Sazuna/UAT_keywords huggingface dataset:
Are We There Yet? Challenges in Quantifying the Frequency of Earth Analogs in the Habitable Zone. Searching for life elsewhere in the universe is one of the most highly prioritized pursuits in astronomy today. However, the ability to observe evidence of Earth-like life through biosignatures is limited by the number of planets in the solar neighborhood with conditions similar to Earth. The occurrence rate of Earth-like planets in the habitable zones of Sun-like stars, η⊕, is therefore crucial for addressing the apparent lack of consensus on its value in the literature. Here we present a review of the current understanding of η⊕. We first provide definitions for parameters that contribute to η⊕. Then, we discuss the previous and current estimated parameter values and the context of the limitations on the analyses that produced these estimates. We compile an extensive list of the factors that go into any calculation of η⊕, and how detection techniques and surveys differ in their sensitivity and ability to accurately constrain η⊕. Understanding and refining the value of η⊕ is crucial for upcoming missions and telescopes, such as the planned Habitable Worlds Observatory and the Large Interferometer for Exoplanets, which aim to search for biosignatures on exoplanets in the solar neighborhood.

Keywords: Exoplanets, Exoplanet systems, Planet hosting stars, Exoplanet detection methods, Habitable zone, Habitable planets
Beaming Effect in TeV Blazars. The detection of TeV emission in extragalactic galaxies has prompted investigations into the beaming effect in blazars, a key feature of relativistic jets modulating multiwavelength radiation, yet quantitative constraints remain limited. This study aims to systematically analyze the beaming effect in TeV blazars by disentangling the beamed and unbeamed components of high-energy spectra and estimating Doppler factors across X-ray, γ-ray, and TeV bands. We also probe the de-beamed (intrinsic) luminosities in these high-energy bands. A comprehensive sample of 51 TeV blazars is compiled. A two-component model is applied to decompose core-dominated and extended emissions, and Doppler factors are derived from the core-dominance parameters and the jet geometries. Low-synchrotron-peaked sources exhibit the strongest beaming, confirming that high-energy core-dominance parameters serve as robust tracers of the beaming effect. Doppler factors are highest in the γ-ray band and show a concave-to-convex evolution from radio to TeV bands, suggesting distinct emission regions or viewing angles. Derived Doppler factors enable the calculation of de-beamed intrinsic luminosities, offering insights into the blazar jet's intrinsic properties.

Keywords: Gamma-ray sources, Blazars, Jets
Machine Learning Classification of Baseband Data of CHIME FRBs. Fast Radio Bursts (FRBs) are bright millisecond radio pulses. Their origin is still unknown in the field of astronomy. A notable distinction among FRBs is that some sources repeat, while others appear to be non-repeating events. Interestingly, repeating FRBs tend to exhibit broader temporal widths and narrower spectral bandwidths compared to non-repeat events, suggesting they may arise from different physical mechanisms. However, current radio telescopes have limited coverage and sensitivity, which hinders a complete survey with continuous long-term monitoring. This issue makes it difficult to confirm repeat activity and potentially leads to misclassification of repeaters as non-repeaters; these are referred to as repeater candidates. To address this, machine learning techniques have emerged as a useful tool for classifying distinct FRB types in previous studies. In this study, we utilize the Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB baseband catalog with three orders of magnitude better time resolution than the intensity catalog. Measured fluences are available in the baseband catalog, while only upper limits are reported in the intensity catalog. We apply machine learning to the baseband catalog to evaluate classification outcomes. We identify 15 repeater candidates among 122 non-repeating FRBs in the baseband catalog. Additionally, our classification identifies 31 sources previously categorized as repeater candidates as non-repeaters, highlighting a significant difference from the prior work. Of these repeater candidates, 14 overlap with previous findings, while 1 is newly identified in this work. Notably, one of our candidates was confirmed as a repeater by CHIME/FRB. Follow-up observations for the 14 candidates are highly encouraged.

Keywords: Radio bursts, Time domain astronomy, Radio transient sources
The X-Ray Flare Spectrum of HR 1099: The Search for Photopumped Ne IX Line Emission. We present high resolution X-ray spectroscopy of the active late-type star HR 1099 obtained with the Chandra Low Energy Transmission Grating Spectrometer. A spectrum extracted from the early stages of a flare was created to search for enhanced emission due to line coincidence photopumping at X-ray wavelengths, rather than the usual optical and ultraviolet cases. Specifically, we have identified a scheme where a He-like Ne IX line at 11 Å is photopumped by He-like Na X, which predicts intensity enhancement in the Ne IX 82.76 Å transition under the high electron density and large coronal pathlength conditions found in stellar and solar flares. We previously tentatively identified a Ne IX enhancement in a solar flare spectrum, but the result was extremely uncertain. However, Ne IX 82.76 Å was detected at the 3-sigma level in the Chandra spectrum, leading to a measured Ne IX 82.76/13.45 intensity ratio of 0.21 ± 0.08. By contrast, the theoretical ratio from the CHIANTI database is at most 0.031, indicating an enhancement factor of at least 7 ± 3 for the 82.76 Å line, in agreement with the expected value of ∼7─15 from a photopumping plasma model. This confirms detection, for the first time to our knowledge, of X-ray photopumping in an astrophysical object. We note that the identification of such X-ray photopumping in other spatially unresolved sources provides in principle a new diagnostic for independently determining the sizes of their coronal regions.

Keywords: X-ray stars, Spectroscopy, Flare stars
BSN. V. The First Detailed Light Curve Modeling of Eight Totally Eclipsing Contact Binary Stars Using Ground-based and TESS Observations. This study broadens our comprehensive investigation of total-eclipse W Ursae Majoris-type contact binaries by analyzing eight additional systems, continuing our previous research. Multiband BV RcIc photometric data were obtained at an observatory in Mexico, from which new times of minima were determined. All target systems also had available space-based Transiting Exoplanet Survey Satellite time-series data. Orbital period variations were studied for eight target systems, showing either linear or parabolic trends. The target systems exhibiting parabolic trends demonstrated a sustained decrease in their orbital periods over time. We modeled the light curves utilizing the PHOEBE Python code in combination with the BSN application. We revisited the relationship between orbital period and the temperature of the hotter component in contact binary systems using an empirical approach. Our analysis identified a clear break at P = 0.27 day, separating the systems into two distinct groups for orbital periods shorter than 0.6 day. Following the determination of stellar extinction, absolute parameters for seven systems were estimated employing parallax measurements from Gaia DR3. Based on the components' effective temperatures and masses, the systems were classified into A- and W-subtypes. Their evolutionary states were illustrated using mass─radius and mass─luminosity diagrams.

Keywords: Fundamental parameters of stars, Astronomy data analysis
Why Estimating η<SUB>⊕</SUB> is Difficult: A Kepler-Centric Perspective. η⊕, the occurrence rate of rocky habitable zone exoplanets orbiting Sun-like stars, is of great interest to both the astronomical community and the general public. The Kepler space telescope has made it possible to estimate η⊕, but estimates by different groups vary by more than an order of magnitude. We identify several causes for this range of estimates. We first review why, despite being designed to estimate η⊕, Kepler's observations are not sufficient for a high-confidence estimate, due to Kepler's detection limit coinciding with the η⊕ regime. This results in a need to infer η⊕, for example extrapolating from a regime of non-habitable zone, non-rocky exoplanets. We examine two broad classes of causes that can account for the large discrepancy in η⊕ found in the literature: (a) differences in definitions and input data between studies, and (b) fundamental limits in Kepler data that lead to large uncertainties and poor accuracy. We highlight the risk of large biases when using extrapolation to describe small exoplanet populations in the habitable zone. We discuss how η⊕ estimates based on Kepler data can be improved, such as reprocessing Kepler data for more complete, higher-reliability detections and better exoplanet catalog characterization. We briefly survey upcoming space telescopes capable of measuring η⊕, and how they can be used to supplement Kepler data.

Keywords: Extrasolar rocky planets, Habitable zone, Habitable planets, Exoplanets
The Dependence of Earth Milankovitch Cycles on Martian Mass. The Milankovitch cycles of Earth result from gravitational interactions with other bodies in the solar system. These interactions lead to slow changes in the orbit and angular momentum vector of Earth, and correspondingly influence Earth's climate evolution. Several studies have shown that Mars may play a significant role in these Milankovitch cycles, such as the 2.4 Myr eccentricity cycle related to perihelion precession dynamics. Here we provide the results of a detailed dynamical analysis that explores the Earth Milankovitch cycles as a function of the Martian mass to quantify the extent that Mars influences variations in Earth's orbital eccentricity, the longitude of perihelion, the longitude of the ascending node, and obliquity (axial tilt). Our results show that, although the 405 kyr long-eccentricity metronome driven by g2 (Venus) and g5 (Jupiter) persists at all Mars masses, the ∼100 kyr short-eccentricity bands driven by g4 (Mars) lengthen and gain power as Mars becomes more massive, consistent with enhanced coupling among inner-planet g-modes. The 2.4 Myr grand cycle is absent when Mars approaches zero mass, reflecting the movement of g4 with the Martian mass. Meanwhile, Earth's obliquity cycles driven by s3 (Earth) and s4 (Mars) lengthen from the canonical ∼41 kyr with increasing Mars mass, relocating to a dominant 45─55 kyr band when the mass of Mars is an order of magnitude larger than its present value. These results establish how Mars' mass controls the architecture of Earth's climate-forcing spectrum and that the Milankovitch spectrum of an Earth-like planet is a sensitive, interpretable probe of its planetary neighborhood.

Keywords: Exoplanet dynamics, Habitable planets, Exoplanets, Orbits, Mars, Exoplanet systems, Earth (planet), Planetary dynamics
The ViSta Method for Stacking in the Fourier Domain and its Application to the Dusty Star-forming Galaxies in the ALMA Science Archive. We present ViSta, a Visibility Stacking method to combine interferometric observations in the Fourier domain at radio to sub-millimeter wavelengths for galaxies. The goal of our method is to maximize the exploitation of available archival interferometric data. By stacking visibilities of galaxies with secure spectroscopic redshifts directly in the Fourier domain and transforming them into the rest-frame, we can enhance the stacked signal, suppress noise, and improve image reconstruction thanks to an extended coverage of the visibility domain. The ViSta method is highly flexible, allowing stacking of visibilities regardless of the array configuration or spectral setup. It is effective for both targeted sources and spurious detections offset from the phase center, whether unresolved or extended, within the field of view of the telescope. We validated the method using simulated interferometric datasets. For point-like sources, we can reconstruct the true emission with approximately 90% accuracy, obtaining similar results to classical image-plane stacking. In contrast, for faint and extended sources below the noise level, our method can provide a more accurate estimate of the signal compared to traditional image-based approaches. Finally, we applied ViSta to a sample of dusty star-forming galaxies observed with the Atacama Large Millimeter/sub-millimeter Array to detect the CO(3─2) emission line. As for the simulated case, we demonstrated that our tool performs better than image-plane stacking when the signal from individual sources is no longer easily detectable, achieving higher SNR. Finally, we outline potential future applications of this stacking approach.

Keywords: Radio spectroscopy, Galaxies, Astronomy data reduction, Astrochemistry
glitterin: Toward Replacing the Role of Lorenz─Mie Theory in Astronomy Using Neural Networks Trained on Light Scattering of Irregularly Shaped Grains. Light scattering by dust particles is often modeled assuming the dust is spherical for numerical simplicity and speed. However, real dust particles have highly irregular morphologies that significantly affect their scattering properties. We have developed glitterin, a neural network trained to predict light scattering from irregularly shaped dust grains, offering a computationally efficient alternative to Lorenz─Mie theory. We computed scattering properties using the discrete dipole approximation code ADDA for irregularly shaped particles across size parameters x from 0.1 to 65, covering a range in complex refractive index m that includes astrosilicates, pyroxene, enstatite, water ice, etc. The neural network operates at millisecond timescales while maintaining superior accuracy compared to linear interpolation. Irregular grains exhibit x-dependent deviations from spherical predictions. At small x, cross sections approach volume-equivalent spheres for low m. At large x, irregular grains show enhanced cross sections due to greater geometric extension. Increasing m also enhances the absorption cross section relative to the volume-equivalent spheres. This differential x and m dependence creates mid-IR solid-state features distinct from predictions from spherical grains. Validation against laboratory measurements of forsterite and hematite demonstrates that our neural network captures both qualitative and quantitative behaviors more accurately than spherical models. Millimeter-wavelength applications reveal that spherical grains produce opposite polarization signatures compared to irregular grains, potentially relaxing stringent ∼100 μm grain size constraints in protoplanetary disks. glitterin is publicly available and alleviates the computational barriers to incorporating emission and scattering of realistic grain morphologies in the dust inference and radiative transfer simulations for debris disks and other astronomical environments.

Keywords: Interstellar dust, Neural networks, Dust continuum emission, Circumstellar disks, Debris disks
Practical Author Name Disambiguation under Metadata Constraints: A Contrastive Learning Approach for Astronomy Literature. The ability to distinctly and properly collate an individual researcher's publications is crucial for ensuring appropriate recognition, guiding the allocation of research funding, and informing hiring decisions. However, accurately grouping and linking a researcher's entire body of work with their individual identity is challenging because of widespread name ambiguity across the growing literature. Algorithmic author name disambiguation (AND) provides a scalable approach to disambiguating author identities, yet existing methods have limitations. Many modern AND methods rely on comprehensive metadata features such as email, venue, or affiliation. Despite advancements in digitally indexing publications, metadata is often unavailable or inconsistent in large digital libraries (e.g., SAO/NASA Astrophysics Data System). We introduce the Neural Author Name Disambiguator (NAND), a method that effectively disambiguates author identities in large digital libraries despite limited metadata availability. We formulate the AND task as a similarity learning problem by employing a Siamese neural network to disambiguate author names across publications relying solely on widely available publication metadata—author names, titles, and abstracts. We construct the Large-Scale Physics Open Researcher and Contributor ID (ORCID)-Linked dataset to evaluate the NAND method by cross-matching NASA/ADS publications ORCiD. By leveraging foundation models to embed metadata into features, the NAND achieves up to 94% accuracy in pairwise disambiguation and over 95% F1 in clustering publications into their correct researcher identities. We release the testing dataset as a benchmark for physics and astronomy, providing realistic evaluation conditions for future disambiguation methods. The NAND algorithm demonstrates effective disambiguation with minimal metadata, offering a scalable solution for name ambiguity in large-scale digital libraries.

Keywords: Astroinformatics, Open source software, Neural networks
Cross-calibration of an eXTP Mirror Prototype at 100XF and PANTER. The enhanced X-ray Timing and Polarimetry (eXTP) mission is China's future flagship X-ray astronomy observatory. The eXTP payload comprises an array of Wolter-I focusing mirrors that utilize nickel electroforming technology. The testing and calibration of the eXTP mirror assemblies will be primarily conducted at the 100 m X-ray Test Facility (100XF) at the Institute of High Energy Physics, with support from the PANTER facility of the Max Planck Institute for Extraterrestrial Physics. Consequently, cross-calibration between the facilities is essential. This paper presents preliminary cross-calibration for mirror module 3 of the eXTP focusing mirror, conducted at both the 100XF and PANTER facilities, focusing on point spread functions (PSFs), vignetting, and effective area. The angular resolutions obtained at the two facilities are 21 .″ 8 ± 0 .″ 2@Al─Kα, 29 .″ 8 ± 0 .″ 5@Cu─Kα (100XF), as well as 21 .″ 9 ± 0 .″ 2@Al─Kα, 27 .″ 6 ± 0 .″ 5@Cu─Kα (PANTER). The measured effective area results at 100XF are 52.0 ± 0.7 cm2@Al─Kα, 12.1 ± 0.1 cm2@Cu─Kα. Meanwhile, after correcting for beam length (or divergence angle), the results from PANTER are 52.8 ± 0.7 cm2@Al─Kα, 12.2 ± 0.2 cm2@Cu─Kα. The cross-calibration results validate the reliability of the calibration methodologies for eXTP mirrors. Consistent outcomes in alignment, focus search, and PSFs were achieved, satisfying stringent mission requirements. Effective area measurements showed good agreement with simulations, with deviations limited to ±10%. These cross-calibration results provide valuable references for subsequent mirror calibrations and corrections, especially concerning effective area calibration, which should be a key focus of future research efforts.

Keywords: Calibration, Astronomical instrumentation, X-ray telescopes
EDGES-3: Instrument Design and Commissioning. EDGES-3 is the third iteration of the Experiment to Detect the Global EoR Signature (EDGES) experiment, designed to measure the predicted global absorption feature in the radio spectrum produced by neutral hydrogen gas at cosmic dawn, a critical observation determining when and how the first stars populated the universe. The EDGES-3 instrument has been redesigned to include both the analog and digital electronics within the antenna, allowing for in-situ calibration and removal of the lossy balun found in EDGES-2. EDGES-3 has been on multiple deployments in the past 4 yr; to Oregon, Devon Island, Adak Island, and is currently installed and taking data in the outback of Western Australia. This paper provides an accounting of the challenges inherent in the detection of the global, cosmological 21 cm signal, the strategies EDGES employs to mitigate each of these challenges, a description of the instrument, and a report on the Western Australia deployment along with observational data.

Keywords: Reionization, Observational cosmology, Astronomical instrumentation
Antarctic Infrared Binocular Telescope. I. System Overview, Laboratory Testing, and On-sky Performance Evaluation. Infrared time-domain surveys remain significantly underdeveloped compared with their optical counterparts. We have developed the Antarctic Infrared Binocular Telescope (AIRBT) to study the dynamic infrared sky at Dome A, Antarctica, taking advantage of the superb infrared observational conditions at this site. AIRBT consists of two identical 15 cm f/3 optical tube assemblies and two cost-effective indium gallium arsenide (InGaAs) cameras equipped with J and H filters, respectively. The cameras have 640 × 512 15 μm pixels, giving a scale of 6 .″ 9 pixel−1 and a field of view of 1.22 × 0.97 deg2. We characterize the performance of the InGaAs cameras, including bias, readout noise, dark current, nonlinearity, and photon transfer curve (PTC). Our analysis highlights the distinct behaviors of InGaAs cameras compared with charge-coupled devices. The bias and readout noise show temperature dependence. In addition, the noise measured from the PTCs has additional components increasing with exposure time. On-sky tests were conducted in 2022 October including system calibration, limiting depth, and photometric precision. For a single 3 s exposure, we achieved 5σ limiting magnitudes of 11.2 mag (Vega system) in J band and 9.7 mag in H band. The best photometric precision reached 20 mmag at the bright end, which could be further improved to sub-percent levels through image stacking. AIRBT was installed at Dome A in 2023 January, and scientific observations began as soon as darkness set in.

Keywords: Time domain astronomy, Astronomical detectors, Infrared telescopes, Infrared photometry
A Butterfly's Eye Camera for Intensity Interferometry with Cherenkov Telescopes. In recent years, imaging atmospheric Cherenkov telescopes (IACTs) have emerged as promising platforms for optical interferometry through the use of intensity interferometry. IACTs combine large segmented mirrors, photodetectors with nanosecond-scale time response capable of detecting signals from just a few photo-electrons, and array configurations with baselines of hundreds of meters. As a result, all major IACT facilities have now been upgraded to function also as optical intensity interferometers, achieving sensitivities an order of magnitude better than their predecessor, the Narrabri Stellar Intensity Interferometer. However, further improvements in sensitivity are currently limited by key IACT design constraints, namely the combination of poor optical quality and small focal ratios. Here we present three practical implementations of the "I3T concept," in which segments of the IACT primary mirror are focused onto different pixels of its camera. This approach yields several unexpected but significant advantages. Optics with larger focal ratios allow to integrate narrow-band optical filters, while lower photon fluxes enable to deploy next-generation photodetectors operating in photon-counting mode. We demonstrate that this so-called "Butterfly's Eye" configuration enhances the sensitivity of IACT-based intensity interferometers by a factor between 4 and 6. Moreover, as originally envisioned, the I3T design introduces imaging capabilities on angular scales from 2 to 40 mas, unlocking new scientific opportunities such as direct surface imaging of nearby red giants. Besides, realistic simulations show that it can have a transformative impact on at least two key science cases: imaging the earliest stages of nova ejecta, and measuring the oblateness and circumstellar disks of fast-rotating stars.

Keywords: Optical interferometry, Fundamental parameters of stars, Astronomical instrumentation, High angular resolution, Classical novae