalog of 88 AGN candidates showing hints of the fading and rising of their activity in the nearby universe. We use AGN scaling relations to select them from an initial sample of 877 candidates using publicly available optical, X-ray, and MIR luminosities. We then use the multiwavelength information to discard sources contaminated with extranuclear emission and those with an X-ray luminosity not well corrected for absorption. We find that 96% of our candidates are fading sources. This result suggests a scenario where the universe had its peak of AGN activity somewhere in the past and is dominated by a fading phase at the present time. Alternatively, the fading phase is longer than the rising phase, which is consistent with galaxy merger simulations. Around 50% of these fading candidates are associated with merging or interacting systems. Finally, we also find the existence of jets in ∼30% of these candidates and that the preferred AGN dust geometry is torus-like instead of wind-like. Our results are compatible with the fading of nuclear activity, expected if they are in an inefficient state.

Keywords: active galactic nuclei; catalogs; active galaxies; infrared galaxies; x-ray active galactic nuclei
Constraining Time Variations in Enceladus's Water-vapor Plume with Near-infrared Spectra from Cassini's Visual and Infrared Mapping Spectrometer

Water vapor produces a series of diagnostic emission lines in the near-infrared between 2.60 and 2.75 μm. The Visual and Infrared Mapping Spectrometer (VIMS) on board the Cassini spacecraft detected this emission signal from Enceladus's plume, and so VIMS observations provide information about the variability of the plume's water-vapor content. Using a data set of 249 spectral cubes with relatively high signal-to-noise ratios, we confirmed the strength of this water-vapor emission feature corresponds to a line-of-sight column density of order 1020 molecules m‑2, which is consistent with previous measurements from Cassini's Ultraviolet Imaging Spectrograph. Comparing observations made at different times indicates that the water-vapor flux is unlikely to vary systematically with Enceladus's orbital phase, unlike the particle flux, which does vary with orbital phase. However, variations in the column density on longer and shorter timescales cannot be ruled out and merit further investigation.

Keywords: enceladus; infrared spectroscopy; volcanism; water vapor; saturnian satellites
The Decaying and Scattering Properties of the d*(2380) Hexaquark Bose-Einstein Condensate Dark Matter

Recently, a study has shown that the Bose-Einstein condensates (BECs) formed by the d*(2380) hexaquarks (d*(2380)-BECs) can be thermally produced in the early universe and they are stable enough to be a competitive candidate for dark matter. Searching for the decaying signature of d*(2380)-BECs is a possible way to verify this dark matter model. In this article, we discuss the scattering and decaying properties of the d*(2380)-BECs and we show that the decay rate of the d*(2380)-BECs is correlated with the TeV cosmic-ray flux. The predicted average decay rate in our Galaxy is several orders of magnitude larger than the current observed upper limit. Therefore, it would be very difficult for us to search for the decaying signature of the d*(2380)-BEC dark matter model. Nevertheless, the size of the d*(2380)-BECs may be large enough to have self-interaction so that we can possibly detect them in the future.

Keywords: dark matter; particle physics; particle astrophysics
Bolometric Hemispherical Albedo Map of Pluto from New Horizons Observations

The New Horizons encounter with the Pluto system revealed Pluto to have an extremely spatially variable surface with expansive dark, bright, and intermediate terrains, refractory and volatile ices, and ongoing/recent endogenous and exogenous processes. Albedo is useful for understanding volatile transport because it quantifies absorbed solar energy; albedo may also provide insights into surface processes. Four filters of the New Horizons LORRI and MVIC imagers are used to approximate the bolometric (flux-weighted, wavelength-integrated) albedo. The bolometric hemispherical albedo (local energy balance albedo) as a function of the incidence angle of the solar illumination is measured for both Cthulhu and Sputnik Planitia, which are extensive, extreme dark and extreme bright terrains on Pluto. For both terrains, the bolometric hemispherical albedo increases by >30% from 0° to 90° incidence. The incidence-angle-average bolometric hemispherical albedo of Cthulhu is 0.12 ± 0.01, and that of Sputnik Planitia is 0.80 ± 0.06, where uncertainties are estimates based on scatter from different photometric functional approximations. The bolometric Bond albedo (global energy balance albedo) of Cthulhu is 0.12 ± 0.01, and that of Sputnik Planitia is 0.80 ± 0.07. A map of Pluto's incidence-angle-average bolometric hemispherical albedo is produced. The incidence-angle-average bolometric hemispherical albedo, spatially averaged over areas north of ≈30° S, is ≈0.54. Pluto has three general albedo categories: (1) very low albedo southern equatorial terrains, including Cthulhu; (2) high-albedo terrains, which constitute most of Pluto's surface; and (3) very high albedo terrains, including Sputnik Planitia. Pluto's extraordinary albedo variability with location is also spatially sharp at some places.

Keywords: pluto; surface photometry; photometry; albedo; planetary science
Pavo: Discovery of a Star-forming Dwarf Galaxy Just Outside the Local Group

We report the discovery of Pavo, a faint (M V = -10.0), star-forming, irregular, and extremely isolated dwarf galaxy at D ≈ 2 Mpc. Pavo was identified in Dark Energy Camera Legacy Survey imaging via a novel approach that combines low surface brightness galaxy search algorithms and machine-learning candidate classifications. Follow-up imaging with the Inamori-Magellan Areal Camera and Spectrograph on the 6.5 m Magellan Baade telescope revealed a color-magnitude diagram (CMD) with an old stellar population, in addition to the young population that dominates the integrated light, and a tip of the red giant branch distance estimate of ${1.99}_{-0.22}^{+0.20}$ Mpc. The blue population of stars in the CMD is consistent with the youngest stars having formed no later than 150 Myr ago. We also detected no Hα emission with SOAR telescope imaging, suggesting that we may be witnessing a temporary low in Pavo's star formation. We estimate the total stellar mass of Pavo to be $\mathrm{log}{M}_{* }/{M}_{\odot }=5.6\pm 0.2$ and measure an upper limit on its H I gas mass of 1.0 × 106 M ⊙ based on the HIPASS survey. Given these properties, Pavo's closest analog is Leo P (D = 1.6 Mpc), previously the only known isolated, star-forming, Local Volume dwarf galaxy in this mass range. However, Pavo appears to be even more isolated, with no other known galaxy residing within over 600 kpc. As surveys and search techniques continue to improve, we anticipate an entire population of analogous objects being detected just outside the Local Group. * This paper includes data gathered with the 6.5 m Magellan Telescope at Las Campanas Observatory, Chile.

Keywords: dwarf irregular galaxies; low surface brightness galaxies; galaxy stellar content; galaxy environments; galaxy distances
The JCMT Transient Survey: Six Year Summary of 450/850 μm Protostellar Variability and Calibration Pipeline Version 2.0

The James Clerk Maxwell Telescope (JCMT) Transient Survey has been monitoring eight Gould Belt low-mass star-forming regions since 2015 December and six somewhat more distant intermediate-mass star-forming regions since 2020 February with the Submillimeter Common User Bolometer Array 2 on board JCMT at 450 and 850 μm and with an approximately monthly cadence. We introduce our pipeline v2 relative calibration procedures for image alignment and flux calibration across epochs, improving on our previous pipeline v1 by decreasing measurement uncertainties and providing additional robustness. These new techniques work at both 850 and 450 μm, where version 1 only allowed investigation of the 850 μm data. Pipeline v2 achieves better than 0.″5 relative image alignment, less than a tenth of the submillimeter beam widths. The version 2 relative flux calibration is found to be 1% at 850 μm and <5% at 450 μm. The improvement in the calibration is demonstrated by comparing the two pipelines over the first 4 yr of the survey and recovering additional robust variables with version 2. Using the full 6 yr of the Gould Belt survey, the number of robust variables increases by 50%, and at 450 μm we identify four robust variables, all of which are also robust at 850 μm. The multiwavelength light curves for these sources are investigated and found to be consistent with the variability being due to dust heating within the envelope in response to accretion luminosity changes from the central source.

Keywords: astronomical techniques; transient sources; protostars; submillimeter astronomy; time domain astronomy