Sazuna/UAT_keywords huggingface dataset:
Revealing the Accretion Flow in M87*: Insights from Faraday Rotation. The Faraday rotation measure (RM) is a commonly used tool to trace electron number density and magnetic fields in hot accretion flows, particularly in low-luminosity accreting supermassive black holes. We focus on the nuclear region of M87, which was observed at 230 GHz (1.3 mm) by the Event Horizon Telescope in 2019. It remains unclear whether this emission originates from the accretion flow, the jet base, or both. To probe the presence of an accretion flow, we explore the scenario where the linearly polarized emission from the counter jet, visible at 43 GHz (7 mm), is Faraday-rotated by the accretion flow. We calculate theoretical predictions for counter-jet polarization using analytical and numerical models. In all cases, we find a Faraday-thick flow at 43 GHz (7 mm), with RM ∼ 106 rad m‑2, and a polarization angle that follows a linear relationship with wavelength squared, consistent with external Faraday rotation. The more realistic model, which includes turbulence and magnetic field fluctuations, predicts that the polarization pattern should be time-dependent, and that the counter-jet emission is depolarized due to Faraday depth fluctuations across the accretion flow. Despite the Faraday thick regime and strong depolarization, the linear relationship persists, enabling us to constrain the flow's physical properties. Comparing the counter-jet and forward-jet linear polarization states should enable detection of M87's accretion flow and provide lower limits on electron density, magnetic field strength, and mass accretion rate.

Keywords: Accretion, Low-luminosity active galactic nuclei
Unraveling the Origins of Gamma-Ray Burst X-Ray Plateaus through a Study of X-Ray Flares. The X-ray light curves of gamma-ray bursts (GRBs) display complex features, including plateaus and flares, that challenge theoretical models. Here, we study the properties of flares that are observed in the early afterglow phase (up to a few thousand seconds). We split the sample into two groups: bursts with and without an X-ray plateau. We find that the distributions of flare properties are similar in each group; specifically, the peak time (tpk) of the flares and the ratio of the flare width to the flare peak time (w/tpk), which is found to be ≍1, regardless of the presence of a plateau. We discuss these results in view of the different theoretical models aimed at explaining the origin of the plateau. These results are difficult to explain by viewing angle effects or late-time energy injection, but do not contradict the idea that GRBs with X-ray plateaus have a low Lorentz factor, on the order of tens. For these GRBs, the dissipation processes that produce the flares naturally occur at smaller radii compared to GRBs with higher Lorentz factors, while the flares maintain a similar behavior. Our results therefore provide independent support for the idea that many GRBs have a Lorentz factor of a few tens rather than a few hundreds.

Keywords: Gamma-ray bursts, Light curves, Relativistic jets, Astronomy data analysis, Non-thermal radiation sources
JWST/MIRI Observations of Newly Formed Dust in the Cold, Dense Shell of the Type IIn SN 2005ip. Dust from core-collapse supernovae (CCSNe), specifically Type IIP supernovae (SNe IIP), has been suggested to be a significant source of the dust observed in high-redshift galaxies. CCSNe eject large amounts of newly formed heavy elements, which can condense into dust grains in the cooling ejecta. However, infrared (IR) observations of typical CCSNe generally measure dust masses that are too small to account for the dust production needed at high redshifts. Type IIn SNe (SNe IIn), classified by their dense circumstellar medium, are also known to exhibit strong IR emission from warm dust, but the dust origin and heating mechanism have generally remained unconstrained because of limited observational capabilities in the mid-IR (MIR). Here, we present a JWST/MIRI Medium Resolution Spectrograph spectrum of the SN IIn SN 2005ip nearly 17 yr post-explosion. The SN IIn SN 2005ip is one of the longest-lasting and most well-studied SNe observed to date. Combined with a Spitzer MIR spectrum of SN 2005ip obtained in 2008, this data set provides a rare 15 yr baseline, allowing for a unique investigation of the evolution of dust. The JWST spectrum shows the emergence of an optically thin silicate dust component (≳0.08 M⊙) that is either not present or more compact/optically thick in the earlier Spitzer spectrum. Our analysis shows that this dust is likely newly formed in the cold, dense shell (CDS), between the forward and reverse shocks, and was not preexisting at the time of the explosion. There is also a smaller mass of carbonaceous dust (≳0.005 M⊙) in the ejecta. These observations provide new insights into the role of SN dust production, particularly within the CDS, and its potential contribution to the rapid dust enrichment of the early Universe.

Keywords: Dust physics, Dust composition, Core-collapse supernovae, Type II supernovae, Dust formation, Astrophysical dust processes, Infrared astronomy, James Webb Space Telescope, Infrared observatories, Dust shells, Circumstellar dust, Supernovae
Differentiable Modeling of Planet and Substellar Atmosphere: High-resolution Emission, Transmission, and Reflection Spectroscopy with ExoJAX2. Modeling based on differentiable programming holds great promise for astronomy, enabling advanced techniques such as gradient-based posterior sampling and optimization. This paradigm motivated us to develop ExoJAX, the first auto-differentiable spectrum model of exoplanets and brown dwarfs. ExoJAX directly calculates cross-sections as functions of temperature and pressure to minimize interpolation errors in high-dispersion spectra, although initial work focused on narrowband emission spectroscopy. Here, we introduce a fast, memory-efficient opacity algorithm and differentiable radiative transfer for emission, transmission, and reflection spectroscopy. In the era of data-rich JWST observations, retrieval analyses are often forced to bin high-resolution spectra due to computational bottlenecks. The new algorithm efficiently handles native-resolution data, preserving the full information content and dynamic range. The advances proposed in this paper enable broader applications, demonstrated by retrievals of GL 229B's high-dispersion emission, WASP-39 b's JWST mid-resolution transmission at original resolution (R ∼ 2700), and Jupiter's reflection spectrum. We derive a C/O ratio for GL 229B consistent with its host star, constrain WASP-39 b's radial velocity from molecular line structures, and infer Jupiter's metallicity in line with previous estimates.

Keywords: High resolution spectroscopy, Brown dwarfs, Exoplanet atmospheres, Markov chain Monte Carlo
Primordial Non-Gaussianity Systematics from Redshift Mismatch with SPHEREx. The ability to differentiate between different models of inflation through the imprint of primordial non-Gaussianity (PNG) requires stringent constraints on the local PNG parameter  fNLloc . Upcoming data from the large-scale structure surveys like Euclid, Vera C. Rubin Observatory, and the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx) will be instrumental in advancing our understanding of the inflationary epoch. In this context, we present forecasts on PNG with tomographic angular power spectra derived from simulations of SPHEREx. We put forward the effects of redshift bin mismatch of galaxies as a significant source of systematic uncertainty in the estimation of both  fNLloc  and galaxy linear halo bias. We simulate 500 SPHEREx-like galaxy density fields and divide the galaxies into redshift bins assuming Gaussian photometric redshift errors. We show that the misclassification of galaxies in redshift bins can result in strong apparent tensions on  fNLloc  up to ∼3–6σ and up to ∼9–12σ on galaxy bias. To address this, we propose a scattering matrix formalism that mitigates bin mismatch of galaxies and enables unbiased estimation of cosmological parameters from tomographic angular clustering measurements.

Keywords: Maximum likelihood estimation, Cosmological models, Cosmic inflation, Large-scale structure of the universe
Implementing Continuous All-sky Monitoring with the OVRO-LWA to Identify Prompt and Precursor Counterparts of Gravitational Wave Events. A number of theoretical studies have proposed a prompt or precursor low-frequency radio counterpart to gravitational wave events detected by LIGO and Virgo. Detection of such events would offer a new window on the immediate environment of the merger and provide an avenue to rapid localization. However, identifying fast transients in real-time in localization regions spanning hundreds to thousands of square degrees presents severe technical challenges. To address these challenges, we present a novel technique embodied in the Time Machine, a system featuring a two-stage voltage buffer and subsequent processing pipeline designed for the Long Wavelength Array at the Owens Valley Radio Observatory. This array is developed to instantaneously image the entire viewable sky. We detail the system's buffer structure that allows data collection from several minutes before a trigger event, up to 30 minutes after an event. The processing of this voltage data involves beamforming and searching the full 90th-percentile localization region above the horizon with ms-time resolution and the ability to detect events with ∼100 Jy ms (7σ) fluence within the 55–85 MHz band. Furthermore, we incorporate an offline cross-correlation pipeline to improve positional accuracy of identified transients to within subarcminute levels. We present a full overview of the system design and initial testing results.

Keywords: LIGO, Neutron stars, Radio astronomy, Astronomical instrumentation
Quasiperiodic Slow-propagating Extreme-ultraviolet "Wave" Trains after the Filament Eruption. The eruption of the filament/flux rope generates the coronal perturbations, which further form extreme-ultraviolet (EUV) waves. There are two types of EUV waves, namely, fast-mode magnetosonic waves and slow waves. In this Letter, we first report an event showing the quasiperiodic slow-propagating (QSP) EUV "wave" trains during an M6.4-class flare (SOL2023-02-25T18:40), using multiple observations from Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA), Chinese Hα Solar Explorer (CHASE)/Hα Imaging Spectrograph (HIS), Advanced Space-based Solar Observatory (ASO-S)/Full-disk vector MagnetoGraph (FMG), SUTRI, and Large Angle and Spectrometric Coronagraph (LASCO)/C2. The QSP "wave" trains occurred as the filament showed a rapid rise. The QSP "wave" trains have the projected speeds of 50–130 km s‑1 on the plane of the sky, which is slower than the fast-mode magnetosonic speed in the solar corona. And the calculated period of the QSP wave trains is 117.9 s, which is in good agreement with the associated flare quasiperiodic pulsation (140.3 s). The QSP wave trains could be observed during the entire impulsive phase of the flare and lasted about 30 minutes in the field of view (FOV) of SDO/AIA. About 30 minutes later, they appeared in the FOV of LASCO/C2 and propagated to the northwest. We suggest that the QSP wave trains are probably apparent waves that are caused by the successive stretching of the inclined field lines overlying the eruptive filament. The periodic pattern of the QSP wave trains may be related to the intermittent energy release during the flare.

Keywords: Solar coronal waves, Solar flares, Solar magnetic reconnection, Solar filaments
The Case for Edge-on Binaries: An Avenue Toward Comparative Exoplanet Demographics. Most Sun-like and higher-mass stars reside in systems that include one or more gravitationally bound stellar companions. These systems offer an important probe of planet formation in the most common stellar systems, while also providing key insights into how gravitational perturbations and irradiation differences from a companion star alter the outcomes of planet formation. Recent dynamical clues have begun to emerge that reveal systematic, nonrandom structure in the configurations of many planet-hosting binary systems: in close- to moderate-separation (s &lt; 800 au) binary star systems, the orbits of exoplanets around individual stellar components are preferentially aligned with the orbital plane of their host stellar binary. In this work, we flip this narrative and search for nearby, edge-on binary star systems that, due to this preferential alignment, are top candidates for radial velocity and transiting exoplanet searches. We present a sample of 591 moderate-separation, relatively bright (G &lt; 14) Gaia-resolved binary star systems in likely near-edge-on configurations. Using a simulated population of exoplanets drawn from transit survey occurrence rate constraints, we provide an overview of the expected planet yields from a targeted search in these systems. We describe the opportunities for comparative exoplanet demographics in the case that both stars can be inferred to host edge-on planetary systems—a configuration toward which the presented sample may be biased, given recent observations of orbit–orbit alignment in exoplanet-hosting binary systems.

Keywords: Binary stars, Exoplanets
A Coherent Radio Burst from an X-Ray Neutron Star in the Carina Nebula. The neutron star zoo comprises several subpopulations that range from energetic magnetars and thermally emitting X-ray neutron stars to radio-emitting pulsars. Despite studies over the last five decades, it has been challenging to obtain a clear physical link between the various populations of neutron stars, vital to constrain their formation and evolutionary pathways. Here we report the detection of a burst of coherent radio emission from a known radio-quiet, thermally emitting neutron star 2XMM J104608.7‑594306 in the Carina Nebula. The burst has a distinctive sharp rise followed by a decay made up of multiple components, which is unlike anything seen from other radio-emitting neutron stars. It suggests an episodic event from the neutron star surface, akin to transient radio emission seen from magnetars. The radio burst confirms that the X-ray source is a neutron star and suggests a new link between these apparently radio-quiet X-ray-emitting sources and other transient or persistent radio-emitting neutron stars. It also suggests that a common physical mechanism for emission might operate over a range of magnetic field strengths and neutron star ages. We propose that 2XMM J104608.7‑594306 straddles the boundary between young, energetic neutron stars and their evolved radio-emitting cousins and may bridge these two populations. The detection of such a radio burst also shows that other radio-quiet neutron stars may also emit such sporadic radio emission that has been missed by previous radio surveys and highlights the need for regular monitoring of this unique subpopulation of neutron stars.

Keywords: Neutron stars, Magnetars, X-ray bursts, Radio transient sources
The H<SUB>2</SUB> Glow of a Quiescent Molecular Cloud Observed with JWST. We report JWST MIRI/MRS observations of the H2 S(1) 17.04 μm transition in two regions in the boundary of the Taurus molecular cloud. The two regions, denoted "Edge" (near the relatively sharp boundary of the 13CO J = 1 → 0 emission) and "Peak" (the location of the strongest H2 emission observed with Spitzer), have average intensities of 14.5 and 32.1 MJy sr‑1, respectively. We find small-scale structures of characteristic size 1 0–2 5, corresponding to 140–350 au, with characteristic intensity above the extended background of 10 MJy sr‑1, corresponding to a J = 3 column density of 1.6 × 1017 cm‑2. The most plausible explanation for the observed intensities from this level 845 K above the J = 1 ortho-H2 ground-state level is excitation by collisions with H2 molecules (the hydrogen in this region being predominantly molecular). Two mechanisms, turbulent dissipation and shocks, have been proposed for the heating of localized regions of the interstellar medium (ISM) to temperatures ≃1000 K to explain abundances of and emission from particular molecules. While we cannot determine unique values of density and kinetic temperature, the solutions in best agreement with predictions of shock models are n(H2) = 370 cm‑3 and Tkin = 1000 K. The total H2 column density of the small-scale structures under these conditions is ≃8 × 1017 cm‑2. This first direct detection of significantly heated tiny-scale structures in the quiescent molecular ISM has significant implications for the physical structure of this phase of the ISM and the maintaining of supersonic motions within it.

Keywords: Dense interstellar clouds, Interstellar line emission, Interstellar medium, Diffuse interstellar clouds
Dual Directional Expansion of Classical Cepheids in the Small Magellanic Cloud Revealed by Gaia Data Release 3. We present the three-dimensional kinematics of classical Cepheids (CCs) in the Small Magellanic Cloud (SMC) using Gaia DR3 data. By crossmatching the CCs obtained from the fourth phase of the Optical Gravitational Lensing Experiment with Gaia DR3, we obtain distances and proper motions (PMs) for 4236 CCs. Among them, radial velocities (RVs) are available for 91 stars, measured by Gaia, enabling the construction of an accurate relationship between distance and RV. Furthermore, we calculate the internal PMs of the CCs, providing the internal dynamics of the SMC while removing the distance projection effects. The CCs exhibit a northeast–southwest distance gradient, with internal PMs pointing northeast for nearer stars and southwest for more distant stars, indicating a northeast–southwest elongation. The RVs of the CCs show a northwest–southeast gradient, consistent with RVs of other stellar populations, and suggesting that the SMC's northwest–southeast elongation results from interactions with the Large Magellanic Cloud. The distances and RVs of the CCs are nearly uncorrelated, implying that the two elongations arise from distinct causes.

Keywords: Galaxy interactions, Small Magellanic Cloud, Cepheid distance, Proper motions, Radial velocity, Gaia
The Stellar Initial Mass Function of Early Dark Matter–free Gas Objects. Among the remarkable strides made by JWST is the discovery of the earliest star clusters found to date. These have been proposed as early progenitors of globular clusters, which are known to come from the early stages of star formation in the Universe. This is an exciting development in modern astronomy, as it offers an opportunity to connect theoretical models of globular cluster formation to actual observations of these high-redshift structures. In this work, we aim to develop observational signatures of a star cluster formation route known as supersonically induced gas objects, which are dark matter–less gas clouds in the early Universe proposed as a potential origin of some globular clusters. For the first time, we follow the star formation process of these early Universe objects using high-resolution hydrodynamical simulations, including mechanical feedback. Our results suggest that the first dark matter–less star clusters are top heavy, meaning that they have a flatter initial mass function slope compared to very young low-metallicity star clusters in the local Universe, and they also have extremely high stellar mass surface densities compared to their local counterparts.

Keywords: Globular star clusters, Galactic and extragalactic astronomy, Primordial galaxies, Star formation, High-redshift galaxies
ADF22-WEB: Detection of a Molecular Gas Reservoir in a Massive Quiescent Galaxy Located in a z ≈ 3 Protocluster Core. We present a study of the molecular gas reservoirs and dust contents in three quiescent galaxies (QGs) located in the core of the z = 3.09 SSA22 protocluster. Using the Atacama Large Millimeter/submillimeter Array, we detect CO(3–2) emission in one galaxy, ADF22-QG1, marking the first direct detection of molecular gas in a QG from the early Universe. The detected galaxy, ADF22-QG1, has a molecular gas mass of log /M⊙ = 10.26 ± 0.07 assuming a CO-to-H2 conversion factor αCO = 4.4 (log /M⊙ = 9.52 ± 0.07 for αCO = 0.8), corresponding to a gas mass fraction of fgas ≈ 14% (2.5%). The gas-to-dust ratio δgdr ≳ 320 (δgdr ≳ 60) for αCO = 4.4 (αCO = 0.8) is also derived for the first time for a QG at the epoch. For the other two galaxies, ADF22-QG2 and ADF22-QG3, nondetections of CO(3–2) emission provide upper limits, fgas ≈ 17% (3.1%) and fgas ≈ 13% (2.4%), respectively. The inferred gas-consumption history of ADF22-QG1, based on its star formation history, suggests that (i) dusty star-forming galaxies at z = 4–6 are plausible progenitors, and (ii) the cessation of gas accretion from cosmic web filaments plays an important role in their evolution to quenched systems. Furthermore, the presence of a detectable molecular gas reservoir in ADF22-QG1 indicates that additional mechanisms, such as morphological quenching, may be required to fully explain its quiescent nature.

Keywords: Post-starburst galaxies
Angle-dependent in Situ Fast Flavor Transformations in Post-neutron-star-merger Disks. The remnant black hole─accretion disk system resulting from binary neutron star mergers has proven to be a promising site for synthesizing the heaviest elements via rapid neutron capture (r-process). A critical factor in determining the full r-process pattern in these environments is the neutron richness of the ejecta, which is strongly influenced by neutrino interactions. One key ingredient shaping these interactions is fast neutrino flavor conversions (FFCs), which arise due to angular crossings in neutrino distributions and occur on nanosecond timescales. We present the first three-dimensional in situ angle-dependent modeling of FFCs in postmerger disks, implemented within general relativistic magnetohydrodynamics with Monte Carlo neutrino transport. Our results reveal that, by suppressing electron neutrinos, FFCs more efficiently cool the disk and weaken the early thermally driven wind. Less releptonization due to electron neutrino absorption makes this cooler wind more neutron rich, producing a more robust r-process at higher latitudes of the outflow. This study underscores the necessity of incorporating FFCs in realistic simulations.

Keywords: Neutrino oscillations, Nucleosynthesis, Compact objects