Sazuna/UAT_keywords huggingface dataset:
Inside-out Planet Formation. VIII. Onset of Planet Formation and the Transition Disk Phase. Inside-out planet formation (IOPF) is a theory of in situ formation via pebble accretion of close-in Earth to super-Earth mass planets at the pressure maximum associated with the dead zone inner boundary (DZIB), whose location is set initially by thermal ionization of alkali metals at ∼1200 K. With midplane disk temperatures determined by viscous accretional heating, the radial location of the DZIB depends on the accretion rate of the disk. Here, we investigate the ability of pebbles to be trapped at the DZIB as a function of the accretion rate and pebble size. We discuss the conditions that are needed for pebble trapping to become efficient when the accretion rate drops to ∼10−9 M⊙ yr−1 and the resulting DZIB is at ∼0.1 au, which is the expected evolutionary phase of the disk at the onset of IOPF. This provides an important boundary condition for IOPF theory, i.e., the properties of pebbles when planet formation begins. We find for our fiducial model that typical pebble sizes of ∼0.5 mm are needed for pebble trapping to first become efficient at DZIBs near 0.1 au. This model may also provide an explanation for the first emergence of the transition disk phase in protoplanetary disks with accretion rates of ∼10−9 M⊙ yr−1.

Keywords: Astrophysical dust processes, Exoplanet formation, Super Earths, Protoplanetary disks
Improving Precision in Kinematic Weak Lensing with MIRoRS: Model-independent Restoration of Reflection Symmetries. We present a novel, model-independent technique for fitting the cross-component of weak lensing shear, γ×, along a line of sight by combining kinematic and photometric measurements of a single lensed galaxy. Rather than relying on parametric models, we fit for the shear parameter that best transforms the velocity field to restore its underlying symmetries, while also incorporating photometric data for the change in position angle due to shear. We first validate our technique with idealized mock data, exploring the method's response to variations in shear, position angle, inclination, and noise. On this idealized mock data, our combined kinematic and photometric model demonstrates superior performance compared to traditional parametric or kinematic-only approaches. We also explore the effects of asymmetric warps and show that rotation direction can impart a small bias on the fit of γ×. Subsequently, we apply our method to a dataset of 358 halos from the Illustris TNG simulations, achieving a notable reduction in the uncertainty of γ× to 0.039, marking a substantial improvement over previous analysis of the dataset with a parametric model. Finally, we introduce an outlier rejection method based on Moran's I test for spatial autocorrelation. Identifying and filtering out halos with spatially correlated residuals reduces the overall uncertainty to 0.028. Our results underscore the efficacy of combining kinematic and photometric data for weak lensing studies, providing a more precise and targeted measurement of shear along an individual line of sight.

Keywords: Weak gravitational lensing, Galaxy clusters, Model selection, Astrostatistics techniques, Gravitational lensing, Galaxy kinematics, Gravitational lensing shear, Magnetohydrodynamical simulations
Refinements to the Solar Polar Magnetic Flux: Implications from Inversion Methodologies. The magnetic fields in the solar polar region are important to our understanding of the internal dynamo process, the global coronal structure, and the origin of the solar wind. The inference of polar fields based on spectropolarimetric observation is highly model-dependent and can suffer from various systematic effects. Here, we analyze a raster map of the southern polar region taken by the Hinode Spectro-Polarimeter, utilizing the Stokes Inversion based on Response functions code. The inversions provide height-dependent vector magnetic field maps between optical depths  log10τ=−2  and 0. We examine the impacts on the total magnetic flux estimates from adopting: (1) one-versus-two-component atmospheric models via a "filling factor" parameter; and (2) different analysis schemes. At  log10τ=−1.5 , the polar magnetic flux is estimated to be (1.84 ± 0.03) × 1021 Mx and (1.38 ± 0.02) × 1021 Mx under the one- and two-component atmosphere assumptions, respectively. The magnetic flux is approximately constant or increases slightly with height, respectively. We find that the two-component (one-component) configuration is preferred for 58.3% (32.3%) of the pixels. Different initial guesses—including the input atmosphere model and the filling factor—as well as different inversion settings can significantly affect the results, especially for locations with weaker polarization signals. Our work highlights the importance of considering unresolved magnetic structures or stray light. Model degeneracy and the convergence to local minima limit the precision of the polar magnetic flux inference (no better than several tens of percent, in this case). Higher-resolution observations and advanced inversion and disambiguation algorithms may alleviate these limitations.

Keywords: Solar magnetic fields, Solar photosphere
Coevolution of Nuclear Star Clusters and Massive Black Holes: Extreme-mass-ratio Inspirals. We explore extreme-mass-ratio inspirals (EMRIs) in the coevolution of massive black holes (MBHs) and nuclear star clusters (NSCs), which host diverse stellar populations across a wide range of masses. The dynamics are simulated self-consistently with GNC, which we have updated to incorporate gravitational-wave orbital decay, the loss cone of a spinning MBH, and stellar evolution. Over 12 Gyr, we investigate the evolution of the NSC with a mass-growing MBH, as well as the EMRIs of stellar black holes, neutron stars, white dwarfs, brown dwarfs (BDs), and low-mass main-sequence stars (MSs), along with tidal disruption events (TDEs) involving MSs, BDs, and post-MSs. The mass growth of the MBH contributed by TDEs is typically ∼107M⊙, ∼106M⊙, and ∼5 × 104M⊙ for massive, Milky Way─like, and smaller NSCs, respectively. Between 40% and 70% of the stellar mass is lost during stellar evolution, which dominates the mass growth of the MBH if a significant fraction of the lost mass is accreted. The evolution of EMRI rates is generally affected by the cluster's size expansion or contraction, stellar population evolution, MBH mass growth, and the stellar initial mass function. The EMRI rates for compact objects peak at early epochs (≲1 Gyr) and then gradually decline over cosmic time. LISA-band (0.1 mHz) EMRIs involving compact objects around Milky Way─like MBHs tend to have high eccentricities, while those around spinning MBHs preferentially occupy low-inclination (prograde) orbits. In contrast, MS- and BD-EMRIs usually have eccentricity and inclination distributions that are distinct from those of compact objects.

Keywords: Accretion, Supermassive black holes, Galactic center, Gravitation, Tidal disruption, Stellar dynamics, Gravitational wave sources, Galaxy nuclei, Star clusters
Solar Wind Heating near the Sun: A Radial Evolution Approach. Characterizing the plasma state in the near-Sun environment is essential to constrain the mechanisms that heat and accelerate the solar wind. In this study, we use Parker Solar Probe observations from Encounters 1 through 24 to investigate the radial evolution of solar wind plasma and magnetic field properties in this region. Using intervals with high field-of-view (&gt;85%) coverage, we derive the radial profiles of magnetic field strength (∣B∣), proton density (N), bulk speed (V), total proton temperature (T), parallel (T∥) and perpendicular (T⊥) temperatures, temperature anisotropy (T⊥/T∥), plasma beta (β), Alfvén Mach number (MA), and magnetic field fluctuations (δB/B) for sub and super-Alfvénic regions. In super-Alfvénic regions, power laws of ∣B∣, N, V, and T as a function of the heliocentric distance are broadly consistent with previous Helios results at &gt;0.3 au. The radial evolution of the components of the temperature tensor reveals distinct behavior: T⊥decreases monotonically with distance, whereas T∥ exhibits a nonmonotonic trend—decreasing in the sub-Alfvénic region, increasing just beyond the Alfvén surface. We interpret the increase in T∥ as a proxy for proton beam occurrence. We further examine the evolution of magnetic field fluctuations, finding decreasing radial/parallel fluctuations but enhanced tangential/normal/perpendicular fluctuations in the sunward direction. These fluctuations may provide free energy for beam generation and particle heating via wave─particle interactions.

Keywords: Slow solar wind, Heliophysics, The Sun, Solar coronal heating, Solar wind
Graph-based Summary Statistics for Revealing the Stochastic Gravitational-wave Background in Pulsar Timing Arrays. In this work, we propose a graph-based method implemented on the pulsar timing residuals for stochastic gravitational-wave background (SGWB) detection within the nanohertz frequency regime and examining uncertainties of its parameters. We construct a correlation graph with pulsars as its nodes, and analyze the graph-based summary statistics, including structural characteristics of a complex network, for identifying an SGWB in real and synthetic datasets. The effect of the number of pulsars, the observation time span, and the strength of the SGWB on the graph-based feature vector is evaluated. Our results demonstrate that the discriminative summary statistics for common signal detection consist of the average clustering coefficient and the edge weight fluctuation. The SGWB detection conducted after the observation of a common signal and then exclusion of non-Hellings─Downs templates is performed by the second cumulant of edge weight for angular separation thresholds  ζ̄≳40∘ . The lowest detectable value of the SGWB strain amplitude utilizing our graph-based measures at the current pulsar timing array's sensitivity is ASGWB ≳ 1.2 × 10−15. Fisher forecasts confirmed that the uncertainty levels of  log10ASGWB  and spectral index reach 1.5% and 19.5%, respectively, at the 2σ confidence interval. Weak evidence for an SGWB at an ∼2.3σ level is obtained by applying our graph-based method to the NANOGrav 15 yr dataset.

Keywords: Astronomy data analysis, Gravitational waves, Millisecond pulsars
An Accretion-Modulated Internal Shock Model for Long GRBs. We introduce the accretion-modulated internal shock model as a possible framework for explaining the observational properties of long gamma-ray burst (GRB) prompt emission. In this scenario, the envelope of the prompt light curve follows the time-dependent mass-supply history to the central engine, associated with stellar collapse and, where applicable, fallback accretion, whose early time onset can be approximated by  Ṁ∝t0−1/2  and which subsequently may decay as  Ṁ∝t−5/3 , producing a photon count rate with a single fast-rise-exponential-decay (FRED)-like profile. In general, the prompt-emission envelope is regulated by a time-dependent mass supply to the central engine, while internal shocks produce the rapid variability. Since we only aim to introduce this framework here, we focus on the simplest single-FRED shape of the prompt emission profiles, while more complex cases involving multiple episodes and interacting shocks will be explored in forthcoming studies. The model indicates correlations between spectral evolution, FRED-pulse narrowing at high energies, and the mass-supply─controlled envelope. Stochastic Lorentz-factor variations of ejected mass- or rate-driven shells, superimposed on the accretion-modulated envelope, explain the coexistence of smooth global trends and irregular short-timescale features, such as the widths of individual pulses in long GRB light curves, offering diagnostic tools for probing the inner engine activity.

Keywords: Gamma-ray bursts
Diverse Origins of Broad Hα Lines in Heavily Obscured Active Galactic Nuclei Revealed by Multiepoch Spectroscopy. According to the classical active galactic nucleus (AGN) model, broad emission lines originate from the broad-line region (BLR) and are observable only when the attenuation by the dusty torus is small. However, we recently found several heavily obscured (AV &gt; 50 mag) AGNs with broad Hα detections: MCG -3-34-64, UGC 5101, and Mrk 268. To investigate the origin of the observed broad line in these AGNs, we performed multiepoch optical spectroscopic observations to search for flux variability of the broad Hα line. For MCG -3-34-64 and UGC 5101, no significant variability was detected, suggesting that the broad line of these AGNs may arise from sources other than the BLR. Spectral fitting analysis suggests a possible large contribution of ionized outflows to the observed broad component of MCG -3-34-64, while both the outflow and scattering by polar material can explain that of UGC 5101. For Mrk 268, we detected a significant (4.3σ) flux variation of the broad Hα line by using the flux ratio of the Hα complex and the [S II]λλ6716, 6731 doublet, indicating that the broad line originates directly from the BLR. The lack of significant flux variation in the optical continuum implies that the line of sight to the nucleus of Mrk 268 is mildly obscured. Our results demonstrate that the observed broad Hα lines in obscured AGNs likely have multiple origins. Such complexity may introduce additional uncertainties in black hole mass measurements of distant AGNs revealed by, e.g., JWST.

Keywords: Observational astronomy, Supermassive black holes, Seyfert galaxies, Active galactic nuclei, Time domain astronomy
Magnetic Flux Tubes Illuminated by Pulsar Winds. Observations of linear structure connecting pulsars to gamma-ray halos reveal injection of TeV electrons into the interstellar medium (ISM). In some cases, this could be attributed to nearly scattering-free electron transport along large-scale magnetic fields connected to pulsar winds with very slow diffusion across the field lines. In this work we model this process with a magnetic flux tube emerging from the pulsar and attached to the ISM magnetic field. We show that particles in this case have an anisotropic distribution of magnetic pitch angle, such that the overall emission is highly beamed. We apply this model to pulsar tails and filaments, including the extended X-ray and TeV emission associated with PSR J1740+1000 and the misaligned X-ray jet in the Guitar Nebula, to constrain their particle population and magnetic fields.

Keywords: Pulsars, Interstellar medium, Pulsar wind nebulae, Radio interferometry, Gamma-rays
Five-minute Periodicities in the Population of Solar Coronal Brightenings. The population of small-scale brightenings observed across broad regions of the quiet-Sun (QS) corona shows coherent strong periodicities of ≍5 minutes and amplitudes of 20% to 30% of the mean. The periodicity is in the total number of detected brightenings, their creation rate, and their mean lifetime. Atmospheric Imaging Assembly/Solar Dynamics Observatory extreme-ultraviolet data spanning 2 hr shows that the periodicity is significant across broad areas of the QS. The periodicities are strong in the hotter 171 Å (300 s period) and 193 Å (340 s period) channels, but absent from the upper chromospheric 304 Å channel, although periodicities are present in the 304 Å channel in other datasets. The density of brightenings is highest above the photospheric network, with the network concentration becoming increasingly pronounced in the hotter channels. An extended study of 11 QS datasets spanning several years shows that these periodic modulations are common, with most periodicities found in the 4 to 6 minutes range. The time profiles of area and brightness for most brightenings show a gradual, nonimpulsive onset inconsistent with local reconnection, and the brightenings are more likely to appear first in the 171 Å channel, then in the hotter 193 Å channel. This suggests that the most plausible formation mechanism is wave or shock dissipation at or near the transition region, likely connected to spicule activity. This heating is modulated by photospheric p-modes and drives the production of transient brightenings in the QS upper chromosphere, transition region, and low corona.

Keywords: Solar oscillations, Solar physics, Solar coronal heating, Solar coronal transients
Type Iax Supernovae as a Source of Iron-rich Silicate Dust. We model the formation of dust in the ejecta of Type Iax supernovae (SNe), which is a low-luminosity subclass of Type Ia SNe. A nonequilibrium chemical kinetic approach is adopted to trace the synthesis of molecules, molecular clusters, and dust grains in the ejecta of thermonuclear SNe. We find that Type Iax SNe provide conditions conducive to the formation of several O-rich dust species in the ejecta. Particularly, iron-rich silicates of chemical types (FeSiO3), (Fe2SiO4), and (MgFeSiO4) are found to form in abundance, suggesting that the ejecta of low-luminosity thermonuclear SNe can be a site where a large fraction of iron is locked up in dust, unlike other stellar sources. The final mass of dust formed in the ejecta ranges between 10−5 and 10−4 M⊙, where most of the dust forms between 1000 and 2000 day postexplosion. Apart from Fe-rich silicates, Mg-silicates and silicon carbide are also formed in the ejecta of Type Iax SNe. When compared to the dust budget of typical Type Ia SNe, we find that the expected dust-to-ejecta mass ratio is 1 or 2 orders of magnitude larger in Type Iax SNe. We conclude that the ejecta of typical Type Ia SNe form a negligible amount of dust, in agreement with observations, while the low-luminosity subclass Type Iax SNe are potential producers of iron-rich silicates.

Keywords: Circumstellar dust, Astrochemistry, Type Ia supernovae, Dust formation
Patterns of X-Ray and γ-Ray Flares: From Blazar to Magnetar and Sun. Using Gaussian process methods, we analyzed the light curves of three extreme solar X-ray flares observed by the RHESSI satellite. Their variability characteristics were then compared with those of HXMT-HE X-ray burst (XRB; in SGR 1935+2154) associated with fast radio burst (FRB) 200428 and blazar γ-ray giant flares to investigate the origins of these extreme flaring events. The variability patterns of the solar X-ray flares follow the stochastically driven damped simple harmonic oscillator model. The derived timescales tB_steep and tB_flat (corresponding to power spectral density breaks) are in the range of 4─7 and 16─53 s, respectively. The FRB-associated HXMT-HE burst has a Q value near 0.3, matching those of the solar flares that occurred on 2002 July 23 (flare 1) and 2003 November 3 (flare 2). By contrast, blazar γ-ray giant flares show Q &gt; 0.3, similar to the solar flare that occurred on 2014 February 25 (flare 3). We proposed that the critically damped state of the system may be the condition triggering the association between the XRB in SGR 1935+2154 and the FRB. In this scenario, the critical damping Q value of the system is around 0.3, not the theoretical 0.5. The similarity in Q values might imply that the FRB-associated HXMT-HE XRB and solar X-ray flares 1 and 2 share comparable dynamic behavior, while blazar γ-ray flares and solar X-ray flare 3 exhibit another distinct but similar dynamic behavior. Like solar X-ray flares, these extreme flares may all be related to the magnetic reconnection process.

Keywords: Burst astrophysics, Gaussian Processes regression, Time series analysis, Solar x-ray flares
An Active Galaxy Cluster Merger at Cosmic Noon Revealed by JWST Weak Lensing and Multiwavelength Probes. The galaxy cluster XLSSC 122 is a rare system at z = 1.98, hosting surprisingly evolved member galaxies when the Universe was only one-third of its present age. Leveraging deep JWST/NIRCam imaging, we perform a weak-lensing analysis and reconstruct the cluster's mass distribution, finding a mass peak that coincides with both the X-ray peak and the position of the brightest cluster galaxy. Consistent with recent strong-lensing analyses, we obtain a mass estimate of 1.60 ± 0.30 (stat.) ± 0.26 (LSS) × 1014 M⊙ and an implied concentration of c200c = 6.3 ± 0.4, where the uncertainty represents the propagation of the mass error through the adopted concentration─mass relation and excludes intrinsic scatter. Placing our weak-lensing mass map in the context of Chandra X-ray data, MeerKAT radio imaging, Atacama Large Millimeter/submillimeter Array + Atacama Compact Array/Atacama Cosmology Telescope Sunyaev─Zel'dovich (SZ) mapping, and new JWST intracluster light measurements, we identify consistent NE─SW elongation across datasets and a pronounced offset along the same axis between the SZ and mass/X-ray peaks, pointing to significant merger activity. XLSSC 122 thus serves as a JWST pilot study for high-z lensing, demonstrating the telescope's unique ability to map cluster mass distributions at z ∼ 2. The concordance of the multiwavelength analysis here, together with the high concentration relative to ΛCDM expectations, motivates a uniform sample of analogous systems with joint lensing, X-ray, SZ, and radio data to probe cluster assembly at cosmic noon.

Keywords: Weak gravitational lensing, High-redshift galaxy clusters, James Webb Space Telescope, Intracluster medium, Dark matter
Unraveling the Emission Mechanism Powering Long Period Radio Transients from Interacting White Dwarf Binaries via Kinetic Plasma Simulations. Recent observations of long period radio transients, such as GLEAM-X J0704─37 and ILT J1101+5521, have revealed a previously unrecognized population of Galactic radio transient sources associated with white dwarf (WD)─M dwarf (MD) binaries. It is an open question how to produce coherent radio emission in these systems, though a model driven by binary interaction seems likely given the nature and correlation of the emission with the binaries' orbital period. Using kinetic plasma simulations, we demonstrate that the relativistic electron cyclotron maser instability (ECMI) is a viable mechanism for generating radio pulses in WD─MD systems, akin to planetary radio emission, such as that from the Jupiter─Io system. We quantify the relativistic ECMI in the nonlinear regime under conditions relevant for WD radio emission for the first time. Our simulations demonstrate that the ECMI can intrinsically produce partially linearly polarized emission relevant to explaining the observed emission spectra of two Galactic sources, though the precise details will depend on the plasma composition. Our work paves the way for a systematic and fully nonlinear computational modeling of radio emission from interacting WD sources.

Keywords: M dwarf stars, Magnetospheric radio emissions, High energy astrophysics, Galactic radio sources, White dwarf stars, Interacting binary stars, Radio transient sources
Discovery of Multiple Ultra-broad-velocity Molecular Features Associated with the W44 Molecular Cloud. We report the discovery of multiple compact molecular features exhibiting extremely broad velocity widths toward the W44 molecular cloud. Atacama Large Millimeter/submillimeter Array CO J = 3─2 data reveal eight "Petit-Bullets" surrounding the previously known "Bullet." Each Petit-Bullet shows a distinct V-shaped structure in position─velocity space, reminiscent of the Y-shaped morphology of the Bullet, suggesting a common origin. These features are interpreted as the result of high-velocity plunges of compact gravitational objects into dense molecular gas. The spatial and kinematic properties of the Petit-Bullets suggest that the plunging material was not a single object but rather a small cluster of compact bodies. A virial mass of 1.0 × 105 M⊙ inferred from their velocity dispersion is comparable to that of typical globular clusters. Momentum analysis further implies that the main Bullet likely formed by an isolated black hole. These findings provide new evidence for dynamical interactions between halo clusters and disk molecular gas.

Keywords: Interstellar molecules, Supernova remnants, Interstellar medium