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宇宙工学・惑星科学・宇宙物理の最新プレプリント。

astro-ph.IM

Optical design of a direct fibre-fed MO-IFS for the NLOT

Nitish Singh, S. Sriram, Totan Chand, Jurgen Schmoll, Bharat Kumar Yerra, Savitha M S

The initial optical design and performance analysis of a dual-channel fibre-fed Multi-Object Integral Field spectrograph (Mo-IFS) being designed for a future National Large Optical/Infrared Telescope (NLOT) in India. The front end will be a moveable lenslet+fiber based integral field unit. The spectrograph is designed to directly accept an f/4 beam from the approximately 200 optical fibers, each with a 100 um core diameter without additional fore-optics. The instrument consists of two optimized…

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astro-ph.GA

On the reconstruction of the Rotation Curve for Milky Way and its spacetime implications: a Machine Learning approach

Aritra Sanyal, Swapan Das, Farook Rahaman, Saibal Ray

We propose a machine learning-assisted analytical reconstruction of the Milky Way rotation curve and discuss its implications in a relativistic spacetime context. The rotation curve is reconstructed using 73 observational data points over the range 0.1-95.56 kpc, and we compare the performances of Ridge regression, LASSO regression, and feed-forward neural networks using a physically motivated functional basis. Ridge regression yields the most stable prediction with R2 = 0.9824 +/- 0.0064 and RM…

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astro-ph.SRastro-ph.HEphysics.flu-dyn

Efficiency of Tidal Dissipation in Convective Flow Under Rapid Tidal Forcing

Hongzhe Zhou, Dong Lai

For close binaries and star-planet systems, tidal interactions mediate the energy transfer between the orbital motion and the internal flows of the bodies involved, thus playing a central role in their evolution. For equilibrium tides, the associated energy transfer is commonly modeled through an effective viscosity acting on the tidal flow. However, the scaling of viscous dissipation efficiency with tidal frequency $ω_\text{T}$ remains debated, particularly when $ω_\text{T}$ greatly exceeds the…

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astro-ph.SRastro-ph.HEphysics.flu-dyn

Efficiency of Tidal Dissipation in Convective Flow Under Rapid Tidal Forcing

Hongzhe Zhou, Dong Lai

For close binaries and star-planet systems, tidal interactions mediate the energy transfer between the orbital motion and the internal flows of the bodies involved, thus playing a central role in their evolution. For equilibrium tides, the associated energy transfer is commonly modeled through an effective viscosity acting on the tidal flow. However, the scaling of viscous dissipation efficiency with tidal frequency $ω_\text{T}$ remains debated, particularly when $ω_\text{T}$ greatly exceeds the…

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astro-ph.SR

The coronal mass ejection productivity of solar active region 13664/8

Lijuan Liu, Yuming Wang, Quanhao Zhang, Jingnan Guo, Yutian Chi

In May 2024, NOAA active region (AR) complex 13664/8 was one of the most productive regions of the current solar cycle, producing 12 X-class flares and over 20 coronal mass ejections (CMEs) and triggering the strongest geomagnetic storm since 2003. We investigate why this AR complex was so CME-productive. Using primarily SDO/AIA and SDO/HMI observations, we analyzed its photospheric magnetic evolution, eruption sources, eruption waiting times, and magnetic parameters in comparison with five othe…

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astro-ph.SR

On the CME productivity of solar active region 13664/8

Lijuan Liu, Yuming Wang, Quanhao Zhang, Jingnan Guo, Yutian Chi

In May 2024, NOAA active region (AR) complex 13664/8 was one of the most productive regions of the current solar cycle, producing 12 X-class flares and over 20 coronal mass ejections (CMEs) and triggering the strongest geomagnetic storm since 2003. We investigate why this AR complex was so CME-productive. Using primarily SDO/AIA and SDO/HMI observations, we analyzed its photospheric magnetic evolution, eruption sources, eruption waiting times, and magnetic parameters in comparison with five othe…

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astro-ph.SRastro-ph.GA

Runaway OB stars within 1 kpc of the Sun

Juan Martinez Garcia, Nicholas Wright, Alexis Quintana

Runaway stars are high-velocity stars ejected from their birth environments that can provide insights into the kinematic history of the stellar cluster they were ejected from. We derived runaway star probabilities for 40 O-type stars and $24,487$ B-type stars taken from a recently published volume-complete sample of OB stars within 1 kpc of the Sun. We fit a Galactic rotation model to the observed proper motions of these stars and identify runaway stars using both a fixed 2D peculiar velocity th…

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astro-ph.GAgr-qchep-ph

Relativistic Tidal Transitions of Saturated Kerr Boson Clouds

Yi-kun Li

Rotating black holes can bind ultralight bosons in macroscopic clouds whose level structure is swept by the tidal field of a binary companion. Existing estimates of the resulting resonant transitions have largely used hydrogenic wave functions, even where the cloud grows most efficiently and the Kerr geometry appreciably deforms its quasibound states. I compute tidal transition matrix elements on the numerically determined saturation branches of the $|211\rangle$, $|322\rangle$, and $|433\rangle…

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gr-qcastro-ph.HE

Random walks around black holes and low-frequency X-ray variability

Arthur G. Suvorov

The stochastic dynamics of a grain embedded within a turbulent fluid subject to strong gravitational fields can be formulated as a random walk on a Riemannian manifold. Such curvature-weighted walks provide a framework to model the intrinsic variability of accretion onto compact objects. By solving the relevant Fokker-Planck equation on a black hole background, we find the counterintuitive result that the escape probability of a grain is actually higher compared to flat space. This is a conseque…

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astro-ph.EPastro-ph.IM

Observational planning for the 2026 August 5 Falcon 9 Upper Stage lunar impact

Benjamin Fernando, Jennifer Heldmann, Bill Grey, John Ortiz, Bryan Euser, Darryl Z. Seligman, Eunhyeuk Kim, Anthony Colaprete et al.

On 2026 August 5, at approximately 06:35 UT, a spent Falcon 9 upper stage will impact the lunar surface near Einstein Crater. This event will occur on sunlit terrain near the eastern limb as seen from Earth. The impact flash and resultant ejecta plume from this event are potentially observable from ground- and space-based observational facilities. This event provides an opportunity to attempt the recording of an artificial impact in real-time; although many of the properties of the event (such a…

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astro-ph.GA

A Catalog of Compact High-Velocity Clouds from the FAST All-Sky HI Survey (FASHI) DR2

Jin-Long Xu, Chuan-Peng Zhang, Xiao-Lan Liu, Nai-Ping Yu, Mei Ai, Ming Zhu

High-velocity clouds (HVCs) -- especially compact HVCs (CHVCs) -- are thought to serve as gaseous tracers of dark-matter-dominated subhalos, providing a crucial empirical link between the predicted dark matter substructure and observed satellite galaxies. In this paper, we present a new catalog of 192 CHVCs identified from the FAST All-Sky HI Survey (FASHI) Data Release 2 (DR2). Among these, 108 are ultra-compact HVCs (UCHVCs), the majority of which are new discoveries. We find that 185 of the 1…

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astro-ph.GA

Features of the distribution of absorbing matter in the local system

V. I. Sorokina, V. V. Bobylev, G. A. Gontcharov, A. T. Bajkova

V. I. Sorokina$^1$\footnote [99]{e-mail: [email protected]}, V. V. Bobylev$^2$, G. A. Gontcharov$^{2}$, A. T. Bajkova$^2$A detailed study of the dust distribution in the Local System was conducted. Using the latest map by Gontcharov et al., smoothed distributions of dust matter were obtained in projection onto the galactic plane $XY$ using various smoothing parameters. Within the 2-kpc radius region around the Sun under study, key structural features associated with the Radcliffe Wave, Sp…

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astro-ph.IM

Design and Development of a Lab Prototype of a Fiber-Based Integral Field Spectrograph

Nitish Singh, S Sriram, Jurgen Schmoll, Bharat Kumar Yerra

Integral Field Spectroscopy provides simultaneous spatial and spectral information, making it a powerful technique for studying both point like and extended astronomical sources. As part of our effort to develop a compact Integral Field Spectrograph (IFS) for optical astronomy, we have designed and realized a fiber based prototype with a resolving power of ~800 at the H-$α$ wavelength. The front end optics, including the fore optics and lenslet based integral field unit (IFU), have been designed…

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astro-ph.COastro-ph.IM

Probabilistic redshift estimation of unresolved galaxies from multi-band background light maps

Shun-Sheng Li, Hendrik Hildebrandt, Ludovic Van Waerbeke

Accurate knowledge of the redshift distributions of unresolved galaxy populations is essential for extracting the cosmological information encoded in the cosmic optical background. We present the first framework for estimating these distributions directly from multi-band maps of unresolved background light, using conditional normalising flows trained on realistic image simulations. For imaging qualities comparable to those expected from the synergy between the Euclid and Rubin LSST surveys, our…

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astro-ph.GAastro-ph.HEastro-ph.SRgr-qchep-th

Revisiting Data Quality Control and Multiple-star Modeling in Wide Binary Gravity Tests: Confirmation of MOND-type Gravitational Anomaly at Low Acceleration

Kyu-Hyun Chae, Youngsub Yoon

Wide binary stars provide natural laboratories for directly probing gravity in the low-acceleration regime, as dark matter inferred from any viable gravity has negligible effects on their internal dynamics. Various recent studies including Bayesian 3D analyses have shown that wide binaries with separations greater than several thousand astronomical units experience MOND-type gravity with a boost factor of $γ\approx 1.3-1.6$. However, results claiming preference for, or no deviation from, standar…

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astro-ph.GA

Accurate proper motions of the protostellar system VLA1623-2417

Ricardo Hernández Garnica, Laurent Loinard, Carlos Carrasco-González, Jazmín Ordóñez-Toro, Johanan Ramírez-Arellano, María José Maureira, Isaac C. Radley, Eleonora Bianchi et al.

We present a detailed astrometric analysis of the quadruple protostellar system VLA1623-2417, deriving accurate absolute proper motions for components A, B, and W, as well as, for the first time, individual motions for the compact binary components of A (Aa and Ab). Our study combines 37 archival interferometric observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very Large Array (VLA) at centimeter and millimeter wavelengths, supplemented with additi…

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astro-ph.GAastro-ph.HE

Merging galaxies and clusters: Insights into the role of magnetic fields and the physics of radio relics

Joseph Whittingham

Mergers have long been understood to be a driver of galaxy and galaxy cluster evolution. They release tremendous amounts of gravitational potential energy - ~$10^{59}$ and ~$10^{64}$ ergs in galaxies and clusters, respectively - which is dissipated in powerful shock waves. In galaxies especially, the strong tidal effects can have profound effects on the remnant morphology. Although the modelling of mergers has a long history, it is only recently that it has been fully appreciated just how sensit…

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astro-ph.HE

Temporal Memory in Repeating Fast Radio Bursts: Epsilon-Machine Reconstruction of Causal Structure in Burst Timing

Tom Kimpson, Joseph O'Leary

The emission mechanism of fast radio bursts (FRBs) remains unknown. Whether the bursts from a repeating FRB arrive at random or in a structured sequence is a key constraint on that mechanism. We apply $\varepsilon$-machine reconstruction, a tool from computational mechanics that infers the minimal model capturing all predictive information in a stochastic process. Applied to the waiting-time sequences of three repeating FRBs (FRB~20121102A and FRB~20201124A from FAST; FRB~20220912A from CHIME),…

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astro-ph.SRastro-ph.EP

Re-evaluating solar irradiance reconstructions: No evidence for large secular trends

Theodosios Chatzistergos, Natalie A. Krivova, Mathew J. Owens, Tatiana A. Egorova

Most current irradiance reconstructions suggest only a modest secular increase in TSI between the 1700 and 1986 activity minima ($<1$ Wm$^{-2}$). However, 2 models, the CHRONOS and Penza et al. (2024; PEA24) models, suggest substantially larger changes of 2.1-5.9 Wm$^{-2}$. Although the two models differ in their architecture, both use cosmogenic isotope records combined with neutron monitor data to describe the long-term irradiance variability. However, cross-calibrating modulation potential re…

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astro-ph.HE

Black-Hole Spin Measurements from X-ray Reflection Spectroscopy: Quality Criteria and Community Recommendations

Javier A. Garcia, Riley Connors, Laura W. Brenneman, James F. Steiner

X-ray reflection spectroscopy provides one of the most powerful electromagnetic methods for measuring the dimensionless spin of accreting black holes. It has yielded spin constraints for stellar-mass black holes in X-ray binaries and supermassive black holes in active galactic nuclei, and is central to the science goals of current and future X-ray observatories. However, the technique is subject to observational and modeling systematics, including continuum-reflection degeneracy, limited spectra…

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astro-ph.IM

Using Muon Rings for the Calibration of the Cherenkov Telescope Array: An Analytical Solution for the Dual-Mirror Telescope Using Vector Geometry

Markus Gaug, Víctor Giráldez-Segalàs, Fiona Redmen

The analysis of ring images produced by muons in Imaging Atmospheric Cherenkov Telescopes (IACTs) provides a powerful and precise method for calibrating the optical throughput of the instrument and monitoring its optical point-spread function. To date, analytical solutions have been derived for single-mirror telescopes with reflectors assumed flat. However, a complete analytical description of the Cherenkov light produced by muons and detected by a dual-mirror telescope - accounting for both the…

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astro-ph.HEastro-ph.IM

CRESCENDO II: Spectral cosmic rays with improved energy losses and realistic supernova seeding

Daniel Karner, Ludwig M. Böss, Klaus Dolag, Ildar Khabibullin

Context. Cosmological simulation codes with subgrid models for cosmic rays (CRs) help us better understand their impact on baryonic feedback and non-thermal radiation in galaxies and galaxy clusters. An accurate numerical description requires a spectrally resolved treatment of the CR population, because virtually all transport, acceleration and loss processes depend on energy. Aims. We advance the treatment of CR electrons and protons in the on-the-fly spectral CR solver CRESCENDO in OpenGadget3…

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astro-ph.GA

The chemodynamical signature of coherent metal-poor inflow and enriched recycled accretion in the cool circumgalactic medium

Glenn G. Kacprzak, Jerrard Doran, Sameer, James Farrington, Jane C. Charlton, Nikole M. Nielsen, Kaustubh R. Gupta, Christopher W. Churchill et al.

The azimuthal and kinematic structure of the CGM is often interpreted as planar accretion and bipolar outflows, yet direct metallicity evidence for this picture remains ambiguous. We combine cloud-by-cloud ionisation modelling with galaxy rotation kinematics for 21 galaxies from the Multiphase Galaxy Halos Survey to investigate how metallicity depends on azimuthal angle and angular momentum. We find that low-ionisation clouds kinematically consistent with disk rotation have ~0.5 dex lower metall…

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astro-ph.HEastro-ph.SRhep-ph

Multiwavelength study of non-thermal emission in the Swift J1834.9-0846/W41 region

Manoel F. Sousa, Rita C. Dos Anjos, Vitor de Souza

We investigate the origin of non-thermal emission from the Swift J1834-0846/W41 region by modeling its broadband spectral energy distribution from radio to TeV energies within leptonic and lepto-hadronic frameworks using Markov Chain Monte Carlo sampling. Motivated by morphological studies of HESS J1834-087 suggesting a two-component TeV structure, we explore a single extended source scenario and a configuration comprising a central point-like component embedded within extended emission. Purely…

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astro-ph.GAastro-ph.HE

VENUS: an ultra-faint galaxy hosting the metal-poor type II supernova at $z=5.13$ Witnessing the initial metal enrichment with extremely frequent core-collapse supernovae?

Yoshihisa Asada, Seiji Fujimoto, Joseph F. V. Allingham, David A. Coulter, Conor Larison, Matthew R. Siebert, Gabriel Brammer, Dan Coe et al.

We present the first characterization of the host galaxy of a recently discovered type IIP SN at $z=5.13$ (SN Eos). SN Eos and its host galaxy are gravitationally lensed and multiply imaged. The total magnification $μ\sim53$ enables spatially resolving the system, allowing us to localize the core-collapse supernova (CCSN) position and to characterize its local environment within an early galaxy. Our observation reveals that the host is an ultra-faint ($M_{\rm UV}=-14.4\pm0.3$ mag) Lyman-$α$ emit…

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astro-ph.HE

X-Ray Timing Properties of the Black Hole Candidate IGR J17091-3624 During the 2022 Outburst Onset with AstroSat

Sree Bhattacherjee, Biplob Sarkar

We present the evolution of rapid X-ray timing variability in the black hole X-ray binary IGR J17091-3624 during the initial phase of its 2022 outburst using a ~3-day-long AstroSat observation. Utilizing the high time-resolution capability of the Large Area X-ray Proportional Counter, we perform a comprehensive study of the evolution of Type-C quasi-periodic oscillations (QPOs) throughout the observation. The QPO centroid frequency evolves from 3.30 to 7.78 Hz, accompanied by the broad-band nois…

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astro-ph.EP

The exozodi spectral effect: Residual habitable zone dust may bias exoEarth characterization

Miles H. Currie, Christopher C. Stark, Eleonora Alei, Aki Roberge

All exoplanetary systems are expected to host exozodiacal dust, or exozodi, originating from planetesimals. For many stars, exozodi will likely be the largest source of astrophysical noise in direct observations of terrestrial exoplanets. Nearby Sun-like systems likely have $\gtrsim3$x more habitable zone (HZ) dust than our solar system, which must be removed from direct images and spectra to reveal exoplanet signals. The albedo of this micron-sized dust varies smoothly over VIS -- NIR wavelengt…

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astro-ph.EP

Helium escaping from the atmosphere of a nearby rocky exoplanet orbiting in a habitable zone

Collin Cherubim, Shreyas Vissapragada, Tim Cunningham, Annabella G. Meech, David Charbonneau, Robin Wordsworth, Aaron Householder, Johanna Teske et al.

Observations of highly irradiated gas giant exoplanets have shown helium escaping from their atmospheres. There is limited evidence for atmospheres on rocky exoplanets, perhaps because they have already escaped. We report spectroscopic observations of LHS 1140b, a rocky exoplanet that orbits in the habitable zone of a nearby low-mass star. The near-infrared transit spectra show absorption by helium escaping from the planet's atmosphere. Helium absorption is detected in 2024 but not in 2025, indi…

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astro-ph.EP

Tidal evolution of packed moon systems around an Earth-mass planet

Alan Briseño, Billy Quarles, Marialis Rosario-Franco

While missions have long targeted terrestrial exoplanets within the habitable zone of their host stars, the number of exomoon candidates is expected to grow as next generation space-based observatories achieve the photometric sensitivity required to detect their transit signals. Constraining the stability limits of tightly packed moon systems is therefore essential for transit searches and predicting the number of moons around terrestrial planets. In our Solar System, only three moons orbit the…

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astro-ph.HE

Einstein Probe Fast X-ray Transients Extend the Physical Parameter Space of Relativistic Jets

Connery Chen, Yihan Wang, Bing Zhang

Fast X-ray Transients (FXTs) detected by the Einstein Probe (EP) mission possess exceptionally low spectral peak energies compared to typical long (Type II) GRBs. Some of these extragalactic transients show phenomenological similarities to X-ray flashes (XRFs), but the physical origins of FXTs remain uncertain. In this work, we investigate EP-detected FXTs using various jet structures relevant to Type II GRBs and test the hypothesis that these FXTs belong to the intrinsically same population of…

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