Sazuna/UAT_keywords huggingface dataset:
Intermittency in Interplanetary Coronal Mass Ejections Observed by Parker Solar Probe and Solar Orbiter. Intermittency has been studied extensively in the fast and slow solar winds but to a far lesser extent in interplanetary coronal mass ejections (ICMEs). While ICMEs are often characterized by their relatively smooth, large-scale magnetic flux rope structures, a spectrum of fluctuations is nonetheless present at smaller scales. We have examined kurtosis and its scaling exponents at magnetohydrodynamic inertial scales in 49 ICMEs observed between 0.25 and 1 au by Parker Solar Probe and Solar Orbiter, and compared the results to those obtained for the ICME sheath regions and ambient solar wind intervals. Kurtosis behaves similarly in all intervals studied and presents a universal behavior typical of intermittent time series. The ICMEs displayed a radially invariant level of intermittency, suggesting that they are relatively static, well-developed turbulent environments. In the sheath regions, the level of intermittency increased with distance, indicating that the turbulence is not yet fully developed at small heliocentric distances. In addition to intermittent fluctuations related to turbulence, the sheath regions may possess a population of nonturbulent structures that increase the absolute value of kurtosis.

Keywords: Interplanetary turbulence, Solar wind, Solar coronal mass ejections
The Temperature Anisotropy and Helium Abundance Features of Alfvénic Slow Solar Wind Observed by Parker Solar Probe, Helios, and Wind Missions. Slow solar wind is typically characterized as having low Alfvénicity, but the occasional occurrence of highly Alfvénic slow solar wind (HASSW) raises questions about its source regions and evolution. In this work, we conduct a statistical analysis of temperature anisotropy and helium abundance in HASSW using data from the Parker Solar Probe (PSP) within 0.25 au, Helios between 0.3 au and 1 au, and Wind near 1 au. Our findings reveal that HASSW is prevalent close to the Sun, with PSP observations displaying a distinct "U-shaped" Alfvénicity distribution with respect to increasing solar wind speed, unlike the monotonic increase trend seen in Helios and Wind data. This highlights a previously unreported population of unusually low-speed HASSW, which is found in both sub-Alfvénic and super-Alfvénic regimes. The observed decreasing overlap in temperature anisotropy between HASSW and fast solar wind (FSW) with increasing heliocentric distance suggests different underlying heating processes. Additionally, HASSW exhibits two distinct helium abundance populations, particularly evident in PSP data, with generally higher helium abundance compared to less Alfvénic slow solar wind. Moreover, the decreasing overlap in temperature anisotropy versus helium abundance distributions between HASSW and FSW with decreasing radial distance implies that not all HASSW originates from the same source region as FSW.

Keywords: Slow solar wind, Space plasmas, Interplanetary magnetic fields
Thermonuclear Superburst of MAXI J1752‑457 Observed with NinjaSat and MAXI. An uncatalogued bright X-ray transient was detected with MAXI on 2024 November 9, named MAXI J1752‑457. The NinjaSat X-ray observatory promptly observed the source from November 10 to 18, while the small angular separation from the Sun hampered follow-up campaigns by other X-ray observatories. The MAXI and NinjaSat light curves in the 2–10 keV band showed first and second decaying components at the early and late phases, approximated by exponential functions with e-folding constants of 1.2 ± 0.2 and 14.9 ± 0.9 hr (1σ errors), respectively. A single blackbody model reproduces the X-ray spectrum with a softening trend of its temperature decreasing from 1.8 ± 0.1 keV to 0.59 ± 0.06 keV. Assuming the unknown source distance at 8 kpc, at which the initial X-ray luminosity roughly corresponds to the Eddington limit, the shrinking blackbody radius was estimated at 5–11 km. This X-ray brightening is interpreted as a superburst in a Galactic low-mass X-ray binary, which is powered by thermonuclear burning triggered presumably by carbon ignition close to the outer crust of the neutron star. The transition between two decaying components occurred at 5.5–7.7 hr, corresponding to the thermal timescale of the burning layer. The ignition column density is estimated to be (1.8–2.8) × 1012 g cm‑2.

Keywords: Neutron stars, X-ray binary stars, X-ray sources, X-ray bursters
Modification of the Power Spectral Density of Magnetic Field Fluctuations by Quasi-perpendicular Interplanetary Shocks. We investigate the role of interplanetary (IP) shocks in solar wind turbulence using observations of Solar Orbiter, Parker Solar Probe, and Wind. Employing statistical analysis of quasi-perpendicular fast forward (FF) and fast reverse (FR) shocks, we revisit evolution of magnetic field turbulence across IP shocks. Our previous work indicates that the spectral properties of magnetic fluctuations are statistically conserved across different types of IP shocks, except FR shocks in the transition range of frequencies. We focus on the spectral index in the transition range ( αtr ) using 1 minute sliding windows at 10 s intervals to probe the turbulent dissipation near shocks. We address the influence of key turbulence parameters, particularly cross helicity (σc) and fluctuation amplitude (σB), on  αtr . Our results demonstrate (1) an immediate change in  αtr  across the shock with no evidence for further gradual or asymptotic evolution over extended intervals, and this implies that shock universally serves as a thin boundary separating two turbulence states; (2) the dominant factor forming the steepness of  αtr  is σc, rather than σB; and (3) the statistically shallower downstream  αtr  of FR shocks results from a systematic reduction in σc across shocks. These findings suggest that the observed spectral modification is primarily governed by changes in turbulence Alfvénicity, not directly by dissipation processes related to the shock, and can be commonly observed toward extensive heliospheric distances.

Keywords: Interplanetary turbulence, Solar wind, Interplanetary shocks
Cosmology in Extended Parameter Space with DESI Data Release 2 Baryon Acoustic Oscillations: A 2σ+ Detection of Nonzero Neutrino Masses with an Update on Dynamical Dark Energy and Lensing Anomaly. We obtain constraints in a 12 parameter cosmological model using the recent Dark Energy Spectroscopic Instrument Data Release (DR) 2 Baryon Acoustic Oscillations (BAO) data, combined with cosmic microwave background (CMB) power spectra (Planck Public Release, PR, 4) and lensing (Planck PR4 + Atacama Cosmology Telescope DR 6) data, uncalibrated Type Ia supernovae (SNe) data from Pantheon+ and Dark Energy Survey (DES) Year 5 (DESY5) samples, and Weak Lensing (WL; DES Year 1) data. The cosmological model consists of six Λ cold dark matter parameters and additionally, the dynamical dark energy parameters (w0, wa), the sum of neutrino masses (∑mν), the effective number of non-photon radiation species (Neff), the scaling of the lensing amplitude (Alens), and the running of the scalar spectral index (αs). Our major findings are the following: (i) With CMB+BAO+DESY5+WL, we obtain the first 2σ+ detection of a non-zero  ∑mν=0.19−0.18+0.15  eV (95%). Replacing DESY5 with Pantheon+ still yields a ∼1.9σ detection. (ii) The cosmological constant lies at the edge of the 95% contour with CMB+BAO+Pantheon+ but is excluded at 2σ+ with DESY5, leaving evidence for dynamical dark energy data-set dependent and inconclusive. (iii) With CMB+BAO+SNe+WL, Alens = 1 is excluded at &gt;2σ, while it remains consistent with unity without WL data—suggesting that the existence of lensing anomaly with Planck PR4 likelihoods may depend on non-CMB data sets. (iv) The Hubble tension persists at 3.6σ─4.2σ with CMB+BAO+SNe; WL data have minimal impact.

Keywords: Dark energy, Cosmic microwave background radiation, Hubble constant, Type Ia supernovae, Cosmological neutrinos, Gravitational lensing shear, Baryon acoustic oscillations, Neutrino masses
Measuring Scaling Relations: Fitting Technique Matters. Scaling relationships, both integrated and spatially resolved, arise owing to the physical processes that govern galaxy evolution and are frequently measured in both observed and simulated data. However, the accuracy and comparability of these measurements are hindered by various differences between studies such as spatial resolution, sample selection criteria, and fitting technique. In this Letter, we compare variations of standard least-squares techniques to the ridge line method for identifying spatially resolved scaling relations (Σ*‑ΣSFR, Σ*‑Σgas, and Σgas‑ΣSFR) for TNG100 galaxies. We find that using the ridge line technique to fit these scaling relations with a double linear function (in logarithmic space) results in significantly better fits than fitting with ordinary least squares. We further illustrate the utility of the ridge line technique with an investigation into the dependence of resolved star formation main-sequence (rSFMS) measurements on spatial resolution and smoothing scale. Specifically, we find that the slope of the rSFMS at low Σ* is independent (within 2σ) of spatial resolution and smoothing scale. Finally, we discuss the need for a consistent reanalysis of resolved scaling relations in the literature and physically motivate adoption of the ridge line technique over other fitting methods.

Keywords: Galaxy properties, Scaling relations, Star formation, Galaxy evolution, Astronomical simulations
Three Fast-spinning Medium-sized Hilda Asteroids Uncovered by TESS. Hilda asteroids, which orbit in a 3:2 resonance with Jupiter, serve as key indicators of dynamical processes in the early solar system. Their spin rates, an important probe of these mechanisms, can constrain their density and collisional evolution, offering valuable insights into their origin. In this Letter, we report on the identification of three fast-rotating Hilda asteroids with spin periods in the 3.2–3.7 hr range using data from the Transiting Exoplanet Survey Satellite. These rotation periods are significantly shorter than the previous ∼5.0 hr shortest rotation periods obtained from ground-based observations in the ∼10 km size range and are comparable with the ∼3.0 hr breakup limit of Hildas a few kilometers in size, derived from the FOSSIL survey. These fast-rotating asteroids require either considerable cohesion (in the order of a few kPa) or densities ρ ≳1.5 g cm‑3, in contrast to the typically assumed ρ ≲1 g cm‑3, to prevent rotational breakup. C-type asteroids, which are common in the outer main belt, have densities of ρ ≈ 1.5 g cm‑3 and are known to comprise a small but notable fraction of Hildas. The observed occurrence rate of the ≤4 hr rotation periods may be explained by the 10%–15% fraction of C-type asteroids, likely mixed into these populations from the outer main belt during giant planet dynamical interactions in the early solar system.

Keywords: Solar system, Small Solar System bodies
A Heavy-metal Scenario of Ultra-high-energy Cosmic Rays. The mass composition of ultra-high-energy cosmic rays is an open problem in astroparticle physics. It is usually inferred from the depth of the shower maximum (Xmax) of cosmic-ray showers, which is only ambiguously determined by modern hadronic interaction models. We examine a data-driven scenario, in which we consider the expectation value of Xmax as a free parameter. We test the novel hypothesis of whether the cosmic-ray data from the Pierre Auger Observatory can be interpreted in a consistent picture, under the assumption that the mass composition of cosmic rays at the highest energies is dominated by high metallicity, resulting in pure iron nuclei at energies above ≈40 EeV. We investigate the implications on astrophysical observations and hadronic interactions, and we discuss the global consistency of the data assuming this heavy-metal scenario. We conclude that the data from the Pierre Auger Observatory can be interpreted consistently if the expectation values for Xmax from modern hadronic interaction models are shifted to larger values.

Keywords: Nuclear abundances, Cosmic ray showers, Spectral energy distribution, Ultra-high-energy cosmic radiation
A Novel Method of Modeling Extended Emission of Compact Jets: Application to Swift J1727.8‑1613. Flat radio spectra of compact jets launched by both supermassive and stellar-mass black holes (BHs) are explained by an interplay of self-absorbed synchrotron emission up to some distance along the jet and optically thin synchrotron at larger distances. Their spatial structure is usually studied using core shifts, in which the position of the peak (core) of the emission depends on the frequency. Here, we propose a novel and powerful method to fit the spatial dependence of the flux density at a given frequency of the jet and counterjet (when observed), using the theoretical spatial dependencies provided as simple analytical formulae. We apply our method to the spatial structure of the jets in the luminous hard spectral state of the BH X-ray binary Swift J1727.8‑1613. It was the most resolved continuous jet from an X-ray binary ever observed. We find that the observed approaching jet is significantly intrinsically stronger than the receding one, which we attribute to an increase in the emission of both jets with time (observationally confirmed), together with the light travel effect, causing the receding jet to be observed at an earlier epoch than the approaching one. The jets are relatively slow, with a velocity of ∼(0.3–0.4)c. Our findings imply that the magnetic field strength increased with time. Additionally, the magnetic flux is significantly lower than in jets launched by "magnetically arrested disks." Our method is general, and we propose that it be applied to jets launched by both stellar-mass and supermassive BHs.

Keywords: Low-mass x-ray binary stars, X-ray transient sources, Relativistic jets, Radio jets
Solar Surface Magnetic Field Simulation from 2010 to 2024 and Anomalous Southern Poleward Flux Transport in Cycle 24. The solar surface magnetic field is fundamental for modeling the coronal magnetic field, studying the solar dynamo, and predicting solar cycle strength. We perform a continuous simulation of the surface magnetic field from 2010 to 2024, covering solar cycle 24 and the ongoing cycle 25, using the surface flux transport model with assimilated observed active regions (ARs) as the source. The simulation reproduces the evolution of the axial dipole strength, polar field reversal timing, and magnetic butterfly diagram in good agreement with Solar Dynamics Observatory/Helioseismic and Magnetic Imager observations. Notably, these results are achieved without incorporating radial diffusion or cyclic variations in meridional flow speed, suggesting their limited impact. Poleward surges of the following polarity typically dominate throughout the cycle, but in the southern hemisphere during cycle 24, they are limited to a short period from 2011 to 2016. This anomalous pattern arises from intermittent AR emergence, with about 46% of the total unsigned flux contributed by ARs emerging during Carrington rotations 2141–2160 (2013 September–2015 February). These ARs show a strong active longitude at Carrington longitudes 200°‑260° and a weaker one at 80°‑100°. After 2016, poleward migrations of leading-polarity flux become dominant, despite most ARs following Joy's and Hale's laws. This reversal is likely due to prolonged intervals between AR emergences, which allow the leading-polarity flux to distribute across a broad latitude range before cancellation by subsequent ARs. These findings highlight the importance of the temporal interval of AR emergence in driving the flux transport pattern.

Keywords: Solar cycle, Astronomy databases, Solar surface, Solar physics, Solar active regions, Solar magnetic fields
Shock Wave Ram Pressure and Global Evolution of the Cygnus Loop. We assess the diagnostic for shock wave ram pressure,  ρVs2∝I[OIII]VDopp , and apply it to high-resolution multifiber spectra of the Cygnus Loop. We find that, while there are many caveats, and while high-resolution profiles are important for controlling some sources of error, the diagnostic is reliable if one selects positions with simple line profiles that are offset away from zero velocity. The Cygnus Loop shows a range of conditions from ≈400 km s‑1 nonradiative shocks that produce X-rays to ≈100 km s‑1 radiative shocks that produce bright optical emission. We find a range of ram pressures in agreement with previous estimates from [O III] and from X-ray measurements. The ram pressure is also consistent with recent analysis of the evolutionary stage of the Cygnus Loop.

Keywords: Supernova remnants, Shocks, Interstellar medium
The Initial Evolution of SN 1993J: Piston Phase versus Standard Model. The evolution of SN 1993J is unlikely to be self-similar. Spatially resolved very long baseline interferometry observations show that the velocity of the outer rim of the radio emission region breaks at a few hundred days. The reason for this break remains largely unknown. It is argued here that it is due to the transition between an initial piston phase to a later phase, which is described by the standard model. The properties of the reverse shock are quite different for a piston phase as compared to the standard self-similar model. This affects the expected X-ray emission; for example, the reverse shock becomes transparent to X-ray emission much earlier in the piston phase. Furthermore, it is shown that the observed box-like emission line profiles of Hα and other optical lines are consistent with an origin from the transition region between the envelope and the core. It is also pointed out that identifying the observed, simultaneous breaks at ≈3100 days in the radio and X-ray light curves with the reverse shock reaching the core makes it possible to directly relate the mass-loss rate of the progenitor star to observables.

Keywords: Hydrodynamics, Core-collapse supernovae, Non-thermal radiation sources, X-ray sources, Radiative processes, Shocks, Magnetic fields
The Dependence of Dark Matter Halo Properties on the Morphology of Their Central Galaxies from Weak Lensing. Xu &amp; Jing reported a monotonic relationship between the host halo mass Mh and the morphology of massive central galaxies, characterized by the Sérsic index n, at fixed stellar mass, suggesting that morphology could serve as a good secondary proxy for the halo mass. Since their results were derived using the indirect abundance matching method, we further investigate the connection between the halo properties and central galaxy morphology using weak gravitational lensing. We apply galaxy–galaxy lensing to measure the excess surface density around CMASS central galaxies with stellar masses in the range of  11.3&lt;logM*/M⊙&lt;11.7 , using the Hyper Suprime-Cam shear catalog processed through the Fourier_Quad pipeline. By dividing the sample based on n, we confirm a positive correlation between n and Mh, and observe possible evidence of the positive correlation of n and halo concentration. After accounting for color, we find that neither color nor morphology alone can determine the halo mass, suggesting that a combination of both may serve as a better secondary proxy. In comparison to hydrodynamic simulations, we find that TNG300 produces much weaker correlations between Mh and n. Furthermore, using SIMBA simulations with different feedback modes, we find that jet-mode active galactic nuclei feedback might be related to the relationship between the Sérsic index and halo mass.

Keywords: Galaxy quenching, Galaxy dark matter halos, Galaxy structure
The NANOGrav 15 yr Data Set: Search for Gravitational-wave Memory. We present the results of a search for nonlinear gravitational-wave (GW) memory in the NANOGrav 15 yr data set. We find no significant evidence for memory signals in the data set, with a maximum Bayes factor of 3.1 in favor of a model including memory. We therefore place upper limits on the strain of potential GW memory events as a function of sky location and observing epoch. We find upper limits that are not always more constraining than previous NANOGrav results. We show that it is likely due to the increase in common red noise between the 12.5 and 15 yr NANOGrav data sets.

Keywords: Gravitational waves
Delayed Thermal Relaxation of Rapid Cooling Neutron Stars: Nucleon Superfluidity and Nonnucleon Particles. The thermal relaxation time of neutron stars, typically defined by a sudden drop in surface temperature, is usually on the order of 10–100 yr. In this study, we investigate neutron star thermal relaxation by incorporating nucleon superfluidity and nonnucleonic particles, specifically considering hyperons as a representative case. We find that rapidly cooling neutron stars driven by neutron superfluidity and direct Urca processes demonstrate delayed thermal relaxation under specific physical conditions. The former requires that the neutron 3P2 critical temperature is small enough, whereas the latter depends on the presence of a small core that permits direct Urca processes. To explore these scenarios, we propose simple theoretical frameworks to describe these delayed thermal relaxation behaviors and discuss how a recently established enhanced modified Urca rate influences the relaxation time. By confronting the theoretical results with the observation of Cassiopeia A, we can effectively constrain the maximum neutron 3P2 critical temperature.

Keywords: Neutron star cores, High energy astrophysics
Main-oval Auroral Emission from a T6 Brown Dwarf: Observations, Modeling, and Astrometry. From a series of 5 GHz Very Long Baseline Array (VLBA) radio observations taken over a 1 yr span, we present the detection of compact, highly polarized radio emission from the T6 brown dwarf WISE J112254.72+255022.2, compatible with electron cyclotron maser emission. Both the total and polarized lightcurves show variability in correspondence with a rotation period of 1.95 ± 0.03 hr. Comparison with models indicates that the quasi-steady radio emission of this brown dwarf is produced in circumpolar auroral rings, with remarkable similarity to the main-oval auroras in Jupiter. We have detected a large 100% polarized flare in one of the VLBA epochs (2022.82), which may imply the existence of active longitudes in the auroral rings with a nonaxisymmetric beaming cone radiation pattern, similar to the dusk/dawn asymmetries seen in the Jovian radio emissions. We also present a high-precision astrometric analysis of the sky motion of WISE J112254.72+255022.2, resulting in revised values of proper motion and parallax with an improvement in precision of 1 order of magnitude. The common kinematics of WISE J112254.72+255022.2 with its wide companion, the M dwarf LHS 302, is confirmed with submilliarcsecond precision, suggesting that this brown dwarf may have formed by gravitational fragmentation of the outer part of a protostellar disk around LHS 302. The astrometric analysis imposes very tight bounds on the presence of low-mass companions around WISE J112254.72+255022.2, ruling out objects more massive than Saturn. Our results strengthen the analogy between radio-emitting brown dwarfs and the magnetized planets of our solar system.

Keywords: Brown dwarfs, Very long baseline interferometry, Radio astrometry, Aurorae, Radio continuum emission