Sazuna/UAT_keywords huggingface dataset:
MAMMOTH-Subaru. II. Diverse Populations of Circumgalactic Lyα Nebulae at Cosmic Noon. Circumgalactic Lyα nebulae are gaseous halos around galaxies exhibiting luminous extended Lyα emission. This work investigates Lyα nebulae from deep imaging of ∼12 deg2 sky, targeted by the MAMMOTH-Subaru survey. Utilizing the wide-field capability of Hyper Suprime-Cam, we present one of the largest blind Lyα nebula selections, including QSO nebulae, Lyα blobs, and radio galaxy nebulae down to the typical 2σ Lyα surface brightness of  . The sample contains 117 nebulae with Lyα sizes of 40–400 kpc, and the most gigantic one spans about 365 kpc, and is referred to as the Ivory Nebula. Combining multiwavelength data, we investigate diverse nebula populations and associated galaxies. We find a small fraction of Lyα nebulae have QSOs (∼7%), luminous infrared galaxies (LIRGs; ∼1%), and radio galaxies (∼2%). Remarkably, among the 28 enormous Lyα nebulae (ELANe) exceeding 100 kpc, about 80% are associated with UV-faint galaxies (M UV &gt; ‑22), and are categorized as Type II ELANe. We underscore that Type II ELANe constitute the majority but remain largely hidden in current galaxy and QSO surveys. Dusty starburst and obscured AGN activity are proposed to explain the nature of Type II ELANe. The spectral energy distribution of stacking all Lyα nebulae also reveals signs of massive dusty star-forming galaxies with obscured AGNs. We propose a model to explain the dusty nature where the diverse populations of Lyα nebulae capture massive galaxies at different evolutionary stages undergoing violent assembly. Lyα nebulae provide critical insights into the formation and evolution of today's massive cluster galaxies at cosmic noon.

Keywords: Emission nebulae, High-redshift galaxies, Galaxies, Circumgalactic medium
The AstroSat UV Deep Field South. I. Far- and Near-ultraviolet Source Catalog of the GOODS South Region. We present the AstroSat UV Deep Field south (AUDFs), an imaging survey using the wide-field Ultraviolet Imaging Telescope on board AstroSat. AUDFs cover ∼236 arcmin2 of the sky area, including the Great Observatories Origins Deep Survey (GOODS) South field in F154W and N242W filters. The deep and shallow parts of AUDFs have an exposure time ∼62,000 and ∼31,000 s, respectively, in the F154W filter, while in the N242W filter, they are ∼64,000 and ∼34,000 s. These observations reached a 3σ depth of 27.2 and 27.7 AB mag with a 50% completeness limit of 27 and 27.6 AB mag in the F154W and N242W filters, respectively. With the acquired depth, AUDFs is the deepest far- and near-UV imaging data covering the largest area known to date at 1.″2─1.″6 spatial resolution. Two primary catalogs were constructed for the F154W and N242W filters, each containing 13,495 and 19,374 sources brighter than the 3σ detection limit, respectively. Our galaxy counts of a power-law slope of ∼0.43 dex mag−1 in the N242W filter match well with Hubble Space Telescope/Wide-Field Camera 3/UVIS observations. A wide range of extragalactic science can be achieved with this unique data, such as providing a sample of galaxies emitting ionizing photons in the redshift range of z ∼1─3 and beyond, constraining the UV luminosity function, investigating the extended UV emission around star-forming galaxies and UV morphologies for z &lt; 1. The UV catalog will enhance the legacy value of the existing optical/IR imaging and spectroscopic observations from ground- and space-based telescopes on the GOODS South field.

Keywords: Galaxy formation, Sky surveys, Ultraviolet astronomy, Galaxy photometry, High-redshift galaxies, Astronomical methods, Catalogs
An Upgraded Line List for Radiative Transitions between the B <SUP>2</SUP>Σ<SUP>+</SUP>, A <SUP>2</SUP>Π, and X <SUP>2</SUP>Σ<SUP>+</SUP> States of the CN Radical. The global mass-invariant coupled-channel deperturbation model of the B 2Σ+, A 2Π, and X 2Σ+ states of the CN radical, which reproduces the overall rovibronic term values of mutually perturbed levels with almost spectroscopic accuracy, has been utilized to produce complete line lists of radiative transitions between the X 2Σ+, B 2Σ+, and A 2Π1/2;3/2 states of CN isotopologues. The Einstein A emission coefficients generated for the A ‑ X, B ‑ X, and B ‑ A transitions provide both lifetimes of the excited states as well as the B → A/X branching ratios. The ab initio permanent and transition dipole moments required are revisited within the framework of the multireference configuration interaction and of the averaged coupled-pair functional methods. An upgraded line list is provided in ExoMol format and employed to simulate intensity distribution into the high-temperature air plasma B → X and A → X spectra as well as in the rotational resolved B → X/A emission bands undergoing strong local B ∼ A ∼ X perturbations. A comparison with laboratory and astronomical spectra shows that the present line list significantly improves the treatment of both locally perturbed and highly excited rotational levels of the B ∼ A ∼ X complex.

Keywords: Molecular data, Stellar atmospheric opacity, Molecular spectroscopy, Molecular spectroscopic constants, Exoplanet atmospheres
Six Maxims of Statistical Acumen for Astronomical Data Analysis. The acquisition of complex astronomical data is accelerating, especially with newer telescopes producing ever more large-scale surveys. The increased quantity, complexity, and variety of astronomical data demand a parallel increase in skill and sophistication in developing, deciding, and deploying statistical methods. Understanding limitations and appreciating nuances in statistical and machine learning methods and the reasoning behind them is essential for improving data-analytic proficiency and acumen. Aiming to facilitate such improvement in astronomy, we delineate cautionary tales in statistics via six maxims, with examples drawn from the astronomical literature. Inspired by the significant quality improvement in business and manufacturing processes by the routine adoption of Six Sigma, we hope the routine reflection on these six maxims will improve the quality of both data analysis and scientific findings in astronomy.

Keywords: Astronomy data analysis, Astrostatistics
Explicit Symplectic Integrators with Adaptive Time Steps in Curved Spacetimes. Recently, our group developed explicit symplectic methods for curved spacetimes that are not split into several explicitly integrable parts but are via appropriate time transformations. Such time-transformed explicit symplectic integrators should have employed adaptive time steps in principle, but they are often difficult in practical implementations. In fact, they work well if time transformation functions cause the time-transformed Hamiltonians to have the desired splits and approach 1 or constants for sufficiently large distances. However, they do not satisfy the requirement of step-size selections in this case. Based on the step-size control technique proposed by Preto &amp; Saha, the nonadaptive time-step time-transformed explicit symplectic methods are slightly adjusted as adaptive ones. The adaptive methods have only two additional steps and a negligible increase in computational cost compared with the nonadaptive ones. Their implementation is simple. Several dynamical simulations of particles and photons near black holes have demonstrated that the adaptive methods typically improve the efficiency of the nonadaptive methods. Because of the desirable property, the new adaptive methods are applied to investigate the chaotic dynamics of particles and photons outside the horizon in a Schwarzschild–Melvin spacetime. The new methods are widely applicable to all curved spacetimes corresponding to Hamiltonians or time-transformed Hamiltonians with the expected splits. In addition, application to the backward ray-tracing method for studying the motion of photons and shadows of black holes is possible.

Keywords: Celestial mechanics, Black hole physics, Computational methods, Computational astronomy
Constraining the Presence of Companion Planets in Hot Jupiter Planetary Systems Using Transit-timing Variation Observations from TESS. The presence of another planetary companion in a transiting exoplanet system can impact its transit light curve, leading to sinusoidal transit-timing variations (TTV). By utilizing both χ 2 and rms analysis, we have combined the TESS observation data with an N-body simulation to investigate the existence of an additional planet in the system and put a limit on its mass. We have developed CMAT, an efficient and user-friendly tool for fitting transit light curves and calculating TTV with a theoretical period, based on which we can give a limit on its hidden companion's mass. We use 260 hot Jupiter systems from the complete TESS data set to demonstrate the use of CMAT. Our findings indicate that, for most systems, the upper mass limit of a companion planet can be restricted to several Jupiter masses. This constraint becomes stronger near resonance orbits, such as the 1:2, 2:1, 3:1, and 4:1 mean-motion resonance, where the limit is reduced to several Earth masses. These findings align with previous studies suggesting that a lack of companion planets with resonance in hot Jupiter systems could potentially support the high-eccentricity migration theory. Additionally, we observed that the choice between χ 2 or rms method does not significantly affect the upper limit on companion mass; however, χ 2 analysis may result in weaker restrictions but is statistically more robust compared to rms analysis in most cases.

Keywords: Exoplanets, Transits, Hot Jupiters, Transit timing variation method
Mass-loss Rate of Highly Evolved Stars in the Magellanic Clouds. Asymptotic giant branch stars (AGBs) and red supergiant stars (RSGs) exhibit significant mass-loss phenomena and are considered important sources of interstellar dust. In this work, we employed a uniform method of spectral energy distribution fitting to analyze a large, and hence statistically significant, sample of approximately 40,000 RSGs and AGBs in the Magellanic Clouds (MCs), providing a new catalog of evolved stars that includes stellar parameters and dust properties. Our results reveal that the total dust-production rate (DPR) of the Large Magellanic Cloud is approximately 9.69 × 10‑6 M ☉ yr‑1, while it is around 1.75 × 10‑6 M ☉ yr‑1 for the Small Magellanic Cloud, with a few stars significantly contributing to the total DPR. No significant differences were observed in the contributions to DPR from carbon-rich and oxygen-rich (O-rich) evolved stars in the MCs. We explored the relations between stellar parameters (luminosity, infrared color, period, amplitude) and mass-loss rate (MLR) for evolved stars. A prominent turning point at   appears in the luminosity–MLR diagram of RSGs, potentially related to their mass-loss mechanism. The luminosity–MLR relation of AGBs is highly scattered. The DPR of AGBs shows a clear change with pulsation period and amplitude, with DPR exhibiting a drastic increase at pulsation periods of approximately 300 days and I-band amplitudes greater than 0.5 mag. Metallicity has some impact on the DPR of O-rich stars, with lower metallicity seeming to result in lower mean DPR and a higher proportion of optically thin stars.

Keywords: Red supergiant stars, Stellar mass loss, Asymptotic giant branch stars, Circumstellar dust, Magellanic Clouds
A Comprehensive Catalog of UVIT Observations. I. Catalog Description and First Release of Source Catalog (UVIT DR1). We present the first comprehensive source catalog (UVIT DR1) of ultraviolet (UV) photometry in four far-UV (FUV ∼ 1300‑1800 Å) and five near-UV (NUV ∼ 2000‑3000 Å) filters of the Ultraviolet Imaging Telescope (UVIT) on board AstroSat. UVIT DR1 includes bright UV sources in 291 fields that UVIT detected during its first 2 yr of pointed observation, encompassing an area of 58 deg2. We used the CCDLAB pipeline to reduce the Level 1 data, SExtractor for source detection, and four photometric procedures to determine the magnitudes of the detected sources. We provided the 3σ and 5σ detection limits for all the filters of UVIT. We describe the details of observation, source extraction methods, and photometry procedures applied to prepare the catalog. In the final UVIT DR1 catalog, we have point sources, extended sources, clumps from nearby galaxies, globular clusters, open clusters, planetary nebulae, and gaseous nebulae. There are 239,520 unique sources in the combined UVIT DR1, of which 70,488 sources have FUV magnitudes, and 211,410 have NUV magnitudes. We crossmatched and compared noncrowded sources of UVIT with the Galaxy Evolution Explorer and Gaia source catalogs. We provide a clean catalog of the unique sources in various UVIT filters that will help further the multiwavelength scientific analysis of the objects.

Keywords: Ultraviolet sources, Catalogs, Ultraviolet astronomy, Gaseous nebulae, Planetary nebulae, Galaxies, Star clusters
Molecular Clouds in the Outer Milky Way Disk: Sample, Integrated Properties, and Radial Trends with Galactocentric Radius. We present a catalog of 32,162 12CO molecular clouds that covers the northern outer Galactic plane (l = [15°, 165°] and l = [195°, 230°], and b = [−5.°25, +5.°25]). The catalog was produced using a DBSCAN algorithm applied to the Milky Way Imaging Scroll Painting project data. We systematically analyze both the integrated properties and scaling relationships of these molecular clouds across different Galactocentric radii (8 &lt; R GC &lt; 26 kpc). An interesting finding is that each cloud property's mean, median, and maximum values generally decrease systematically with increasing R GC, approximated quantitatively by exponential functions. The mass and size spectra for the entire sample show power-law indices of γ = −2.00 ± 0.13 and an upper mass limit of M 0 = (4.5 ± 2.8) × 106 M ⊙, and γ = −3.68 ± 0.48 with an upper size limit of R 0 = 144 ± 80 pc, respectively. These spectra exhibit steeper slopes and reduced upper limits as R GC increases. The derived scaling relations are  ,  , and α vir = 37.2M −0.40 ± 0.002 for the whole outer Galaxy clouds. These scaling relations show slightly steeper correlations observed in more distant locations and notably deviate from Larson's relations. We find that 44.3% of the molecular mass resides in gravitationally bound structures, a proportion significantly higher than systematic studies from the CfA survey and external galaxies. Moreover, comparisons among different R GC subsamples also reveal a decrease in the amount of bound mass with increasing R GC. The scale length of the molecular disk is estimated to be approximately 2 kpc. These results, based on a constant CO conversion factor of  , may be slightly altered by variations in X CO. In summary, our findings provide robust evidence for the influence of Galactic evolution on molecular cloud properties, at least in the outer Galaxy region studied.

Keywords: Interstellar line emission, Molecular clouds, Milky Way disk, CO line emission, Milky Way Galaxy
ALMA Lensing Cluster Survey: Deep 1.2 mm Number Counts and Infrared Luminosity Functions at z ≃ 1–8. We present a statistical study of 180 dust continuum sources identified in 33 massive cluster fields by the Atacama Large Millimeter/submillimeter Array Lensing Cluster Survey (ALCS) over a total of 133 arcmin2 area, homogeneously observed at 1.2 mm. ALCS enables us to detect extremely faint millimeter sources by lensing magnification, including near-infrared (NIR) dark objects showing no counterparts in existing Hubble Space Telescope and Spitzer images. The dust continuum sources belong to a blind sample (N = 141) with signal-to-noise ratio (S/N) ≳ 5.0 (a purity of &gt;0.99) or a secondary sample (N = 39) with S/N = 4.0–5.0 screened by priors. With the blind sample, we securely derive 1.2 mm number counts down to ∼7 μJy, and find that the total integrated 1.2 mm flux is   Jy deg‑2, resolving ≃80% of the cosmic infrared background light. The resolved fraction varies by a factor of 0.6–1.1 due to the completeness correction depending on the spatial size of the millimeter emission. We also derive infrared (IR) luminosity functions (LFs) at z = 0.6–7.5 with the   method, finding the redshift evolution of IR LFs characterized by positive luminosity and negative density evolution. The total (= UV + IR) cosmic star formation rate density (SFRD) at z &gt; 4 is estimated to be  % of the Madau and Dickinson measurements mostly based on rest-frame UV surveys. Although our general understanding of the cosmic SFRD is unlikely to change beyond a factor of 2, these results add to the weight of evidence for an additional (≈60%) SFRD component contributed by the faint millimeter population, including NIR-dark objects.

Keywords: Luminosity function, Starburst galaxies, Galaxy formation, Millimeter astronomy, Galaxy evolution, Cosmic background radiation, Interferometry
Multifilter UV to Near-infrared Data-driven Light-curve Templates for Stripped-envelope Supernovae. While the spectroscopic classification scheme for stripped-envelope supernovae (SESNe) is clear, and we know that they originate from massive stars that lost some or all of their envelopes of hydrogen and helium, the photometric evolution of classes within this family is not fully characterized. Photometric surveys, like the Vera C. Rubin Legacy Survey of Space and Time, will discover tens of thousands of transients each night, and spectroscopic follow-up will be limited, prompting the need for photometric classification and inference based solely on photometry. We have generated 54 data-driven photometric templates for SESNe of subtypes IIb, Ib, Ic, Ic-bl, and Ibn in U/u, B, g, V, R/r, I/i, J, H, K  s , and Swift w2, m2, w1 bands using Gaussian processes and a multisurvey data set composed of all well-sampled open-access light curves (165 SESNe, 29,531 data points) from the Open Supernova Catalog. We use our new templates to assess the photometric diversity of SESNe by comparing final per-band subtype templates with each other and with individual, unusual and prototypical SESNe. We find that SNe Ibn and SNe Ic-bl exhibit a distinctly faster rise and decline compared to other subtypes. We also evaluate the behavior of SESNe in the PLAsTiCC and ELAsTiCC simulations of LSST light curves, highlighting differences that can bias photometric classification models trained on the simulated light curves. Finally, we investigate in detail the behavior of fast-evolving SESNe (including SNe Ibn) and the implications of the frequently observed presence of two peaks in their light curves.

Keywords: Type Ic supernovae, Astronomy databases, Core-collapse supernovae, Type Ib supernovae, Astronomy data analysis, Gaussian Processes regression, Time series analysis
pathfinder: A Semantic Framework for Literature Review and Knowledge Discovery in Astronomy. The exponential growth of astronomical literature poses significant challenges for researchers navigating and synthesizing general insights or even domain-specific knowledge. We present pathfinder, a machine learning framework designed to enable literature review and knowledge discovery in astronomy, focusing on semantic searching with natural language instead of syntactic searches with keywords. Utilizing state-of-the-art large language models (LLMs) and a corpus of 385,166 peer-reviewed papers from the Astrophysics Data System, pathfinder offers an innovative approach to scientific inquiry and literature exploration. Our framework couples advanced retrieval techniques with LLM-based synthesis to search astronomical literature by semantic context as a complement to currently existing methods that use keywords or citation graphs. It addresses complexities of jargon, named entities, and temporal aspects through time-based and citation-based weighting schemes. We demonstrate the tool's versatility through case studies, showcasing its application in various research scenarios. The system's performance is evaluated using custom benchmarks, including single-paper and multipaper tasks. Beyond literature review, pathfinder offers unique capabilities for reformatting answers in ways that are accessible to various audiences (e.g., in a different language or as simplified text), visualizing research landscapes, and tracking the impact of observatories and methodologies. This tool represents a significant advancement in applying artificial intelligence to astronomical research, aiding researchers at all career stages in navigating modern astronomy literature.

Keywords: Astronomy web services, Astronomical reference materials, History of astronomy, Computational methods, Astronomy data visualization
X-Ray Hardening Preceding the Onset of SGR 1935+2154's Radio Pulsar Phase. Magnetars are neutron stars with extremely strong magnetic fields, frequently powering high-energy activity in X-rays. Pulsed radio emission following some X-ray outbursts has been detected, albeit its physical origin is unclear. It has long been speculated that the origin of magnetars' radio signals is different from those from canonical pulsars, although convincing evidence is still lacking. Five months after magnetar SGR 1935+2154's X-ray outburst and its associated fast radio burst 20200428, a radio pulsar phase was discovered. Here we report the discovery of X-ray spectral hardening associated with the emergence of periodic radio pulsations from SGR 1935+2154 and a detailed analysis of the properties of the radio pulses. The observations suggest that radio emission originates from the outer magnetosphere of the magnetar, and the surface heating due to the bombardment of inward-going particles from the radio emission region is responsible for the observed X-ray spectral hardening.

Keywords: Magnetars
Double-lined Spectroscopic Binaries from the LAMOST Low-resolution Survey. We report on a data-driven spectral model that we have developed for the identification of double-lined spectroscopic binary stars (SB2s) in the Large Sky Area Multi-Object fiber Spectroscopic Telescope low-resolution survey (R ∼ 1800). Employing simultaneous fitting with both single-star and binary-star models, we detected over 4800 SB2 candidates, where both components are detectably contributing to the spectrum, from an initial pool of 2.6 million objects. Tests show that our model favors FGK-type main-sequence binaries with high mass ratio (q ≥ 0.7) and large radial velocity (RV) separation (ΔRV ≥ 100 km s‑1). Almost all of these candidates are positioned above the main sequence in the color–magnitude diagram, indicating their binary nature. Additionally, we utilized various observational data, including spectroscopy, photometry, parallax, and extinction, to determine multiple physical parameters such as the effective temperature, age, metallicity, RV, mass, mass ratio, stellar radius, along with their associated uncertainties for these SB2 candidates. For the 44 candidates with seven or more observational epochs, we provide complete orbital solutions. We make available catalogs containing various stellar parameters for identified SB2 systems.

Keywords: Sky surveys, Close binary stars, Astronomy data analysis, Spectroscopic binary stars, Spectroscopy