Sazuna/UAT_keywords huggingface dataset:
Discovery of the Antiglitch in PSR J1835-1106. We report the detection of an antiglitch with a fractional frequency change of Δν/ν = ‑3.46(6) × 10‑9 in the rotation-powered pulsar PSR J1835‑1106 at MJD 55813(9), based on timing observations collected with the Nanshan 26 m and Parkes 64 m radio telescopes from 2000 January to 2022 July. A comparison of the average pulse profiles within ±300 days of the event reveals no significant morphological changes. We also estimate the angular velocity lag between the normal and superfluid components at the time of the glitch, showing that one of the superfluid glitch models is incompatible with PSR J1835‑1106 due to its insufficient spin-down rate and angular velocity lag. The wind braking scenario offers a viable alternative, consistent with the observed spin-down behavior, glitch amplitude, and postglitch recovery. High-cadence, high-sensitivity monitoring of similar events is essential to distinguish between internal (superfluid) and external (wind-related) glitch mechanisms.

Keywords: Neutron stars, Pulsars
The Gravitational-wave Background from Massive Black Holes in the ASTRID Simulation. Recent pulsar timing array (PTA) observations detected nanohertz gravitational waves, likely originating from massive black hole binaries (MBHBs). The detected amplitude is unexpectedly higher than inferred from the electromagnetic measurements. We present new gravitational-wave background (GWB) results from the ASTRID simulation. Its large volume and on-the-fly dynamics for massive black holes (MBHs) provide new insights into the MBHB population, offering a more accurate assessment of its contribution to the observed GWB. ASTRID predicts a GWB from MBHBs of hc = 2.8 × 10‑15, or ∼45% of the observed amplitude at ∼4 nHz with a slope consistent with f‑2/3, and hc = 2.5 × 10‑16 with hc ∝ f‑1.6 at ∼30 nHz. These predictions remain below current PTA constraints but align with empirical models based on the observed MBH mass functions. By comparison, TNG300 with postprocessed MBH dynamics yields a range between 70% and 90% (20% and 30%) of the observed levels at low (high) frequencies. At low frequencies, ASTRID predicts that the bulk of the GWB originates from MBHBs with masses Mtot = 1–3 × 109 M⊙ peaking at z ≈ 0.3, consistent with TNG300. Notably, both simulations predict significant contributions from minor mergers (q &lt; 0.2) by up to ∼40%. By tracing the full merger trees of local MBHs in ASTRID, we show that they generate gravitational waves at ∼10%–80% of the maximum signal assuming no accretion and recent equal-mass mergers. Finally, we demonstrate the importance of on-the-fly MBH dynamics, the lack of which leads to 3–5 times excessive mass growth by merger, and a boost to the GWB prediction from this overestimated mass function, especially at high frequencies.

Keywords: Gravitational waves
A Deep VLA Search for a Persistent Radio Counterpart to the One-off FRB 20250316A. Fast radio burst (FRB) 20250316A, detected by CHIME on 2025 March 16 with a fluence of 1.7 ± 0.1 kJy ms and a dispersion measure of 161.3 ± 0.4 pc cm‑3, ranks among the brightest extragalactic FRBs at ∼40 Mpc. We obtain deep Karl G. Jansky Very Large Array follow-up at 15 GHz on 2025 April 5 and 9 and find no persistent radio source (PRS). Our best image reaches an rms of 2.8 μJy beam‑1, yielding a 3σ upper limit of &lt;8.4 μJy at the FRB position, corresponding to νLν &lt; 2.4 × 1035 erg s‑1. These results represent among the most stringent constraints for a nonrepeating FRB, lying ≳3 orders of magnitude below the νLν of compact PRSs around well-studied repeaters, thereby disfavoring bright magnetar-nebula scenarios and pointing to low-density, weakly magnetized environments. Interpreting our limit through pulsar-/magnetar-wind synchrotron frameworks places joint constraints on ambient density and engine power. If the empirical PRS–rotation-measure trend reported for repeaters extends to one-off sources, our limit implies ∣RM∣ ≲ 30 rad m‑2, consistent with a clean magnetoionic sight line and progenitor channels such as neutron-star mergers or giant flares from older magnetars.

Keywords: Extragalactic radio sources, Radio bursts, Compact objects, Radio continuum emission, Radio transient sources
The Atomic Gas Properties of Green Pea Galaxies: Connections to Lyman Continuum Leakage. We have used the Green Bank Telescope to search for H I 21 cm emission from 30 Green Pea galaxies (GPs) at z ≈ 0.012–0.045, obtaining 7 detections of H I 21 cm emission and 17 upper limits on the H I mass. Including GPs from the literature, we obtain a sample of 60 GPs at z &lt; 0.05, with 19 detections and 41 nondetections of H I 21 cm emission and with stellar masses in the range 106–109 M⊙. We use the line luminosity ratio O32 ≡ [O III]λ5007 + λ4959/[O II]λ3727,3729 as an indicator of Lyman continuum (LyC) leakage and examine the dependence of the H I properties of the 60 GPs on the O32 ratio. We obtain a far higher H I 21 cm detection rate ( ≈53‑13+16 %) for the 32 GPs with O32 &lt; 10 than that ( 7.1‑4.6+9.4 %) for the 28 GPs with O32 &gt; 10. We find statistically significant evidence that the H I mass, the H I-to-stellar mass ratio, and the H I gas depletion timescale of GPs with O32 &gt; 10 are lower than the corresponding values for GPs with O32 &lt; 10. Earlier studies have shown that galaxies with O32 &gt; 10 tend to show significant LyC leakage: our results indicate that this is due to the lack of H I in such galaxies, with most of the H I consumed in the starburst. Our results further suggest that H I 21 cm studies of the galaxies that reionized the Universe at z ≳ 6 are likely to find an anticorrelation between the H I 21 cm and Lyα emission signals, due to the paucity of H I in the strongest LyC and Lyα leakers.

Keywords: Radio spectroscopy, Starburst galaxies, Dwarf galaxies, Galaxies
Gravitational Instability and Fragmentation in Collapsar Disks Supports the Formation of Subsolar Neutron Stars. We perform three-dimensional shearing box hydrodynamical simulations to explore the outcome of gravitational instability in the outer regions of neutrino-cooled disks such as those formed from the collapse of rotating massive stars ("collapsars"). We employ a physical equation of state and optically thin neutrino cooling and assume an electron fraction set by the balance of e± pair-capture reactions. Disks in a marginally stable initial state (Toomre parameter Q ≈ 1) undergo runaway cooling and fragmentation when the dimensionless cooling timescale obeys τcool ≡ tcoolΩ ≲ 10, where Ω is the orbital frequency; these conditions correspond to accretion rates ≳M⊙ s‑1 on the upper end of those achieved by collapsar progenitor stars. Fragmentation leads to the formation of neutron-rich clumps (electron fraction Ye ≲ 0.1) spanning a range of masses ∼0.01–1 M⊙ around the local Jeans value. Most clumps exceed the local Chandrasekhar mass  MCh∝Ye2  and hence will continue to collapse to nuclear densities, forming neutron stars (NSs) with subsolar masses otherwise challenging to create through ordinary stellar core collapse. Even cool disks dominated by α particles (Ye ≃ 0.5) can fragment and collapse into neutron-rich clumps capable of forming subsolar NSs. Although our simulations cannot follow this process directly, if the disk-formed NSs subsequently pair into binaries, the GW chirps from their rapid mergers are potentially detectable by ground-based observatories. The temporal coincidence of such a hierarchical NS merger chain with the collapsar gamma-ray burst and supernova would offer a uniquely spectacular multimessenger "symphony."

Keywords: Neutron stars, Gravitational instability, Gamma-ray bursts, Gravitational wave sources
3D Simulations of Convective Entrainment in Gas Giants: Rotation and Decreasing Luminosity as Barriers to Mixing. Observations from Juno and Cassini suggest that Jupiter and Saturn may possess fuzzy cores—central regions where the abundance of heavy elements varies smoothly with depth. Such gradients pose a longstanding puzzle for models of planetary evolution and formation, which predict that vigorous convection would homogenize the interiors of gas giants within the first ∼106–108 yr of cooling. Previous 3D simulations and analytic predictions for the propagation of a convection zone into a stable region have demonstrated that the rapid rotation of gas giants can significantly slow convective mixing, but not enough to stop it. Another piece of the puzzle is luminosity. Gas giants cool as they age, and with that comes a declining heat flux over time. Recent ideas suggest that when this declining luminosity is combined with rotational effects, convection may stall. We explore this possibility using 3D hydrodynamic simulations that include both rotation and a surface cooling flux that decreases as 1/t. Our results demonstrate that, even without rotation, a declining luminosity can suppress mixing sufficiently to preserve an initial compositional gradient in the deep interior of gas giants. If confirmed by more realistic simulations, this may help to explain the long-term survival of fuzzy cores.

Keywords: Hydrodynamical simulations, Hydrodynamics, Solar system gas giant planets, Planetary cores, Planetary interior
A Supermassive Black Hole in a Diminutive Ultracompact Dwarf Galaxy Discovered with JWST/NIRSpec+IFU. The integral-field unit mode of the Near-Infrared Spectrograph (NIRSpec+IFU) mounted on the James Webb Space Telescope has now enabled kinematic studies of smaller and less massive compact stellar systems in which to search for central massive black holes (BHs) than ever before. We present here the first such detection using NIRSpec+IFU in its highest resolution (R ∼ 2700) mode. We report the detection of a central BH with mass  MBH  = 2.1 ± 1.1 × 106 M⊙ (1σ uncertainties) in UCD736 orbiting within the Virgo galaxy cluster. Schwarzschild modeling of the 1D kinematic profile rules out a zero-mass central BH at the 3σ level; however, two other independent modeling approaches fail to rule out a zero-mass BH at &gt;1σ significance. The presence of such a massive BH strongly argues against a globular cluster origin of this ultracompact dwarf galaxy (UCD), and rather suggests a tidally stripped formation route from a former ≳109 M⊙ dwarf galaxy host. This represents the detection of a BH in the most compact (rh ≍ 15 pc) stellar system to date, with a  MBH  corresponding to ∼8% of the system's stellar mass, roughly in line with previously reported UCD BH detections and comparable to the BH detected in the compact elliptical galaxy NGC4486B.

Keywords: Galaxy clusters, Supermassive black holes, Black holes, Virgo Cluster, Dwarf galaxies, Galactic and extragalactic astronomy, Galaxy kinematics, Ultracompact dwarf galaxies, Star clusters
Stellar Mass–Dispersion Measure Correlations Constrain Baryonic Feedback in Fast Radio Burst Host Galaxies. Low-redshift fast radio bursts (FRBs) enable robust measurements of the host galaxy contribution to the dispersion measure (DM), offering valuable constraints on the circumgalactic medium (CGM) of FRB hosts. We curate a sample of 20 nearby FRBs with low scattering timescales and face-on host galaxies with stellar masses in the range 109 &lt; M*/M⊙ &lt; 1011. We fit the distribution of the host galaxy DM to a quadratic model as a function of stellar mass with a mass-independent scatter and find that the more massive the host, the lower its host DM. We report that this relation has a negative slope of m = ‑97 ± 44 pc cm‑3 dex‑1 in stellar mass. We compare this measurement against similar fits to three subgrid models implemented in the CAMELS suite of simulations from Astrid, IllustrisTNG, and SIMBA, which predict the CGM contribution to this relation, finding disagreement with the fiducial CAMELS-Astrid model, particularly for the most massive hosts (M* &gt; 1010.5 M⊙). More generally, models that attribute a positive correlation between stellar mass and host DM (m &gt; 0) to the CGM are in tension with our measurement unless compensated by fine-tuning of the host interstellar medium contribution as a function of stellar mass, e.g., at the low-mass end. We show that this conclusion is robust to a wide range of assumptions, such as the offset distribution of FRBs from their hosts and the statistics of the cosmic contribution to the DM budget along each sight line. Our results indirectly imply a lower limit on the strength of baryonic feedback in the local Universe (z &lt; 0.2) in isolated ∼L* halos, complementing results from weak-lensing surveys and kSZ observations that target higher halo mass and redshift ranges.

Keywords: Radio transient sources, Interstellar medium, Circumgalactic medium
Which Solar Latitude Follows the Sunspot Cycle Exactly?. The large-scale convection in the Sun known as supergranulation is manifested as a network structure on the solar surface. The network cells have an average lifetime of 24 hr, a size of about 30 Mm, and a lane width of about 6 Mm. We have obtained the lane widths and intensities at different latitudes from the Ca II K spectroheliograms from the 100 yr Kodaikanal archival data. We have then calculated the cross-correlation function of lane widths and intensities with sunspot number at every latitude from 60°N to 60°S. The correlation coefficients of the quantities show an approximate north–south symmetry with broad peaks around ±(11–22)° latitude with values of about 0.8. The results imply that these latitudes follow the sunspot cycle strongly. The maximum correlation for the lane widths occurs (18 ± 2)°N and (20 ± 2)°S with no phase difference. For intensities, this happens at (13 ± 2)°N and (14 ± 2)°S with a phase difference of 1.25–1.5 yr. It is interesting to note that the lane width correlations peak during the solar maximum, whereas the intensity correlations peak 1.25–1.5 yr after the solar maximum. The results generally show that no unique latitude exactly follows the solar cycle for all quantities. The results are important in flux transport on the solar surface and have implications for the quiet Sun UV irradiance variations.

Keywords: Solar cycle, Solar atmosphere
A Dense Dark Matter Core of the Subhalo in the Strong Lensing System JVAS B1938+666. The nature of dark matter remains unknown, motivating the study of fuzzy/wave dark matter (FDM/ψDM) and self-interacting dark matter (SIDM) as alternative frameworks to address small-scale discrepancies in halo profiles inferred from observations. This study presents a nonparametric reconstruction of the mass distribution of the previously found dark subhalo in the strong lensing system JVAS B1938+666. Compared with the standard Navarro–Frenk–White profile, both SIDM and ψDM ( mψ=1.32‑0.31+0.22×10‑22eV ) provide significantly better fits to the resulting density profile. Moreover, the SIDM model is favored over ψDM with a Bayes factor of 14.44. The reconstructed density profile features a characteristic kiloparsec-scale core (rc ≈ 0.5 kpc) with central density  ρc≈2.5×107M⊙kpc‑3 , exhibiting remarkable consistency with the core–halo mass scaling relations observed in Local Group dwarf spheroidals. These findings offer insights that may help address the core–cusp discrepancy in ΛCDM substructure predictions.

Keywords: Dark matter distribution, Dwarf galaxies, Dark matter, Strong gravitational lensing
Energetic Protons in the Inner Heliosphere Exhibit Consistent ∼1 MeV Temperatures. The solar energetic particle (SEP) proton population follows a kappa distribution distinct from the solar wind. This conclusion has been reached based on a method that tests whether there is a kappa distribution behind observed SEP power-law spectra, also estimating thermodynamic properties (density, temperature, and kappa) of the SEP population. Previously, this method was applied to a single SEP event using only measurements from IS⊙IS/HET on board the Parker Solar Probe. In this study, we applied this method to Parker Solar Probe data from 2018 to 2024. A surprising result is that despite both having small local fluctuations, the temperature is almost always close to ∼1 MeV, whereas the density spans several orders of magnitude. To validate this finding, we use an alternative method by directly fitting kappa distributions to measurements over energies ranging from 3 to 50 MeV using both LET and HET. This allows us to include energies sufficiently close to the typical temperature of ∼1 MeV. We also applied both methods to measurements from STEREO-A from 2006 to 2024. The results from both methods with both spacecraft were in agreement that the temperature of the SEP proton population is almost always close to ∼1 MeV.

Keywords: Regression, Solar energetic particles, Solar wind, Interplanetary particle acceleration, Poisson distribution, Maximum likelihood estimation, Interplanetary physics
Parallel and Perpendicular Diffusion of Energetic Particles in the Near-Sun Solar Wind Observed by Parker Solar Probe. We investigate energetic particle diffusion in the inner heliosphere (∼0.06–0.3 au) explored by Parker Solar Probe (PSP). Parallel (κ∥) and perpendicular (κ⊥) diffusion coefficients are calculated using second-order quasi-linear theory (SOQLT) and unified nonlinear transport theory, respectively. PSP's in situ measurements of magnetic turbulence spectra, including sub-Alfvénic solar wind, are decomposed into parallel and perpendicular wavenumber spectra via a composite two-component turbulence model. These spectra are then used to compute κ∥ and κ⊥ across energies ranging from sub-GeV to GeV. Our results reveal a strong energy and radial distance dependence in κ∥. While κ⊥remains much smaller, it can rise accordingly in regions with relatively high turbulence levels δB/B0. To validate our results, we estimate κ∥ using an upstream time-intensity profile of a solar energetic particle event observed by the PSP and compare it with theoretical values from different diffusion models. Our results suggest that the SOQLT-calculated parallel diffusion generally shows better agreement with solar energetic particle intensity-derived estimates than the classic quasi-linear theory model. This indicates that the SOQLT framework, which incorporates resonance broadening and nonlinear corrections and does not require the introduction of an ad hoc pitch-angle cutoff, may provide a more physically motivated description of energetic particle diffusion near the Sun.

Keywords: Interplanetary turbulence, Solar wind, Solar energetic particles
The Mid-infrared-emitting Jet in the Black Hole V404 Cygni in Quiescence. Observations of some quiescent black hole X-ray binaries have revealed an excess of mid-infrared (MIR) emission above that expected from their donor stars. In one system, V404 Cygni, this excess has been variously suggested to arise from the accretion disk, circumbinary material, or a compact relativistic jet. Here we present simultaneous James Webb Space Telescope (JWST), Atacama Large Millimeter/submillimeter Array, and complementary multiwavelength observations undertaken to resolve this uncertainty. We observed large-amplitude 21 μm variability on short timescales with JWST, particularly a dramatic flare, which swiftly rose to ≍2.4 mJy, over 10 times the lowest observed MIR flux density. Similar variability was simultaneously observed from radio to X-ray wavelengths with other facilities throughout the campaign. This variability and the flat radio/millimeter/MIR spectral index (α = 0.04 ± 0.01) suggest that the MIR excess at and longward of 21 μm in V404 Cyg does not arise from the accretion disk or circumbinary material. Instead, the emission at 21 μm is dominated by synchrotron radiation from a jet, which persists into quiescence. This result reinforces the ubiquity of the disk─jet connection in accreting black holes across a range of masses and accretion rates.

Keywords: Low-mass x-ray binary stars, Relativistic jets, Accretion, Stellar mass black holes
Brown Dwarf Formation through Gravitational Collapse: Insights from 3D Numerical Simulations. The formation mechanism of brown dwarfs (BDs), whether akin to stars or ejected planetary-mass objects, remains debated. We present the first 3D radiation-MHD simulations of magnetized, turbulent, gravitationally unstable low-mass cores (0.05─0.1M⊙) collapsing into proto-BDs. Using the RAMSES code with adaptive mesh refinement, we model the full dynamical range (105─1022 cm−3), including radiative transfer (flux limited diffusion) and nonideal MHD (ambipolar diffusion). Our simulations self-consistently follow the isothermal collapse, first hydrostatic core formation, H2 dissociation, and BD birth. The resulting BDs have initial radii ≍0.75 R⊙ and masses ≍0.8 MJup, growing via accretion as we follow the early evolution of the object. Crucially, we find that BDs may form similarly to low-mass stars but with a prolonged first-core phase, supporting a starlike formation scenario.

Keywords: Brown dwarfs, Radiative magnetohydrodynamics, Stellar jets, Star formation, Low mass stars, Protostars
Effect of Galactic Chemical Evolution on Exoplanet Properties. We couple a simplified model for galactic chemical evolution with software that models the condensation of dust in protoplanetary disks and software that models the interior structure of planets, in order to estimate the effects that galactic chemical evolution has on the properties of planets as they form over time. We find that the early abundances of elements formed from the evolution and death of high-mass stars (such as oxygen, silicon, and magnesium) yields planets with larger mantles and smaller cores. The later addition of elements produced in low-mass stars (such as iron and nickel) causes the planet cores to become relatively larger. The result is planets that orbit older stars are less dense than planets orbiting younger stars. These results are broadly consistent with recent observations of planet properties from stars of varying ages.

Keywords: Exoplanet structure, Exoplanet formation, Chemical abundances, Galaxy chemical evolution
JWST Detection of Hydrocarbon Ices and Methane Gas on Makemake. JWST/NIRSpec observations of Makemake reveal a chemically complex surface and evidence of gaseous CH4. Our spectral modeling indicates a surface composition consisting of CH4, CH3D, and possibly CH3OH, combined with aggregates of C2H2 and C2H6. The presence of C2H4 is also considered given its expected photochemical origin. Both areal and layered configurations reproduce the observed spectrum, with the latter being preferred. This composition confirms earlier hydrocarbon detections and suggests that CH4 photolysis is either ongoing or occurred recently. The detection of CH3D yields a D/H ratio in CH4 ice of (3.98 ± 0.34) × 10‑4, consistent within 2σ with previous estimates. We report the first detection of CH4 fluorescence from Makemake, establishing it as only the second trans-Neptunian object—after Pluto—with confirmed volatile release. We explore two scenarios consistent with the observed CH4 emission, though neither fully reproduces the data: an expanding coma, yielding production rates of (0.2–1.6) × 1028 molecules s‑1 and a rovibrational temperature of ∼35 K, possibly originating from a localized plume, and a gravitationally bound atmosphere, which, if adopted, implies gas kinetic temperatures near 40 K and surface pressures of ∼10 pbar—values consistent with stellar occultation constraints and an atmosphere in equilibrium with surface CH4 ice. Discriminating between these scenarios will require higher spectral resolution and improved signal-to-noise observations. Together, the gas-phase CH4, intermediate D/H ratio between that in water and CH4 in comets, and complex surface composition challenge the traditional view of Makemake as a quiescent, frozen body.

Keywords: Infrared spectroscopy, Ice spectroscopy, Molecular spectroscopy, James Webb Space Telescope, Dwarf planets