Sazuna/UAT_keywords huggingface dataset:
Observation of Two Splitting Processes in a Partial Filament Eruption on the Sun: The Role of Breakout Reconnection. Partial filament eruptions have often been observed; however, the physical mechanisms that lead to filament splitting are not yet fully understood. In this study, we present a unique event of a partial filament eruption that undergoes two distinct splitting processes. The first process involves vertical splitting and is accompanied by brightenings inside the filament, which may result from internal magnetic reconnection within the filament. Following the first splitting process, the filament is separated into an upper part and a lower part. Subsequently, the upper part undergoes a second splitting, which is accompanied by a coronal blowout jet. An extrapolation of the coronal magnetic field reveals a hyperbolic flux tube structure above the filament, indicating the occurrence of breakout reconnection that reduces the constraining field above. Consequently, the filament is lifted up, but at a nonuniform speed. The high-speed part reaches the breakout current sheet to generate the blowout jet, while the low-speed part falls back to the solar surface, resulting in the second splitting. In addition, continuous brightenings are observed along the flare ribbons, suggesting the occurrence of a slipping reconnection process. This study presents, for the first time, the unambiguous observation of a two-stage filament-splitting process, advancing our understanding of the complex dynamics of solar eruptions.

Keywords: Jets, Solar flares, Solar magnetic reconnection
Revisiting the Oldest Stars as Cosmological Probes: New Constraints on the Hubble Constant. Despite the tremendous advance of observational cosmology, the value of the Hubble constant (H 0) is still controversial (the so-called "Hubble tension") because of the inconsistency between local/late-time measurements and those derived from the cosmic microwave background. As the age of the Universe is very sensitive to H 0, we explored whether the present-day oldest stars could place independent constraints on the Hubble constant. To this purpose, we selected from the literature the oldest objects (globular clusters, stars, white dwarfs, and ultrafaint and dwarf spheroidal galaxies) with accurate age estimates. Adopting a conservative prior on their formation redshifts (11 ≤ z f ≤ 30) and assuming Ω M  = 0.3 ± 0.02, we developed a method based on Bayesian statistics to estimate the Hubble constant. We selected the oldest objects (&gt;13.3 Gyr) and estimated H 0 both for each of them individually and for the average ages of homogeneous subsamples. Statistical and systematic uncertainties were properly taken into account. The constraints based on individual ages indicate that H 0 &lt; 70.6 km s-1 Mpc-1 when selecting the most accurate estimates. If the ages are averaged and analyzed independently for each subsample, the most stringent constraints imply H 0 &lt; 73.0 km s-1 Mpc-1 with a probability of 90.3% and errors around 2.5 km s-1 Mpc-1. We also constructed an "accuracy matrix" to assess how the constraints on H 0 become more stringent with further improvements in the accuracy of stellar ages and Ω M . The results show the great potential of the oldest stars as independent and competitive cosmological probes not limited to just the Hubble constant.

Keywords: Cosmology, Stellar ages, Cosmological parameters, Observational cosmology, Hubble constant
Understanding the Deflection of the "Cartwheel CME": Data Analysis and Modeling. We study the low corona evolution of the "Cartwheel" coronal mass ejection (CME; 2008 April 9) by reconstructing its three-dimensional path and modeling it with magnetohydrodynamic simulations. This event exhibited a double deflection that has been reported and analyzed in previous works but whose underlying cause remained unclear. The Cartwheel CME traveled toward a coronal hole (CH) and against the magnetic gradients. Using a high-cadence, full-trajectory reconstruction, we accurately determine the location of the magnetic flux rope (MFR) and, consequently, the magnetic environment in which it is immersed. We find a pseudostreamer (PS) structure whose null point may be responsible for the complex evolution of the MFR at the initial phase. From the preeruptive magnetic field reconstruction, we estimate the dynamic forces acting on the MFR and provide a new physical insight into the motion exhibited by the 2008 April 9 event. By setting up a similar magnetic configuration in a 2.5D numerical simulation we are able to reproduce the observed behavior, confirming the importance of the PS null point. We find that the magnetic forces directed toward the null point cause the first deflection, directing the MFR toward the CH. Later, the magnetic pressure gradient of the CH produces the reversal motion of the MFR.

Keywords: Solar magnetic fields, Solar coronal mass ejections, Solar prominences, Magnetohydrodynamical simulations
Diffuse Neutrino Flux Based on the Rates of Core-collapse Supernovae and Black Hole Formation Deduced from a Novel Galactic Chemical Evolution Model. Fluxes of the diffuse supernova neutrino background (DSNB) are calculated based on a new modeling of galactic chemical evolution, where a variable stellar initial mass function (IMF), depending on the galaxy type, is introduced and black hole (BH) formation from the failed supernova is considered for progenitors heavier than 18M ⊙. The flux calculations are performed for different combinations of the star formation rate, nuclear equation of state, and neutrino mass hierarchy, to examine the systematic effects from these factors. In any case, our new model predicts the enhanced DSNB ${\bar{\nu }}_{e}$ flux at E  ν  ≳ 30 MeV and E  ν  ≲ 10 MeV, due to more frequent BH formation and a larger core-collapse rate at high redshifts in early-type galaxies, respectively. Event rate spectra of the DSNB ${\bar{\nu }}_{e}$ at a detector from the new model are shown, and the detectability at water-based Cherenkov detectors, Super-Kamiokande with a gadolinium dissolution and Hyper-Kamiokande, is discussed. In order to investigate the impacts of the assumptions in the new model, we prepare alternative models, based on different IMF forms and treatments of BH formation, and estimate the discrimination capabilities between the new and alternative models at these detectors.

Keywords: Neutron stars, Supernova neutrinos, Initial mass function, Black holes, Core-collapse supernovae, Galaxy chemical evolution, Massive stars, Neutrino astronomy, Star formation
The Role of Natal Kicks in Forming Asymmetric Compact Binary Mergers. In their most recent observing run, the LIGO-Virgo-KAGRA Collaboration observed gravitational waves from compact binary mergers with highly asymmetric mass ratios, including both binary black holes (BBHs) and neutron star-black holes (NSBHs). It appears that NSBHs with mass ratios q ≃ 0.2 are more common than equally asymmetric BBHs, but the reason for this remains unclear. We use the binary population synthesis code COSMIC to investigate the evolutionary pathways leading to the formation and merger of asymmetric compact binaries. We find that within the context of isolated binary stellar evolution, most asymmetric mergers start off as asymmetric stellar binaries. Because of the initial asymmetry, these systems tend to first undergo a dynamically unstable mass transfer phase. However, after the first star collapses into a compact object, the mass ratio is close to unity and the second phase of mass transfer is usually stable. According to our simulations, this stable mass transfer fails to shrink the orbit enough on its own for the system to merge. Instead, the natal kick received by the second-born compact object during its collapse is key in determining how many of these systems can merge. For the most asymmetric systems with mass ratios of q ≤ 0.1, the merging systems in our models receive an average kick magnitude of 255 km s-1 during the second collapse, while the average kick for non-merging systems is 59 km s-1. Because lower mass compact objects, like neutron stars, are expected to receive larger natal kicks than higher mass BHs, this may explain why asymmetric NSBH systems merge more frequently than asymmetric BBH systems.

Keywords: Neutron stars, Binary stars, Core-collapse supernovae, Massive stars, Gravitational wave sources, Astrophysical black holes
Detection Prospects of Fast-merging Gravitational Wave Sources in M31. It is widely accepted that quite a number of double compact objects (DCOs) in the Milky Way can be identified by future space-based gravitational wave (GW) detectors, while systematic investigations on the detection of the GW sources in nearby galaxies are still lacking. In this paper, we present calculations of potential populations of GW sources for all types of DCOs in the Local Group galaxy M31. For M31, we use an age-dependent model for the evolution of the metallicity and the star formation rate. By varying assumptions of common-envelope ejection efficiencies and supernova-explosion mechanisms during binary evolution, we make predictions on the properties of DCOs that can be detected by the Laser Interferometer Space Antenna (LISA). Our calculations indicate that a few (a dozen) DCOs are likely to be observed by LISA during its 4 (10) yr mission. We expect that the sources with black hole components are more likely to be first identified during a 4 yr mission since these binaries have relatively large chirp masses, while the systems with white-dwarf components dominate the overall population of detectable GW sources during a 10 yr mission. LISA can only detect very tight fast-merging systems in M31, corresponding to the peak of orbital period distribution from ~2 minutes for double white dwarfs to ~20 minutes for double black holes.

Keywords: Binary stars, Gravitational waves, Compact objects, Supernovae, Stellar evolution
Comparing Globular Cluster System Properties with Host Galaxy Environment. We present Hubble Space Telescope photometry in the optical (F475X) and near-infrared (F110W) bands of the globular cluster (GC) systems of the inner halos of a sample of 15 massive elliptical galaxies. The targets are selected from the volume-limited MASSIVE survey, and chosen to sample a range of environments from sparsely populated groups to the brightest cluster galaxies in dense clusters. We also present a quantitative model of the relation between (F475X - F110W) color and cluster metallicity [M/H], using simulated GCs. Because much of the GC population in such galaxies is built up through accretion, the metallicity distribution of the GC systems might be expected to vary with galaxy environment. The photometry is used to create a completeness-corrected metallicity distribution for each galaxy in the sample, and to fit a double Gaussian curve to each histogram in order to model the two standard red and blue subpopulations. Finally, the properties of the GC metallicity distribution are correlated against galaxy environment. We find that almost no GCS properties and host galaxy environmental properties are correlated, with the exception of a weak but consistent correlation between blue fraction and nth-nearest-neighbor surface density. The results suggest that the systemic properties of the GC systems, at least in the inner to midhalo regions, are influenced more strongly by the local environment at early times, rather than by the environmental properties we see today. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with programs 14219 and 15265.

Keywords: Galaxy stellar halos, Galaxy formation, Elliptical galaxies, Globular star clusters
BatAnalysis: A Comprehensive Python Pipeline for Swift BAT Survey Analysis. The Swift Burst Alert Telescope (BAT) is a coded-aperture gamma-ray instrument with a large field of view that primarily operates in survey mode when it is not triggering on transient events. The survey data consist of 80-channel detector plane histograms that accumulate photon counts over periods of at least 5 minutes. These histograms are processed on the ground and are used to produce the survey data set between 14 and 195 keV. Survey data comprise &gt;90% of all BAT data by volume and allow for the tracking of long-term light curves and spectral properties of cataloged and uncataloged hard X-ray sources. Until now, the survey data set has not been used to its full potential due to the complexity associated with its analysis and the lack of easily usable pipelines. Here, we introduce the BatAnalysis Python package, a wrapper for HEASoftpy, which provides a modern, open-source pipeline to process and analyze BAT survey data. BatAnalysis allows members of the community to use BAT survey data in more advanced analyses of astrophysical sources, including pulsars, pulsar wind nebula, active galactic nuclei, and other known/unknown transient events that may be detected in the hard X-ray band. We outline the steps taken by the Python code and exemplify its usefulness and accuracy by analyzing survey data of the Crab Nebula, NGC 2992, and a previously uncataloged MAXI transient. The BatAnalysis package allows for ~18 yr of BAT survey data to be used in a systematic way to study a large variety of astrophysical sources.

Keywords: Open source software, Astronomy data analysis, Astronomy data acquisition
Information-theoretic Analysis of Longitude Distribution of Photospheric Magnetic Fields from MDI/HMI Synoptic Maps: Evidence for Rossby Waves. Much of the research on the magnetic activity of the Sun has been focused on its axisymmetric component. However, the longitudinal complexity plays a fundamental role in the solar magnetic activity. Rossby waves have recently been proposed as a fundamental mechanism regarding the nonaxisymmetric nature of the solar magnetic fields. Here, we use HMI and MDI magnetic field synoptic maps to evaluate the magnetic field structures' (mainly active regions) organization and propagation as a function of time and latitude. We demonstrate, using information theory, that the organization of longitudinal structures observed on synoptic maps is proportional to the level of activity at a given latitude. We further show that this organization on the longitudinal structures is persistent and due to long-lived features. The drift velocity of these long-lived photospheric features is inferred and is shown to significantly vary with latitude, and is compatible with the phase speed of tachocline magnetic Rossby waves with a toroidal field in the range of 5-10 kG. Our results suggest that Rossby waves contribute to the organization and propagation of photospheric magnetic features on the timescale of several months and beyond.

Keywords: Solar oscillations, Solar activity, Solar magnetic fields
Subarcsecond-resolution Imaging of M51 with the International LOFAR Telescope. We present an International LOFAR Telescope (ILT) subarcsecond-resolution image of the nearby galaxy M51 with a beam size of 0.″436 × 0.″366 and rms of 46 μJy. We compare this image with a European VLBI Network study of M51 and discuss the supernovae in this galaxy, which have not yet been probed at these low radio frequencies. We find a flux density of 0.97 mJy for SN 2011dh in the ILT image, which is about five times smaller than the flux density reported by the LOFAR Two-metre Sky Survey (LoTSS) at 6″ resolution using the same data set without the international stations. This difference makes evident the need for LOFAR international baselines to reliably obtain flux density measurements of compact objects in nearby galaxies. Our LOFAR flux density measurement of SN 2011dh directly translates into fitting the radio light curves for the supernova and constraining the mass-loss rates of the progenitor star. We do not detect two other supernovae in the same galaxy, SN 1994I and SN 2005cs, and our observations place limits on the evolution of both supernovae at radio wavelengths. We also discuss the radio emission from the center of M51, in which we detect the active galactic nucleus and other parts of the nuclear emission in the galaxy, with a possible detection of Component N. We discuss a few other sources, including the detection of a high-mass X-ray binary not detected by LoTSS but with a flux density in the ILT image that matches well with higher-frequency catalogs.

Keywords: Core-collapse supernovae, Active galactic nuclei, Radio continuum emission, High angular resolution, Galaxies
Absorption of Gamma-Ray Burst X-Ray Afterglows by the Missing Baryons: Confronting Observations with Cosmological Simulations. A large fraction of the baryons at low redshift are undetected and likely reside in the tenuous, hot intergalactic medium (IGM). One way to probe the missing baryons is through their absorption of bright sources. The anomalous absorption excess in the X-ray afterglows of gamma-ray bursts (GRBs) has been suggested to result from the missing baryons. In order to test this hypothesis, the present paper employs IllustrisTNG simulations to compute the X-ray absorption effect on cosmological distances. The simulation shows that ionization of H and He in the IGM leaves the metals responsible for &gt;60% of the X-ray opacity of high-z sources. The high-z asymptotic optical depth at 0.5 keV in the simulation reaches 0.15 ± 0.07, while the GRB afterglow values tend to ≈0.4, implying that the missing baryons can account for a significant fraction of the observed opacity. The remaining discrepancy is ascribed mainly to the low average metallicity in the simulation, which drops from 0.06 solar at z = 0 to 0.01 at z = 3, and which is below previously measured values.

Keywords: X-ray transient sources, Gamma-ray bursts, Intergalactic medium
Examining the Source Regions of Solar Energetic Particles Using an AI-generated Synchronic Potential Field Source Surface Model. We study the source regions of six solar energetic particle (SEP) events accelerated near or behind the limbs of the Sun. We use AI-generated farside magnetograms at a near real-time basis developed by Jeong et al. and AIHMI-PFSS extrapolations up to 2.5R ⊙ computed using the input of the synchronic data combining AI-generated farside and HMI magnetograms. By comparing the AIHMI, HMI, Global Oscillations Network Group (GONG) synoptic magnetograms, and Air force Data Assimilative Photospheric flux Transport synchronic magnetograms, as well as the PFSS extrapolations, we find interesting differences between them in view of SEP source regions and magnetic field configurations. First, the structures and sizes of the source active regions (ARs) are changed. The total unsigned magnetic field fluxes of the ARs are mostly stronger in the AIHMI than in the HMI and GONG magnetograms. Second, newly emerging ARs are observed in the SEP source regions in the AIHMI magnetograms for two events. Third, the alterations in the magnetic flux, the emergence, and the dissipation of ARs lead to modifications in the locations of the global polarity inversion lines (PILs). The EUV wave propagation is typically observed to be oriented nearly perpendicular with respect to the local PIL, suggesting that the AIHMI-PFSS extrapolations around the source region are more realistic. This study shows that the continuous farside evolution of AR magnetic fields, which is accomplished by our AI synchronic magnetograms, can lead to an improved understanding of SEP source ARs.

Keywords: Solar flares, Solar energetic particles, Convolutional neural networks, Solar coronal mass ejections, Solar magnetic fields
Search for sub-TeV Neutrino Emission from Novae with IceCube-DeepCore. The understanding of novae, the thermonuclear eruptions on the surfaces of white dwarf stars in binaries, has recently undergone a major paradigm shift. Though the bolometric luminosity of novae was long thought to arise directly from photons supplied by the thermonuclear runaway, recent gigaelectronvolt (GeV) gamma-ray observations have supported the notion that a significant portion of the luminosity could come from radiative shocks. More recently, observations of novae have lent evidence that these shocks are acceleration sites for hadrons for at least some types of novae. In this scenario, a flux of neutrinos may accompany the observed gamma rays. As the gamma rays from most novae have only been observed up to a few GeV, novae have previously not been considered as targets for neutrino telescopes, which are most sensitive at and above teraelectronvolt (TeV) energies. Here, we present the first search for neutrinos from novae with energies between a few GeV and 10 TeV using IceCube-DeepCore, a densely instrumented region of the IceCube Neutrino Observatory with a reduced energy threshold. We search both for a correlation between gamma-ray and neutrino emission as well as between optical and neutrino emission from novae. We find no evidence for neutrino emission from the novae considered in this analysis and set upper limits for all gamma-ray detected novae.

Keywords: Neutrino telescopes, Neutrino astronomy, High energy astrophysics, Novae
Non-field-aligned Proton Beams and Their Roles in the Growth of Fast Magnetosonic/Whistler Waves: Solar Orbiter Observations. The proton beam is an important population of the non-Maxwellian proton velocity distribution in the solar wind, but its role in wave activity remains unclear. In particular, the velocity vector of the proton beam and its influence on wave growth/damping have not been addressed before. Here we explore the origin and the associated particle dynamics of a kinetic wave event in the solar wind by analyzing measurements from Solar Orbiter and comparing them with theoretical predictions from linear Vlasov theory. We identify the waves as outward-propagating circularly polarized fast magnetosonic/whistler (FM/W) waves. The proton's velocity distribution functions can destabilize FM/W waves. According to linear Vlasov theory, the velocity fluctuations of the core and the beam associated with FM/W waves render the original field-aligned background drift velocity non-field-aligned. This non-field-aligned drift velocity carrying the information of the velocity fluctuations of the core and the beam is responsible for the wave growth/damping. Specifically, for the FM/W waves we analyze, the non-field-aligned fluctuating velocity of the beam population is responsible for the growth of these unstable waves in the presence of a proton beam. In contrast, the core population plays the opposite role, partially suppressing the wave growth. Remarkably, the observed drift velocity vector between the core and the beam is not field aligned during an entire wave period. This result contrasts the traditional expectation that the proton beam is field aligned.

Keywords: Solar wind, Heliosphere