Sazuna/UAT_keywords huggingface dataset:
Investigating Possible Stellar Coronal Mass Ejections in M-type Dwarfs Using the CARMENES Data Release 1 Spectra. Stellar coronal mass ejections (CMEs) have significant impacts on surrounding exoplanets and stellar evolution. For M-type dwarf stars, hosting close-in habitable zones, frequent and intense stellar CMEs may render their potentially habitable planets uninhabitable. In this study, we used the CARMENES DR 1 spectra to investigate potential stellar CMEs in M-type dwarfs by analyzing asymmetric features of the Hα profiles. Through a comprehensive visual inspection, we identified 61 distinct asymmetric features in the Hα line profiles across 33 M-type dwarfs. These asymmetries were associated with increased emissions in several chromospheric activity lines, indicating likely connections to flare events. The velocities of these features remain below the escape velocities of the investigated stars, except for one case where an asymmetric feature's maximum velocity approaches the star's escape velocity. While stellar CMEs are one potential explanation, the observed features are also consistent with other flare-related plasma motions. The estimated moving plasma masses range from 1015 to 1019 g, with corresponding kinetic energies of 1029 to 1032 erg. Stars with asymmetric Hα profiles are generally associated with stronger surface-average magnetic field () and higher normalized X-ray luminosity (log LXLbol ). However, we find no significant correlation between the line asymmetry rate and either or log LXLbol .

Keywords: M dwarf stars, Stellar chromospheres, Stellar activity, Optical flares, Stellar coronal mass ejections, Stellar coronae, Magnetic fields
BICEP/Keck. XX. Component-separated Maps of the Polarized Cosmic Microwave Background and Thermal Dust Emission Using Planck and BICEP/Keck Observations through the 2018 Observing Season. We present component-separated polarization maps of the cosmic microwave background (CMB) and Galactic thermal dust emission, derived using data from the BICEP/Keck experiments through the 2018 observing season and Planck. By employing a maximum-likelihood method that utilizes observing matrices, we produce unbiased maps of the CMB and dust signals. We outline the computational challenges and demonstrate an efficient implementation of the component map estimator. We show methods to compute and characterize power spectra of these maps, opening up an alternative way to infer the tensor-to-scalar ratio from our data. We compare the results of this map-based separation method with the baseline BICEP/Keck analysis. Our analysis demonstrates consistency between the two methods, finding an 84% correlation between the pipelines.

Keywords: Cosmology, Cosmic microwave background radiation, Cosmic inflation, Linear regression, Maximum likelihood estimation
Mid-infrared Variability from the Central Point Source as Direct Evidence for Obscured Low-luminosity Nuclear Activity in the Nearby Edge-on Galaxy IC 2207. Reliable identification of ongoing nuclear activity in nearby galaxies is challenging when central regions are heavily obscured, especially for low-luminosity active galactic nuclei (AGN) whose emission can also be contaminated by the host galaxy. Here, we demonstrate that mid-infrared variability from Wide-field Infrared Survey Explorer observations can serve as direct evidence for obscured low-luminosity AGN. We present IC 2207, a nearby edge-on galaxy, as a case study. Despite showing no clear AGN signatures in its optical spectrum and light curves, IC 2207 exhibits stochastic variations in W1 and W2 bands. The "peak-to-valley luminosity difference" ∆νLν parameter, providing a host-independent AGN luminosity constraint, is greater than 1042 erg s−1 in both bands. Mid-infrared image differencing localizes a point source at the galaxy center, showing that IC 2207 has a hidden AGN nucleus. We test common AGN identification criteria. Color variability can shift sources outside the AGN criteria in color─color diagrams. Due to low luminosity, multiband spectral energy distribution fitting and soft X-ray/radio luminosities are insufficient to confirm nuclear activity. However, the Swift-BAT hard X-ray detection provides independent AGN indication. The X-ray spectral analysis reveals a hydrogen column density  NH=1.94−1.50+1.86×1023cm−2 , indicating that the AGN is highly obscured. The estimated Eddington ratio Lbol/LEdd ≍ 0.007 lies near the theoretical transition threshold from standard thin disk to advection-dominated accretion flow, hinting at a special variability mechanism. This case study of IC 2207 implies that long-term mid-infrared variable point sources can serve as direct evidence for obscured low-luminosity nuclear activity in nearby galaxies, complementary to X-ray observations.

Keywords: Supermassive black holes, Galaxy nuclei, Infrared astronomy, Low-luminosity active galactic nuclei, Active galactic nuclei, Time domain astronomy
On the Evolution of Disk-embedded Binaries: Framing Local Models in Global Context. The disks of active galactic nuclei (AGNs) have in recent years been recognized as possible sites for gravitational-wave sources, leading to a series of numerical studies on the evolution of disk-embedded black hole binaries. The majority of these works have been carried out so far using the shearing box, a local Cartesian domain corotating with the binary center-of-mass around the supermassive black hole. The local nature of this framework allows for focusing computational power close to the binary at the expense of detaching the gas flow around the binary from the global dynamics. In this paper, we provide a framework to assess the applicability of the shearing box for studying the long-term evolution of the orbital elements of the embedded binary in viscous hydrodynamic disks. We accomplish this by identifying the conditions under which relevant global timescales are longer than the gas-induced evolution timescale of the embedded binary across various AGN disk models. For black hole masses of interest, we report the existence of radii beyond which the global influence of the disk may be reasonably neglected, supporting the use of the shearing box. More generally, we introduce a systematic approach to link local simulations with the global problem they aim to approximate while providing a way to gauge their accuracy. This will prove to be essential, as we seek to add additional physics, such as magnetic fields and radiative transport, to develop more realistic models for black hole binary mergers and their potential electromagnetic signatures in AGN disks.

Keywords: Accretion, Hydrodynamical simulations, Black holes, Gravitational wave sources, Active galactic nuclei, Astrophysical fluid dynamics
H<inline-formula> <mml:math><mml:msubsup><mml:mrow></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mn>18</mml:mn></mml:mrow></mml:msubsup></mml:math> </inline-formula>O in the Terrestrial Planet-forming Regions of Protoplanetary Disks. Isotopologues play an important role in solar system cosmochemistry studies, revealing details of early planet formation physics and chemistry. Oxygen isotopes, as measured in solar system materials, reveal evidence for both mass-dependent fractionation processes and a mass-independent process commonly attributed to isotope-selective photodissociation of CO in the solar nebula. The sensitivity of JWST's MIRI-MRS enables studies of isotopologues in the terrestrial planet-forming regions around nearby young stars. We report here on a search for H 218 O in 22 disks from the JDISC Survey with evidence for substantial water vapor reservoirs, with the goal of measuring H 216 O/H 218 O ratios, and potentially revealing the predicted enhancement of H 218 O caused by isotope-selective photodissociation. We find marginal detections of H 218 O in six disks, and a more significant detection of H 218 O in the disk around WSB 52. Modeling of the detected H 218 O lines assuming an interstellar medium (ISM) ratio of H 216 O/H 218 O predicts H 218 O features consistent with observations for four of the modeled disks, but stronger H 218 O features than are observed in three of the modeled disks, which includes WSB 52. Therefore, these latter three disks require a higher H 216 O/H 218 O ratio than the ISM in the water-emitting region, in contrast to long-standing theoretical expectations. We suggest that either the H 218 O-rich water has been removed from the emitting region and replaced by H 218 O-poor water formed by reactions with 18O-poor CO, or that the gas-phase water is depleted in 18O via mass-dependent fractionation processes at the water snowline.

Keywords: Isotopic abundances, Molecular spectroscopy, Protoplanetary disks, Planet formation
SN 2023zcu: A Type IIP SN with Early Flash Features. We present a detailed photometric and spectroscopic analysis of the Type IIP supernova (SN) SN 2023zcu, which exploded in the galaxy NGC 2139 (redshift z = 0.006). SN 2023zcu exhibits a well-sampled light curve covering the rise, plateau, and nebular phases. It has an optically thick phase of 100.6 ± 0.6 days with a magnitude drop of ∼1.7 mag in the V band during the transition between the plateau and nebular phases. Weak emission features in the early-time spectra indicate a low-level interaction between circumstellar material and the SN ejecta. The spectral evolution is well sampled and exhibits a prominent P Cygni profile of Hα, a defining characteristic of Type IIP SNe. Signatures of metal-line formation (e.g., Fe II, Ca II near-infrared triplet) are also evident in the spectra as the SN evolves. Spectral modeling with the radiative transfer code TARDIS during the early photospheric phase (8.7─35.5 days since explosion) yields photospheric temperatures decreasing from ∼9000 to ∼6000 K and expansion velocities declining from ∼10,000 to ∼5400 km s−1. A tailored expanding photosphere method fit based on the TARDIS models provides a distance estimate of 27.8 ± 2.0 Mpc. Nebular-phase spectra and bolometric light-curve modeling suggest a progenitor mass in the range 12─15 M⊙. This thorough analysis helps to constrain progenitor properties and explosion parameters, thereby strengthening our understanding of Type IIP SNe.

Keywords: Core-collapse supernovae, Type II supernovae, Astronomical techniques, Photometry, Spectroscopy
Revising the Milky Way Cepheid Calibration: Quantifying and Correcting for Previously Undetected Distance Modulus Errors in the Gaia-based Multiwavelength Period─Luminosity Relations. We examine the multiwavelength period─luminosity─color (PLC) relations for Cepheid variables in the Large and Small Magellanic Clouds and the Milky Way. From first-principles stellar physics, the luminosity of a Cepheid is determined by its radius and surface temperature, yielding a fundamental PLC relation whose observational proxies are the pulsation period and intrinsic color. Using Cepheids in the Magellanic Clouds, we show that the PLC relation recovers the known geometries and line-of-sight tilts of their disks, confirming its ability to detect true distance modulus variations that are achromatic and consistent across all filters. Surprisingly, for Milky Way Cepheids with individually determined reddenings and Hubble Space Telescope and Gaia parallaxes, the residuals from multiwavelength PL fits are also found to be achromatic and identical in sign and amplitude across all passbands, in this case indicating that parallax errors are the dominant source of the scatter. Applying bandpass-averaged corrections to individual Cepheids recovers the theoretically expected wavelength-dependent narrowing of the instability strip and results in revised parallaxes with a median improvement in precision of roughly a factor of 2. In addition, they show no statistically significant correlation with metallicity over the range ─0.2 &lt; [Fe/H] 0 &lt; +0.5 dex. The final extinction-and-reddening-corrected PLC relation yields an rms scatter of ±0.04 mag, corresponding to ∼2% precision in distance per star. The use of a physically grounded PLC will provide a more robust foundation for the Cepheid-based extragalactic distance scale and the determination of the Hubble constant.

Keywords: Cepheid distance
REBELS─MOSFIRE: Weak C III] Emission Is Typical among Extremely UV-bright, Massive Galaxies at z ∼ 7. We present Keck/MOSFIRE H-band spectroscopic measurements covering the [C III] λ1907, C III] λ1909 doublet for a sample of eight z ∼ 7 spectroscopically confirmed star-forming galaxies drawn from the Reionization Era Bright Emission Line Survey (REBELS). This REBELS─MOSFIRE sample is notable for its bright median UV luminosity ( MUV= −22.5 AB) and large median stellar mass ( logM*/M⊙=9.2 ). Although three sources show tentative evidence of a C III] detection, we obtain no confident detections for any of the eight REBELS─MOSFIRE sources. The median [C III] λ1907+C III] λ1909 3σ upper limit in equivalent width (EW) for the REBELS─MOSFIRE sample is 6.5 Å, and a stack of their H-band MOSFIRE spectra yields a nondetection with an associated 3σ upper limit of 2.6 Å. These upper limits fall significantly below the C III] EW measured in a composite spectrum of representative z ∼ 7 star-forming galaxies, as well as those measured for notable early star-forming galaxies such as GN-z11, GHZ2, GS-z12, and RXCJ2248-ID. The lack of strong C III] emission can be understood within the context of the stellar populations of the REBELS galaxies, as well as the ionization conditions and gas-phase metallicity implied by rest-frame optical spectroscopic properties ([O III]+Hβ EWs, and [O III] λ5007/[O II] λ3727 and [Ne III] λ3869/[O II] λ3727 line ratios). The REBELS─MOSFIRE sample represents the higher-mass, higher-metallicity, lower-excitation tail of the z ∼ 7 galaxy population, whose ionizing properties must be fully characterized to constrain the role of star-forming galaxies during cosmic reionization.

Keywords: Emission line galaxies, Galaxy formation, High-redshift galaxies, Interstellar medium
Complete Sampling of the uv Plane with Realistic Radio Arrays: Introducing the RULES Algorithm, with Application to 21 cm Foreground Wedge Removal. We introduce the Radio-array uv Layout Engineering Strategy (RULES), an algorithm for designing radio arrays that achieve complete coverage of the uv plane. Coverage is defined as, at minimum, regular sampling at half the observing wavelength (λ) along the u- and v-axes within a specified range of baseline lengths. Using RULES, we generate uv-complete layouts that cover the range 10λ ≤ ∥u∥ ≤ 100λ with fewer than 1000 antennas of diameter 5λ, comparable to current and planned arrays. We demonstrate the effectiveness of such arrays for mitigating contamination from bright astrophysical foregrounds in 21 cm Epoch of Reionization observations—particularly in the region of Fourier space known as the foreground wedge—by simulating visibilities of foreground-like sky models over the 130─150 MHz band and processing them through an image-based power spectrum estimator. We find that with complete uv coverage, the wedge power is suppressed by 16 orders of magnitude compared to an array with a compact hexagonal layout (used as a reference for sparse uv coverage). In contrast, we show that an array with the same number of antennas but in a random configuration only suppresses the wedge by 3 orders of magnitude, despite sampling more distinct uv points over the same range. We address real-world challenges, and find that our results are sensitive to small antenna position errors and missing baselines, while still performing equally or significantly better than random arrays in any case. We propose ways to mitigate those challenges such as a minimum redundancy requirement or tighter uv packing density.

Keywords: Cosmology, Radio interferometers, H I line emission, Astronomical instrumentation, Radio observatories, Reionization, Radio astronomy
Measuring the Central Dark Mass in NGC 4258 with JWST/NIRSpec Stellar Kinematics. We present a new stellar-dynamical measurement of the supermassive black hole (SMBH) mass in the nearby spiral galaxy NGC 4258 (M106), a critical benchmark for extragalactic mass measurements. We use archival James Webb Space Telescope (JWST) Near-Infrared Spectrograph (NIRSpec) integral field unit data (G235H/F170LP grating) to extract high-resolution two-dimensional stellar kinematics from the CO bandhead absorption features within the central 3″ × 3″. We extract the stellar kinematics after correcting for instrumental artifacts and separating the stellar light from the nonthermal active galactic nucleus (AGN) continuum. We employ Jeans anisotropic models to fit the observed kinematics, exploring a grid of 12 models to systematically test the impact of different assumptions for the point-spread function, stellar mass-to-light ratio profile, and orbital anisotropy. All 12 models provide broadly acceptable fits, albeit with minor differences. The ensemble median and 68% (1σ) bootstrap confidence interval of our 12 models yield a black hole mass of  MBH=(4.08−0.33+0.19)×107  M⊙. This paper showcases the utility of using the full model ensemble to robustly account for systematic uncertainties, rather than relying on formal errors from a single preferred model, as has been common practice. Our result is just 5% larger than, and consistent with, the benchmark SMBH mass derived from water-maser dynamics, validating the use of NIRSpec stellar kinematics for robust SMBH mass determination. Our analysis demonstrates JWST's ability to resolve the SMBH's sphere of influence and deliver precise dynamical masses, even in the presence of significant AGN continuum emission.

Keywords: Astronomy data modeling, Galaxy dynamics, Galaxy nuclei, Galaxy kinematics, Galaxy spectroscopy, Astrophysical black holes
A Search for Millimeter-bright Blazars as Astrophysical Neutrino Sources. The powerful jets of blazars have been historically considered as likely sites of high-energy cosmic-ray acceleration. However, the particulars of the launched jet and the locations of leptonic and hadronic jet loading remain unclear. In the case when leptonic and hadronic particle injection occur jointly, a temporal correlation between synchrotron radiation and neutrino production is expected. We use a first catalog of millimeter wavelength (95─225 GHz) blazar light curves from the Atacama Cosmology Telescope for a time-dependent correlation with 12 yr of muon neutrino events from the IceCube South Pole Neutrino Observatory. Such millimeter emission traces activity of the bright jet base, which is often self-absorbed at lower frequencies and potentially gamma-ray opaque. We perform an analysis of the population, as well as analyses of individual, selected sources. We do not observe a significant signal from the stacked population. TXS 0506+056 is found as the most significant, individual source, though this detection is not globally significant in our analysis of selected active galactic nuclei. Our results suggest that the majority of millimeter-bright blazars are neutrino dim. In general, it is possible that many blazars have lighter, leptonic jets, or that only selected blazars provide exceptional conditions for neutrino production.

Keywords: Radio jets, High energy astrophysics, Millimeter astronomy, Neutrino astronomy, Active galactic nuclei
Bifractality and Crossover Behavior Observed in Solar Wind Intermittency by Parker Solar Probe: Rank-ordered Analysis and Partition Function Approach. Multifractal analysis of the intermittent solar wind magnetic energy fluctuations reveals new features of the young slow solar wind measured by Parker Solar Probe. The multifractal structure of magnetic fluctuations is analyzed with Rank-Ordered Multifractal Analysis (ROMA) and Partition Function Multifractal Analysis (PFMA). ROMA considers the raw fluctuations at all scales, grouped according to their rank; PFMA provides a multifractal spectrum from a measure extracted from data and assumed to be the result of a multiplicative process. ROMA identifies the bifractal behavior of magnetic fluctuations near the Sun at 0.17─0.19 au, manifesting as quasi-monofractal behavior over two contiguous subranges of inertial-range scales. The bifractality naturally implies the presence of a crossover scale, determined at roughly 100 ion inertial lengths (∼1000 km). The crossover is detected by four different approaches: (1) flatness behavior, (2) structure functions power-law scaling, (3) change of turbulence regime across the inertial range, and (4) change of the ROMA spectra over the two inertial scale ranges. Remarkably, spatial scales of the order of 1000 km have long been shown to be linked to a change in the fractal structure of solar granulation, hinting at a possible effect of solar surface phenomena on the topology of magnetic energy fluctuations close to the Sun. Left-skewed asymmetry of PFMA multifractal spectra further supports the complexity of the underlying dynamics dominated by large fluctuations. Conversely, the lack of right-skewed multifractal spectra at 0.17 au, as detected in the outer heliosphere, underlines the different state of fluctuations near the Sun.

Keywords: Slow solar wind, Time series analysis, Interplanetary magnetic fields, Interplanetary turbulence
Orbital Classification in Rotating Bar Potentials Using an Empirical Proxy of the Second Integral of Motion. We present a novel method for classifying two-dimensional orbits in rotating bar potentials based on an empirical proxy for the second integral of motion, calibrated angular momentum (CAM), which is defined as the ratio of the time-averaged angular momentum ( Lz̄ ) to its temporal dispersion ( σLz ) in the corotating frame. We show that CAM is determined by the ratio of the azimuthal to radial actions ( Jϕ'/Jr' ) in the analytical Freeman bar model. We then construct a new parameter space defined by CAM versus the rms radius (Rrms) and apply this framework to orbits in several representative rotating bar potentials. In the CAM─Rrms plane, periodic orbits generate well-defined branches separating distinct regions corresponding to different orbital families. Several of these branches enclose isolated areas that can be associated with specific orbital families, such as the x2 orbital family. We further validate the method using orbits from test-particle simulations, which show a well-ordered and nonoverlapping distribution of orbital families in the CAM─Rrms plane. Since CAM is fundamentally linked to intrinsic orbital properties and readily applied to three-dimensional orbits in N-body simulations, our results establish the CAM─Rrms plane as a robust and efficient framework for orbit classification in rotating bars that complements conventional methods.

Keywords: Orbits, Barred spiral galaxies, Galaxy dynamics