Sazuna/UAT_keywords huggingface dataset:
A Measurement of the Largest-scale CMB E-mode Polarization with CLASS. We present measurements of large-scale cosmic microwave background E-mode polarization from the Cosmology Large Angular Scale Surveyor 90 GHz data. Using 115 det-yr of observations collected through 2024 with a variable-delay polarization modulator, we achieved a polarization sensitivity of  82μKarcmin , comparable to Planck at similar frequencies (100 and 143 GHz ). The analysis demonstrates effective mitigation of systematic errors and addresses challenges to large-angular-scale power recovery posed by time-domain filtering in maximum-likelihood map-making. A novel implementation of the pixel-space transfer matrix is introduced, which enables efficient filtering simulations and bias correction in the power spectrum using the quadratic cross-spectrum estimator. Overall, we achieved an unbiased time-domain filtering correction to recover the largest angular scale polarization, with the only power deficit, arising from map-making nonlinearity, being characterized as &lt;3%. Through cross-correlation with Planck, we detected the cosmic reionization at 99.4% significance and measured the reionization optical depth  τ=0.053‑0.019+0.018 , marking the first ground-based attempt at such a measurement. At intermediate angular scales (ℓ &gt; 30), our results, both independently and in cross-correlation with Planck, remain fully consistent with Planck's measurements.

Keywords: Polarimeters, Observational cosmology, Reionization, Cosmic microwave background radiation
The Ultradiffuse Galaxy AGC 242019 with a Negative Metallicity Gradient. The origin of ultradiffuse galaxies (UDGs) remains poorly understood. While the metallicity gradient can offer key clues about the formation mechanisms of UDGs, no such studies have been conducted for field UDGs. We carry out deep MUSE observations of one of the brightest UDGs in the H I—AGC 242019. With various strong emission-line metallicity calibrators, we found that this galaxy shows a negative metallicity gradient:  −0.08±0.02kpc−1/−0.30±0.07Re−1  for N2S2Hα metallicity calibrator and  −0.028±0.006kpc−1/−0.11±0.02Re−1  for O3N2, with average metallicities of 7.6 ± 0.2 and 8.4 ± 0.1, respectively. By comparing with local dwarfs and spirals, we find that AGC 242019 shows a similar metallicity gradient to local dwarfs. This result suggests that AGC 242019 may not be the result of a dwarf that experiences very strong feedback.

Keywords: Galaxy formation, Dwarf galaxies, Galaxy evolution, Galaxy spectroscopy, Metallicity, Low surface brightness galaxies
Correlations between the Crustal Field and the Magnetization Layer's Geometry in the Martian Magnetic Lineation Area. Magnetic lineations on Mars, the remanent magnetization presents east–west-trending banded features, were suggested to be associated with seafloor spreading, dike intrusion, hot spot tracking, mantle convection, discrete source merging, etc. However, a missing link remains between the magnetization layer's geometry, controlled by these processes, and the scale and magnitude of magnetic signals in the satellite orbit. Combining the magnetic field anomalies with the geometry of the crust, we find high correlations between the polarity of the radial field and the crustal thickness in the Martian southern highlands. Forward modeling is also used to reproduce the magnetic lineations based on the magnetization layer with a nonuniform thickness in a 25 km crust. The forward modeling results show lateral variation in the radial field ranges 10∼40 nT per degree, comparable to the result from the spherical harmonic model based on satellite data. Our study suggests the mantle plume upwelling causes the nonuniformity in the magnetization layer, producing strip-shaped magnetic anomalies with periodic polarity reversals.

Keywords: Magnetic anomalies, Mars, Planetary science
Mutual Validation of Data Sets for Analyzing Tilt Angles in Solar Active Regions. The tilt angle of solar active regions (ARs) is crucial for the Babcock–Leighton-type dynamo models in the buildup of the polar field. However, divergent results regarding properties of tilt angles were reported due to their wide scatter, caused by intrinsic solar mechanisms and measurement errors. Here, we mutually validate the magnetogram-based AR tilt angle data set from Wang, Jiang, and Luo with the Debrecen Photoheliographic Data by identifying common data points where both data sets provide comparable tilt angles for the same AR/sunspot. The mutually validated data sets effectively reduce measurement errors, enabling a more accurate analysis of the intrinsic properties of tilt angles. Our mutually validated data sets reveal that the difference between white-light-based and magnetogram-based tilt angles is not significant. Also, the data sets show that an upward revision of average tilt angle ( α¯ ) and a downward revision of the tilt scatter (σα) compared to previous results are necessary, with typical values of about 7° and 16°, respectively. The σα values demonstrate a strong correlation with AR flux and sunspot area, with the dependency functions reevaluated using mutually validated data sets. Furthermore, both  α¯  and the tilt coefficient for the weak cycle 24 are larger than those for cycle 23. This supports the tilt quenching mechanism, which posits an anticorrelation between the cycle-averaged tilt angle and cycle amplitude. Additionally, tilt angle from the mutually validated data set has a weak nonmonotonic relationship with magnetic flux and does not depend on the maximum magnetic field strength of ARs.

Keywords: Solar cycle, Astronomy databases, Sunspots, Solar active regions, Solar magnetic fields
A Statistical Analysis of the Returning Flux Tubes in the Jovian Magnetosphere Based on Juno Observations. The interchange process is an important mechanism for radial transport of plasma in the magnetospheres of the gas giants, namely Jupiter and Saturn. During this process, dense and cold flux tubes that move outwards are replaced by returning flux tubes with warm and tenuous plasma. In this study, we conduct a statistical analysis of the magnetic variation and plasma properties inside the returning flux tubes, based on the observations from magnetometer (MAG) and JADE onboard the Juno spacecraft during its first 45 perijove traverses. We detect the returning flux tubes by recognizing the low-energy electron flux sudden drop, within the range of M &lt; 20 RJ (Jupiter radii). The results have illustrated that the flux tubes with increased magnetic field account for the majority of the events. There is no significant relationship between the events with increased or decreased magnetic field and magnetic latitude, and both types of events are observed mostly near the equatorial plane, while events with depressed magnetic field are more frequently observed at larger distances from Jupiter with longer time duration (or larger flux tube volume). Furthermore, the crossover energy separating decreased low-energy electron flux and increased high-energy electron flux of the returning flux tubes is around several keV, depending on the type of magnetic field variation. These results provide great insight into the mass and magnetic flux transport in the inner Jovian magnetosphere.

Keywords: Planetary magnetospheres, Space plasmas, Jupiter, Plasma physics
Bottom-up Background Simulations of the 2016 COSI Balloon Flight. The Compton Spectrometer and Imager (COSI) is a Compton telescope designed to survey the 0.2–5 MeV sky, consisting of a compact array of cross-strip germanium detectors. As part of its development, in 2016 COSI had a successful 46 day flight on board NASA's Super Pressure Balloon platform. This was a precursor to the COSI Small Explorer (COSI-SMEX) satellite mission that will launch in 2027 into an equatorial low Earth (530 km) orbit. The observation of MeV gamma rays is dominated by background radiation, especially due to the activation of the detector materials induced by cosmic-ray interactions. Thus, background simulation and identification are crucial for the data analysis. Because the COSI-SMEX detectors will be similar to the ones used for the balloon flight, the balloon measurements provide an important tool for testing and cross-checking our background simulations for the upcoming space mission. In this work we perform Monte Carlo simulations of the background emission from the 2016 COSI balloon flight. Including a phenomenological shape correction, we obtain an agreement with the data at the 10%–20% level for energies between 0.1 and 1.6 MeV, and we successfully reproduce most of the activation lines induced by cosmic-ray interactions.

Keywords: High altitude balloons, Gamma-ray telescopes
A Third Star in the HAT-P-7 System and a New Dynamical Pathway to Misaligned Hot Jupiters. The retrograde orbit of the hot Jupiter HAT-P-7b is suggestive of high-eccentricity (high-e) migration caused by dynamical interactions with a massive companion. However, the only other known body in the system is an M dwarf located ∼103 au away, too distant to cause high-e migration without fine-tuning. Here, we present transit-timing and radial-velocity evidence for an additional stellar companion with a semimajor axis of  32‑11+16  au, eccentricity  0.76‑0.26+0.12 , and minimum mass of  0.19‑0.06+0.11  M⊙. We investigate several dynamical routes by which this nearby companion star could have played a role in converting a cold Jupiter into the retrograde hot Jupiter that is observed today. Of particular interest is a novel "eccentricity cascade" mechanism involving both of the companion stars: the outer companion periodically excites the eccentricity of the inner companion through von Zeipel–Lidov–Kozai cycles, and this eccentricity excitation is slowly transferred to the cold Jupiter via successive close encounters, eventually triggering its high-e migration. The plausibility of this mechanism in explaining HAT-P-7b shows that stellar companions traditionally considered too distant to cause hot Jupiter formation might nevertheless be responsible, with the aid of closer-orbiting massive companions. With these developments, HAT-P-7b is one of the few hot Jupiters for which a complete high-e migration history can be simulated based only on observed bodies, rather than invoking bodies that are beneath detection limits or that are no longer in the system.

Keywords: Exoplanet dynamics, Hot Jupiters, Exoplanets
A Generalized Method to Measure the Lorentz Factor from Gamma-Ray Burst Photospheric Emission. The properties of gamma-ray bursts (GRBs) that are inferred from observations depend on the value of the bulk Lorentz factor, Γ. Consequently, accurately estimating it is an important aim. In this work, we present a method of measuring Γ based on observed photospheric emission, which can also be used for highly dissipative flows that may lead to nonthermal spectral shapes. For the method to be applicable, two conditions need to be met: the photon number should be conserved in the later stages of the jet, and the original photon temperature must be inferred from the data. The case of dissipation via subphotospheric shocks is discussed in detail, and we show that the method is particularly efficient when a low-energy spectral break is identified. We demonstrate the capabilities of the method by applying it to two different GRB spectra. From one of the spectra, we obtain a value for Γ with statistical uncertainties of only ∼15%, while for the other spectrum we only obtain an upper limit.

Keywords: Shocks, Gamma-ray bursts, Astronomical methods, Radiative processes
Evidence of Interaction between Ion-scale Waves and Ion Velocity Distributions in the Solar Wind. Recent in situ observations from Parker Solar Probe (PSP) near perihelia reveal ion beams, temperature anisotropies, and kinetic wave activity. These features are likely linked to solar wind heating and acceleration. During PSP Encounter 17 (at 11.4Rs) on 2023 September 26, the PSP/FIELDS instrument detected enhanced ion-scale wave activity associated with deviations from local thermodynamic equilibrium in ion velocity distribution functions (VDFs) observed by the PSP/Solar Probe Analyzers-Ion. Dense beams (secondary populations) were present in the proton VDFs during this wave activity. Using bi-Maxwellian fits to the proton VDFs, we found that the density of the proton beam population increased during the wave activity and, unexpectedly, surpassed the core population at certain intervals. Interestingly, the wave power was reduced during the intervals when the beam population density exceeded the core density. The drift velocity of the beams decreases from 0.9 to 0.7 of the Alfvén speed, and the proton core shows a higher temperature anisotropy (T⊥/T∥ &gt; 2.5) during these intervals. We conclude that the observations during these intervals are consistent with a reconnection event during a heliospheric current sheet crossing. During this event, α-particle parameters (density, velocity, and temperature anisotropy) remained nearly constant. Using linear analysis, we examined how the proton beam drives instability or wave dissipation. Furthermore, we investigated the nonlinear evolution of ion kinetic instabilities using hybrid kinetic simulations. This study provides direct clues about energy transfer between particles and waves in the young solar wind.

Keywords: Interplanetary turbulence, Space plasmas, Solar wind, Plasma astrophysics
Testing the Rossby Paradigm: Weakened Magnetic Braking in Early K-type Stars. There is an intricate relationship between the organization of large-scale magnetic fields by a stellar dynamo and the rate of angular momentum loss due to magnetized stellar winds. An essential ingredient for the operation of a large-scale dynamo is the Coriolis force, which imprints organizing flows on the global convective patterns and inhibits the complete cancellation of bipolar magnetic regions. Consequently, it is natural to expect a rotational threshold for large-scale dynamo action and for the efficient angular momentum loss that it mediates through magnetic braking. Here we present new observational constraints on magnetic braking for an evolutionary sequence of six early K-type stars. To determine the wind braking torque for each of our targets, we combine spectropolarimetric constraints on the large-scale magnetic field, Lyα or X-ray constraints on the mass-loss rate, as well as uniform estimates of the stellar rotation period, mass, and radius. As identified previously from similar observations of hotter stars, we find that the wind braking torque decreases abruptly by more than an order of magnitude at a critical value of the stellar Rossby number. Given that all of the stars in our sample exhibit clear activity cycles, we suggest that weakened magnetic braking may coincide with the operation of a subcritical stellar dynamo.

Keywords: Spectropolarimetry, Stellar magnetic fields, Stellar winds, Stellar rotation, Stellar evolution
Exoplanet Ephemerides Change Observations (ExoEcho). II. Transit Timing Variation Analysis of Brown Dwarfs around Solar-type Stars. Transit timing variation (TTV) is a useful tool for studying the orbital properties of transiting objects. However, few TTV studies have been done on transiting brown dwarfs (BDs) around solar-type stars. Here we study the long-term TTV of a population of close BD companions around solar-type stars using Transiting Exoplanet Survey Satellite data. We use the measured orbital period change rate to constrain the tidal interaction strength between the host star and the BD companion and put limits on the destruction timescale of these transiting BDs. However, we find no statistically significant evidence of orbital decay or expansion in our sample based on the current data. This may be due to either poor observational data or inherently weak tidal dissipation. We then perform simulations to investigate future observation strategies for detecting orbital decay of transiting BDs, which show that NGTS-7A b, TOI-263 b, and LP 261-75 b are the most promising targets in the next few years. Our study demonstrates the potential of TTV technique to probe the formation and evolution of close BD companions around solar-type stars.

Keywords: Exoplanet astronomy, Brown dwarfs, Transit timing variation method
NO and c-C<SUB>3</SUB>H<SUB>2</SUB> in the Outer Galaxy: High Molecular Abundances at R<SUB>GC</SUB> &gt; 13 kpc. Observations of the JKa, Kc = 41,4 → 30,3, 40,4 → 31,3, and 22,0 → 11,1 rotational lines of c-C3H2 and the J = 3/2 → 1/2, Ω = 1/2 transition of NO (X2Πr) were conducted at 2 mm toward 20 Galactic edge clouds with RGC = 10.8–23.5 kpc using the Arizona Radio Observatory 12 m telescope. The c-C3H2 molecule was detected in all 20 objects in the sample, based typically on 2–3 transitions. NO, which exhibits a distinct pattern of lambda doubling and hyperfine splitting in the measured line, was identified in 16 clouds, with distances as far as RGC ∼ 23.5 kpc. While a 3 mm transition of c-C3H2 had been observed before in some of the sample clouds, NO had not previously been detected at such large distances from the Galactic center. These new identifications double the number of molecular clouds known to contain NO. From a radiative transfer analysis, fractional abundances, relative to H2, were determined to be f(c-C3H2) ∼ 0.5–39.8 × 10‑10 and f(NO) ∼ 0.2–21.2 × 10‑8. These abundances are comparable to values observed in molecular clouds in the inner Galaxy (RGC &lt; 12 kpc). The abundances therefore appear to remain relatively constant with increasing galactocentric distance. These results suggest that elemental abundance gradients at RGC ≥ 15 kpc in C, N, and O are not as severe as predicted. They also indicate that gas-phase chemistry in the outer Galaxy is quite robust, strengthening the case for widening the extent of the Galactic habitable zone.

Keywords: Interstellar molecules, Molecular clouds, Astrochemistry, Astrobiology, Galactic abundances, Metallicity, Milky Way Galaxy
Alien Type Ia Supernovae from the Milky Way Merger History and One Possible Candidate: Kepler's Supernova. The Milky Way is a dynamic and evolving system shaped by numerous merger events throughout its history. These mergers bring stars with kinematic and dynamic properties differing from the main stellar population. However, it remains uncertain whether any of the Galactic supernova remnants can be attributed to such a merger origin. In this work, we compare the progenitor of Kepler's supernova to its nearby stars, "alien" stars, and in situ Milky Way stellar populations. We uncover the abnormal kinematics and dynamics of Kepler's supernova and propose that its progenitor may have an extragalactic origin. We call the Type Ia supernovae (SNe Ia) produced by stars accreted into the Milky Way through merger events "alien SNe Ia" since they are cosmic immigrants. We estimate the rate of alien SNe Ia exploded recently using two methods: through galactic chemical evolution, and through a method without considering exact star formation history, introduced for the first time in this paper. We consider the past accretion of a few major satellite galaxies—Kraken, Gaia–Enceladus–Sausage, the Helmi streams, Sequoia, Sagittarius, Wukong/LMS-1, and Cetus—assuming these were dry mergers. The first method yields 1.5 × 10‑5–5.0 × 10‑5 yr‑1, while the second method yields a comparable  3.1‑1.1+1.8×10‑5yr‑1  as the rate estimates for recent alien SNe Ia. These estimates represent lower bounds because we assumed no postmerger star formation.

Keywords: Galaxy chemical evolution, Stellar kinematics, Galaxy structure, Supernova remnants, Galaxy mergers, Supernovae
A High-resolution, Inversion-based Synoptic Study of Solar Granulation. The convectively driven, weakly magnetized regions of the solar photosphere dominate the Sun's surface at any given time, but the temporal variations of these quiet regions of the photosphere throughout the solar cycle are still not well known. To look for cycle-dependent changes in the convective properties of the quiet Sun photosphere, we use high spatial and spectral resolution spectropolarimetric observations obtained by the Hinode Solar Optical Telescope and apply the Spectropolarimetric Inversions Based on Response Functions code to infer physical conditions in the lower solar photosphere. Using a homogeneous set of 49 data sets, all taken at the disk center, we analyze the temperature stratification and the line-of-sight velocities of the granules and intergranules over a period of 15 years. We use a k-means clustering technique applied to the spectral profiles to segment the granules and intergranules based on both intensity and velocity. We also examine the profile bisectors of these different structures and compare them to past analyses. Our results show fairly constant properties over this period with no clear dependence on the solar cycle. We do, however, find a slight increase in the photospheric temperature gradient during the declining phase of the solar cycle. Our findings could have significant implications for understanding the coupling between the quiet Sun atmosphere and the global solar dynamo.

Keywords: Solar cycle, Solar atmosphere, Spectropolarimetry, Solar photosphere, Quiet sun, Solar granules
Finding Massive Double-exponential Disk Galaxies with Extended Low Surface Brightness Stellar Disk: An IllustrisTNG Exploration. We study massive disk galaxies (stellar mass &gt; = 1011M⊙) at z = 0 from IllustrisTNG simulation to detect galaxies that contain two exponential stellar disks—a central high surface brightness (HSB) disk surrounded by an extended low surface brightness (LSB) envelope. This is motivated by the observation of several giant LSB galaxies (Malin 1, UGC 1378, UGC 1382 etc), reported in the literature, showing such complex morphology. Studying such systems can help us to understand the mass assembly process and growth of stellar disks in massive galaxies, and thus can shed light on massive galaxy formation and evolution scenarios. We use the high-resolution IllustrisTNG50 data and perform Sérsic plus exponential profile modeling on the idealized, synthetic Sloan Digital Sky Survey g- and r-band images of the massive disk galaxies using GALFIT. We identify seven disk galaxies (12% of the parent sample of disk galaxies) that are best represented by a central Sérsic plus a central HSB disk surrounded by an extended LSB disk. The radial scale lengths of the LSB disk lie in the range of ∼9.7–31.7 kpc, in agreement with that found in the literature. We study the star formation properties of these simulated double-disk galaxies to understand the distribution of these from blue star-forming to red-quenched region. Some of these double-disk galaxies display a characteristic minima in their (g ‑ r) color radial profiles. The double-disk galaxies are found to lie within ∼1.5σ region of the Baryonic Tully–Fisher relation from observation.

Keywords: Galaxy formation, Giant galaxies, Galaxy disks, Galaxies, Low surface brightness galaxies