Sazuna/UAT_keywords huggingface dataset:
A Photochemical Phosphorus-Hydrogen-Oxygen Network for Hydrogen-dominated Exoplanet Atmospheres. Due to the detection of phosphine (PH3) in the solar system gas giants Jupiter and Saturn, PH3 has long been suggested to be detectable in exosolar substellar atmospheres too. However, to date, direct detection of phosphine has proven to be elusive in exoplanet atmosphere surveys. We construct an updated phosphorus-hydrogen-oxygen (PHO) photochemical network suitable for the simulation of gas giant hydrogen-dominated atmospheres. Using this network, we examine PHO photochemistry in hot Jupiter and warm Neptune exoplanet atmospheres at solar and enriched metallicities. Our results show for HD 189733b-like hot Jupiters that HOPO, PO, and P2 are typically the dominant P carriers at pressures important for transit and emission spectra, rather than PH3. For GJ1214b-like warm Neptune atmospheres our results suggest that at solar metallicity PH3 is dominant in the absence of photochemistry, but is generally not in high abundance for all other chemical environments. At 10 and 100 times solar, small oxygenated phosphorus molecules such as HOPO and PO dominate for both thermochemical and photochemical simulations. The network is able to reproduce well the observed PH3 abundances on Jupiter and Saturn. Despite progress in improving the accuracy of the PHO network, large portions of the reaction rate data remain with approximate, uncertain, or missing values, which could change the conclusions of the current study significantly. Improving understanding of the kinetics of phosphorus-bearing chemical reactions will be a key undertaking for astronomers aiming to detect phosphine and other phosphorus species in both rocky and gaseous exoplanetary atmospheres in the near future.

Keywords: Atmospheric composition, Exoplanet atmospheric composition , Chemical kinetics
Dynamical Origin of the Vertical Metallicity Gradient of the Milky Way Bulge. A vertical metallicity gradient (VMG) in the Milky Way bulge is well-established. Yet, its origin has not been fully understood under the Galactic secular evolution scenario. We construct single-disk and triple-disk N-body models with an initial radial metallicity gradient (RMG) for each disk. These models generate a VMG through a "two-step heating" mechanism: the outer, metal-poor particles move inward via the bar instability and subsequently undergo more significant vertical heating during the buckling instability, so they end up at greater vertical height. The "two-step heating" mechanism nearly linearly transforms the RMGs in precursor disks into VMGs. Comparing the models with a triple-disk model tagged with radially independent Gaussian metallicity, we find that, despite certain limitations, the "two-step heating" mechanism is still important in shaping the Galactic VMG. If the bar and buckling instabilities contributed to the formation of boxy/peanut-shaped bulges, then the "two-step heating" mechanism is inevitable in the secular evolution of a boxy/peanut-shaped bulge.

Keywords: Milky Way Galaxy physics, Galactic abundances, Galactic bulge, N-body simulations
Advection-nonlinear-diffusion Model of Flare Accelerated Electron Transport in Type III Solar Radio Bursts. Electrons accelerated by solar flares and observed as type III solar radio bursts are not only a crucial diagnostic tool for understanding electron transport in the inner heliosphere but also a possible early indication of potentially hazardous space weather events. The electron beams traveling in the solar corona and heliosphere along magnetic field lines generate Langmuir waves and quasilinearly relax toward a plateau in velocity space. The relaxation of the electron beam over the short distance in contrast to large beam-travel distances observed is often referred to as Sturrok's dilemma. Here, we develop a new electron transport model with quasilinear distance/time self-consistently changing in space and time. This model results in a nonlinear advection-diffusion equation for the electron beam density with a nonlinear diffusion term that is inversely proportional to the beam density. The solution predicts slow super-diffusive (ballistic) spatial expansion of a fast-propagating electron beam. This model also provides the evolution of the spectral energy density of Langmuir waves, which determines brightness temperature of plasma radiation in solar bursts. The model solution is consistent with the results of numerical simulation using kinetic equations and can explain some characteristics of type III solar radio bursts.

Keywords: Solar radio emission, Solar flares
Ages of Stars and Planets in the Kepler Field Younger than Four Billion Years. Recent analyses of FGK stars in open clusters have helped clarify the precision with which a star's rotation rate and lithium content can be used as empirical indicators for its age. Here we apply this knowledge to stars observed by Kepler. Rotation periods are drawn from previous work; lithium is measured from new and archival Keck/HIRES spectra. We report rotation-based ages for 23,813 stars (harboring 795 known planets) for which our method is applicable. We find that our rotational ages recover the ages of stars in open clusters spanning 0.04–2.5 Gyr; they also agree with ≳90% of the independent lithium ages. The resulting yield includes 63 planets younger than 1 Gyr at 2σ, and 109 with median ages below 1 Gyr. This is about half the number expected under the classic assumption of a uniform star formation history. The age distribution that we observe, rather than being uniform, shows that the youngest stars in the Kepler field are 3–5 times rarer than stars 3 Gyr old. This trend holds for both known planet hosts and for the parent stellar sample. We attribute this "demographic cliff" to a combination of kinematic heating and a declining star formation rate in the Galaxy's thin disk, and highlight its impact on the age distribution of known transiting exoplanets.

Keywords: Stellar ages, Field stars, Exoplanet evolution, Planet hosting stars, Milky Way evolution
Predicting Arrival Times of the CCMC CME/Shock Events Based on the SPM3 Model. Coronal mass ejection (CME) is a powerful solar phenomenon that can lead to severe space weather events. Forecasting whether and when the corresponding interplanetary coronal mass ejection (ICME) will reach the Earth is very important in space weather study and forecast. At present, many different kinds of models use the near-Sun CME observations as model inputs to predict its propagation with similar prediction accuracies for large sample events. Among a series of physics-based models, the best-performing version of the shock propagation model (SPM) for large sample events, i.e., SPM3, had achieved a good forecast effect for the 23rd Solar Cycle events (1997.02–2006.12). To further evaluate SPM3, we collected CME events from 2013 January to 2023 July from the Community Coordinated Modeling Center (CCMC) CME scoreboard as a new data set. SPM3 achieved a total prediction success rate of 57% for these new events with a mean absolute error of 8.93 hr and a rms error of 10.86 hr for the shock's arrival time. Interestingly, SPM3 provided better predictions for the CME/shock events during high solar activity years than low solar activity years. We also analyzed the influence of input parameters on CME propagation and found that the larger the angular width of the CME event, the higher the probability of the corresponding IP shock's reaching the Earth. Source latitude had little effect on the arrival probability of the corresponding shock, while source longitude did. The CMEs originating from around W15° had the largest probability of hitting the Earth.

Keywords: Solar-terrestrial interactions, Space weather, Interplanetary shocks, Solar coronal mass ejections
Thermal Evolution of the Intergalactic Medium due to Lyα Photons during the Cosmic Dawn. The first star-forming objects that formed at high redshifts during the cosmic dawn (CD) also emitted photons between Lyα and Lyman-limit frequencies. These photons are instrumental in coupling the spin temperature of the neutral hydrogen (H I) atoms with the kinetic temperature of the intergalactic medium (IGM). Along with this coupling effect, these photons also impact the kinetic temperature by exchanging energy with the H I atoms. The injected Lyα photons in general cool the medium, while the continuum photons heat the medium. While studying this effect in the literature, a quasi-static profile around the Lyα frequency is assumed. In this paper, we solve the time-dependent coupled dynamics of the photon intensity profile along with the evolution of the thermal state of the IGM and H I spin temperature. It is expected that, during the CD era, the IGM has a mix of continuum photons with 10%–20% of injected photons. For this case, we show that the system reaches thermal equilibrium in around 1 Myr, with the final temperature in the range 50–100 K. This timescale is comparable to the source lifetime of Population III stars at high redshifts. One impact of switching off short-lived sources is that it can keep the system heated above the temperature of the quasi-static state. We also show that the quasi-static equilibrium for the continuum photons is only achieved on timescales of 100 Myr at z ≃ 20, comparable to the age of the Universe. We also briefly discuss how the Lyα induced heating can impact the 21 cm signal from CD.

Keywords: Cosmology, Population III stars, H I line emission, Intergalactic medium, Reionization
Impacting Atmospheres: How Late-stage Pollution Alters Exoplanet Composition. The atmospheric composition of exoplanets is often considered as a probe of the planet's formation conditions. How exactly the initial chemical memory may be altered from the birth to the final state of the planet, however, remains unknown. Here, we develop a simple model of pollution of planetary atmosphere by the vaporization of infalling planetesimals of varying sizes and composition (SiO2 inside 1 au and H2O outside 1 au), following their trajectory and thermal evolution through the upper advective and radiative layers of a sub-Neptune-class planet during the late stage of disk evolution. We vary the rate of pollution by changing the solid content of the disk and by dialing the level of disk gas depletion, which in turn determines the rate of planetary migration. We find that pollution by silicate grains will always be limited by the saturation limit set by the thermal state of the atmosphere. By contrast, pollution by water ice can lead to ∼2–4 orders of magnitude variation in the atmospheric water mass fraction depending on the solid and gas content of the disk. Both cases suggest that post-formation pollution can erase the initial compositional memory of formation. Post-formation pollution can potentially transform sub-Neptunes with H/He-dominated envelopes that initially formed beyond the ice line to water worlds (i.e., with a water-enriched envelope) when the disk gas is depleted by ≳2 orders of magnitude, allowing gentle migration. We additionally discuss the expected C/O ratio profile under pollution by water and refractory carbon species.

Keywords: Exoplanet structure, Exoplanet evolution, Exoplanet formation
Unlocking Discovery Potential for Decaying Dark Matter and Faint X-Ray Sources with XRISM. Astrophysical emission lines arising from particle decays can offer unique insights into the nature of dark matter (DM). Using dedicated simulations with background and foreground modeling, we comprehensively demonstrate that the recently launched X-Ray Imaging and Spectroscopy Mission (XRISM) space telescope with powerful X-ray spectroscopy capabilities is particularly well suited to probe decaying DM, such as sterile neutrinos and axion-like particles, in the mass range of a few to tens of keV. We analyze and map XRISM's DM discovery potential parameter space by considering the Milky Way Galactic DM halo, including establishing an optimal line-of-sight search, as well as dwarf galaxies, where we identify Segue 1 as a remarkably promising target. We demonstrate that with only 100 ks exposure, the XRISM/Resolve instrument is capable of probing the underexplored DM parameter window around a few keV and testing DM couplings with a sensitivity that exceeds by two orders existing Segue 1 limits. Further, we demonstrate that XRISM/Xtend instrument sensitivity enables discovery of the nature of faint astrophysical X-ray sources, especially in Segue 1, which could shed light on star formation history. We discuss implications for decaying DM searches with improved detector energy resolution in future experiments.

Keywords: X-ray astronomy, Dwarf galaxies, Dark matter
The Catalogue of Gamma-Ray Burst Observations by HEPD-01 in the 0.3–50 MeV Energy Range. The High-Energy Particle Detector (HEPD-01) on board the China Seismo-Electromagnetic Satellite, located on a Sun-synchronous orbit at 500 km of altitude with an inclination of 97°, features a dedicated logic counting low-energy event rates, which proved sensitive to intense Gamma-Ray Burst (GRB). The present work reports a comprehensive analysis of signals induced by GRBs in the event-rate data collected between 2018 August and 2022 June. After accurately modeling the background rate as observed in different passages of the satellite over the same geographical area, we detected significant deviations to be compared with observations of GRB candidates from other observatories. The analysis revealed 12 statistically significant excesses, that have been associated with GRB 181222B, GRB 190114C, GRB 190129B, GRB 190305A, GRB 190928A, GRB 200412B, GRB 200422A, GRB 200826B, GRB 201009A, GRB 210702A, GRB 211211A, and GRB 220624A. We report light curves for 0.3–50 MeV photons, comparing them with findings from other space telescopes. The catalog of observations is published, complete of GRB observation time, duration, integrated counts, and fluence.

Keywords: Cosmic ray detectors, Gamma-ray bursts, Catalogs
Combined JWST─MUSE Integral Field Spectroscopy of the Most Luminous Quasar in the Local Universe, PDS 456. Fast accreting, extremely luminous quasars contribute heavily to the feedback process within galaxies. While these systems are most common at cosmic noon (z ∼ 2), here we choose to study PDS 456, an extremely luminous (L bol ∼ 1047 erg s−1) but nearby (z ∼ 0.185) quasar where the physics of feedback can be studied in greater detail. We present the results from our analysis of the JWST MIRI/Medium Resolution Spectroscopy (MRS) integral field spectroscopic (IFS) data of this object. The extreme brightness of PDS 456 makes it challenging to study the extended emission even in this nearby object. MIRI/MRS instrumental effects are mitigated by using complementary NIRSpec and MUSE IFS data cubes. We show clear evidence of a multiphase gas outflow extending up to 15 kpc from the central source. This includes emission from warm molecular (H2 ν = 0─0 and 1─0) and ionized (e.g., Paα, [O III], [Ne III], and [Ne VI]) gas with typical blueshifted velocities down to −500 km s−1. We are also able to probe the nuclear dust emission in this source through silicate and polycyclic aromatic hydrocarbon emission features but are unable to spatially resolve it. Our results are consistent with this powerful quasar driving a radiatively driven wind over a broad range of distances and altering the ionization structure of the host galaxy.

Keywords: AGN host galaxies, Active galaxies, Galaxy winds, Quasars
The ALMA-QUARKS Survey: Fibers' Role in Star Formation Unveiled in an Intermediate-mass Protocluster Region of the Vela D Cloud. In this paper, we present a detailed analysis of the IRS 17 filament within the intermediate-mass protocluster IRAS 08448-4343 (of ∼103 L ⊙), using ALMA data from the ATOMS 3 mm and QUARKS 1.3 mm surveys. The IRS 17 filament, which spans ∼54,000 au (0.26 pc) in length and ∼4000 au (0.02 pc) in width, exhibits a complex, multicomponent velocity field and harbors hierarchical substructures. These substructures include three bundles of seven velocity-coherent fibers and 29 dense (n ∼ 108 cm‑3) condensations. The fibers have a median length of ∼4500 au and a median width of ∼1400 au. Among these fibers, four are identified as "fertile," each hosting at least three dense condensations, which are regarded as the "seeds" of star formation. While the detected cores are randomly spaced within the IRS 17 filament based on the 3 mm dust continuum image, periodic spacing (∼1600 au) of condensations is observed in the fertile fibers according to the 1.3 mm dust map, consistent with the predictions of linear isothermal cylinder fragmentation models. These findings underscore the crucial role of fibers in star formation and suggest a hierarchical fragmentation process that extends from the filament to the fibers and, ultimately, to the smallest-scale condensations.

Keywords: Star forming regions, Interstellar filaments
Precision Timing of Eclipsing Binaries from TESS Full Frame Images: Method and Performance. Several hundreds of thousands of eclipsing binaries (EBs) are expected to be detected in the Transiting Exoplanet Survey Satellite (TESS) full frame images (FFIs). This represents a significant increase in the number of EBs available for eclipse timing variation studies. In this paper, we investigate the feasibility of performing precise eclipse timing of TESS EBs using the FFIs. To this end, we developed a fast, automated method and applied it to a sample of ∼100 EBs selected from the Villanova TESS EB catalog. Our timing analysis resulted in the detection of 10 new triple candidates with outer periods shorter than ∼1300 days. For five of them, we were able to constrain the outer orbit by analyzing independently the short-cadence (SC) and FFI data and to derive the minimum mass of the third body with a precision better than 4% for SC and 11% for FFI data. We then compared the results obtained from the two data sets and found that using the FFI data leads to (1) a degradation of both the accuracy and precision of the tertiary mass determination for the tightest EBs and (2) an overall underestimation of the third component's mass. However, we stress that our main conclusions on the nature of the detected signals do not depend on which data set is used. This confirms the great potential of TESS FFIs, which will allow us to search for rare objects such as substellar circumbinary companions and compact triple stellar systems.

Keywords: Eclipsing binary stars, Multiple stars, Eclipsing binary minima timing method
Double-edged Sword: The Influence of Tidal Interaction on Stellar Activity in Binaries. Using the LAMOST DR7 low-resolution spectra, we carried out a systematic study of stellar chromospheric activity in both single and binary stars. We constructed a binary sample and a single-star sample, mainly using the binary belt and the main sequence in the Hertzsprung–Russell diagram, respectively. By comparing the S indices between single and binary stars within each color bin, we found for K-type stars, binaries exhibit enhanced activity compared to single stars, which could be attributed to the increase in spin rate caused by tidal synchronization or to the interactions of magnetic fields. Both single stars and binaries fall on a common sequence in the activity-period relation, indicating that the chromospheric activities of binaries are dominated by the more active components. More intriguingly, in some color ranges, a slight decline of the S index for smaller orbital periods was observed for binary stars. Although the possibility of sample selection effects cannot be excluded, this may mark the first example of supersaturation (i.e., caused by reduced active regions) being detected in chromospheric activity, or provide evidence of the suppressing effect on the magnetic dynamo and stellar activities by strong tidal interaction in very close binaries. Our study suggests that tidal interaction acts as a double-edged sword in relation to stellar activities.

Keywords: Stellar chromospheres, Late-type stars, Stellar activity
Cosmological Prediction of the Void and Galaxy Clustering Measurements in the CSST Spectroscopic Survey. The void power spectrum is related to the clustering of low-density regions in the large-scale structure (LSS) of the Universe and can be used as an effective cosmological probe to extract information on the LSS. We generate galaxy mock catalogs from a Jiutian simulation and identify voids using the watershed algorithm for studying the cosmological constraint strength of the China Space Station Telescope spectroscopic survey. The galaxy and void autopower spectra and void‑galaxy cross-power spectra at z = 0.3, 0.6, and 0.9 are derived from the mock catalogs. To fit the full power spectra, we propose to use the void average effective radius at a given redshift to simplify the theoretical model, and we adopt the Markov Chain Monte Carlo technique to implement the constraints on the cosmological and void parameters. The systematic parameters, such as galaxy and void biases and noise terms in the power spectra, are also included in the fitting process. We find that our theoretical model can correctly extract the cosmological information from the galaxy and void power spectra, which demonstrates its feasibility and effectivity. The joint constraint accuracy of the cosmological parameters can be improved by ∼20% compared to that of the galaxy power spectrum only. The fitting results of the void density profile and systematic parameters are also well constrained and consistent with the expectation. This indicates that the void-clustering measurement can be an effective complement to the galaxy-clustering probe, especially for the next-generation galaxy surveys.

Keywords: Cosmology, Voids, Large-scale structure of the universe, Cosmological parameters
The IMF Clock Angle Effect on the Tail Cross Section of the Martian Magnetic Pileup Boundary and Bow Shock. Using a three-dimensional global magnetohydrodynamic (MHD) simulation model, we investigate the effects of different interplanetary magnetic field (IMF) clock angles on the tail configuration of the Martian magnetic pileup boundary (MPB) and bow shock (BS). The study reveals the following: (1) The cross sections of the tail MPB and BS are approximately elliptical. The MPB tail cross section generally elongates in the direction of the IMF clock angle, whereas the BS tail cross section is roughly elongated perpendicular to the IMF clock angle direction. (2) An IMF with a northward component can cause the tail cross section of the MPB to shift slightly to the south when the intense crustal magnetic fields are located on the dayside. (3) As the tail distance from Mars increases, the eccentricity of the cross section ellipses of both the MPB and BS tail increases, as well as the major and minor axes. Additionally, the major and minor axes of the tail MPB's cross section ellipses begin to decrease at the far magnetotail, suggesting that the Martian MPB tail might be a closed structure on the nightside.

Keywords: Planetary bow shocks, Planetary magnetospheres, Mars, Interplanetary magnetic fields