Instrumentation and Methods for Astrophysics · Cross-listed from cs.AI
Natural Language-Driven Global Mapping of Martian Landforms
Yiran Wang, Shuoyuan Wang, Zhaoran Wei et al. (+7 more)
Planetary surfaces are typically analyzed using high-level semantic concepts in natural
language, yet vast orbital image archives remain organized at the pixel level. This mismatch limits scalable, open-ended exploration of planetary surfaces. Here we present MarScope, a planetary-scale
vision-
language framework enabling natural
language-driven, label-free mapping of Martian landforms. MarScope aligns planetary images and text in a shared semantic space, trained on over 200,000 curated image-text pairs. This framework transforms global geomorphic mapping on Mars by replacing pre-defined classifications with flexible semantic
retrieval, enabling arbitrary user queries across the entire
planet in 5 seconds with F1 scores up to 0.978. Applications further show that it extends beyond morphological classification to facilitate process-oriented analysis and similarity-based geomorphological mapping at a planetary scale. MarScope establishes a new paradigm where natural
language serves as a direct interface for scientific discovery over massive geospatial
datasets.
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All authors Yiran Wang, Shuoyuan Wang, Zhaoran Wei, Jiannan Zhao, Zhonghua Yao, Zejian Xie, Songxin Zhang, Jun Huang, Bingyi Jing, Hongxin Wei
Earth and Planetary Astrophysics
A 2 au resolution view by ALMA of the planet-hosting WISPIT 2 disk
Stefano Facchini, Pietro Curone, Myriam Benisty et al. (+4 more)
We present deep, high spatial resolution interferometric observations of 0.88 mm continuum emission from the TYC 5709-354-1 system, hereafter WISPIT 2, obtained with the goal of detecting circumplanetary emission in the vicinity of the newly discovered WISPIT 2b
planet. Observations with the most extended baseline configuration offered by ALMA, achieving an angular resolution of $25 \times 17$ mas ($3.3 \times 2.2$ au), revealed a single, narrow ring with a deprojected radius of 144.4 au and width of 7.2 au, and no evidence of circumplanetary emission within the cavity. Injection and recovery tests demonstrate that these observations can rule out point-like emission at the location of WISPIT 2b brighter than $\approx 45$ $\mu$Jy at the $3\sigma$ level. While these data can rule out PDS 70c like circumplanetary emission, the upper limit is consistent with empirical mass-flux relationships extrapolated from the
stellar regime. Visibility modeling of the continuum ring confirms that WISPIT 2b lies significantly interior to the mm
dust ring, raising doubts about the ability of WISPIT 2b to be the only driver of the
dust structure. Possible solutions include either another lower mass companion, residing between WISPIT 2b and the cavity edge, likely in the gap seen by SPHERE at $\sim130$ au, or that WISPIT 2b is either substantially more massive than IR-photometry based estimates ($\sim15$ $M_{\rm Jup}$) or on a moderately eccentric orbit. The combination of observations sensitive to the gas and
dust distributions on larger spatial scales and dedicated hydrodynamical modeling will help differentiate between scenarios.
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All authors Stefano Facchini, Pietro Curone, Myriam Benisty, Francesco Zagaria, Richard Teague, Gabriele Cugno, Jaehan Bae
Cosmology and Nongalactic Astrophysics
Validating Digital Twins of the Local Universe with the Thermal Sunyaev-Zel'dovich Signal
Richard Stiskalek and Harry Desmond
The thermal Sunyaev-Zel'dovich (tSZ) effect provides a powerful probe of the thermal pressure of ionised gas in
galaxy clusters and the
cosmic web; constrained simulations reconstruct the mass and velocity fields of the local Universe. We explore how these two may be mutually informative: the tSZ signal provides a
benchmark for assessing the fidelity of constrained simulations, and constrained simulations contribute information on the positions, total masses and density profiles of
cosmic web structures for use in tSZ studies. We focus on cluster predictions in the
Bayesian Origin Reconstruction from
Galaxies (BORG) paradigm, introducing CSiBORG-Manticore, a new state-of-the-art suite of digital twins – data-constrained posterior simulations whose initial conditions are inferred via
Bayesian forward modelling. We develop a framework for scoring constrained simulations on their ability to match measured Planck Compton-$y$ maps around clusters, and use it to demonstrate improvement from previous BORG reconstructions. We further validate
halo masses against weak-
lensing-calibrated X-ray masses from eROSITA. We also show how high-fidelity digital twins offer a practical route to extracting additional information from tSZ data through a novel calibration of the mass-observable relation, and provide a complementary framework to purely statistical analyses of Compton-$y$ maps. This paves the way for integrating the large-scale structure information inherent in constrained simulations into the study of CMB secondary anisotropies.
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Earth and Planetary Astrophysics
Hot and cloudy: High temperature clouds in super-Earths and sub-Neptunes
Leoni J. Janssen, Yamila Miguel, Michiel Min et al. (+3 more)
JWST observations provide for the first time evidence for an atmosphere on a rocky
exoplanet - 55 Cnc e. The atmosphere of 55 Cnc e is hot with $\text{T}_{\text{eq}}>2000$K and shows strong variability, for which cloud formation above a molten crust could be one possible explanation. The composition of the atmosphere of 55 Cnc e is still unknown but suggests the presence of volatiles. We have run cloud formation models on a grid of N-dominated, O-dominated, C-dominated and H-dominated atmospheres to investigate which type of cloud we could expect on hot super-Earths and hot sub-Neptunes ($1000$K $<$ T $<$ $3000$K). Our models combine radiative transfer with
equilibrium chemistry of the gaseous and condensed phases, vertical mixing of condensable species, sedimentation, nucleation and coagulation. We find that the condensability of species is highly dependent on the oxygen abundance of an atmosphere. Oxygen poor atmospheres can be heated by UV and optical absorbers PS, TiO and CN which create temperature inversions. These inhibit condensation. Oxygen rich atmospheres are colder without temperature inversions, and are therefore more favourable environments for cloud formation. The major expected cloud component in O-dominated atmospheres with
solar refractory abundance is TiO$_2$(s). Spectral features of clouds in these worlds are stronger in transmission than in emission, in particular at short wavelengths. We find a lack of optical data of solid species in comparison to the variety of stable cloud components which can form on hot, rocky
planets.
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All authors Leoni J. Janssen, Yamila Miguel, Michiel Min, Helong Huang, Mantas Zilinskas, Christiaan P. A. van Buchem
Solar and Stellar Astrophysics
Out-of-Sample Validation of MagNet
Aryiadna Yesmanchyk, Yan Xu, Jason T. L. Wang et al. (+3 more)
Machine learning is starting to be used in almost every industry and academic research, and
solar physics is no exception. A newly developed machine learning model named MagNet helps us to tackle some of the most serious challenges in data mining by generating transverse fields of
solar active regions. Being trained on line-of-sight magnetograms from Michelson Doppler Imager at
Solar and Heliospheric Observatory (SOHO/MDI), H{\alpha} maps from Big Bear
Solar Observatory and Kanzelhohe
Solar Observatory and vector magnetograms from Helioseismic and
Magnetic Imager at
Solar Dynamic Observatory (SDO/HMI), this model provides vector magnetograms in active regions for SOHO/MDI data covering the strong
solar cycle 23. In this study, we performed out-of-sample validation of the MagNet model with data from Imaging Vector Magnetograph (IVM) at Mees
Solar Observatory, which was not included in the training process. Our results show good correlation between the AI generated data and the observed vector magnetograms and therefore strengthen the confidence of implementing MagNet to the entire SOHO/MDI archive and future scientific analysis of the AI generated data.
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All authors Aryiadna Yesmanchyk, Yan Xu, Jason T. L. Wang, Haodi Jiang, Chunhui Xu, Haimin Wang
Solar and Stellar Astrophysics
Does the solar oxygen abundance change over the solar cycle? An investigation into activity-induced variations of the O I infrared triplet
A.G.M. Pietrow, M. Baratella, I.V. Ilyin et al. (+2 more)
The determination of the
solar oxygen abundance remains a central problem in astrophysics, as its accuracy is limited not only by models but also by systematics. While many of these factors have been thoroughly characterized, the effect of the
solar activity cycle has so far remained unexplored. Due to its relative strength and accessibility, the O I infrared triplet is typically the primary choice for abundance studies. However, previous investigations have shown that abundances inferred from this triplet tend to be higher than expected on active
stars, whereas such an overabundance effect is not observed for the much weaker forbidden O I 6300 Å line. This raises the question of whether a similar trend can be found for the Sun. To address this question, we analyze two decades' worth of synoptic disk-integrated Sun-as-a-
star datasets from the FEROS, HARPS-N, PEPSI, and NEID spectrographs, focusing on the infrared triplet (7772, 7774, 7775 Å) and the forbidden O I 6300 Å line. The excellent signal-to-noise ratio of the PEPSI observations allows us to detect a weak but significant variation in the equivalent widths of the infrared triplet, corresponding to about 0.01 dex difference in abundance between activity minimum and maximum. This value is significantly smaller than the typical uncertainties on the
solar oxygen abundance. Due to higher scatter, no comparable trend is found in the other data sets. Based on these results, we conclude that within the typical uncertainties presented in other works, we can assume the inferred
solar oxygen abundance to be stable across the
solar cycle, but that this effect may be significant for other, more active
stars.
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All authors A.G.M. Pietrow, M. Baratella, I.V. Ilyin, M. Steffen, K. G. Strassmeier
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
H. B. Câmara, A. Smetana and A. A. Tursunov
We study parity-violating birefringence induced by an asymmetric
neutrino background in
plasmas associated with active
galactic nuclei (AGN). We derive a directionality factor arising from the relative bulk motion between the
neutrino medium and
plasma, and show that it can produce an anomalous frequency dependence of the polarization-rotation angle, distinct from the $\omega^{-2}$ scaling of Faraday rotation. This anomalous scaling can occur either at the resonance
plasma frequency condition $\omega \simeq \omega_p$, or when $E_\nu^{0}\simeq m_\nu \omega/\omega_p$ lies within the range of the
neutrino energy spectrum. We estimate the effect for three scenarios: jets propagating through the
cosmic neutrino background (C$\nu$B), jets with an internal flux of high-energy
neutrinos, and
accretion-disk
plasma permeated by the C$\nu$B. Of the three scenarios, the latter gives the largest rotation angle $\phi_{\rm d} \sim 10^{-35}\,\mathrm{rad}$, at X-ray frequencies. Although the predicted rotation angles are below current polarimetric sensitivity, the identified spectral signatures provide a theoretical framework for probing
neutrino asymmetries and AGN
plasma properties independent of
magnetic field models.
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Cosmology and Nongalactic Astrophysics
Intrinsic alignments in the FLAMINGO simulations with two-point statistics
A. Herle, N. E. Chisari, H. Hoekstra et al. (+3 more)
Intrinsic
alignments are a major astrophysical contaminant for next generation large-sky surveys like Euclid and LSST. Large hydrodynamic simulations are crucial for informing the
alignment modelling for these surveys. We measure position-position and position-shape correlations of a Luminous Red
Galaxy sample from the FLAMINGO suite of hydrodynamical simulations, measuring the
alignment signal for more than 4.9 million
galaxies at
redshift 0. We jointly model the clustering and
alignment correlations to provide the tightest constraints on the
alignment amplitude to date from a hydrodynamic simulation. We find that both the Non-Linear
Alignment (NLA) and the more complex
Tidal Alignment Tidal Torquing (TATT) models provide good fits to the data. We compare the measured $A_1$ amplitude to observational data and find good agreement. We measure the dependence of the NLA and TATT free parameters on
halo mass. We also introduce a mass-dependent TATT model, TATT-M, by finding empirical relations between the
halo mass and the TATT parameters. This allows us to fit TATT with only one parameter, $A_1$, with $A_2/A_1$ being a constant and $A_{1\delta}/A_1$ being a function of
halo mass. Using a
Bayesian approach, we find that TATT-M is very strongly preferred by the data over NLA. Using the baryonic feedback variations of the FLAMINGO simulation suite, we test whether the TATT parameters are sensitive to feedback. Variations in AGN and
supernova feedback do not significantly change the
alignment amplitude beyond the change associated with the dependence of
galaxy stellar mass on the strength of feedback. Our results inform the IA modelling for upcoming surveys by providing guidance on model choices, priors and sensitivities to feedback.
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All authors A. Herle, N. E. Chisari, H. Hoekstra, D. Navarro-Gironés, M. Schaller, J. Schaye
Instrumentation and Methods for Astrophysics
Radio-Interferometric Image Reconstruction with Denoising Diffusion Restoration Models
Michel Morales, Emma Tolley and Remi Poitevineau
Reconstructing images of the
radio sky from incomplete
Fourier information is a key challenge in
radio astronomy. In this work, we present a method for
radio interferometric image reconstruction using a data-driven prior for the
radio sky based on denoising
diffusion probabilistic models (DDPMs). We train a DDPM on
radio galaxy observations from the VLA FIRST survey, then create simulated VLBA, EHT, and ALMA observations of
radio galaxies. We use an unsupervised posterior sampling method called Denoising
Diffusion Restoration Models (DDRM) to reconstruct the corresponding images using our DDPM as a prior. Our approach naturally incorporates the PSF of the instrument. We are able to reconstruct images with very high fidelity and demonstrate a marked improvement over CLEAN and MS CLEAN. While DDRM naturally produces multiple samples, these are not calibrated and do not constitute reliable uncertainty estimates in the current implementation. The code for training and inference of the model is available at https://github.com/epfl-
radio-astro/diffusionRI.git
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Instrumentation and Methods for Astrophysics · Cross-listed from physics.hist-ph
Determination of the longitude difference between Baghdad and Khwarezm using a lunar eclipse (the method of Abu Rayhan al-Biruni and Abu al-Wafa al-Buzjani)
Rizoi Bakhromzod
This paper examines how, in the tenth century, medieval Iranian scholars Abu Rayhan al-Biruni and Abu al-Wafa al-Buzjani determined the difference in geographical longitude between the cities of Baghdad and Khwarezm through simultaneous observation of a lunar eclipse. Brief academic biographies of these scholars are presented, with emphasis on their contributions to mathematics and astronomy. The study discusses the importance of determining geographical coordinates - especially longitude - in the science of the 10th-11th centuries, provides an overview of the methods of coordinate determination available at the time, and highlights the problem of synchronizing remote observations prior to the advent of electronic communication. Particular
attention is devoted to a detailed analysis of the method based on observing a lunar eclipse to simultaneously measure longitude differences: the necessary conditions and organization of the experiment, the instruments employed, the mathematical calculations, and error estimates are described. The longitude difference obtained by al-Biruni and al-Buzjani is compared with modern values. The conclusion discusses the scientific significance of this method for the history of science and astronomy.
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Solar and Stellar Astrophysics
Failed ejection and oscillations of a current-carrying filament balanced by gravity
P. Jelínek, M. Karlický and S. Belov
In this study, we investigate the post-destabilization
evolution of a filament in a
gravity-balanced model. We adopt the filament model proposed by Solov'ev (2010), in which a dense filament is supported against
gravity by the repulsive force between the filament current and its sub-photospheric image. We first performed an analytical investigation of this model. For the numerical study, we use a two-dimensional magnetohydrodynamic (MHD) model that solves the MHD equations with the Lare2d numerical code. Results: In this filament model, analytical expressions are derived for the electric current density,
plasma density, and their spatial distributions as functions of the model parameters. The total electric current and the filament weight are also calculated. For the numerical simulations, we constructed an
equilibrium filament characterized by a
magnetic field of $B_0$ = $10^{-3}$ T, mass density $\rho_0$ ~ 1.3 x $10^{-9}$ kg m$^{-3}$, and temperature T ~ 13000 K. The system was destabilized either by increasing the currents or by reducing the filament density, and its
evolution was computed. In both destabilization regimes, the filament was ejected, then halted at a certain altitude, and subsequently fell back, repeating this cycle with a period of about 600 s. The maximum filament ejection velocity was approximately 80 and 40 km $s^{-1}$, respectively. Beneath the ejected filament a current sheet forms, where
magnetic reconnection occurs. The maximum ejection altitudes were determined as functions of both the destabilizing currents and the degree of filament
plasma dilution. Finally, we compared results of this MHD model with those of an ideal
vacuum model and discussed all results.
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Instrumentation and Methods for Astrophysics
Distance-Independent Atmospheric Refraction Correction for Accurate Retrieval of Fireball Trajectories
Jaakko Visuri, Maria Gritsevich and Janne Sievinen
Accurate determination of fireball direction is essential for retrieving trajectories and velocities. Errors in these measurements have significant implications, affecting the calculated pre-impact orbit, influencing mass estimates, and impacting the accuracy of dark flight simulations, where applicable. Here we implement a new atmospheric refraction correction technique that addresses a significant aspect previously overlooked in the field of meteor science. Traditional refraction correction techniques, originally designed for objects positioned at infinite distances, tend to overcompensate when applied to objects within the Earth's atmosphere. To rectify this issue, our study introduces the concept of the atmospheric refraction delta z correction technique, involving the artificial elevation of the observer site height above sea level. We utilize analytically derived formulas for the delta z correction in conjunction with commonly used refraction models, validating these results against a numerical solution that traces light rays through the atmosphere. This ray-tracing model is applied to finely meshed atmospheric layers, yielding precise correction values. We evaluate multiple sources of error in order to quantify the achievable accuracy of the proposed method. Our approach (1) enables the determination of fireball positions with improved astrometric accuracy, (2) removes the explicit dependence on the fireball distance from the observer or its height above Earth's surface within the limits imposed by realistic atmospheric variability, and (3) simplifies meteor data processing by providing a robust framework for analyzing low-elevation fireball observations, for which atmospheric refraction is significant and is automatically corrected by the method. As a result of this work, we provide open, publicly accessible software for calculating the delta z correction.
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Astrophysics of Galaxies
Deuteration of HC3N and CH3CCH in the pre-stellar core L1544
K. Giers, S. Spezzano, Y. Lin et al. (+2 more)
Deuterated molecules are a useful diagnostic tool to probe the
evolution and the kinematics in the earliest stages of
star formation. Due to the low temperatures and high densities in the centre of pre-
stellar cores, the deuterium fraction is enhanced by several orders of magnitude. We study the distribution of the emission and the deuteration of the two carbon chains HC3N and CH3CCH throughout the pre-
stellar core L1544. We analyse emission maps of CH3CCH, CH2DCCH, CH3CCD, HC3N, HCC13CN, and DC3N, observed with the IRAM 30m single-dish
radio telescope. We use non-LTE radiative transfer calculations, combined with chemical modelling of the molecular abundances, to constrain physical parameters of the observed species. Following this, we derive the column density and deuteration maps. We find D-fractions of N(DC3N)/N(HC3N)=0.04-0.07, N(CH2DCCH)/N(CH3CCH)=0.09-0.15, and N(CH3CCD)/N(CH3CCH)=0.07-0.09. The deuteration of HC3N appears homogeneous across the core, with widespread D-fraction values above 0.06, tracing intermediate-density gas in the outer layers of the core. CH3CCD is most efficiently formed in the higher-density regions towards the core centre, while the D-fraction of CH2DCCH traces a local density enhancement in the north-east of the core, coinciding with the CH3OH emission peak. The results suggest that gas-phase reactions dominate the formation and deuteration of both HC3N and CH3CCH in L1544, with spatial variations driven by physical structure, density and external radiation. The significantly higher D-fraction of CH2DCCH compared to CH3CCD and a tentative gradient with higher values in the north suggest different deuteration mechanisms for the two functional groups. Similarities between the CH2DCCH emission and CH2DOH might indicate an additional deuteration pathway of CH3CCH on the surfaces of
dust grains, as observed for H2CO.
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All authors K. Giers, S. Spezzano, Y. Lin, P. Caselli, O. Sipilä
Cosmology and Nongalactic Astrophysics
Redshift-binned constraints on the Hubble constant under $\Lambda$CDM, CPL, and Padé cosmography
Zhi-Yuan Mo, Kang Jiao and Tong-Jie Zhang
Motivated by recent claims of a possible
redshift dependence in late-Universe determinations of the Hubble constant (H_0), we test the robustness of this behavior using multiple cosmological probes. We perform a joint
redshift-binned analysis of H_0 across eight bins using late-Universe probes including Pantheon+ type Ia
supernovae, Dark Energy Spectroscopic Instrument
baryon acoustic oscillations,
cosmic chronometers, and water megamasers under three cosmological frameworks: flat Lambda cold dark matter, Chevallier-Polarski-Linder, and Pade cosmography. Under a common baseline scheme, all three models show a qualitatively similar low-amplitude variation in the per-bin H_0 estimates. A simple
Fourier-like parametrization captures this behavior, but the amplitude differs from zero only at a marginal significance of about 1.71-1.94 sigma, with similar behavior observed across all three cosmological frameworks. We then investigate the robustness and possible origin of this feature. Alternative binning schemes preserve its qualitative form, whereas single-probe per-bin fits (
supernova-only,
cosmic chronometer-only, BAO-only) yield ratios H_0,i / H_0,global mostly consistent with unity and do not reproduce the pronounced drift seen in the joint baseline constraints. Finally, by comparing different global versus piecewise-constant configurations for {H_0, Omega_m, M, r_d}, we find that a baselinelike oscillatory pattern reemerges only when multiple degenerate parameter combinations are allowed to vary across bins, while it is strongly suppressed when only H_0 is bin dependent. Taken together, these results indicate that the apparent oscillatory behavior of H_0(z) in late time arises from known parameter degeneracies and does not constitute robust evidence for a genuine
redshift evolution.
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Solar and Stellar Astrophysics
Nucleosynthesis in Type Ia Supernovae, Classical Novae, and Type I X-Ray Bursts. A Primer on Stellar Explosions
Jordi Jose
Nuclear astrophysics aims at unraveling the
cosmic origins of chemical elements and the physical processes powering
stars. It constitutes a truly multidisciplinary field, that integrates tools, advancements, and accomplishments from theoretical astrophysics, observational astronomy, cosmochemistry, and theoretical and experimental atomic and
nuclear physics. For instance, the advent of high-energy astrophysics, facilitated by space-borne observatories, has ushered in a new era, offering a unique, panchromatic view of the universe (i.e., allowing multifrequency observations of
stellar events); supercomputers are also playing a pivotal role, furnishing astrophysicists with computational capabilities essential for studying the intricate
evolution of
stars within a multidimensional framework; cosmochemists, through examination of primitive meteorites, are uncovering tiny fragments of stardust, shedding light on the physical processes operating in
stars and on the mechanisms that govern condensation of
stellar ejecta into solids; simultaneously,
nuclear physicists managed to measure
nuclear reactions at (or close to)
stellar energies, using both stable and radioactive ion beam facilities. This paper provides a multidisciplinary view on nucleosynthesis accompanying
stellar explosions, with a specific focus on thermonuclear
supernovae, classical novae, and type I X-ray bursts.
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High Energy Astrophysical Phenomena
GRB~250704B/EP250704a a Short Gamma-Ray Burst Powered by a Magnetar
Nissim Fraija, Antonio Galván, Boris Betancourt Kamenetskaia et al. (+1 more)
GRB~250704B/EP250704a, identified as a short gamma-ray burst (sGRB), exhibited prolonged X-ray emission following the
prompt phase and, in optical and infrared (IR) bands, an unusual one-day plateau succeeded by a rapid decline. This sGRB was observed by multiple satellites and ground-based observatories across the electromagnetic spectrum. This study presents temporal and spectral analyses from
radio to gamma-ray frequencies, spanning several observation periods beginning after the trigger and continuing for nearly 2 days. The results of the temporal and spectral analyses of the
prompt episode, the extended X-ray component, and the afterglow phase are consistent with a millisecond magnetar undergoing
accretion. The long-lasting X-ray emission is attributed to the internal energy dissipation of the magnetar
spin-down power, governed by the magnetization parameter; the extended optical/IR plateau to synchrotron afterglow emission with energy injection; and the steep decay to changes in microphysical parameters during the post-jet break phase. The X-ray observations are consistent with the superposition of
spin-down luminosity and synchrotron afterglow scenario. These findings suggest that the compact-object remnant is most likely a long-lived magnetar.
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All authors Nissim Fraija, Antonio Galván, Boris Betancourt Kamenetskaia, Maria G Dainotti
Solar and Stellar Astrophysics
Interaction between the ejecta, the accretion disk, and the secondary star in the recurrent nova system U Sco
Joana Figueira, Jordi Jose, Ruben Cabezon et al. (+1 more)
Most efforts in the modeling of recurrent novae have centered on the initial phases of the explosion and ejection, overlooking the subsequent interaction of the ejecta, first with the
accretion disk orbiting the white
dwarf and ultimately with the secondary
star. To address this gap, a series of 3D smoothed-particle hydrodynamics simulations was conducted. These simulations explored the dynamic interactions between the nova ejecta,
accretion disk, and
stellar companion within the framework of the recurrent nova system U Sco. Notably, the simulations incorporate rotation around the system's center of mass. The primary goal of these simulations was to qualitatively examine the impact of various model parameters, including ejecta mass, velocity, and density, as well as the mass and geometry of the
accretion disk. Simulations reveal complete disruption and sweeping of the
accretion disk orbiting the white
dwarf star for models with flared disks and Mejecta/Mdisk larger than 1. In contrast, V-shaped disks with a (constant) high initial density and Mejecta/Mdisk < 1 partially survive the impact with the nova ejecta. A very minor chemical contamination of the secondary
star is anticipated in the U Sco case based on the limited impact of nova ejecta particles on the subgiant in all simulations. Minor mass ejection from the subgiant's outer layers is observed during the late-stage collision with ejecta and disk material, with some particles ejected from the binary system and some accreted by the white
dwarf.
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All authors Joana Figueira, Jordi Jose, Ruben Cabezon, Domingo Garcia-Senz
Cosmology and Nongalactic Astrophysics
Fuzzy dark matter soliton core hosting a supermassive black hole as a dense low-mass perturber in strong gravitational lensing
Masamune Oguri and Naoi Kubo
Recent high-resolution imaging observations of strong lens systems reveal dense low-mass perturbers. We propose a
soliton core, whose central density is boosted by a supermassive black hole (SMBH), in the fuzzy dark matter (FDM) model as an efficient perturber in strong gravitational
lensing. The higher central density makes it less efficient in the
tidal mass loss, and leads to the higher impact in gravitational
lensing. We show that the mass profile of a $\sim 10^6M_\odot$ perturber in JVAS B1938+666, which does not resemble any known astronomical object, can be well explained by a
soliton core in the FDM model with the mass of $4\times 10^{-21}$eV hosting an SMBH with the mass of $4\times 10^5M_\odot$. The high mass of the SMBH may be explained by several scenarios that predict heavy SMBH seeds such as the direct collapse black hole formation and
primordial black holes.
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Solar and Stellar Astrophysics
Hydrodynamic simulations of the recurrent nova T Coronae Borealis: Nucleosynthesis predictions
Jordi Jose and Margarita Hernanz
T Coronae Borealis (T CrB) is one of the eleven known recurrent novae in our
Galaxy. It was observed in outburst in 1866 and 1946, with additional likely eruptions recorded in 1217 and 1787. Given its predicted recurrence period of approximately 80 yr, the next outburst is anticipated to occur imminently, thus motivating a thorough examination of the main characteristics of this system. We present new hydrodynamic models of the explosion of T CrB for different combinations of parameters (i.e., the mass, composition, and initial luminosity of the white
dwarf, the
metallicity of the accreted matter, and the mass-transfer rate). We show that mass-
accretion rates between 10-8 - 10-7 Msun yr-1 are required to trigger an outburst after 80 yr of
accretion of
solar-composition material onto white
dwarfs with masses about 1.30 - 1.38 Msun. For lower white
dwarf luminosities, less massive white
dwarfs, or reduced
metallicity in the accreted material, higher mass-
accretion rates are required to drive an explosion within this timescale. A decrease in
metallicity or initial white
dwarf luminosity leads to higher accumulated masses and ignition pressures, resulting in more violent outbursts. These outbursts exhibit higher peak temperatures, higher ejected masses, and greater kinetic energies. Models computed for different white
dwarf masses but identical initial luminosities reveal significant differences in the elemental abundances of a wide range of species, including Ne, Na, Mg, Al, Si, P, S, Ar, K, Ca, and Sc. These compositional differences offer a potential diagnostic tool for constraining the parameter space and discriminating between the various T CrB models reported in this study.
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Earth and Planetary Astrophysics
Evidence for stellar contamination and water absorption in NGTS-5b's transmission spectra with GTC/OSIRIS
Wan-Hao Wang, Guo Chen, Chengzi Jiang et al. (+3 more)
Transmission spectroscopy serves as a valuable tool for probing atmospheric absorption features in the terminator regions of
exoplanets.
Stellar surface heterogeneity can introduce wavelength-dependent contamination that complicates the interpretation of planetary spectra. We aim to investigate the atmosphere of the warm sub-Saturn NGTS-5b through optical transmission spectroscopy. Two transits were observed with the low-resolution Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) on the 10.4 m Gran Telescopio Canarias (GTC). Chromatic transit light curves were modeled to derive optical transmission spectra and multiple
Bayesian spectral
retrievals were performed to characterize the atmospheric properties. Model comparisons provide strong evidence for contamination from unocculted
stellar spots. A joint
retrieval of the transmission spectra, assuming
equilibrium chemistry, indicates a relatively clear atmosphere with a sub-
solar C/O ratio of $<$0.22 (90% upper limit) and a low
metallicity of $0.10^{+0.34}_{-0.05} \times$
solar.
Retrievals assuming free chemistry yield strong evidence for the presence of $\rm H_2O$, with its abundance constrained to $\log X_{\mathrm{H_2O}} = -0.79^{+0.14}_{-0.17}$. However, the abundances of other species remain unconstrained due to the limited optical wavelength coverage. The discrepancies between the two NGTS-5b transit spectra can be attributed to varying levels of
stellar contamination. NGTS-5b thus appears to host a relatively clear, water-rich atmosphere, pending confirmation from additional observations of molecular bands in the infrared.
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All authors Wan-Hao Wang, Guo Chen, Chengzi Jiang, Enric Palle, Felipe Murgas, Hannu Parviainen
High Energy Astrophysical Phenomena
Development of an early warning method incorporating pre-supernova neutrino light curves
Keita Saito, Minori Eizuka, Zhuojun Hu et al. (+9 more)
Massive
stars ($M>8\mathrm{M_\odot}$) emit
neutrinos known as pre-
supernova (pre-SN)
neutrinos through thermal and
nuclear interactions for cooling the
stellar core during the final stage of
stellar evolution. Real-time monitoring of their pre-SN
neutrino interaction rate offers a crucial opportunity to issue an early warning to a core-collapse
supernova. Some
neutrino detectors, including KamLAND and Super-Kamiokande already operate pre-SN alarm systems based on a statistically significant excess of the observed event rate over the expected background. To improve alarm sensitivity, an alarm method which incorporates the time
evolution of the observed pre-SN
neutrino event rate was proposed in A. Sheshukov et al. (2021). We evaluate the performance of the light-curve likelihood approach under realistic KamLAND and SK operating conditions, including realistic background rates, global false-alarm-rate calibration, and the combined alarm. The results demonstrate a significant improvement in the alarm time and distance compared to the conventional rate-only method, while maintaining the same false alarm rate.
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All authors Keita Saito, Minori Eizuka, Zhuojun Hu, Koichi Ichimura, Motoyasu Ikeda, Koji Ishidoshiro, Nanami Kawada, Lucas N. Machado, Lluis Marti-Magro, Kazuha Mikami, Koga Tachibana, Roger A. Wendell
Solar and Stellar Astrophysics
The reason for the occurrence of W-type contact binaries
Jia Zhang, Sheng-Bang Qian, Li-Ying Zhu et al. (+1 more)
For more than half a century, the puzzling W-type phenomenon in contact binaries has challenged astrophysicists. In these systems, the less massive component exhibits a higher surface temperature than its more massive companion, which is a reversal of the typical A-type configuration, where the more massive
star is hotter. This counterintuitive temperature inversion defies the basic
stellar physics and still lacks a widely accepted explanation. In this study, we assembled a sample of over 3,000 extensively observed contact binaries and derived their complete set of physical parameters. Our statistical analysis revealed a strong positive correlation between the occurrence of W-type contact binaries and the intensity and frequency of
magnetic activities. This result strongly supports the hypothesis that
magnetic activities are the primary driver of the W-type phenomenon and offers a compelling explanation for the observed transitions between the W-type and A-type.
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All authors Jia Zhang, Sheng-Bang Qian, Li-Ying Zhu, Xu-Zhi Li
Astrophysics of Galaxies
K-DRIFT Science Theme: Galactic Cirrus Clouds and Circumgalactic Medium
Kwang-il Seon, Jaehyun Lee, Jongwan Ko et al. (+8 more)
In this paper, we review the extended
halo material and the circumgalactic medium (CGM), including both
dust and gas, and discuss promising science cases that could be realized using the KASI Deep Rolling Imaging Fast
Telescope (K-DRIFT). Scattered starlight from cirrus clouds in our
Galaxy poses one of the major challenges to studying the low surface brightness features of extragalactic sources. Therefore, it is essential to investigate how to discriminate extragalactic sources from the cirrus cloud features. At the same time, interstellar
dust clouds themselves are fundamental to understanding
dust properties and the interstellar radiation field, both of which are essential for studies of chemical
evolution and
star formation in our
Galaxy. Measuring the reddening of background sources, such as
quasars, with K-DRIFT, which benefits from its broad field of view and accurate background subtraction, allows for effective detection of extended
dust in
galactic halos, the CGM, and intracluster space. Observations of the H-alpha emission lines can be used to identify signatures of
star formation activity within
galaxies, as well as the environmental effects acting on them.
Galactic winds driven by active
galactic nuclei and starbursts can be traced through H-alpha emission. Strong ram pressure stripping effectively removes the interstellar medium (ISM) from
galaxies. The stripped ISM becomes ionized or dissociated through mixing with the hot intracluster medium (ICM), forming H-alpha tails. The surface brightness of these H-alpha tails correlates not only with the presence of
star formation in the tails but also the mixing stage of the stripped ISM and ICM. The H-alpha survey with K-DRIFT will enable the investigation of the evolutionary stages of ram pressure stripped
galaxies in cluster environments, as well as the multiphase gas reservoir around
galaxies and in the CGM.
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All authors Kwang-il Seon, Jaehyun Lee, Jongwan Ko, Woowon Byun, Jaewon Yoo, Kyungwon Chun, Sang-Hyun Chun, Sungryong Hong, Jae-Woo Kim, Hong Soo Park, Jihye Shin
High Energy Astrophysical Phenomena
The initial spin matters: the impact of rapid rotation on magnetic-field amplification at merger
Harry Ho-Yin Ng, Jin-Liang Jiang and Luciano Rezzolla
A couple of milliseconds after the merger of a binary system of
neutron stars can play a fundamental role in amplifying the comparatively low initial
magnetic fields into magnetar strengths. The basic mechanism responsible for this amplification is the Kelvin-Helmholtz instability (KHI) and we here report the first systematic study of the impact of rapid rotation on the KHI-amplification process exploiting general-relativistic magnetohydrodynamic simulations at very high-resolutions of $35\,{\rm m}$. Concentrating on four different spinning configurations, we find that aligned, anti-aligned, and mixed (aligned/anti-aligned)
spin configurations lead to markedly different growth rates of the electromagnetic (EM) energy, field
topologies, and
vortex properties when compared to the irrotational case. These differences arise from intrinsic variations in the system dynamics, such as
tidal deformation, collision strength, and contact surface area, with the anti-aligned configuration producing the largest vorticity and growth in EM energy. Importantly, while different
spin configurations lead to significantly different initial growth rates of the poloidal/toroidal components, all systems converge to a specific topological partition. Our simulations are confined to a short window in time, but the different EM energies produced as a result of
spin will imprint the EM emission at merger and provide information on the spinning state at merger.
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Solar and Stellar Astrophysics
A compact object with a K type star companion in the solar neighborhood: a wide post common envelope binary with a white dwarf candidate
Jie Lin, Hailiang Chen, Bojun Wang et al. (+3 more)
Post-common envelope binaries (PCEBs) consisting of a white
dwarf (WD) plus a main-sequence (MS)
star can constrain current prescriptions of common envelope
evolution (CEE) and calibrate theoretical models of binary formation and
evolution. Most PCEBs studied to date have typical orbital periods of hours to a few days and can be well explained by assuming inefficient CEE to expel the envelope. However, there are currently several systems with relatively wide orbital periods ($>$18 days). To explain these wide PCEBs, additional sources of energy have been suggested to be taken into account. Here, we present the discovery and observational characterization of a compact object ($M\,\geq\,0.58\,\rm M_{\odot}$) with a K-type
star companion in the
solar neighborhood ($d\sim 112$ pc) and an orbital period of $P_{\rm orb}\sim 14$ days. The compact object binary is likely to be a system consisting of a WD and a barium
dwarf, making it the shortest-period barium
star binary candidate. Such a system with an orbital period within the gap between tight and wide binaries provides a test of whether additional energy sources are required to explain its formation. Using binary
evolution models, we investigate the evolutionary history of this wide PCEB system and find that the observed properties of this source can be explained without invoking any extra energy source.
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All authors Jie Lin, Hailiang Chen, Bojun Wang, Yudong Luo, Wenshi Tang, Bo Huang
Astrophysics of Galaxies
Multi-band Reconstruction of Sixteen Gravitational Lens Systems using PISCO data
Huimin Qu, Daniel J. Ballard, Geraint F. Lewis et al. (+12 more)
Next-generation surveys such as the Euclid survey, the Legacy Survey of Space and Time (LSST), and the China Space Station
Telescope (CSST) survey are expected to discover ~10^5
galaxy-
galaxy scale strong gravitational lenses. This motivates the development of scalable and robust lens modeling approaches that can efficiently and reliably learn from wide-field survey
datasets before high-resolution follow-up. We design a scalable,
Bayesian, Lenstronomy-based pipeline and apply it to a sample of sixteen lens candidates observed with the Parallel Imager for Southern Cosmology Observations (PISCO) on the Magellan
telescope. PISCO provides four-band imaging (z, i, r, g) with colours, depth and seeing conditions comparable to LSST. To fully exploit the constraining power of this
dataset, our pipeline performs simultaneous multi-band modeling, using a common mass profile across all four bands while allowing independent light profiles in each. This approach leverages color information to provide joint constraints on the lens mass and yields reduced uncertainties compared to single-band analyses. Fifteen out of sixteen PISCO lens candidates are successfully recovered with interpretable
lensing configurations, including DESJ0533-2536, the first reported
hyperbolic-umbilic
galaxy-
galaxy scale strong
lensing candidate. We further assess how much model complexity can be reliably constrained given the resolution and seeing of PISCO-like data. Overall, our results demonstrate that scalable, multi-band lens modeling of ground-based data can extract meaningful constraints on mass and source morphology, providing a practical pathway to maximize the scientific return from large samples in upcoming surveys.
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All authors Huimin Qu, Daniel J. Ballard, Geraint F. Lewis, Karl Glazebrook, Antony Stark, Sarah M. Sweet, Colin Jacobs, Kim-Vy Tran, Brian Stalder, Tania M. Barone, Tucker Jones, Keerthi Vasan G.C., Thomas E. Collett, Glenn G. Kacprzak, Dorota Bayer
Cosmology and Nongalactic Astrophysics
Mapping dark matter and the emergence of large-scale structure
Jon Loveday, Jochen Liske, Ivan K. Baldry et al. (+5 more)
We discuss a potential survey to map dark matter and the emergence of large-scale structure to
redshift z ~ 1.5 (baseline) or z~3.5 (with near-IR extension) using a massively multiplexed spectrograph on a 10m-class
telescope, such as the proposed Widefield Spectroscopic
Telescope.
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All authors Jon Loveday, Jochen Liske, Ivan K. Baldry, Simon P. Driver, Aaron Robotham, Sabine Bellstedt, Luke Davies, Trystan Lambert
High Energy Astrophysical Phenomena
Source identification for the Swift-BAT 150-month hard X-ray catalog using soft X-ray observations
K. Imam, N. Torres-Alba, S. Marchesi et al. (+10 more)
We present a comprehensive catalog of 251 potential counterparts for 250 unassociated hard X-ray sources detected in the Swift Burst Alert
Telescope (BAT) 150-month hard X-ray survey. Over 150 months of observation, BAT has detected 2339 sources in the 15-150 keV energy range. Among these, 344 do not have a previously identified low-energy counterpart. Our study focuses on the analysis of soft X-ray observations at energies below 10 keV, spatially overlapping with these new Swift-BAT hard X-ray sources. Such observations were taken with Chandra, Swift-XRT, eROSITA, and XMM-Newton. Within the sample of 251 potential counterparts, 94 (37 percent) are identified as active
galactic nuclei and 58 (23 percent) as
galaxies. The remaining 99 sources (40 percent) include
pulsars, cataclysmic variables, and unclassified soft X-ray counterparts in the 0.5-10 keV band.
Redshift information is available for 139 out of the 251 sources, and its distribution is in close agreement with the
redshift distribution of previous BAT catalogs. We also present the results of a small optical spectroscopy campaign of 9 out of 58
galaxies. The majority of these are classified as Seyfert 2
galaxies at
redshifts slightly larger than the median of the BAT AGN sample.
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All authors K. Imam, N. Torres-Alba, S. Marchesi, M. Ajello, S. Joffre, I. Cox, A. Pizzetti, X. Zhao, A. Segreto, A. Banerjee, I. Pal, V. E. Gianolli, D. Stern