bluuebunny/crossref_metadata_2025_split huggingface dataset:
QSOFEED: Relationship between star formation and active galactic nuclei feedback
Authors: Bessiere P. S. , Ramos Almeida C. , Holden L. R. , Tadhunter C. N. , Canalizo G. 
Published: June 2024

Context. Large-scale cosmological simulations suggest that feedback from active galactic nuclei (AGN) plays a crucial role in galaxy evolution. More specifically, outflows are one of the mechanisms by which the accretion energy of the AGN is transferred to the interstellar medium (ISM), heating and driving out gas and impacting star formation (SF).
Aims. The purpose of this study is to directly test this hypothesis utilising SDSS spectra of a well-defined sample of 48 low-redshift (z < 0.14) type 2 quasars (QSO2s).
Methods. By exploiting these data, we were able to characterise the kinematics of the warm ionised gas by performing a non-parametric analysis of the [OIII]λ5007 emission line. We also constrained the properties of the young stellar populations (YSP; tysp < 100 Myr) of their host galaxies via spectral synthesis modelling.
Results. These analyses revealed that 85% of the QSO2s display velocity dispersions in the warm ionised gas phase greater than that of the stellar component of their host galaxies, indicating the presence of AGN-driven outflows. We compared the gas kinematics with the intrinsic properties of the AGN and found that there is a positive correlation between gas velocity dispersion and 1.4 GHz radio luminosity – but not with the AGN bolometric luminosity or Eddington ratio. This either suggests that the radio luminosity is the key factor driving outflows or that the outflows themselves are shocking the ISM and producing synchrotron emission. We found that 98% of the sample host YSPs to varying degrees, with star formation rates (SFRs) of 0 ≤ SFR ≤ 92 M⊙ yr−1, averaged over 100 Myr. We compared the gas kinematics and outflow properties to the SFRs to establish possible correlations that could suggest that the presence of the outflowing gas could be impacting SF, but we found that no such correlation exists. This leads us to the conclusion that on the scales probed by the SDSS fibre (between 2 and 7 kpc diameters), AGN-driven outflows do not impact SF on the timescales probed in this study. However, we find a positive correlation between the light-weighted stellar ages of the QSO2s and the black hole mass, which might indicate that successive AGN episodes lead to the suppression of SF over the course of galaxy evolution.
A linearized coupled model of acoustic-gravity waves and the lower ionosphere at Mars
Authors: Wang Xing , Xu Xiaojun , Cui Jun , Yi Siqi , Gu Hao , Zhou Zilu , Man Hengyan , Luo Lei , He Peishan , Yang Pu , Li Hui 
Published: June 2024

Context. Highly variable ionospheric structures were recently detected on Mars using spacecraft measurements. Acoustic-gravity waves (AGWs) could be the underlying mechanism. Studying the response of the Martian ionosphere to AGWs could provide us with an important understanding of the neutral wave-ionospheric coupling processes.
Aims. We developed a linearized wave model to explore the plasma-neutral coupling driven by AGWs in the lower ionosphere of Mars. This model can describe the propagation and dissipation of AGWs in a realistic atmosphere and is the first of its kind to incorporate plasma behaviors associated with photochemistry and electromagnetic fields.
Methods. We adopted a full-wave model as the first part of our coupled model to delineate wave propagation in a realistic atmosphere. The second part of our model consists of the governing equations describing the plasma behaviors. Therefore, our model not only replicates the result of the full-wave model, but can also be used to investigate the wave-driven variations in the plasma velocity and density, electromagnetic field, and thermal structures.
Results. Our model results reveal that ions are mainly dragged by neutrals and oscillate along the wave phase line below ~200 km altitude. Electrons are primarily subject to gyro-motion along the magnetic field lines. The wave-driven distinct motions among charged particles can generate the perturbed electric current and electric field, further contributing to localized magnetic field fluctuations. Major charged constituents, including electrons, O+, O2+, and CO2+, have higher density amplitudes when interacting with waves of larger periods. The presence of photochemistry leads to a decrease in the plasma density amplitude, and there exists a moderate correlation between the density variations of plasma and those of neutrals. Our numerical results indicate that the wave-driven variations range from several percent to ~80% in the plasma density and from ~0.2% to 17% in the magnetic field, values that are consistent with the spacecraft observations. Further calculations reveal that the wave-induced plasma–neutral coupling can heat the neutrals yet cool the plasmas. Electrons are cooler than ions in the coupling process. The wave-driven heating by neutral–ion collisions exceeds that by neutral-electron collisions but tends to be lower than the wave dissipative heating and photochemical heating. Our model has potential applications in studying the AGW-driven variable ionospheric structures and can be used for other planets.
Physical parameters and orbital evolution of asteroids in retrograde orbits
Authors: Wlodarczyk I. 
Published: June 2024

Context. We studied the dynamical orbital and physical evolution of all 21 numbered and 13 selected unnumbered asteroids in retrograde orbits.
Aims. Based on all published observations of studied asteroids in retrograde orbits, we computed their starting orbital elements, absolute magnitudes, and diameters, together with the non-gravitational parameters A2 and da/dt.
Methods. Using publicly available orbital computation methods, we studied the dynamical evolution of orbital elements and the physical parameters of asteroids: rotation period, spin direction, and the non-gravitational parameters A2.
Results. Lyapunov times (LT) for studied asteroids are short, from 60 to 36 496 yr, with a mean of 5978. Without considering non-gravitational effects, LT is longer: values range from 328 to 63 165 yr, with a mean of 6392. Over the next 10 Myr and beyond, the rotation period of the studied asteroids P decreases by approximately 8%. Moreover, 15% of the clones slow down.
Conclusions. The starting spin distribution becomes flatter, with only one large maximum in the range (0–5) deg containing 279 clones (i.e. approximately 13%). However, the non-gravitational parameter da/dt has a maximum value of around (0–0.04)× 10−5 au day−2 .
Vertical shear instability with dust evolution and consistent cooling times
Authors: Pfeil Thomas , Birnstiel Til , Klahr Hubert 
Published: June 2024

Context. Gas in protoplanetary disks mostly cools via thermal accommodation with dust particles. Thermal relaxation is thus highly sensitive to the local dust size distributions and the spatial distribution of the grains. So far, the interplay between thermal relaxation and gas turbulence has not been dynamically modeled in hydrodynamic simulations of protoplanetary disks with dust.
Aims. We aim to study the effects of the vertical shear instability (VSI) on the thermal relaxation times, and vice versa. We are particularly interested in the influence of the initial dust grain size on the VSI and whether the emerging turbulence is sustained over long timescales.
Methods. We ran three axisymmetric hydrodynamic simulations of a protoplanetary disk including four dust fluids that initially resemble MRN size distributions of different initial grain sizes. From the local dust densities, we calculated the thermal accommodation timescale of dust and gas and used the result as the thermal relaxation time of the gas in our simulation. We included the effect of dust growth by applying the monodisperse dust growth rate and the typical growth limits.
Results. We find that the emergence of the VSI is strongly dependent on the initial dust grain size. Coagulation also counteracts the emergence of hydrodynamic turbulence in our simulations, as shown by others before. Starting a simulation with larger grains (100 μm) generally leads to a less turbulent outcome. While the inner disk regions (within ∼70 au) develop turbulence in all three simulations, we find that the simulations with larger particles do not develop VSI in the outer disk.
Conclusions. Our simulations with dynamically calculated thermal accommodation times based on the drifting and settling dust distribution show that the VSI, once developed in a disk, can be sustained over long timescales, even if grain growth is occurring. The VSI corrugates the dust layer and even diffuses the smaller grains into the upper atmosphere, where they can cool the gas. Whether the instability can emerge for a specific stratification depends on the initial dust grain sizes and the initial dust scale height. If the grains are initially ≳100 μm and if the level of turbulence is initially assumed to be low, we find no VSI turbulence in the outer disk regions.
TDCOSMO
Authors: Wells Patrick R. , Fassnacht Christopher D. , Birrer Simon , Williams Devon 
Published: June 2024

Context. Time-delay cosmography is a technique for measuring H0 with strong gravitational lensing. It requires a correction for line-of-sight perturbations, and thus it is necessary to build tools to assess populations of these lines of sight efficiently.
Aims. We demonstrate the techniques necessary to analyze line-of-sight effects at a population level, and investigate whether strong lenses fall in preferably overdense environments.
Methods. We analyzed a set of 25 galaxy-galaxy lens lines of sight in the Strong Lensing Legacy Survey sample using standard techniques, then performed a hierarchical analysis to constrain the population-level parameters. We introduce a new statistical model for these posteriors that may provide insight into the underlying physics of the system.
Reults. We find the median value of κext in the population model to be 0.033 ± 0.010. The median value of κext for the individual lens posteriors is 0.008 ± 0.015. Both approaches demostrate that our systems are drawn from an overdense sample. The different results from these two approaches show the importance of population models that do not multiply the effect of our priors.
Energetic explosions from collisions of stars at relativistic speeds in galactic nuclei
Authors: Hu B. X. , Loeb A. 
Published: June 2024

Aims. We investigated collisions that could occur between stars moving near the speed of light around supermassive black holes (SMBHs) with mass M• ≳ 108 M⊙, without being tidally disrupted. Within this approximate SMBH mass range, for sun-like stars, the tidal-disruption radius is smaller than the SMBH’s event horizon; therefore we did not anticipate tidal disruption events (TDEs).
Methods. Differential collision rates were calculated by defining probability distribution functions for various parameters of interest, such as the impact parameter, distance from the SMBH at the time of the collision, the relative velocity between the two colliding stars, and the masses of the two colliding stars. The relative velocity parameter was drawn from an appropriate distribution function for SMBHs. We integrated over all these parameters to arrive at a total collision rate for a galaxy with a specific SMBH mass. We then considered how the stellar population in the vicinity of the SMBH was depleted and replenished over time, and calculated the effect this can have on the collision rate over time. We further calculated the differential collision rate as a function of the total energy released, the energy released per unit mass lost, and the galactocentric radius.
Results. The overall rate for collisions taking place within the inner ∼1 pc of galaxies with M• = 108, 109, and 1010 M⊙ are Γ ∼ 2.2 × 10−3, 2.2 × 10−4, and 4.7 × 10−5 yr−1, respectively. The most common collisions would release energies on the order of ∼1049 − 1051 ergs, with the energy distribution peaking at higher energies in galaxies with more massive SMBHs. In addition, we examined sample light curves for collisions with varying parameters, and find that the peak luminosity could reach or even exceed that of superluminous supernovae (SLSNe), albeit in the case of light curves with much shorter durations.
Conclusions. Weaker events may initially be mistaken for low-luminosity supernovae. In addition, we note that these events would likely create streams of debris that would accrete onto the SMBH, potentially creating accretion flares that may resemble TDEs.
Study of hydrated asteroids via their polarimetric properties at low phase angles
Authors: Geem Jooyeon , Ishiguro Masateru , Naito Hiroyuki , Hasegawa Sunao , Takahashi Jun , Bach Yoonsoo P. , Jin Sunho , Takagi Seiko , Ono Tatsuharu , Kuroda Daisuke , Sekiguchi Tomohiko , Kuramoto Kiyoshi , Nakamura Tomoki , Watanabe Makoto 
Published: June 2024

Context. Ch-type asteroids are distinctive among other dark asteroids in that they exhibit deep negative polarization branches (NPBs). Nevertheless, the physical and compositional properties that cause their polarimetric distinctiveness are less investigated.
Aims. We aim to investigate the polarimetric uniqueness of Ch-type asteroids by making databases of various observational quantities (i.e., spectroscopic and photometric properties as well as polarimetric ones) of dark asteroids.
Methods. We conducted an intensive polarimetric survey of 52 dark asteroids (including 31 Ch-type asteroids) in the RC band to increase the size of polarimetric samples. The observed data were compiled with previous polarimetric, spectroscopic, and photometric archival data to find their correlations.
Results. We find remarkable correlations between these observed quantities, particularly the depth of NPBs and their spectroscopic features associated with the hydrated minerals. The amplitude of the opposition effect in photometric properties also shows correlations with polarimetric and spectral properties. However, these observed quantities do not show noticeable correlations with the geometric albedo, thermal inertia, and diameter of asteroids.
Conclusions. Based on the observational evidence, we arrive at our conclusion that the submicrometer-sized structures (fibrous or flaky puff pastry-like structures in phyllosilicates) in the regolith particles could contribute to the distinctive NPBs of hydrated asteroids.
Characteristics and energy flux distributions of decayless transverse oscillations depending on coronal regions
Authors: Lim Daye , Van Doorsselaere Tom , Berghmans David , Petrova Elena 
Published: June 2024

Context. It has been proposed that the slope (δ) of the power-law distribution between the energy flux and oscillation frequency could determine whether high-frequency transverse oscillations make a dominant contribution to the heating (δ <  1). A meta-analysis of decayless transverse oscillations revealed that high-frequency oscillations potentially play a key role in heating the solar corona.
Aims. We aim to investigate whether or not (and, if so, how) the distributions of the energy flux contained in transverse oscillations, and their slopes, depend on the coronal region in which the oscillation occurs.
Methods. We analysed transverse oscillations from 41 quiet Sun (QS) loops and 22 active region (AR) loops observed by Solar Orbiter/Extreme Ultraviolet Imager (EUI) HRIEUV. We estimated the energy flux and energy using analysed oscillation parameters and loop properties, such as periods, displacement amplitudes, loop lengths, and minor radii of the loops.
Results. We find that about 71% of QS loops and 86% of AR loops show decayless oscillations, and that the amplitude does not change depending on different regions, but the difference in the period is more pronounced. Although the power law slope (δ = −1.79) in AR is steeper than that (δ = −1.59) in QS, both of them are significantly less than the critical slope of 1.
Conclusions. Our statistical study demonstrates that high-frequency transverse oscillations can heat the QS. For ARs, the total energy flux is insufficient unless yet-unobserved oscillations with frequencies of up to 0.17 Hz are present. Future EUI campaigns will be planned to confirm whether a corresponding high-frequency oscillation exists.
An in-depth analysis of the differentially expanding star cluster Stock 18 (Villafranca O-036) using Gaia DR3 and ground-based data
Authors: Maíz Apellániz J. , Youssef A. R. , El-Nawawy M. S. , Elsanhoury W. H. , Sota A. , Pantaleoni González M. , Ahmed A. 
Published: June 2024

Context. The Villafranca project is combining Gaia data with ground-based surveys to analyze Galactic stellar groups (clusters, associations, or parts thereof) with OB stars.
Aims. We want to analyze the poorly studied cluster Stock 18 within the Villafranca project, as it is a very young stellar cluster with a symmetrical and compact H II region around it, Sh 2-170, so it is likely to provide insights into the structure and dynamics of such objects at an early stage of their evolution.
Methods. We used Gaia astrometry, photometry, spectrophotometry, and variability data as well as ground-based spectroscopy and imaging to determine the characteristics of Stock 18. We used these data to analyze its core, massive star population, extinction, distance, membership, internal dynamics, density profile, IMF, stellar variability, and Galactic location.
Results. Stock 18 is a very young (∼1.0 Ma) cluster located at a distance of 2.91 ± 0.10 kpc and is dominated by the GLS 13 370 system, whose primary (Aa) is an O9 V star. We propose that Stock 18 was in a very compact state (∼0.1 pc) about 1.0 Ma ago and that most massive stars were ejected at that time without significantly affecting the less massive stars as a result of multi-body dynamical interactions. Different age estimates also point toward an age close to 1.0 Ma, indicating that the dynamical interactions took place very shortly after massive star formation. Well-defined expanding stellar clusters have been observed before, but none are as young as this one. If we include all of the stars, the initial mass function is top heavy, but if we discard the ejected ones, it becomes nearly canonical. Therefore, this is another example (in addition to the previous one we found – the Bermuda cluster) of (a) a very young cluster with an already evolved present day mass function (b) that has significantly contributed to the future population of free-floating compact objects. If confirmed in more clusters, the number of such compact objects may be higher in the Milky Way than previously thought. Stock 18 has a variable extinction with an average value of R5495 higher than the canonical one of 3.1. We have discovered a new visual component (Ab) in the GLS 13 370 system. The cluster is above our Galactic mid-plane, likely as a result of the Galactic warp, and it has a distinct motion with respect to its surrounding old population, which is possibly an influence of the Perseus spiral arm.
Spectral analysis of three hot subdwarf stars: EC 11481-2303, Feige 110, and PG 0909+276
Authors: Landstorfer A. , Rauch T. , Werner K. 
Published: June 2024

Context. For the precise spectral analysis of hot stars, advanced stellar-atmosphere models that consider deviations from the local thermodynamic equilibrium are mandatory. This requires accurate atomic data to calculate all transition rates and occupation numbers for atomic levels in the considered model atoms, not only for a few prominent lines exhibited in an observation. The critical evaluation of atomic data is a challenge because it requires precise laboratory measurements. Ultraviolet spectroscopy of hot stars with high resolving power provide such “laboratory” spectra.
Aims. We compare observed, isolated lines of the iron group (here calcium to nickel) with our synthetic line profiles to judge the accuracy of the respective oscillator strengths. This will verify them or yield individual correction values to improve the spectral analysis, that is the determination of, for example, effective temperature (Teff) and abundances.
Methods. To minimize the error propagation from uncertainties in Teff, surface gravity (𝑔), and abundance determination, we start with a precise reanalysis of three hot subdwarf stars, namely EC 11481-2303, Feige 110, and PG0909+276. Then, we measure the abundances of the iron-group elements individually. Based on identified, isolated lines of these elements, we compare observation and models to measure their deviation in strength (equivalent width).
Results. For EC 11481–2303 and Feige 110, we confirmed the previously determined Teff and log 𝑔 values within their error limits. For all three stars, we fine-tuned all metal abundances to achieve the best reproduction of the observation. For more than 450 isolated absorption lines of the iron group, we compared modeled and observed line strengths. Considering the uncertainty of the analysis and evaluation procedure, an upper limit for the uncertainty of the underlying atomic data was established.
Conclusions. We selected strong, reliable isolated absorption lines, which we recommend to use as reference lines for abundance determinations in related objects.
Risk Factors, Antithrombotic Management, and Long-Term Outcomes of Patients Undergoing Endovascular Treatment of Unruptured Intracranial Aneurysms
Authors: Xiang Yanxiao , Zhang Ping , Lai Yongjie , Wang Donghai , Liu Anchang 
Published: June 2024

Background Patients receiving endovascular treatment for unruptured intracranial aneurysms (UIAs) face varying risks and benefits with antithrombotic management. This study aimed to evaluate the perioperative and long-term effects of antithrombotic strategies, identify the populations that would benefit, and explore the predictive factors affecting the long-term outcomes.
Methods UIA patients undergoing endovascular treatment including stent-assisted coiling or flow diversion between June 2019 and June 2022 were enrolled. We compared perioperative and long-term complications between tirofiban and dual antiplatelet therapy groups. Optimal candidates for each antithrombotic treatment were identified using multivariate logistic regression. Nomograms were developed to determine the significant predictors for thromboembolic complications during follow-up.
Results Among 181 propensity-score matched pairs, the tirofiban group showed a trend toward a lower rate of thromboembolic complications than the DAPT group without elevating major bleeding risk in either period. Homocysteine (Hcy) level ≥10 μmol/L was a significant independent factor associated with thromboembolic complication in both periods. Subgroup analysis highlighted that in patients with high Hcy levels, tirofiban and sustained antiplatelet treatment for ≥12 months were protective factors, while a history of stroke was an independent risk factor for thromboembolic events in follow-up. Four variables were selected to construct a prognostic nomogram, history of hypertension, prior stroke, Hcy level, and the duration of antiplatelet therapy.
Conclusion Perioperative low-dose tirofiban and extended antiplatelet therapy demonstrated a favorable trend in long-term outcomes for UIA patients with preoperative Hcy levels ≥10 μmol/L undergoing endovascular treatment. The prognostic model offers reliable risk prediction and guides antithrombotic strategy decisions.