Astrophysics of Galaxies
Optical QPOs with different periodicities in CSS and ZTF light curves of the quasar 4C 50.43
Liao GuiLin, Chen XingQian, Cheng PeiZhen et al. (+1 more)
Long-standing optical quasi-periodic oscillations (QPOs) with periodicity of hundreds to thousands of days have been accepted as indicators for central sub-pc binary black hole systems (BBHs) in broad line active
galactic nuclei (BLAGN). However, there are so far no direct reports on whether such reported optical QPOs have their periodicities constant in different periods. Here, based on different methods applied to light curves of 4C 50.43 in different periods, optical QPOs with periodicity of 1124days was detected in the CSS V-band light curve, while a shorter periodicity of 513days was detected in the ZTF g/r band light curves. Despite the two periodicities near-harmonic 2:1 ratio, their absence of simultaneous detection in the lomb-scargle periodograms of the ZTF light curves suggests that they are unlikely to be harmonically related. Potential factors were considered to explain these two distinct periodicities, especially different temporal coverage, signal-to-noise ratio and time steps between the CSS and ZTF light curves, as well as the effects of red noises related to intrinsic AGN variability. Our analysis shows that red noises have strong influence on the different periodicities in 4C 50.43 supporting our previous simulations. The results in this manuscript strongly indicate that it should be cautioned for applications of determined optical QPOs in BLAGN having strong intrinsic AGN variability.
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All authors Liao GuiLin, Chen XingQian, Cheng PeiZhen, Zhang XueGuang
Solar and Stellar Astrophysics
Half-year Evolution of a Decaying Solar Active Region and Peripheral Dimming Regions
Jiasheng Wang, Yu Xu and Zhengyong Hou
Using multi-wavelength observations from the
Solar Dynamics Observatory (SDO), we investigated the six-month decay process of the
solar active region NOAA AR 12738 from April to October 2019. We systematically analyzed the region's
evolution by examining extreme ultraviolet (EUV) intensity variations, quantifying
magnetic flux
diffusion, and investigating thermodynamic changes via Differential Emission Measure (DEM) analysis. This study presents the first long-term tracking of a peripheral dimming region (dark moat), revealing its continuous areal decrease over time. DEM results reveal cooling
plasma signatures and thermal restructuring, with the dimming region exhibiting a distinct temperature deficit in range 10$^{5.5}$ – 10$^{5.9}$~K. Potential field extrapolation identifies two dominant
magnetic configurations: low-lying loops with cool
plasma ($<$10$^{5.5}$ K), and high-arching structures connecting to the AR core, contributing to localized emission reduction. We found that the dimming is dominated by high-lying loops extending from the AR core, which are heated to temperatures above the main response of the 171~Å\ passband ($>$ 10$^{5.8}$ K), consequently lacking
plasma at the typical 10$^{5.8}$~K formation temperature. The thermal deficit, not just the absence of material, is the key driver of the reduced emission. Our results demonstrate that long-duration dimming provides a valuable diagnostic for understanding active region decay, thermal
evolution, and coronal
magnetic restructuring.
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Cosmology and Nongalactic Astrophysics
Statistical consistency of sign-switching vacuum energy with cosmological observations
Sehjal Khandelwal, Abraão J. S. Capistrano and Suresh Kumar
We assess
dataset agreement and late-time predictive adequacy in $\Lambda$CDM and its sign-switching extension, $\Lambda_{\rm s}$CDM, using a suite of Gaussian and exact non-Gaussian consistency diagnostics. Both models are constrained with
cosmic microwave background measurements from Planck, ACT, and SPT,
baryon acoustic oscillation data from DESI DR2, and low-
redshift Type Ia
supernova data from PantheonPlus+SH0ES. We find that commonly used Gaussian tension metrics can significantly overstate inconsistencies when broad, non-Gaussian posteriors are combined with tightly constrained
datasets. In contrast, the exact non-Gaussian parameter shift indicates excellent consistency between CMB and BAO observations in both models. The $\Lambda_{\rm s}$CDM extension modestly improves
geometric compatibility at intermediate
redshifts, although reductions in parameter-level tension do not necessarily imply improved predictive consistency. These results highlight the importance of exact, non-Gaussian, and predictive diagnostics for robust assessments of cosmological model consistency.
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Earth and Planetary Astrophysics
Atmospheric Collapse and Habitability on Tidally-Locked Exoplanets
Keigo Taniguchi, Takanori Kodama, Martin Turbet et al. (+3 more)
The habitability of terrestrial
exoplanets orbiting M
dwarfs is a key topic in the search for extraterrestrial life. The climates of these
planets differ significantly from the Earth's due to their likely
tidal locking, resulting in a hotter dayside and a colder nightside caused by uneven
stellar irradiation. On tidally-locked
planets around the outer edge of the habitable zone (HZ), although the definition of the classical HZ requires thick CO2 atmosphere, CO2 can condense onto the surface, leading to the reduction of greenhouse effect. However, the dayside permanent
stellar irradiation could maintain a surface
liquid water area. The onset of atmospheric collapse and the persistence of surface
liquid water are governed by global heat redistribution which is influenced by factors such as atmospheric mass,
stellar irradiation, and greenhouse effects. In this study, we used a three-dimensional global
climate model to investigate the impact of atmospheric collapse on the presence of dayside surface
liquid water. Our results indicate that surface
liquid water could counter-intuitively persist despite atmospheric collapse. This is because the loss of atmospheric CO2 weakens not only the greenhouse effect but also daynight heat transport, leading to less redistribution of the energy of dayside insolation to the nightside. While atmospheric collapse is typically seen as an obstacle to maintaining a habitable
climate, our findings suggest that it could play a positive role in sustaining surface
liquid water on tidally-locked
planets. Our work provides new light into the relationship between atmospheric collapse and planetary habitability.
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All authors Keigo Taniguchi, Takanori Kodama, Martin Turbet, Guillaume Chaverot, Ehouarn Millour, Hidenori Genda
Earth and Planetary Astrophysics
Mass Production of 2023 KMTNet Microlensing Planets I: Low Mass Ratio
Yoon-Hyun Ryu, Andrzej Udalski, Hongjing Yang et al. (+34 more)
We initiate the systematic search for
planets in the 2023 data of the Korea Microlensing
Telescope Network (KMTNet), focusing on those
planets found by the KMTNet AnomalyFinder with low preliminary estimates of the mass-ratio, $q<2\times 10^{-4}$. The 2023 season is the first for which the photometry of all events was re-reduced prior to the AnomalyFinder search, potentially increasing its sensitivity to
planets. We find three strong low-$q$
planet candidates, KMT-2023-BLG-0164 ($q\sim 1.3\times 10^{-4}$), KMT-2023-BLG-1286 ($q\sim 1.9\times 10^{-4}$), and KMT-2023-BLG-1746 ($q\sim 8\times 10^{-5}$). KMT-2023-BLG-0164 is notable in that the source is projected on a very bright ($I=16.0$) foreground
star, which is either the
planet's host or (more likely) a companion to the host. We obtain a spectrum, finding that its mass and distance are $M\sim 1.0\,M_\odot$ and $D\sim 1.5$ kpc, the latter being the distance of the lens ($D_L$) regardless of whether the spectroscopic target is the host or its companion. We also analyze two other candidates, KMT-2023-BLG-0614 and KMT-2023-BLG-1593, which are unlikely to enter the statistical sample due to their ambiguous interpretations as possible non-planetary events.
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All authors Yoon-Hyun Ryu, Andrzej Udalski, Hongjing Yang, Kyu-Ha Hwang, Weicheng Zang, Yang Huang, Andrew Gould, Michael D. Albrow, Ping Chen, Sun-Ju Chung, Subo Dong, Cheongho Han, Youn Kil Jung, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Sang-Mok Cha, Dong-Jin Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Przemek Mroz, Radoslaw Poleski, Jan Skowron, Michal K. Szymanski, Igor Soszynski, Pawel Pietrukowicz, Szymon Kozlowsk, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Mateusz J. Mroz
High Energy Astrophysical Phenomena
Searching for Black Hole Candidates in Quiescence by Using Multi-band Observations in Globular Cluster M22 (NGC 6656)
Yu-Jing Xu, Wei-Min Gu, Yuanqi Liu et al. (+3 more)
We present a multi-wavelength investigation of
radio sources in the globular cluster M22 (NGC 6656) using the Karl G. Jansky Very Large Array, Chandra and Hubble Space
Telescope. By cross-matching the
radio and X-ray source catalogs, we identify eight
radio/X-ray counterparts, of which VLA22 is the most promising
stellar-mass black hole (BH) candidate. Its
radio and X-ray luminosities are consistent with the established $L_{\rm X}-L_{\rm R}$ correlation for BH low-mass X-ray binaries. The observed X-ray variability supports an accreting nature. One possible optical counterpart ($M_{\mathrm{814}} \approx 16.695 \pm 0.011$ mag) is identified. Based on its inferred
stellar parameters, the estimated orbital period of $P_{\rm orb} \sim 16 \pm 6~{\rm h}$ places the proposed counterpart predominantly in the BH region rather than in the NS region in the $L_{\rm X}-P_{\rm orb}$ plane. These results demonstrate the effectiveness of joint
radio, X-ray, and optical observations in identifying quiescent BH candidates in globular clusters.
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All authors Yu-Jing Xu, Wei-Min Gu, Yuanqi Liu, Xin-Yu Fang, Shan-Shan Weng, Tao An
Solar and Stellar Astrophysics
Weighing Hidden Companions of Compact Object Candidates via Rotational Broadening
Rui Wang, Zhi-Xiang Zhang, Wei-Min Gu et al. (+3 more)
The determination of unseen companion masses ($M_1$) is essential for identifying compact objects in binary systems, yet obtaining reliable orbital inclinations remains one of the most difficult challenges. In this study, we focus on ten targets selected from a sample of 89 compact object candidates characterized by large mass functions, rapid rotation, and high-quality Large Sky Area Multi-object Fiber Spectroscopic
Telescope (LAMOST) spectra. We measure their projected rotational velocities ($v \sin i$) from the LAMOST medium-resolution spectra and, combined with
stellar radii, derive orbital inclinations and the corresponding companion masses. Our results show that five sources exhibit mass ratios $M_1 / M_2 > 2/3$, with no detectable spectral signatures of the unseen companions, providing strong evidence for their compact nature. Two particularly notable cases, J0341 and J0359, host companions with inferred masses of $1.39^{+0.09}_{-0.10}$ $M_\odot$ and $1.34^{+0.08}_{-0.09}$ $M_\odot$, respectively. These masses suggest that the invisible objects are either
neutron stars or massive white
dwarfs with masses close to the Chandrasekhar limit. If they are white
dwarfs, these two targets are highly likely to be Type Ia
supernova progenitors. This study highlights the potential of $v \sin i$ measurements as a systematic approach to unveiling compact objects in binaries.
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All authors Rui Wang, Zhi-Xiang Zhang, Wei-Min Gu, Hao-Bin Liu, Tuan Yi, Zhong-Rui Bai
Astrophysics of Galaxies
HI Observations of Giant Low Surface Brightness Galaxies
Philip Lah, Nikhil Arora, Ivan Yu. Katko et al. (+5 more)
Giant low surface brightness
galaxies (gLSBs) are
galaxies with extremely extended, faint, optical disks over 50 kpc in radius and have high total masses which can reach 10^12
solar masses. The existence of such
galaxies is problematic for current models of
galaxy formation, since the major mergers responsible for the large total mass would likely have destroyed the extended optical disk. Examining the gas content of these
galaxies is an important step in determining their formation mechanism, whether it be through slow gas
accretion or the large disk (re)forming after a major merger. We present neutral atomic hydrogen (HI) observations of 19 gLSBs identified with the Hyper Suprime-Cam Subaru Strategic Program survey. Although most have high HI masses, they are generally lower than expected based on their large optical sizes, and we do identify some gLSBs with unusually low gas content. The HI spectra of these
galaxies show evidence for a rotational disk, though these disks are more asymmetric than other
galaxies with comparable mass. Four
galaxies with similar surface brightness profiles to the gLSBs have also been selected from the Numerical Investigation of a Hundred Astrophysical Objects (NIHAO) simulation for comparison. There is evidence for significant
galaxy mergers in the past for three of these NIHAO
galaxies and these three
galaxies show similar asymmetry in their HI spectra. Together, these results could indicate the large optical disk of gLSBs are the result of a recent merger.
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All authors Philip Lah, Nikhil Arora, Ivan Yu. Katko, Joseph D. Gelfand, Anna S. Saburova, Igor V. Chilingarian, Ivan Gerasimov, Damir Gasymov
Solar and Stellar Astrophysics
Joint Diagnostics of Circumsolar Sky Brightness Using Coronagraphic Measurements and Aerosol Optical Inversions at Mauna Loa
Thomas A. Schad, Paul Bryans, Andre Fehlmann et al. (+5 more)
Atmospheric aerosols strongly influence daytime sky quality for
solar coronal imaging, yet few studies directly link aerosol properties and sky-brightness measurements within ~2{\deg} of the Sun. Here we compare externally occulted coronagraphic measurements of near-Sun radiance with aerosol-constrained inferences derived from direct-Sun and sky photometry. Our analysis focuses on Mauna Loa Observatory, a well-characterized high-altitude site for atmospheric and
solar observations. We present coronagraphic measurements of near-Sun radiance at 1.54 +/- 0.77{\deg} from
solar disk center acquired between 2006 and 2007 by an ATST Sky Brightness Monitor (SBM). These data are directly compared with circumsolar radiances inferred at 1.54{\deg} using AERONET almucantar measurements and aerosol optical
retrievals. We find quantitative agreement between these two approaches, enabling extension to multi-decadal analyses of circumsolar radiance and its relationship to aerosol properties and related proxies (e.g., the Angstrom exponent) using AERONET data from 2000-2025. Near-Sun radiances are expressed relative to the
solar disk-center radiance, facilitating direct comparison with related studies. Finally, we synthesize physically based true-color images of the circumsolar sky under representative aerosol conditions as an observational aid, in part to illustrate that visually enhanced
solar aureoles do not necessarily imply poor infrared coronal observing conditions. This methodology provides an extended framework for assessing daytime coronal sky quality at existing and future observing sites.
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All authors Thomas A. Schad, Paul Bryans, Andre Fehlmann, Sarah Gibson, David M. Harrington, Lucas A. Tarr, Steven Tomczyk, Jeffrey G. Yepez
Instrumentation and Methods for Astrophysics
A Robust Geometric Distortion Solution for Main Survey Camera of CSST
Yibo Yan, You Wu, Jundan Nie et al. (+30 more)
The advancement in sensitivity and field of view of next-generation wide-field survey
telescopes requires astrometric measurements with high precision, even in the presence of significant
geometric distortions. To address this challenge, we develop a Weighted
Polynomial Distortion Correction in 2-Phase (WPDC-2P) method. This approach enhances
stellar cross-matching, incorporates distance-based weighting into the traditional
polynomial fitting, and employs a look-up table to absorb the remaining distortion residuals. Validated on simulated data from the Main Survey Camera of the Chinese Space Station Survey
Telescope (CSST), incorporating
geometric distortions up to approximately $200$ pixels, the method achieves astrometric standard deviation ranging from 0.013 to 0.107 pixels (0.03 pixels for the $g$-1 detector) across all 18 detectors. Under extreme crowding conditions (e.g., globular cluster NGC 2298), the astrometric precision for the $g$-1 detector reaches 0.05-pixel level within the central region ($r_d < 4000$), despite a centroiding precision of $\sim$0.04 pixels. When applied to the Beijing-Arizona Sky Survey data, for which the standard pipeline delivers an astrometric uncertainty of $\sim$20 mas, our method reduces the positional scatter to $ \sigma_{\Delta\alpha}=5.494$ mas (0.01 pixels) and $ \sigma_{\Delta\delta}=9.981$ mas (0.02 pixels) using only a weighted 3rd-order
polynomial correction. The method has been integrated into the CSST data processing pipeline and is prepared for further refinement using on-orbit calibration data.
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All authors Yibo Yan, You Wu, Jundan Nie, Tianmeng Zhang, Chao Liu, Zhang Ban, Zihuang Cao, Wei Du, Yuedong Fang, Yi Hu, Guoliang Li, Xiaobo Li, Chenxiaoji Ling, Jiaqi Lin, Dezi Liu, Yu Luo, Bin Ma, Xianmin Meng, Juanjuan Ren, Li Shao, Hao Tian, Chengliang Wei, Peng Wei, Shoulin Wei, Yun-Ao Xiao, Zhou Xie, Su Yao, Yan Yu, Shengwen Zhang, Xin Zhang, Bowei Zhao, Zhimin Zhou, Hu Zou
High Energy Astrophysical Phenomena
HAWC J0630+186 Could Not Be Powered by PSR J0630+19
Bojun Wang, Xiaohong Cui, Jiguang Lu et al. (+2 more)
3HWC J0630+186 is one of the very-high-energy gamma-ray sources in the third High-Altitude Water Cherenkov (HAWC) catalog, its origin and source are, however, not clearly identified. The only possible associated source is PSR J0630+19 depart from the center of 3HWC J0630+186. A few TeV
halos of
pulsars are currently believed the most dominant TeV-PeV gamma-ray sources, and PSR J0630+19 was firstly discovered by Arecibo survey with normal
pulsar period, but its age and
spin-down luminosity are not available. It is then difficult to determine if 3HWC J0630+186 and PSR J0630+19 are associated or not. With the awarded
telescope time in five-hundred-meter aperture spherical
radio telescope (FAST) observing cycle, we have obtained the follow-up timing observations of PSR J0630+19 with observed duration more than one year. From our
pulsar data analysis, we determined a more precise position and derived parameters via
pulsar timing. The parameters indicate that it is an old
pulsar with energy loss too low to power the very-high-energy emissions from 3HWC J0630+186.
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All authors Bojun Wang, Xiaohong Cui, Jiguang Lu, Heng Xu, Renxin Xu
High Energy Astrophysical Phenomena
Detection of afterglow emission up to 100 GeV through a stacking analysis of gamma-ray bursts
Shi Chen, Qiang Yuan, Yi-Qing Guo et al. (+3 more)
High-energy gamma-ray (>GeV) emission of gamma-ray bursts (GRBs) is very important in probing the jet
evolution and particle acceleration of GRBs. The observations of high-energy
photons are limited except for a few very bright GRBs, hindering precise measurements of the spectral and temporal evolutions of GRBs. Here we report the detection of high-energy gamma-ray emission up to 100 GeV with
Fermi-LAT using a stacking analysis of a collection of 330 GRBs. High significance detection of the emission has been found, and the precise light curves and energy spectra can be measured. The light curves and time-resolved spectra of the sub-sample of 220 LAT individually detected GRBs can be well explained by the standard afterglow emission from a population of GRBs with both synchrotron and synchrotron self-Compton mechanisms, assuming a distribution of initial Lorentz factors. However, the emission of the relatively weak sample of the 110 LAT individually undetected GRBs cannot be well reproduced in the same framework, indicating the existence of possible energy injection effect in the GeV band for the first time. The observations hence provide new insights in understanding the high-energy emission of GRBs.
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All authors Shi Chen, Qiang Yuan, Yi-Qing Guo, Ben-Zhong Dai, He Gao, Bing Zhang
Instrumentation and Methods for Astrophysics
Characterizing the Instrumental Profile of LAMOST
Qian Liu, Zhongrui Bai, Ming Zhou et al. (+9 more)
The instrumental profile (IP) of a
telescope is of great significance for spectroscopic analyses, especially for wavelength calibration and
stellar parameter measurements. The Large Sky Area Multi-Object Fiber Spectroscopic
Telescope (LAMOST) employs arc lamps for wavelength calibration. These lamps produce sharp emission lines with known wavelengths, and the observed arc lamp spectra can well characterize the IP. However, IPs are influenced by multiple factors, making them difficult to model accurately with traditional methods. Neural networks, which can automatically capture complex patterns and nonlinear features in data, provide a promising approach for high-precision IP measurement. We therefore construct a multi-layer perceptron (MLP) based on The Payne neural network to derive IPs for LAMOST. After training, the model can retrieve the IP for any fiber, at any wavelength, and at any time. We then apply the derived IP to
stellar radial velocity (RV) measurements and analyze the impact of different IP center localization methods on the results. Finally, the dispersion of the measured RVs is reduced by approximately 3 km/s. This improvement will facilitate the search for long-period binary
stars via RV variations.
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All authors Qian Liu, Zhongrui Bai, Ming Zhou, Mingkuan Yang, Xiaozhen Yang, Ziyue Jiang, Hailong Yuan, Ganyu Li, Yuji He, Mengxin Wang, Yiqiao Dong, Haotong Zhang
Solar and Stellar Astrophysics
Modern Rate-of-Decline Relations for Novae
Allen W. Shafter
A large sample of $t_2$ and $t_3$ times from the recent compilation of nova properties given in Schaefer (2025) have been analyzed to determine relationships between these two parameters. Fits were performed in both directions (from $\log t_2$ to $\log t_3$ and vice-versa) to account for the asymmetry inherent in ordinary least-squares regression, which minimizes residuals only in the dependent variable. The following best-fit relations were found: $\log t_3 = (0.877\pm0.019) \log t_2 + (0.444\pm0.027)$, and $\log t_2 = (1.018\pm0.023) \log t_3 - (0.316\pm0.037)$, corresponding to $t_3 = (2.78\pm0.17)~t_2^{(0.877\pm0.019)}$ and $t_2 = (0.483\pm0.041)~t_3^{(1.018\pm0.023)}$, respectively. Within the uncertainties, the latter relation reduces to a simple proportionality: $t_2 \simeq 0.5~t_3$.
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Instrumentation and Methods for Astrophysics
POLISH'ing the Sky: Wide-Field and High-Dynamic Range Interferometric Image Reconstruction with Application to Strong Lens Discovery
Zihui Wu, Liam Connor, Samuel McCarty et al. (+1 more)
Radio interferometry enables high-resolution imaging of astronomical
radio sources by synthesizing a large effective aperture from an array of
antennas and solving a deconvolution problem to reconstruct the image. Deep learning has emerged as a promising solution to the imaging problem, reducing computational costs and enabling super-resolution. However, existing DL-based methods often fall short of the requirements for real-world deployment due to limitations in handling high dynamic range, large field of view, and mismatches between training and test conditions. In this work, we build upon and extend the POLISH framework, a recent DL model for
radio interferometric imaging. We introduce key improvements to enable robust reconstruction and super-resolution under real-world conditions: (1) a patch-wise training and stitching strategy for scaling to wide-field imaging and (2) a nonlinear arcsinh-based intensity transformation to manage high dynamic range. We conduct comprehensive evaluations using the T-RECS simulation suite with realistic sky models and point spead functions (PSF), and demonstrate that our approach significantly improves reconstruction quality and robustness. We test the model on realistic simulated strong gravitational lenses and show that lens systems with Einstein radii near the PSF scale can be recovered after deconvolution with our POLISH model, potentially yielding 10$\times$ more
galaxy-
galaxy lensing systems from the Deep Synoptic Array (DSA) survey than with image-plane CLEAN. Our results highlight the potential of DL models as practical, scalable tools for next-generation
radio astronomy.
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All authors Zihui Wu, Liam Connor, Samuel McCarty, Katherine L. Bouman
Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc
Binary Black Hole inspirals cannot hide their eccentricity
Johann Fernandes, Praveer Tiwari and Archana Pai
The events detected by the LIGO Virgo KAGRA collaboration over a period of 10 years have yielded a treasure trove of signals from compact binary coalescences. None of these events have shown a confident signature of eccentricity. With upgrades to the existing network and potential next generation gravitational wave detectors, we will be able to see much further into the universe increasing the likelihood of detecting eccentric systems. We improve upon the phenomenological approach of providing eccentricity constraints using an effective chirp mass model in the time frequency domain. We introduce an improved pixel collection method along with a likelihood based sampling approach inspired by
Bayesian parameter estimation. Our approach constructs a likelihood from the product of energies collected across different eccentric harmonics in the time frequency representation. This formulation enables coarse but meaningful constraints on orbital eccentricity. Additionally, we incorporate information from the energy ratios between eccentric harmonics, further refining the eccentricity estimates. We test our approach on 500 non spinning equal mass eccentric systems and demonstrate that we can constrain the eccentricity within 0.2 around the true value. Moreover, our approach can deliver these constraints in 5 minutes on a machine with 50 cores. These results demonstrate that our phenomenological approach provides fast and reasonably accurate eccentricity estimates, making it a promising tool for rapid gravitational wave data analysis.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Dual Cutler-Vallisneri Corrections: Mitigating PSD Drift in Zero-Latency Gravitational-Wave Searches
James Kennington
Maximizing pre-merger warning times in gravitational-wave searches requires minimizing algorithmic latency. While current pipelines typically rely on truncated linear-phase filters, minimum-phase whitening offers a zero-latency alternative that eliminates the acausal look-ahead buffer. However, this causal approach exposes the analysis to spectral drift, where the whitening operator applied to live data diverges from the static template bank, creating a functional perturbation of the matched-filter metric. We develop a perturbative framework generalizing the Cutler-Vallisneri formalism to address these metric errors, deriving analytic expressions for the resulting timing, phase, and SNR biases. Validated against exact stationary-phase models and numerical injections, these corrections achieve $<1\%$ error. Applying this framework to GWTC-4.0 events with realistic 1-week power spectral density (PSD) lags, we find that uncorrected drift induces severe systematics: detector-pair timing biases exceeding $200 \mu$s, phase shifts up to 0.2 rad, and sky-localization errors of $5^{\circ}-10^{\circ}$. Additionally, we observe a median signal-to-noise ratio (SNR) loss of $3-5\%$, with outliers exceeding $8\%$. These results demonstrate that while minimum-phase whitening maximizes the early-warning window, analytic drift corrections are essential to maintain detection volume and pointing accuracy in future observing runs.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Dark matter in classically conformal theories: WIMP and supercooling
Ke-Pan Xie and Cheng-Hao Zhan
Beyond solving the hierarchy problem, classically conformal (CC) theories naturally accommodate dark matter (DM). In this work, we explore the CC $SU(2)_X$ gauge theory with a triplet dark scalar, uncovering two distinct DM scenarios: weakly interacting massive particle (WIMP) and supercooled DM. The production mechanisms are strongly influenced by the CC model's unique first-order phase transition
evolution history, which differs significantly from those in non-conformal models. We obtain the viable parameter space for each scenario and investigate the current constraints and future sensitivities at experiments, demonstrating that gravitational wave signals from the phase transition provide a common detection channel for both the WIMP and supercooled DM regimes.
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High Energy Astrophysical Phenomena
Dynamics of thin accretion disks and accretion around a charged-PFDM black hole
Taiyang Zhang, Zhongyuan Qin, Qian Feng et al. (+1 more)
This paper investigates the dynamical behavior of steady spherical
accretion onto a static, magnetically charged black hole embedded in a perfect fluid dark matter (PFDM) background. Using the shadow observations of M87* from the Event Horizon
Telescope (EHT), we establish constraints on the parameter space for the
magnetic charge and the PFDM parameter. Within this constrained range, we analyze the orbital dynamics of particles in a thin
accretion disk surrounding the black hole and find that the black hole parameters significantly influence the effective potential, angular velocity, specific energy, and specific angular momentum of the particles. Subsequently, we calculate the radiative energy flux, temperature profile, and observed spectrum of the disk. Our results show that, while the local radiative flux and temperature at a given radius are lower for the charged-PFDM black hole compared to a Schwarzschild black hole, its overall radiative efficiency and total luminosity are higher. Finally, we explore the spherically symmetric, steady-state
accretion process around the black hole, revealing how the parameters govern how the fluid velocity, density profile, and black hole mass
accretion rate are influenced.
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All authors Taiyang Zhang, Zhongyuan Qin, Qian Feng, Zheng-Wen Long
Earth and Planetary Astrophysics
The Influence of Clouds and Deuterium-Burning on Brown Dwarf Habitable Zones
Kayla J. Smith and Mark S. Marley
To better understand the potential habitability of
planets orbiting brown
dwarfs, this work presents a new set of
equilibrium temperature
evolution tracks. Unlike most previous work that relied on analytic scaling relationships for brown
dwarf luminosity
evolution, we use the outputs of modern brown
dwarf evolution models that account for the effects of deuterium burning, cloud formation and dissipation, and the most recent atmospheric opacities. While clouds are present, brown
dwarfs cool more slowly than if they did not have clouds, allowing orbiting
planets to remain in the habitable zone (HZ) for millions of years longer than previously estimated. Similarly, we find that during the deuterium-burning phase of brown
dwarfs, which also slows the
evolution,
planets at the same orbital radius but orbiting brown
dwarfs of different masses can remain in the HZ for the same duration, creating deuterium “sweet spots” for habitability around brown
dwarfs near the deuterium-burning limit. For example, at 0.01 au a
planet orbiting both a 0.012 and a 0.020
solar mass brown
dwarf stays in the HZ for ~170 - 180 Myr because deuterium-burning more strongly affects the cooling of lower-mass brown
dwarfs. The size of the effect decreases with decreasing orbital radius, with larger orbital radii having a more pronounced deuterium burning influence. These effects are absent from the analytic cooling approximations used in prior studies of substellar HZs and are revealed by our application of modern substellar
evolution models.
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High Energy Astrophysical Phenomena
Time-dependent photospheric radiative transfer in structured GRB jets: spectral evolution and polarization diagnostics
Yue Xu, Ming Jin and Qingwen Tang
Photospheric emission from relativistic gamma-ray burst (GRB) jets is a promising mechanism for producing the Band-like spectra observed in the
prompt phase, yet the connections between jet structure, dissipation location, and polarization signatures remain unclear.We investigate time-dependent photospheric radiation transfer in structured relativistic jets by coupling two-dimensional axisymmetric special relativistic hydrodynamic (SRHD) simulations with Monte Carlo
photon propagation.
Photon escape and subphotospheric dissipation are characterized using the residual line-of-sight optical depth tau_out evaluated along each
photon trajectory, allowing a direction-dependent treatment of
photon decoupling in structured jets. The radiative transfer includes Klein-Nishina Compton scattering and polarization
evolution using the Mueller
matrix formalism.We perform a systematic parameter study exploring the effects of viewing angle, electron-positron pair loading (Zpm), and the optical-depth window of subphotospheric dissipation. The model produces time-resolved spectra, peak-energy
evolution Epk(t), Band parameters, polarization degree Pi(E,t), and last-scattering statistics.We find that jet angular structure and the geometry of the line-of-sight optical depth strongly regulate spectral
evolution and polarization signatures. The dissipation depth and pair loading jointly control the stability of Epk, the formation of high-energy spectral tails, and the energy dependence of polarization. These results provide quantitative predictions for GRB
prompt-emission spectra and polarization that can be tested with current and upcoming high-energy polarimeters.
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Earth and Planetary Astrophysics
Two Low Mass-Ratio Microlensing Planets and Two Types of Central-Resonant Degeneracy
Yuchen Tang, Weicheng Zang, Yoon-Hyun Ryu et al. (+39 more)
We present observations and analysis of two low
planet/host mass-ratio ($q$) microlensing
planets discovered in high-magnification events. KMT-2025-BLG-0811Lb has $q \sim 4.5 \times 10^{-5}$, and a
Bayesian analysis favors a super-Earth/mini-Neptune orbiting an M- or K-
dwarf host at a projected separation of $\sim 3$ au. KMT-2025-BLG-0912Lb has $q = 2.6 \times 10^{-4}$ and likely hosts a super-Earth/mini-Neptune around either a low-mass M
dwarf or a brown
dwarf at $\sim 1$ au. Even with an observing cadence of $\Gamma > 30~{\rm hr}^{-1}$ during the planetary signal, KMT-2025-BLG-0811 still exhibits the "central-resonant" degeneracy. Reviewing nine such events, we find that the "central-resonant" degeneracy can be divided into two distinct types that occupy separate regions in the plane of $q$ and normalized source radius ($\rho$). Type~I events have similar $q$ but substantially different $\rho$ and are more difficult to resolve from the light curves. For Type~II events, the "resonant" solutions have relatively lower $q$ and larger $\rho$. Our review provides guidance for searching for the alternative solution once one solution has been identified.
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All authors Yuchen Tang, Weicheng Zang, Yoon-Hyun Ryu, Andrzej Udalski, Hongjing Yang, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Dong-Jin Kim, Chung-Uk Lee, Byeong-Gon Park, Leandro de Almeida, Yunyi Tang, Zhixing Li, Jiyuan Zhang, Hongyu Li, Shude Mao, Qiyue Qian, Dan Maoz, Christian Elias Borges, Fabrício Santos Kalaki, Altair Ramos Gomes Júnior, Wei Zhu, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radosław Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof A. Rybicki, Patryk Iwanek, Krzysztof Ulaczyk, Marcin Wrona, Mariusz Gromadzki, Mateusz J. Mróz