Sazuna/UAT_keywords huggingface dataset:
Investigating the Efficacy of Topologically Derived Time Series for Flare Forecasting. I. Data Set Preparation. The accurate forecasting of solar flares is considered a key goal within the solar physics and space weather communities. There is significant potential for flare prediction to be improved by incorporating topological fluxes of magnetogram data sets, without the need to invoke three-dimensional magnetic field extrapolations. Topological quantities such as magnetic helicity and magnetic winding have shown significant potential toward this aim, and provide spatiotemporal information about the complexity of active region magnetic fields. This study develops time series that are derived from the spatial fluxes of helicity and winding that show significant potential for solar flare prediction. It is demonstrated that time-series signals, which correlate with flare onset times, also exhibit clear spatial correlations with eruptive activity, establishing a potential causal relationship. A significant database of helicity and winding fluxes and associated time series across 144 active regions is generated using Space-Weather HMI Active Region Patches data processed with the Active Region Topology (or ARTop) code that forms the basis of the time-series and spatial investigations conducted here. We find that a number of time series in this data set often exhibit extremal signals that occur 1–8 hr before a flare. This publicly available living data set will allow users to incorporate these data into their own flare prediction algorithms.

Keywords: Solar active region magnetic fields, Space weather, Solar flares
Assessing the Impact of Binary Systems on Microlensing Using SPISEA and PopSyCLE Population Simulations. Gravitational microlensing provides a unique opportunity to probe the mass distribution of stars, black holes, and other objects in the Milky Way. Population simulations are necessary to interpret results from microlensing surveys. The contribution from binary objects is often neglected or minimized in analysis of observations and simulations despite the high percentage of binary systems and microlensing's ability to probe binaries. To simulate the population effects, we added multiple systems to Stellar Population Interface for Stellar Evolution and Atmospheres (SPISEA), which simulates stellar clusters. We then inject these multiples into Population Synthesis for Compact-object Lensing Events (PopSyCLE), which simulates Milky Way microlensing surveys. When making OGLE observational selection criteria, we find that 55% of observed microlensing events involve a binary system. Specifically, 14.5% of events have a multiple lens and a single source, 31.7% have a single lens and a multiple source, and 8.8% have a multiple lens and a multiple source. The majority of these events have photometric light curves that appear single and are fit well by a single-lens, single-source model. This suggests that binary source and binary lens‑binary source models should be included more frequently in event analysis. The mean Einstein crossing time shifts from 19.1 days for single events only to 21.3 days for single and multiple events, after cutting binary events with multiple peaks. The Einstein crossing time distribution of single and single-peaked multiple events is better aligned with observed distributions from OGLE than singles alone, indicating that multiple systems are a significant missing piece between simulations and reality.

Keywords: Stellar mass black holes, Binary lens microlensing, Gravitational lensing, Binary source microlensing, Astrophysical black holes
Cluster Candidates with Massive Quiescent Galaxies at z ∼ 2. Galaxy clusters are crucial to understanding the role of the environment in galaxy evolution. However, due to their rarity, only a limited number of clusters have been identified at z ≳ 2. In this paper, we report a discovery of seven cluster candidates with massive quiescent galaxies at z ∼ 2 in the 3.5 deg2 area of the XMM Large Scale Structure field, roughly doubling the known cluster sample at this frontier redshift if confirmed. We construct a photometric redshift catalog based on deep (i ∼ 26, Ks ∼ 24) multiwavelength photometry from the u* band to the K band gathered from the Hyper Suprime-Cam Subaru Strategic Program and other collaborative/public surveys. We adopt a Gaussian kernel density estimate with two different spatial scales (10″ and 60″) to draw a density map of massive ( ) and quiescent ( ) galaxies at z ∼ 2. Then, we identify seven prominent overdensities. These candidates show clear red sequences in color─magnitude diagrams (z − H versus H). Moreover, one of them shows an extended X-ray emission with LX = (1.46 ± 0.35) × 1044 erg s−1, suggesting its virialized nature. There is no clear evidence of enhancement nor suppression of the star formation rate of the main-sequence galaxies in the clusters. We find that cluster galaxies have a higher fraction of transition population with   (12%) than the field (2%), which implies the ongoing star formation quenching. The quiescent fraction in the cluster candidates also exceeds that in the field. We confirm that the excess of a quiescent fraction is larger for higher-mass galaxies. This is the first statistical evidence for the mass-dependent environmental quenching at work in clusters even at z ∼ 2.

Keywords: Galaxy clusters, Galaxy formation, Quenched galaxies, Galaxy evolution, High-redshift galaxies
Synthetic Modeling of Polarized Dust Emission in Intermediate-mass YSOs. I. Constraining the Role of Iron Inclusions and Inelastic Relaxation on Grain Alignment with ALMA Polarization. Iron inclusions embedded inside dust grains play a crucial role in both internal alignment (IA) via Barnett relaxation and external alignment via the MAgnetically Enhanced RAdiative Torque (MRAT) mechanism. Moreover, inelastic relaxation is predicted to dominate over Barnett relaxation in driving the IA of micron-sized grains and very large grains (VLGs) above 10 μm. Yet, a detailed modeling of polarized thermal dust emission from Class 0/I young stellar objects (YSOs) taking into account these effects and their observational constraints is still lacking. In this paper, we update the POLARIS code and use it to perform synthetic dust polarization modeling for MHD simulations of an intermediate-mass YSOs. Results will be post-processed with CASA to confront Atacama Large Millimeter/submillimeter Array (ALMA) polarimetric observations. We found that to reproduce the high polarization degree of p ∼ 5%–30% observed in protostellar envelopes by ALMA, micron-sized grains and VLGs must contain iron inclusions with Ncl ∼ 5–103 iron atoms per cluster, assuming 30% of iron abundance locked inside dust grains under the cluster form. Inside the inner ∼500 au region, inelastic relaxation must participate in driving the grain IA, and grains must contain larger iron inclusions of Ncl ∼ 102–104 and grow beyond ≥10 μm to reproduce ∼3%–10% of dust polarization observed by ALMA. But given such a combination, the IA and MRAT efficiency acting on VLGs still decreases toward the center, inducing the decrease of p(%) with increasing gas density, reaching p ∼ 1% inside the disk.

Keywords: Dust physics, Young stellar objects, Star formation
Solar Modulation of Low-energy Cosmic-Ray Nitrogen and Its Comparison with Oxygen. The heliospheric environment is very complex and filled with diverse high-energy particles from various origins, and among these particles, cosmic rays (CRs), including anomalous and Galactic components (ACRs and GCRs), are unique as they originate from beyond the solar system. Due to their stable and long-lasting presence in the heliosphere, the study of CRs is crucial for protecting humanity and other lifeforms against the hazards of high-energy radiation. In this work, we aim to study the prolonged changes in CR nitrogen, a fundamental element that constitutes amino acids, using the measurements from the Advanced Composition Explorer (ACE) spacecraft. The comparison of solar modulation on CR nitrogen and oxygen is also made using the yearly averaged ACE observations. The ACR nitrogen has a more even spectrum than ACR oxygen while the spectrum of GCR nitrogen is more abrupt than GCR oxygen. Further model results indicate that GCR nitrogen and oxygen undergo comparable modulation processes within the heliosphere and the slight difference between the observed power-law indices of nitrogen and oxygen spectrum is due to the distinct local interstellar spectrum of the two species. Besides, an analysis is made to explain the observed more flattened ACR spectrum of nitrogen than oxygen caused by the slightly different charge-to-mass ratio Z/A.

Keywords: Cosmic ray astronomy
Minor-merger-induced Star Formation Rejuvenation in an Elliptical Radio-loud Quasar Host, 3C 59. We report a rare case where an elliptical radio-loud quasar host, 3C 59, rejuvenates star formation activity through minor mergers with its nearby satellite galaxies. The inferred star formation history of 3C 59 has shown significant star formation rejuvenation within the past 500 Myr, before which it remained rather quiescent for most of the cosmic time. The three nearest satellite galaxies of 3C 59 exhibit significant morphological disturbances, and two of them present strong tidal tails pointing toward 3C 59. In addition, all the satellite galaxies within a projected distance of 200 kpc show low star formation activities. They also have systematically lower effective radius (Re) than local late-type galaxies, while 3C 59 has significantly larger Re than both early- and late-type galaxies. All these features suggest that ongoing minor mergers between 3C 59 and its nearby satellites could be causing gas to flow into 3C 59, which induces the star formation rejuvenation and possibly also triggers the quasar activity. The enormous power from the large-scale radio jet of 3C 59 may in turn help keep the halo hot, prevent gas cooling, and further reduce star formation in its satellite galaxies. These results provide important insights into the mass and size growth of central galaxies and star formation quenching of satellite galaxies in galaxy groups.

Keywords: Lenticular galaxies, Radio lobes, Radio loud quasars, Galaxy mergers, Galaxy groups, Elliptical galaxies
Tackling the Problem of Distributional Shifts: Correcting Misspecified, High-dimensional Data-driven Priors for Inverse Problems. Bayesian inference for inverse problems hinges critically on the choice of priors. In the absence of specific prior information, population-level distributions can serve as effective priors for parameters of interest. With the advent of machine learning, the use of data-driven population-level distributions (encoded, e.g., in a trained deep neural network) as priors is emerging as an appealing alternative to simple parametric priors in a variety of inverse problems. However, in many astrophysical applications it is often difficult or even impossible to acquire independent and identically distributed samples from the underlying data-generating process of interest to train these models. In these cases, corrupted data or a surrogate, e.g., a simulator, is often used to produce training samples, meaning that there is a risk of obtaining misspecified priors. This, in turn, can bias the inferred posteriors in ways that are difficult to quantify, which limits the potential applicability of these models in real-world scenarios. In this work, we propose addressing this issue by iteratively updating the population-level distributions by retraining the model with posterior samples from different sets of observations, and we showcase the potential of this method on the problem of background image reconstruction in strong gravitational lensing when score-based models are used as data-driven priors. We show that, starting from a misspecified prior distribution, the updated distribution becomes progressively closer to the underlying population-level distribution, and the resulting posterior samples exhibit reduced bias after several updates.

Keywords: Bayesian statistics, Sky surveys, Posterior distribution, Strong gravitational lensing, Astrostatistics distributions, Bayes' Theorem, Hierarchical models, Prior distribution, Galaxies, Sampling distribution
Formation of Stripped Stars from Stellar Collisions in Galactic Nuclei. Tidal disruption events (TDEs) are an important way to probe the properties of stellar populations surrounding supermassive black holes. The observed spectra of several TDEs, such as ASASSN-14li, show high nitrogen-to-carbon (N/C) abundance ratios, leading to questions about their progenitors. Disrupting an intermediate- or high-mass star that has undergone CNO processing, increasing the nitrogen in its core, could lead to an enhanced nitrogen TDE. Galactic nuclei present a conducive environment for high-velocity stellar collisions that can lead to high mass loss, stripping the carbon- and hydrogen-rich envelopes of the stars and leaving behind the enhanced nitrogen cores. TDEs of these stripped stars may therefore exhibit even more extreme nitrogen enhancement. Using the smoothed particle hydrodynamics code StarSmasher, we provide a parameter space study of high-velocity stellar collisions involving intermediate-mass stars, analyzing the composition of the collision products. We conclude that high-velocity stellar collisions can form products that have abundance ratios similar to those observed in the motivating TDEs. Furthermore, we show that stars which have not experienced high CNO processing can yield low-mass collision products that retain even higher N/C abundance ratios. We analytically estimate the mass fallback for a typical TDE of several collision products to demonstrate consistency between our models and TDE observations. Lastly, we discuss how the extended collision products, with high central to average density ratios, can be related to repeated partial TDEs like ASASSN-14ko and G objects in the Galactic center.

Keywords: Hydrodynamical simulations, Supermassive black holes, Galactic center, Stellar interiors, Stellar structures, Helium-rich stars, Tidal disruption, Transient sources, Galaxy nuclei, S stars, Chemically peculiar stars, Astrophysical black holes
Laboratory Measurement of CH<SUB>3</SUB><SUP>17</SUP>OH Transitions in the Frequency Range from 216 to 264 GHz for Astronomical Application. Methanol is one of the most abundant complex organic molecules in interstellar environments. Molecular lines of its rare isotopologues 12CH317OH and 12CH318OH therefore play a crucial role in examining the column density of 12CH316OH, which serves as a reference for organic molecular chemistry in interstellar clouds. In this study, we have recorded the spectroscopic emission spectrum of 12CH317OH in the frequency range between 216 and 264 GHz by making use of an emission-type millimeter and submillimeter spectrometer. We have specifically paid attention to the Q-branch transitions, which are the strongest line series in this frequency region. Among the stable oxygen isotopes, 16O, 17O, and 18O of methanol, only 12CH317OH obviously shows line profiles having double and/or triple peaks in low-J transitions, due to the nuclear quadrupole interaction. The newly obtained 12CH317OH data will play an important role in facilitating a deeper understanding of the organic chemistry related to star and planet formation. The 12CH317OH line data allow us to trace and constrain the isotopic ratio 17O/18O in methanol, which is efficient to investigate the galactic-scale evolution of elements. In addition, we also assigned some transitions of 13CH317OH in the recorded spectrum.

Keywords: Astrochemistry, Molecular spectroscopy, Line positions, Experimental data
Spin-down of Solar-mass Protostars in Magnetospheric Accretion Paradigm. Stellar spin is one of the fundamental quantities that characterize a star itself and its planetary system. Nevertheless, stellar spin-down mechanisms in protostellar and pre-main-sequence stellar phases have been a long-standing problem in star formation theory. To realize the spin-down, previous axisymmetric models based on the conventional magnetospheric paradigm have had to assume massive stellar winds or produce highly time-variable magnetospheric ejections. However, this picture has been challenged by both numerical simulations and observations. With a particular focus on the propeller regime for solar-mass stars, we propose a new picture of stellar spin-down based on our recent 3D magnetohydrodynamic simulation and stellar evolution calculation. We show that failed magnetospheric winds, unique to 3D models, significantly reduce the spin-up accretion torque, which make it easier for the star to spin-down. Additionally, the amplitude of time variability associated with magnetospheric ejections is reduced by 3D effects. Our simulation demonstrates that the star spins down by generating a conical disk wind, driven by a rotating stellar magnetosphere. Our theoretical estimates, inspired by the numerical model, suggest that the conical disk wind is likely to play a crucial role in extracting stellar angular momentum during the protostellar phase. As magnetospheric accretion is expected to occur in other accreting objects such as protogiant planets, this study will also contribute to the understanding of the angular momentum of such objects.

Keywords: Protostars, Pre-main sequence stars, Early stellar evolution, Stellar magnetic fields
Fundamental Understanding of Magnetic Reconnection via Spiral CT Scan. I. Density, Temperature, Pressure, and Method Validation. For the first time, we reveal the distribution of plasma density, electron temperature, thermal pressure, and total pressure around a reconnection X-line, by using the spiral CT scan technique, which is a novel technique analogous to that in the hospital. This X-line was detected by the Magnetospheric Multiscale spacecraft and has been widely believed to host a non-guide-field reconnection in previous studies. With the help of such an advanced technique, we find that (1) the plasma density is low on the magnetosphere side but high on the magnetosheath side; (2) the electron temperature is high on the magnetosphere side but low on the magnetosheath side; (3) the thermal pressure is high near the current sheet but low away from the current sheet; (4) the total pressure in the inflow region is higher than near the current sheet. Among these findings, the first three agree with classical theories, hence validating our novel scan technique; the last one implicates that antiparallel magnetic field lines were being pushed together and the reconnection process was ongoing.

Keywords: Space plasmas, Solar magnetic reconnection, Plasma physics
Testing the Flux Rope Paradigm for Coronal Mass Ejections Using a Three-spacecraft Encounter Event. We present a 3D morphological and field reconstruction of a coronal mass ejection (CME) from 2023 November 28, which hits three spacecraft near 1 au: Wind at Earth's L1 Lagrange point, STEREO-A with a longitudinal separation of 6 5 west of Earth, and Solar Orbiter (SolO) at 10 7 east of Earth. The reconstruction assumes a magnetic flux rope (MFR) structure for the CME. With this event, we test whether field tracings observed by a spacecraft passing near the central axis of a CME MFR (STEREO-A) can be used to successfully predict the field behavior seen by a spacecraft 17∘ away (SolO), which has a more grazing encounter with the CME. We find that the MFR model does have significant success in simultaneously reproducing the field signs and rotations seen at STEREO-A, Wind, and SolO. This provides support for the MFR paradigm for CME structure. However, the SolO measurements, which are farthest from the central axis of the MFR, show less defined MFR signatures, presumably due to a greater degree of erosion and degradation of the MFR structure far from its central axis.

Keywords: Space plasmas, Interplanetary physics, Interplanetary magnetic fields, Solar coronal mass ejections
Intrinsic Pulse Widths of FRB 20121102A and Calculation of Broadening from Propagation and Instrumental Effects. The pulse widths of fast radio bursts are always broadened due to the scattering of the plasma medium through which the electromagnetic wave passes. The recorded pulse width will be further affected by the radio telescopes since the sampling time and the bandwidth cannot be infinitely small. In this study, we focus on the pulse widths of at least 3287 bursts detected from FRB 20121102A as of 2023 October. Various effects such as the scattering broadening, the redshift-induced broadening, and the instrumental broadening are examined. At a redshift of 0.193, the pulse width is broadened by a factor of approximately 0.16 due to cosmological time dilation. It is found that the instrumental broadening only contributes a fraction of 10‑3–10‑1 to the observed pulse width. The scattering broadening is even smaller, which constitutes a tiny fraction of 10‑5–10‑2 in the observed pulse width. After correcting for these broadenings, the intrinsic pulse width is derived for each burst. The maximum and minimum pulse widths at different frequencies are highlighted. The intrinsic widths of most bursts are in a narrow range of 1–10 ms, which leads to a quasi-linear correlation between the fluence and the peak flux. Additionally, the mean value and the dispersion range of intrinsic pulse width are found to scale with the central frequency as ν‑1.2±0.2 and ν‑1.7±0.6, respectively.

Keywords: Compact radiation sources, Radio bursts, Interstellar medium, Intergalactic medium, Radio transient sources
The Doubly Librating Plutinos. Named for orbital kinship with Pluto, the Plutinos are a prominent group of Kuiper Belt objects whose orbital periods are in libration about a 3/2 ratio with Neptune's. We investigate the long-term orbital dynamics of known Plutinos, with attention to the additional libration (or lack thereof) of their argument of perihelion, g, a well-known characteristic of Pluto's orbit. We show that the g librators among the Plutinos cluster around an arc in the eccentricity–inclination parameter plane. This previously unreported dynamical structure is owed to a family of periodic orbits of the third kind in the restricted problem of three bodies, identified by Poincaré at the end of the 19th century. Approximately 16% of the currently known Plutinos exhibit g librations, a far greater fraction than the ratios of the associated libration frequencies. These results may offer new constraints for theoretical models of the dynamical history of the Plutinos and of the orbital migration history of the giant planets.

Keywords: Small Solar System bodies, Resonant Kuiper belt objects, Orbital resonances, Periodic orbit, Trans-Neptunian objects, Plutinos, Pluto
Solar Modulation of AMS-02 Daily Proton and Helium Fluxes with Modified Force-field Approximation Models. As galactic cosmic rays (GCRs) propagate through the turbulent plasma environment within the heliosphere, they undergo a process of diffusion, drift, and energy loss, leading to a notable reduction in their flux. This is the solar modulation impact. Recently, the cosmic-ray experiment AMS-02 published daily fluxes of proton and helium for the period from 2011 May 20 to 2019 October 29 in the rigidity interval from about 1 to 100 GV, exhibiting fine time structures that correlate with solar wind properties on a daily basis. In this work, we employ three different modified force field approximation models to fit the data. By fitting to the daily proton and helium fluxes, we get the time series of solar modulation potential. We find good agreement of data and model predictions for both proton and helium with the same parameters in two modified force field approximation models. The results in this study verify that the modified force-field approximation model is a valid parameterization of the GCR spectrum also at daily timescales.

Keywords: Galactic cosmic rays, Solar activity, Heliosphere