adsabs/SciX_UAT_keywords huggingface dataset:
Rapidly Evolving Transients in Archival ZTF Public Alerts

We search the archival Zwicky Transient Facility public survey for rapidly evolving transient (RET) candidates based on well-defined criteria between 2018 May and 2021 December. The search yielded 19 bona fide RET candidates, corresponding to a discovery rate of ~5.2 events per year. Even with a Galactic latitude cut of 20°, eight of the 19 events (~42%) are Galactic, including one with a light-curve shape closely resembling that of the GW170817 kilonova (KN). An additional event is a nova in M31. Four out of the 19 events (~21%) are confirmed extragalactic RETs (one confirmed here for the first time) and the origin of six additional events cannot be determined. We did not find any extragalactic events resembling the GW170817 KN, from which we obtain an upper limit on the volumetric rate of GW170817-like KNe of R ≤ 2400 Gpc-3 yr-1 (95% confidence). These results can be used for quantifying contaminants to RET searches in transient alert streams, specifically when searching for KNe independently of gravitational-wave and gamma-ray-burst triggers.

Keywords: high energy astrophysics; supernovae; transient sources; time domain astronomy
Parker Solar Probe Observations of Energetic Particles in the Flank of a Coronal Mass Ejection Close to the Sun

We present an event observed by Parker Solar Probe (PSP) at ∼0.2 au on 2022 March 2 in which imaging and in situ measurements coincide. During this event, PSP passed through structures on the flank of a streamer blowout coronal mass ejection (CME) including an isolated flux tube in front of the CME, a turbulent sheath, and the CME itself. Imaging observations and in situ helicity and principal variance signatures consistently show the presence of flux ropes internal to the CME. In both the sheath and the CME interval, the distributions are more isotropic, the spectra are softer, and the abundance ratios of Fe/O and He/H are lower than those in the isolated flux tube, and yet elevated relative to typical plasma and solar energetic particle abundances. These signatures in the sheath and the CME indicate that both flare populations and those from the plasma are accelerated to form the observed energetic particle enhancements. In contrast, the isolated flux tube shows large streaming, hard spectra, and large Fe/O and He/H ratios, indicating flare sources. Energetic particle fluxes are most enhanced within the CME interval from suprathermal through energetic particle energies (∼keV to >10 MeV), indicating particle acceleration, as well as confinement local to the closed magnetic structure. The flux-rope morphology of the CME helps to enable local modulation and trapping of energetic particles, in particular along helicity channels and other plasma boundaries. Thus, the CME acts to build up energetic particle populations, allowing them to be fed into subsequent higher-energy particle acceleration throughout the inner heliosphere where a compression or shock forms on the CME front.

Keywords: solar coronal mass ejections; solar energetic particles; solar magnetic fields; solar flares
Near-infrared Imaging of a Spiral in the CQ Tau Disk

We present L'-band Keck/NIRC2 imaging and H-band Subaru/AO188+HiCIAO polarimetric observations of the CQ Tau disk with a new spiral arm. Apart from the spiral feature, our observations could not detect any companion candidates. We traced the spiral feature from the r2-scaled High-Contrast Coronographic Imager for Adaptive Optics (HiCIAO) polarimetric intensity image and the fitted result is used for forward modeling to reproduce the ADI-reduced NIRC2 image. We estimated the original surface brightness after throughput correction in the L' band to be ∼126 mJy arcsec-2 at most. We suggest that the grain temperature of the spiral may be heated up to ∼200 K in order to explain both of the H- and L'-band results. The H-band emission at the location of the spiral originates from the scattering from the disk surface while both scattering and thermal emission may contribute to the L'-band emission. If the central star is only the light source of scattered light, the spiral emission at the L' band should be thermal emission. If an inner disk also acts as the light source, the scattered light and the thermal emission may equally contribute to the L'-band spiral structure.

Keywords: protoplanetary disks; coronagraphic imaging
An Atlas of Color-selected Quiescent Galaxies at z > 3 in Public JWST Fields

We present the results of a systematic search for candidate quiescent galaxies in the distant universe in 11 JWST fields with publicly available observations collected during the first 3 months of operations and covering an effective sky area of ~145 arcmin2. We homogeneously reduce the new JWST data and combine them with existing observations from the Hubble Space Telescope. We select a robust sample of ~80 candidate quiescent and quenching galaxies at 3 < z < 5 using two methods: (1) based on their rest-frame UVJ colors, and (2) a novel quantitative approach based on Gaussian mixture modeling of the near-UV - U, U - V, and V - J rest-frame color space, which is more sensitive to recently quenched objects. We measure comoving number densities of massive (M ⋆ ≥ 1010.6 M ⊙) quiescent galaxies consistent with previous estimates relying on ground-based observations, after homogenizing the results in the literature with our mass and redshift intervals. However, we find significant field-to-field variations of the number densities up to a factor of 2-3, highlighting the effect of cosmic variance and suggesting the presence of overdensities of red quiescent galaxies at z > 3, as could be expected for highly clustered massive systems. Importantly, JWST enables the robust identification of quenching/quiescent galaxy candidates at lower masses and higher redshifts than before, challenging standard formation scenarios. All data products, including the literature compilation, are made publicly available.

Keywords: galaxy evolution; high-redshift galaxies; galaxy quenching; quenched galaxies; post-starburst galaxies; surveys
Meteoroid Stream of Comet C/1961 T1 (Seki) and Its Relation to the December -Virginids and -Sagittariids

We answer the question of whether long-period comet C/1961 T1 (Seki) is the parent body of a meteor shower observed in Earths atmosphere. We model discrete parts of a meteoroid stream associated with this comet and follow the orbital evolution of its particles via a numerical integration of their orbits. The gravitational perturbations of major planets and the PoyntingRobertson effect, which influences the motion of the particles, are taken into account. We predict two showers which are related to C/1961 T1. One of these showers was identified with the December -Virginids, #502. This identification confirms an earlier suggested relationship between the shower and the comet. The second predicted shower was identified with the -Sagittariids, #657. The radiant areas of both showers are symmetrical in respect to the apex of Earths heliocentric motion.

Keywords: comets; meteor streams; meteor showers
Herschel Optimized Tau and Temperature (HOTT) Maps: Uncertainty Analysis and Robust Parameter Extraction

We introduce the HOTT dust optical depth and temperature maps parameterizing thermal dust emission. Such maps have revolutionized studies of the distribution of matter in molecular clouds and processes relevant to star formation, including virial stability. HOTT maps for a suite of fields, including the Herschel Gould Belt Survey, are available online. The standardization of our robust pipeline for modified blackbody fitting of the spectral energy distribution (SED) of high-quality archival submillimeter data from the Herschel Space Observatory is based on a thorough analysis and quantification of the uncertainties of the data. This enables proper weighting in the SED fits. The uncertainties assessed fall into four main categories: instrument noise; the cosmic infrared background anisotropy, a contaminating sky signal; gradient-related noise arising because of dust signal morphology; and calibration uncertainty, scaling with the signal strength. Zero-level adjustments are important too. An analysis of residuals from the SED fits across many fields supports the overall appropriateness of the assumed modified blackbody model and points to where it breaks down. Finding χ 2 distributions close to the theoretical expectation boosts confidence in the pipeline and the optimized quality of the parameter maps and their estimated uncertainties. We compared our HOTT parameter maps to those from earlier studies to understand and quantify the potential for systematic differences.

Keywords: molecular clouds; astronomy data analysis; interstellar medium; interstellar dust
The Solar Cycle Temporal Variation of the Solar Wind Charge Exchange X-Ray Lines

Solar wind charge exchange (SWCX) is the primary contamination of soft X-ray emission lines from the Milky Way (MW) hot gas. We report a solar cycle (≈10 yr) temporal variation of observed O VII and O VIII emission line measurements in the XMM-Newton archive, which is tightly correlated with the solar cycle traced by the sunspot number (SSN). This temporal variation is expected to be associated with the heliospheric SWCX. Another observed correlation is that higher solar wind (SW) fluxes lead to higher O VII or O VIII fluxes, which is due to the magnetospheric SWCX. We construct an empirical model to reproduce the observed correlation between the line measurements and the solar activity (i.e., the SW flux and the SSN). With this model we discovered a lag of ${0.91}_{-0.22}^{+0.20}$ yr between the O VII flux and the SSN. This time lag is a combination of the SW transit time within the heliosphere, the lag of the neutral gas distribution responding to solar activity, and the intrinsic lag between the SSN and the launch of a high-energy SW (i.e., O7+ and O8+). MW O VII and O VIII fluxes have mean values of 5.4 L.U. and 1.7 L.U., which are reduced by 50% and 30%, compared to studies where the SWCX contamination is not removed. This correction also changes the determination of the density distribution and the temperature profile of the MW hot gas.

Keywords: solar wind; circumgalactic medium; charge exchange ionization; milky way galaxy
Deviation from a Continuous and Universal Turbulence Cascade in NGC 6334 due to Massive Star Formation Activity

We use molecular line data from the Atacama Large Millimeter/submillimeter Array, Submillimeter Array, James Clerk Maxwell Telescope, and NANTEN2 to study the multiscale (~15-0.005 pc) velocity statistics in the massive star formation region NGC 6334. We find that the nonthermal motions revealed by the velocity dispersion function (VDF) stay supersonic over scales of several orders of magnitude. The multiscale nonthermal motions revealed by different instruments do not follow the same continuous power law, which is because the massive star formation activities near central young stellar objects have increased the nonthermal motions in small-scale and high-density regions. The magnitudes of VDFs vary in different gas materials at the same scale, where the infrared dark clump N6334S in an early evolutionary stage shows a lower level of nonthermal motions than other more evolved clumps due to its more quiescent star formation activity. We find possible signs of small-scale-driven (e.g., by gravitational accretion or outflows) supersonic turbulence in clump N6334IV with a three-point VDF analysis. Our results clearly show that the scaling relation of velocity fields in NGC 6334 deviates from a continuous and universal turbulence cascade due to massive star formation activities.

Keywords: star formation; molecular clouds; interstellar medium
Massive Stellar Triples Leading to Sequential Binary Black Hole Mergers in the Field

Stellar triples with massive stellar components are common and can lead to sequential binary black hole mergers. Here we outline the evolution toward these sequential mergers and explore these events in the context of gravitational-wave astronomy and the pair-instability mass gap. We find that binary black hole mergers in the pair-instability mass gap can be of triple origin and therefore are not exclusively formed in dense dynamical environments. We discuss the sequential merger scenario in the context of the most massive gravitational-wave sources detected to date: GW170729 and GW190521. We propose that the progenitor of GW170729 is a low-metallicity field triple. We support the premise that GW190521 could not have been formed in the field. We conclude that triple stellar evolution is fundamental to the understanding of gravitational-wave sources and likely other energetic transients as well.

Keywords: astrophysical black holes
Parameter-estimation Biases for Eccentric Supermassive Binary Black Holes in Pulsar Timing Arrays: Biases Caused by Ignored Pulsar Terms

The continuous nanohertz gravitational waves (GWs) from individual supermassive binary black holes (SMBBHs) can be encoded in the timing residuals of pulsar timing arrays (PTAs). For each pulsar, the residuals actually contain an Earth term and a pulsar term, but usually only the Earth term is considered as a signal and the pulsar term is dropped. This leads to parameter-estimation biases (PEBs) for the SMBBHs, and currently there are no convenient evaluations of the PEBs. In this article, we formulate the PEBs for a SMBBH with an eccentric orbit. In our analyses, the unknown phases of pulsar terms are treated as random variables obeying the uniform distribution U[0, 2π), due to the fact that pulsar distances are generally poorly measured. Our analytical results are in accordance with the numerical work by Zhu et al. at 1.5σ level, which implies that our formulae are effective in estimating magnitudes of the PEBs. Additionally, we find that the biases Δφ E and Δe/e for two parameters-that is, Earth-term phase φ E and orbital eccentricity e-monotonically decrease as e increases, which partly confirms a hypothesis in our previous work. Furthermore, we also calculate the PEBs caused by the recently observed common-spectrum process (CSP). We find that if the strain amplitude of the continuous GW is significantly stronger (three times larger, in our cases) than the stochastic GW background, then the PEBs from pulsar terms are larger than those from the CSP. Our formulae of the PEBs can be conveniently applied in the future PTA data analyses.

Keywords: gravitational waves; pulsar timing method; astronomy data analysis
A Tip of the Red Giant Branch Distance to the Dark Matter Deficient Galaxy NGC 1052-DF4 from Deep Hubble Space Telescope Data

Previous studies have shown that the large, diffuse galaxies NGC 1052-DF2 and NGC 1052-DF4 both have populations of unusually luminous globular clusters as well as a very low dark matter content. Here we present newly obtained deep Hubble Space Telescope Advanced Camera for Surveys imaging of one of these galaxies, NGC 1052-DF4. We use these data to measure the distance of the galaxy from the location of the tip of the red giant branch (TRGB). We find a rapid increase in the number of detected stars fainter than mF814W ∼ 27.3, which we identify as the onset of the red giant branch. Using a forward modeling approach that takes the photometric uncertainties into account, we find a TRGB magnitude of ${m}_{{\rm{F}}814{\rm{W}},\mathrm{TRGB}}=27.47\pm 0.16$ . The inferred distance, including the uncertainty in the absolute calibration, is DTRGB = 20.0 ± 1.6 Mpc. The TRGB distance of NGC 1052-DF4 is consistent with the previously determined surface brightness fluctuation distance of DSBF = 18.7 ± 1.7 Mpc to NGC 1052-DF2 and is consistent with the distance of the bright elliptical galaxy NGC 1052. We conclude that the unusual properties of these galaxies cannot be explained by distance errors.

Keywords: dwarf galaxies; globular star clusters; distance measure; hst photometry; galaxy dark matter halos; low surface brightness galaxies; red giant tip
On the Stickiness of CO2 and H2O Ice Particles

Laboratory experiments revealed that CO2 ice particles stick less efficiently than H2O ice particles, and there is an order of magnitude difference in the threshold velocity for sticking. However, the surface energies and elastic moduli of CO2 and H2O ices are comparable, and the reason why CO2 ice particles were poorly sticky compared to H2O ice particles was unclear. Here we investigate the effects of viscoelastic dissipation on the threshold velocity for sticking of ice particles using the viscoelastic contact model derived by Krijt et al. We find that the threshold velocity for the sticking of CO2 ice particles reported in experimental studies is comparable to that predicted for perfectly elastic spheres. In contrast, the threshold velocity for the sticking of H2O ice particles is an order of magnitude higher than that predicted for perfectly elastic spheres. Therefore, we conclude that the large difference in stickiness between CO2 and H2O ice particles would mainly originate from the difference in the strength of viscoelastic dissipation, which is controlled by the viscoelastic relaxation time.

Keywords: planetesimals; planet formation; protoplanetary disks; circumstellar disks; solid matter physics; astrochemistry
Improved Constraints for the XUV Luminosity Evolution of Trappist-1

We re-examine the XUV luminosity evolution of TRAPPIST-1 utilizing new observational constraints (XUV and bolometric luminosity) from multi-epoch X-ray/UV photometry. Following the formalism presented in Fleming et al., we infer that TRAPPIST-1 maintained a saturated XUV luminosity, relative to the bolometric luminosity, of log10(LXUV/Lbol) $=-{3.03}_{-0.23}^{+0.25}$ at early times for a period of tsat $={3.14}_{-1.46}^{+2.22}$ Gyr. After the saturation phase, we find LXUV decayed over time by an exponential rate of βXUV $=-{1.17}_{-0.28}^{+0.27}$ . Compared to our inferred age of the system, $\mathrm{age}={7.96}_{-1.87}^{+1.78}$ Gyr, our result for tsat suggests that there is only a ∼4% chance that TRAPPIST-1 still remains in the saturated phase today, which is significantly lower than the previous estimate of 40%. Despite this reduction in tsat, our results remain consistent in the conclusion that the TRAPPIST-1 planets likely received an extreme amount XUV energy—an estimated integrated XUV energy of ∼1030-1032 erg over the star's lifetime.

Keywords: stellar evolution; low mass stars; planet hosting stars
The Extended Gaia-PS1-SDSS (GPS1+) Proper Motion Catalog

The Gaia + PanSTARRS1 (PS1) + Sloan Digital Sky Survey (SDSS) + Two Micron All-Sky Survey (2MASS) (GPS1) catalog was released in 2017. It delivered precise proper motions for around 350 million sources down to a magnitude of $r\sim 20$ mag. In this study, we present GPS1+, the extension GPS1 catalog down to $r\sim 22.5$ mag, based on Gaia data release 2 (DR2), PS1, SDSS, and 2MASS astrometry. GPS1+ totally provides proper motions for ∼400 million sources with a characteristic systematic error of less than 0.1 mas yr-1. This catalog is divided into two subsamples, i.e., the primary and secondary parts. The primary ∼264 million sources have either or both Gaia and SDSS astrometry, with a typical precision of 2.0-5.0 mas yr-1. In this part, ∼160 million sources have Gaia proper motions, and we provide another new proper motion for each of them by building a Bayesian model. Relative to Gaia's values, the precision is improved by ∼0.1 dex on average; ∼50 million sources are the objects whose proper motions are missing in Gaia DR2, and we provide their proper motions with a precision of ∼4.5 mas yr-1. The remaining ∼54 million faint sources are beyond Gaia detecting capability, and we provide their proper motions for the first time with a precision of 7.0 mas yr-1. However, the secondary ∼136 million sources only have PS1 astrometry, where the average precision is worse than 15.0 mas yr-1. The large uncertainty probably limits it to qualitative applications. All the proper motions have been validated using QSOs and the existing Gaia proper motions. The catalog will be available via the TAP Service in the German Astrophysical Virtual Observatory.

Keywords: galaxy kinematics; astrometry; catalogs; galaxy dynamics; proper motions
Opportunistic Search for Continuous Gravitational Waves from Compact Objects in Long-period Binaries

Most all-sky searches for continuous gravitational waves assume the source to be isolated. In this paper, we allow for an unknown companion object in a long-period orbit and opportunistically use previous results from an all-sky search for isolated sources to constrain the continuous gravitational-wave amplitude over a large and unexplored range of binary orbital parameters without explicitly performing a dedicated search for binary systems. The resulting limits are significantly more constraining than any existing upper limits for unknown binary systems, albeit the latter apply to different orbital parameter ranges that are computationally much costlier to explore.

Keywords: gravitational waves
The Southern Stellar Stream Spectroscopic Survey (S5): Chemical Abundances of Seven Stellar Streams

We present high-resolution Magellan/MIKE spectroscopy of 42 red giant stars in seven stellar streams confirmed by the Southern Stellar Stream Spectroscopic Survey (S5): ATLAS, Aliqa Uma, Chenab, Elqui, Indus, Jhelum, and Phoenix. Abundances of 30 elements have been derived from over 10,000 individual line measurements or upper limits using photometric stellar parameters and a standard LTE analysis. This is currently the most extensive set of element abundances for stars in stellar streams. Three streams (ATLAS, Aliqa Uma, and Phoenix) are disrupted metal-poor globular clusters, although only weak evidence is seen for the light-element anticorrelations commonly observed in globular clusters. Four streams (Chenab, Elqui, Indus, and Jhelum) are disrupted dwarf galaxies, and their stars display abundance signatures that suggest progenitors with stellar masses ranging from 106 to 107 M⊙. Extensive description is provided for the analysis methods, including the derivation of a new method for including the effect of stellar parameter correlations on each star's abundance and uncertainty. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Keywords: globular star clusters; stellar abundances; dwarf galaxies; milky way stellar halo
ALMA Images the Eccentric HD 53143 Debris Disk

We present ALMA 1.3 mm observations of the HD 53143 debris disk-the first infrared or millimeter image produced of this ~1 Gyr old solar analog. Previous HST STIS coronagraphic imaging did not detect flux along the minor axis of the disk, which could suggest a face-on geometry with two clumps of dust. These ALMA observations reveal a disk with a strikingly different structure. In order to fit models to the millimeter visibilities and constrain the uncertainties on the disk parameters, we adopt a Markov Chain Monte Carlo approach. This is the most eccentric debris disk observed to date with a forced eccentricity of 0.21 ± 0.02, nearly twice that of the Fomalhaut debris disk, and also displays an apocenter glow. Although this eccentric model fits the outer debris disk well, significant interior residuals remain, which may suggest a possible edge-on inner disk, which remains unresolved in these observations. Combined with the observed structure difference between HST and ALMA, these results suggest a potential previous scattering event or dynamical instability in this system. We also note that the stellar flux changes considerably over the course of our observations, suggesting flaring at millimeter wavelengths. Using simultaneous TESS observations, we determine the stellar rotation period to be 9.6 ± 0.1 days.

Keywords: radio astronomy; submillimeter astronomy; circumstellar disks; debris disks; exoplanet formation; planet formation; exoplanet dynamics; exoplanet evolution; stellar activity; stellar flares; starspots; stellar physics