adsabs/SciX_UAT_keywords huggingface dataset:
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. XI. Accretion Disk Reverberation Mapping of Mrk 142

We performed an intensive accretion disk reverberation mapping campaign on the high accretion rate active galactic nucleus Mrk 142 in early 2019. Mrk 142 was monitored with the Neil Gehrels Swift Observatory for four months in X-rays and six different UV/optical filters. Ground-based photometric monitoring was obtained from the Las Cumbres Observatory, the Liverpool Telescope, and the Dan Zowada Memorial Observatory in ugriz filters, as well as from the Yunnan Astronomical Observatory in V. Mrk 142 was highly variable throughout, displaying correlated variability across all wavelengths. We measure significant time lags between the different wavelength lightcurves. In the UV and optical, we find that the wavelength-dependent lags, τ(λ), generally follow the relation τ(λ) ∝ λ4/3, as expected for the T ∝ R-3/4 profile of a steady-state, optically thick, geometrically thin accretion disk, though they can also be fit by τ(λ) ∝ λ2, as expected for a slim disk. The exceptions are the u and U bands, where an excess lag is observed, as has been observed in other active galactic nuclei and attributed to continuum emission arising in the broad-line region. Furthermore, we perform a flux-flux analysis to separate the constant and variable components of the spectral energy distribution, finding that the flux dependence of the variable component is consistent with the fν ∝ ν1/3 spectrum expected for a geometrically thin accretion disk. Moreover, the X-ray to UV lag is significantly offset from an extrapolation of the UV/optical trend, with the X-rays showing a poorer correlation with the UV than the UV does with the optical. The magnitude of the UV/optical lags is consistent with a highly super-Eddington accretion rate.

Keywords: active galactic nuclei; accretion
H I Self-absorption toward the Cygnus X North: From Atomic Filament to Molecular Filament

Using the H I self-absorption data from the Five-hundred-meter Aperture Spherical radio Telescope, we perform a study of the cold atomic gas in the Cygnus X North region. The most remarkable H I cloud is characterized by a filamentary structure, associated in space and in velocity with the principal molecular filament in the Cygnus X North region. We investigate the transition from atomic filament to molecular filament. We find that the H II regions Cygnus OB2 and G081.920+00.138 play a critical role in compressing and shaping the atomic Cygnus X North filament, where the molecular filament subsequently forms. The cold H I in the DR21 filament has a much larger column density (N(H I) ~1 × 1020 cm-2) than the theoretical value of the residual atomic gas (~1 × 1019 cm-2), suggesting that the H I-to-H2 transition is still in progress. The timescale of the H I-to-H2 transition is estimated to be 3 × 105 yr, which approximates the ages of massive protostars in the Cygnus X North region. This implies that the formation of molecular clouds and massive stars may occur almost simultaneously in the DR21 filament, in accord with a picture of rapid and dynamic cloud evolution.

Keywords: interstellar atomic gas; interstellar filaments; molecular clouds; star forming regions
Validations and Corrections of the SFD and Planck Reddening Maps Based on LAMOST and Gaia Data

Precise correction of dust reddening is fundamental to obtain the intrinsic parameters of celestial objects. The Schlegel et al. (SFD) and the Planck 2D extinction maps are widely used for reddening correction. In this work, using accurate reddening determinations of about 2 million stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Data Release 5 and Gaia DR2, we check and calibrate the SFD and Planck maps in the middle and high Galactic latitudes. The maps show similar precision in reddening correction. We find small yet significant spatially dependent biases for the four maps, which are similar between the SFD and Planck2014-R maps, and between the Planck2014-Tau and Planck2019-Tau maps. The biases show a clear dependence on the dust temperature and extinction for the SFD and Planck2014-R maps. While those of the Planck2014-Tau and Planck2019-Tau maps have a weak dependence on the dust temperature, they both strongly depend on the dust spectral index. Finally, we present corrections of the SFD and Planck extinction maps within the LAMOST footprint, along with empirical relations for corrections outside the LAMOST footprint. Our results provide important clues for the further improvement of the Galactic all-sky extinction maps and lay a significant foundation for accurate extinction correction in the era of precision astronomy.

Keywords: interstellar dust extinction; galaxy stellar content
BD+47 378: An Eclipsing Binary Containing a δ Sct Pulsating Star

New high-resolution spectra of the eclipsing binary BD+47 378 were obtained on five nights between 2020 and 2021 with the Bohyunsan Observatory Echelle Spectrograph in Korea. We collected the TESS light curve of the system obtained from Sectors 17 to 18, which shows a flat bottom at the secondary eclipse, an O'Connell effect, and oscillation features. From the spectral analysis, the radial velocities (RVs) of the primary and secondary stars were obtained, and the temperature of the brighter and more massive primary component was determined to be 7140 ± 100 K. According to a simultaneous analysis of the double-lined RVs and TESS light curves, the masses and radii of both components are M 1 = 1.69 ± 0.03 M ⊙, M 2 = 0.80 ± 0.02 M ⊙, R 1 = 2.01 ± 0.01 R ⊙, and R 2 = 0.79 ± 0.01 R ⊙, respectively. The primary component of the system is located on the δ Sct and γ Dor instability strips. After subtracting the theoretical light curve from the TESS data, a total of four independent frequencies (5.7235 day-1, 6.2577 day-1, 6.9588 day-1, and 14.7675 day-1) were detected using the multiple frequency analysis. These frequencies are typical of a δ Sct pulsator. The results reveal that BD+47 378 is a detached system consisting of two main-sequence stars with a δ Sct type primary component.

Keywords: eclipsing binary stars; fundamental parameters of stars; stellar oscillations; spectroscopy; multi-periodic pulsation; asteroseismology; stellar evolution
ALMA Measures Molecular Gas Reservoirs Comparable to Field Galaxies in a Low-mass Galaxy Cluster at z = 1.3

We report the serendipitous discovery of an overdensity of CO emitters in an X-ray-identified cluster (Log10 M halo/M ⊙ ~ 13.6 at z = 1.3188) using ALMA. We present spectroscopic confirmation of six new cluster members exhibiting CO(2-1) emission, adding to two existing optical/IR spectroscopic members undetected in CO. This is the lowest-mass cluster to date at z > 1 with molecular gas measurements, bridging the observational gap between galaxies in the more extreme, well-studied clusters (Log10 M halo/M ⊙ ≳ 14) and those in group or field environments at cosmic noon. The CO sources are concentrated on the sky (within ~1 arcmin diameter) and phase space analysis indicates the gas resides in galaxies already within the cluster environment. We find that CO sources sit in similar phase space as CO-rich galaxies in more massive clusters at similar redshifts (have similar accretion histories) while maintaining field-like molecular gas reservoirs, compared to scaling relations. This work presents the deepest CO survey to date in a galaxy cluster at z > 1, uncovering gas reservoirs down to ${M}_{{{\rm{H}}}_{2}}\gt 1.6\times {10}^{10}$ M ⊙ (5σ at 50% primary beam). Our deep limits rule out the presence of gas content in excess of the field scaling relations; however, combined with literature CO detections, cluster gas fractions in general appear systematically high, on the upper envelope or above the field. This study is the first demonstration that low-mass clusters at z ~ 1-2 can host overdensities of CO emitters with surviving gas reservoirs, in line with the prediction that quenching is delayed after first infall while galaxies consume the gas bound to the disk.

Keywords: high-redshift galaxy clusters; molecular gas; galaxy evolution
Line-by-line Velocity Measurements: an Outlier-resistant Method for Precision Velocimetry

We present a new algorithm for precision radial velocity (pRV) measurements, a line-by-line (LBL) approach designed to handle outlying spectral information in a simple but efficient manner. The effectiveness of the LBL method is demonstrated on two data sets, one obtained with SPIRou on Barnard's star, and the other with the High Accuracy Radial velocity Planet Searcher (HARPS) on Proxima Centauri. In the near-infrared, the LBL provides a framework for meters-per-second-level accuracy in pRV measurements despite the challenges associated with telluric absorption and sky emission lines. We confirm with SPIRou measurements spanning 2.7 yr that the candidate super-Earth on a 233 day orbit around Barnard's star is an artifact due to a combination of time sampling and activity. The LBL analysis of the Proxima Centauri HARPS post-upgrade data alone easily recovers the Proxima b signal and also provides a 2σ detection of the recently confirmed 5 day Proxima d planet, but argues against the presence of the candidate Proxima c with a period of 1900 days. We provide evidence that the Proxima c signal is associated with small, unaccounted systematic effects affecting the HARPS-TERRA template-matching radial velocity extraction method for long-period signals. Finally, the LBL framework provides a very effective activity indicator, akin to the FWHM derived from the cross-correlation function, from which we infer a rotation period of ${92.1}_{-3.5}^{+4.2}$ days for Proxima.

Keywords: exoplanets; radial velocity; astronomy data analysis
Evolution of the Thermodynamic Properties of Clusters of Galaxies out to Redshift of 1.8

The thermodynamic properties of the hot plasma in galaxy clusters retain information on the processes leading to the formation and evolution of the gas in their deep, dark matter potential wells. These processes are dictated not only by gravity but also by gas physics, e.g., active galactic nucleus feedback and turbulence. In this work, we study the thermodynamic properties, e.g., density, temperature, pressure, and entropy, of the most massive and the most distant (seven clusters at z > 1.2) clusters selected by the South Pole Telescope and compare them with those of the nearby clusters (13 clusters at z < 0.1) to constrain their evolution as a function of time and radius. We find that thermodynamic properties in the outskirts of high-redshift clusters are remarkably similar to the low-redshift clusters, and their evolution follows the prediction of the self-similar model. Their intrinsic scatter is larger, indicating that the physical properties that lead to the formation and virialization of cluster outskirts show evolving variance. On the other hand, thermodynamic properties in the cluster cores deviate significantly from self-similarity, indicating that the processes that regulate the core are already in place in these very high redshift clusters. This result is supported by the unevolving physical scatter of all thermodynamic quantities in cluster cores.

Keywords: galaxy clusters; intracluster medium; galactic and extragalactic astronomy; high-redshift galaxy clusters
MIDIS: The Relation between Strong (Hβ + [O III]) Emission, Star Formation, and Burstiness around the Epoch of Reionization

We investigate the properties of strong (Hβ + [O III]) emitters before and after the end of the "Epoch of Reionization" from z = 8 to z = 5.5. We make use of ultradeep JWST/NIRCam imaging in the parallel field (P2) of the MIRI Deep Imaging Survey (MIDIS) in the Hubble eXtreme Deep Field (H-XDF), in order to select prominent (Hβ + [O III]) emitters (with rest-frame equivalent width (EW0) ≳ 100 Å) at z = 5.5–7, based on their flux density enhancement in the F356W band with respect to the spectral energy distribution continuum. We complement our selection with other (Hβ + [O III]) emitters from the literature at similar and higher (z = 7‑8) redshifts. We find (nonindependent) anticorrelations between EW0(Hβ + [O III]) and both galaxy stellar mass and age, in agreement with previous studies, and a positive correlation with specific star formation rate (sSFR). On the SFR–M ⋆ plane, the (Hβ + [O III]) emitters populate both the star formation main sequence and the starburst region, which become indistinguishable at low stellar masses ( ). We find tentative evidence for a nonmonotonic relation between EW0(Hβ + [O III]) and SFR, such that both parameters correlate with each other at SFR ≳ 1 M ⊙ yr‑1, while the correlation flattens out at lower SFRs. This suggests that low metallicities producing high EW0(Hβ + [O III]) could be important at low SFR values. Interestingly, the properties of the strong emitters and other galaxies (33% and 67% of our z = 5.5–7 sample, respectively) are similar, including, in many cases, high sSFR. Therefore, it is crucial to consider both emitters and nonemitters to obtain a complete picture of the cosmic star formation activity around the Epoch of Reionization.

Keywords: galaxy evolution; reionization; starburst galaxies
Zero Net Flux MRI Turbulence in Disks: Sustenance Scheme and Magnetic Prandtl Number Dependence

We investigate sustenance and dependence on magnetic Prandtl number (Pm) for magnetorotational instability (MRI)-driven turbulence in Keplerian disks with zero net magnetic flux using standard shearing box simulations. We focus on the turbulence dynamics in Fourier space, capturing specific/noncanonical anisotropy of nonlinear processes due to disk flow shear. This is a new type of nonlinear redistribution of modes over wavevector orientations in Fourier space—the nonlinear transverse cascade—which is generic to shear flows and fundamentally different from the usual direct/inverse cascade. The zero flux MRI has no exponentially growing modes, so its growth is transient, or nonmodal. Turbulence self-sustenance is governed by constructive cooperation of the transient growth of MRI and the nonlinear transverse cascade. This cooperation takes place at small wavenumbers (on the flow size scales) referred to as the vital area in Fourier space. The direct cascade transfers mode energy from the vital area to larger wavenumbers. At large Pm, the transverse cascade prevails over the direct one, keeping most of modes' energy contained in small wavenumbers. With decreasing Pm, however, the action of the transverse cascade weakens and can no longer oppose the action of the direct cascade, which more efficiently transfers energy to higher wavenumbers, leading to increased resistive dissipation. This undermines the sustenance scheme, resulting in the turbulence decay. Thus, the decay of zero net flux MRI turbulence with decreasing Pm is attributed to the topological rearrangement of the nonlinear processes when the direct cascade begins to prevail over the transverse cascade.

Keywords: stellar accretion disks; magnetohydrodynamics; plasma astrophysics; high energy astrophysics; protoplanetary disks; magnetic fields; interplanetary turbulence
The Case for a New Frontiers-Class Uranus Orbiter: System Science at an Underexplored and Unique World with a Mid-scale Mission

Current knowledge of the Uranian system is limited to observations from the flyby of Voyager 2 and limited remote observations. However, Uranus remains a highly compelling scientific target due to the unique properties of many aspects of the planet itself and its system. Future exploration of Uranus must focus on cross-disciplinary science that spans the range of research areas from the planet's interior, atmosphere, and magnetosphere to the its rings and satellites, as well as the interactions between them. Detailed study of Uranus by an orbiter is crucial not only for valuable insights into the formation and evolution of our solar system but also for providing ground truths for the understanding of exoplanets. As such, exploration of Uranus will not only enhance our understanding of the ice giant planets themselves but also extend to planetary dynamics throughout our solar system and beyond. The timeliness of exploring Uranus is great, as the community hopes to return in time to image unseen portions of the satellites and magnetospheric configurations. This urgency motivates evaluation of what science can be achieved with a lower-cost, potentially faster-turnaround mission, such as a New Frontiers-class orbiter mission. This paper outlines the scientific case for and the technological and design considerations that must be addressed by future studies to enable a New Frontiers-class Uranus orbiter with balanced cross-disciplinary science objectives. In particular, studies that trade scientific scope and instrumentation and operational capabilities against simpler and cheaper options must be fundamental to the mission formulation.

Keywords: uranus; solar system planets; extrasolar gaseous giant planets; planetary rings; uranian satellites; planetary magnetospheres; planetary atmospheres; planetary interior
The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. IV. The Star Formation History of Andromeda VII Derived from Long-period Variable Stars

We have examined the star formation history (SFH) of Andromeda VII (And VII), the brightest and most massive dwarf spheroidal (dSph) satellite of the Andromeda galaxy (M31). Although M31 is surrounded by several dSph companions with old stellar populations and low metallicity, it has a metal-rich stellar halo with an age of 6-8 Gyr. This indicates that any evolutionary association between the stellar halo of M31 and its dSph system is frail. Therefore, the question is whether And VII (a high-metallicity dSph located ∼220 kpc from M31) can be associated with M31's young, metal-rich halo. Here we perform the first reconstruction of the SFH of And VII employing long-period variable (LPV) stars. As the most evolved asymptotic giant branch and red supergiant stars, the birth mass of LPVs can be determined by connecting their near-infrared photometry to theoretical evolutionary tracks. We found 55 LPV candidates within two half-light radii, using multiepoch imaging with the Isaac Newton Telescope in the i and V bands. Based on their birth mass function, the star formation rate (SFR) of And VII was obtained as a function of cosmic time. The main epoch of star formation occurred ≃ 6.2 Gyr ago with an SFR of 0.006 ± 0.002 M⊙ yr-1. Over the past 6 Gyr, we find slow star formation, which continued until 500 Myr ago with an SFR ∼ 0.0005 ± 0.0002 M⊙ yr-1. We determined And VII's stellar mass M = (13.3 ± 5.3) × 106 M⊙ within a half-light radius ${r}_{\tfrac{1}{2}}=3\buildrel{\,\prime}\over{.} 8\pm 0\buildrel{\,\prime}\over{.} 3$ <!-- --> and metallicity Z = 0.0007, and we also derived its distance modulus of μ = 24.38 mag.

Keywords: dwarf spheroidal galaxies; star formation
Young, Blue, and Isolated Stellar Systems in the Virgo Cluster. II. A New Class of Stellar System

We discuss five blue stellar systems in the direction of the Virgo cluster, analogous to the enigmatic object SECCO 1 (AGC 226067). These objects were identified based on their optical and UV morphology and followed up with H I observations with the Very Large Array (and Green Bank Telescope), Multi Unit Spectroscopic Explorer (on the Very Large Telescope) optical spectroscopy, and Hubble Space Telescope imaging. These new data indicate that one system is a distant group of galaxies. The remaining four are extremely low mass (M * ~ 105 M ⊙), are dominated by young blue stars, have highly irregular and clumpy morphologies, are only a few kiloparsecs across, yet host an abundance of metal-rich, 12+\mathrm{log}({\rm{O}}/{\rm{H}})\gt 8.2$ , H II regions. These high metallicities indicate that these stellar systems formed from gas stripped from much more massive galaxies. Despite the young age of their stellar populations, only one system is detected in H I, while the remaining three have minimal (if any) gas reservoirs. Furthermore, two systems are surprisingly isolated and have no plausible parent galaxy within ~30' (~140 kpc). Although tidal stripping cannot be conclusively excluded as the formation mechanism of these objects, ram pressure stripping more naturally explains their properties, in particular their isolation, owing to the higher velocities, relative to the parent system, that can be achieved. Therefore, we posit that most of these systems formed from ram-pressure-stripped gas removed from new infalling cluster members and survived in the intracluster medium long enough to become separated from their parent galaxies by hundreds of kiloparsecs and that they thus represent a new type of stellar system.

Keywords: low surface brightness galaxies; dwarf galaxies; galaxy interactions; tidal tails; ram pressure stripped tails; h i line emission; virgo cluster
The Local Stellar Halo is Not Dominated by a Single Radial Merger Event

We use halo dwarf stars with photometrically determined metallicities that are located within 2 kpc of the Sun to identify local halo substructure. The kinematic properties of these stars do not indicate a single, dominant radial merger event (RME). The retrograde Virgo Radial Merger (VRM) component has [Fe/H] = -1.7. A second, nonrotating RME component we name Nereus is identified with [Fe/H] = -2.1 and has similar energy to the VRM. We identify a possible third RME, which we name Cronus, that is corotating with the disk, has lower energy than the VRM, and has [Fe/H] = -1.2. We identify the Nyx Stream in the data. In addition to these substructures, we observe metal-poor halo stars ([Fe/H] ~ -2.0 and σ v ~ 180 km s-1) and a disk/Splash component with lower rotational velocity than the disk and lower metallicity than typically associated with the Splash. An additional excess of halo stars with low velocity and metallicity of [Fe/H] = -1.5 could be associated with the shell of a lower-energy RME or indicate that lower-energy halo stars have higher metallicity. Stars that comprise the "Gaia Sausage" velocity structure are a combination of the components identified in this work.

Keywords: milky way galaxy; galaxy mergers; galaxy accretion; milky way dynamics
Measuring Stellar Masses of Emission-line Galaxies at 1.2 < z < 1.9

The accurate measurement of stellar masses over a wide range of galaxy properties is essential for better constraining models of galaxy evolution. Emission-line galaxies (ELGs) tend to have better redshift estimates than continuum-selected objects, and have been shown to span a large range of physical properties, including stellar mass. Using data from the 3D-HST Treasury program, in this work, we construct a carefully vetted sample of 4350 ELGs at redshifts of 1.16 < z < 1.90. We combine the 3D-HST emission-line fluxes with far-UV through near-IR photometry, and use the MCSED spectral energy distribution fitting code to constrain the galaxies' physical parameters, such as their star-formation rate and stellar masses. Our sample is consistent with the z ∼ 2 mass-metallicity relation. More importantly, we show that there is a simple, but tight correlation between stellar mass and absolute magnitude in a near-IR filter, which should prove particularly useful in terms of the rapid calculation of accurate stellar masses for millions of galaxies in upcoming missions such as Euclid, and the Nancy Grace Roman Space Telescope.

Keywords: galaxy evolution; stellar masses; spectral energy distribution; high-redshift galaxies