研究動向

astro-ph.HEastro-ph.IM2026年9月7日

Mining the time axis with TRON - III. Discovery of a nulling pulsar towards the SMC with MeerKAT

T. Blecher, M. Geyer, O. M. Smirnov, A. Coelen, I. Heywood, I. Pelisoli, A. K. Hughes, J. S. Bright et al.

We report on the discovery of a nulling pulsar, PSR J0052$-$7551, in archival MeerKAT L-band observations of the Small Magellanic Cloud (SMC). The discovery was made using the image-plane transient detection pipeline, TRON, which creates a residual image for each time sample and uses a heuristic pruning strategy to identify promising candidates in the resulting temporal image cube. The TRON pipeline triggered on the approximately minute timescale variability associated with the nulling behaviour…

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astro-ph.GA2026年9月7日

ALMA Reveals an Explosive Outflow Candidate in IRAS 16119--5048

Yongquan Luo, Jianjun Zhou, Tie Liu, Jarken Esimbek, Siju Zhang, Xindi Tang, Sami Dib, Prasanta Gorai et al.

We present a multiwavelength study of the massive star formation region IRAS 16119-5048 (I16119) using ALMA ATOMS Band 3 and QUARKS Band 6 observations, complemented by archival ATCA radio continuum and Spitzer mid-infrared data. The CO (2-1) emission reveals a system of high-velocity streamer-like structures around the central region. Using dendrogram analysis of velocity-channel maps followed by linking in position-position-velocity space, we identify 16 approximately radially distributed stre…

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astro-ph.GA2026年9月7日

Irreducible-Mass Balance for Magnetized Null Horizons with an Internal Current Sheet

Remo Ruffini, Giorgio Sonnino

We begin with a general question: how does the irreducible mass of a magnetized black hole change when the horizon is not stationary? The null Raychaudhuri equation gives an exact area balance for any smooth null horizon, without assuming stationarity or axisymmetry. When the horizon is axisymmetric and admits an integrable quasilocal Hamiltonian, this geometrical identity becomes an energy balance. The equation keeps area growth, rotational and electromagnetic work, nonstationary focusing, cano…

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astro-ph.HE2026年9月7日

Oblique Collision of a Relativistic Cold Shell with an Ideal Reflecting Wall

Jonathan Granot, Prasanta Bera, Michael Rabinovich, Paz Beniamini

Relativistic flows are common in astrophysics and often form shocks when different parts of the flow collide at relativistic relative velocities. Such collisions are often oblique, forming two shocks whose shocked fluids are separated by a contact discontinuity, which is treated here as an ideal reflecting ``wall'' where the flow on either side is modeled separately. The latter is modeled in the lab frame $S$ as a uniform cold planar shell propagating into vacuum at velocity $v_1=β_1c$ normal to…

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astro-ph.HEgr-qc2026年9月7日

Timing Gravity with Pulsars in the Strong Field

Riccardo Della Monica, Ivan de Martino

We propose a novel approach for the timing of pulsars orbiting a supermassive black hole, which implements the fully relativistic calculations of the photon travel time into a robust timing model. We generate realistic mock catalogues of pulsar times-of-arrival for several putative pulsars on tight orbits around the Galactic Center supermassive black hole, Sagittarius A* (Sgr A*). Then, we perform a proof-of-concept sensitivity analysis to forecast the accuracy that future observational faciliti…

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astro-ph.EP2026年9月7日

Long-baseline ATLAS photometry of the seven main-belt asteroid targets of the Emirates Mission to the Asteroid Belt

Nicolas Erasmus, Josef Ďurech, David E. Trilling, Larry Denneau, John L. Tonry, Henry Weiland, Ken W. Smith, Javier Licandro et al.

The Emirates Mission to the Asteroid Belt (EMA) will use the MBR Explorer spacecraft to fly past six main-belt asteroids -- (10253) Westerwald, (623) Chimaera, (13294) Rockox, (88055) Ghaf, (23871) Ousha and (59980) Moza -- before rendezvousing with, and deploying a lander onto, the extremely red (269) Justitia. We present a homogeneous analysis of a decade of sparse photometry of all seven targets from the Asteroid Terrestrial-impact Last Alert System (ATLAS). For each object we derive absolute…

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physics.opticsphysics.app-phphysics.space-phquant-ph2026年9月7日

Mechanical quality factor estimation from a nonlinear optical cavity response

Zohran Ali, Davide Tomasella, Daniel Allepuz Requena, Alexander Huck, Ulrik Lund Andersen

Intrinsic damping rate and quality factor ($Q$) are key parameters in optomechanical systems. However, in high-Q devices, their measurement is often challenging because probe-induced dynamical backaction (DBA) and the need to resolve and accurately track the mechanical resonance limit the performance of state-of-the-art techniques. Here, we introduce an all-optical ringdown method in the unresolved-sideband regime that exploits the nonlinear, time-averaged optical response induced by strong mech…

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astro-ph.SRastro-ph.GA2026年9月7日

An Eccentric Massive Protobinary Assembled via a Core-merger Parabolic Encounter

Yao Wang, Yichen Zhang, Rubén Fedriani, Kei E. I. Tanaka, Viviana Rosero, Kai Yang, Morten Andersen, Maria T. Beltrán et al.

Most massive stars form in binary systems, which profoundly influence their subsequent evolution. However, how such systems form remains poorly understood, with several competing scenarios proposed, including disk fragmentation, core fragmentation and capture. Determining the orbital architectures of massive binaries, particularly during their earliest embedded phases, is therefore crucial for distinguishing among these formation pathways, but direct measurements of their three-dimensional motio…

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astro-ph.HE2026年9月7日

Correlation between X-ray and gamma data of Swift measurements

Istvan I. Racz, Lajos G. Balazs, Istvan Horvath, Sandor Pinter

Several studies over the last two decades have used canonical correlation analysis (CCA) to study the relationships between main γ-ray (e.g. fluence, peak flux, and duration) and main X-ray (flux, decay and spectral index, and hydrogen column density) data from gamma-ray bursts (GRBs). In this paper, we revisit this approach using a much larger dataset to identify potential new insights into these relationships. We used CCA to investigate the interrelationship of the aforementioned gamma-ray and…

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astro-ph.EP2026年9月7日

A semi-analytical Ring-Arc model for Plutino perturbations

Yue Chen, Jian Li

Neptune's 2:3 mean motion resonance induces an asymmetric spatial distribution of Plutinos. We previously proposed a 9000-point-mass arc model that successfully captures the resulting influence on planetary ephemerides. However, integrating thousands of point masses involves significant computational cost. In this paper, to more efficiently simulate the total perturbation of Plutinos, we develop a semi-analytical Ring-Arc model described by gravitational potentials. This model consists of an out…

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gr-qcastro-ph.HEhep-th2026年9月7日

Exact Cancellation of Horizon Modes in Kerr Ringdown

Kei-ichiro Kubota, Yusuke Manita, Hayato Motohashi, Daiki Watarai

Ringdown gravitational waves probe black hole spacetimes via quasinormal modes (QNMs). Recent studies have reported oscillatory features in QNM-filtered waveforms, and have led to conflicting interpretations as to whether they represent a near-horizon "direct wave". Reexamining a particle plunging into a Kerr black hole, we show that the saddle-point approximation underlying the proposed interpretation fails near the horizon. Our exact analysis reveals that every source-induced horizon-mode pole…

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astro-ph.EPastro-ph.IM2026年9月7日

That's no moon: Exomoon survival and detection limitations

Alicia Pérez-Rodrigo, Isabel Rebollido

While moons are ubiquitous in the Solar System, exomoons have not yet been unambiguously confirmed despite the discov- ery of over 5,600 exoplanets. We investigated the reasons for this lack of detections by reviewing high-impact literature searches, assessing dynamical stability and detectability constraints, and comparing these with the moon population in the Solar System. We compiled a homogeneous catalogue of 24 proposed exomoon candidates, including stellar, planetary, and inferred lunar pa…

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astro-ph.SR2026年9月7日

Statistical structure and physical interpretation of the fillout factor distribution in contact binary stars

A. Poro, K. Li, E. Paki, F. Alicavus, N. Alan

Contact binary systems exhibit complex evolutionary behavior governed by mass transfer, angular momentum loss (AML), and Roche geometry. The fillout factor ($f$) is widely used as a descriptor of the degree of overcontact, yet its physical and statistical role remains nonuniformly defined across the literature. We used a compiled observational sample of W UMa-type contact binaries to construct a data-driven classification framework based on $f$ and its relation to fundamental system parameters.…

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astro-ph.EP2026年9月7日

The effect of the atmospheric C/O ratio on interiors of hot Jupiters

Esther van Dijk, Yamila Miguel, Paul Mollière

The atmosphere is the outer boundary of a gas giant exoplanet's interior. Therefore, compositional changes in the atmosphere can affect interior inferences. Typically, only metallicity is considered in atmospheric boundary conditions, while other elemental ratios, in particular the C/O ratio, are assumed to be solar. In light of the observational constraints now achievable with JWST, this assumption might no longer be justified. In this work, we investigate the effect of the C/O ratio on atmosph…

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astro-ph.IM2026年9月7日

One Merger, Three Bands: Multiband Detection Rates and Parameter Estimation of Stellar-mass Binary Black Hole Coalescences from Millihertz to Kilohertz

Anson Chen, Jun Zhang

Stellar-mass binary black holes sweep through the millihertz, decihertz, and kilohertz gravitational-wave bands before merger, making them prime targets for multiband observations. We forecast their detection rates and parameter-estimation precision for networks combining the millihertz observatories LISA, Taiji, and TianQin; the decihertz concepts LGWA, AMIGO, and AMIGO-5; and the ground-based LVK and Cosmic Explorer. Using the binary-black-hole mass and redshift distributions inferred from GWT…

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astro-ph.HE2026年9月7日

LOFAR follow-up of sources in the First LHAASO Catalogue

Maria Arias, Timothy Shimwell, Martin Hardcastle, Roland Timmerman

The First LHAASO Catalogue lists 90 sources of very-high-energy gamma-ray emission, many without an established counterpart at other frequencies, reopening the question of which Galactic accelerators produce the highest-energy cosmic rays. We search for low-frequency radio counterparts to the 55 1LHAASO sources that fall within the Galactic fields of the LOFAR Two-metre Sky Survey Data Release Three (LoTSS-DR3), using 144~MHz continuum maps at $6''$ and $20''$ resolution, complemented with archi…

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astro-ph.IMcs.AI2026年9月7日

AstroSpecLM: A Spectrum-Language Model for Evidence-Grounded Astronomical Spectral Analysis

Jinghang Shi, Yanxia Zhang, Ali Luo, Changhua Li, Xiao Kong

Astronomical spectra encode rich physical information, but drawing scientific conclusions from spectral features typically requires expert interpretation. This paper presents AstroSpecLM, a spectrum-language model that connects one-dimensional DESI spectra with Qwen3-4B to answer questions and provide explanations grounded in spectral evidence. Instead of generating question-answer pairs directly from templates or raw catalog fields, we first distill each spectrum into a compact set of catalog-…

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astro-ph.EPastro-ph.IM2026年9月7日

The First Observations of Moonlit Satellites

Sarah E. Caddy, Stephen E. Catsamas, Michele Trenti, Lee R. Spitler, Patrick North

Optical Space Domain Awareness (SDA) operations have traditionally relied on Sunlit passes near the terminator, limiting continuous tracking of low-Earth orbit (LEO) satellites. In this work, we show that by accounting for all four major illumination sources: Sunlight, Earthshine, Moonlight, and Lunar-Earthshine, large LEO satellites like the ISS can be optically monitored for a full 24 hour period. We present what we believe to be the first quantitative observations of the International Space S…

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astro-ph.GAastro-ph.CO2026年9月7日

Recovering the characteristic halo mass of rare populations from clustering: a benchmark using the Millennium Simulation

Amrita Banerjee, Darren Croton

We measure how accurately the characteristic halo mass of a rare, massive population can be recovered from clustering alone, using dark matter haloes in the Millennium simulation, where the true masses are known. Massive samples of 25 to 10000 haloes are cross-correlated against field reference samples of 5000 to 50000 haloes at six redshifts over $0 \leq z \leq 5.29$. The bias is measured at $r = 8\,h^{-1}\,\mathrm{Mpc}$ and inverted to return a characteristic mass, which we compare with the me…

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astro-ph.GA2026年9月7日

Between Little Red Dots and Star-Forming Galaxies: A Sequence in the Optical Continuum Slope

Kristiphong Boonmee, Akio K. Inoue, Masafusa Onoue, Xingyao Cai

The "Little Red Dots" (LRDs) uncovered by JWST are typically analyzed as a distinct class of objects; however, whether they are separated from ordinary star-forming galaxies by a genuine boundary has not been tested at the population level. Using a sample of $\sim3,500$ galaxies at $3 \lesssim z \lesssim 8$ with NIRSpec/PRISM spectra from the DAWN JWST Archive, we modeled their rest-frame UV-to-optical continuum emission with power laws and located the sources in the $β_{\rm{UV}}$-$β_{\rm{opt}}$…

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astro-ph.IM2026年9月7日

An adaptive parameter optimization method for astronomical image alignment using Bayesian optimization. I. A hierarchical search strategy for FWHM and SNR

Yongjie Zhang, Yigong Zhang, Zhenjun Zhang, Xiangming Cheng, Lei Xiong, Xiaoguang Yu, Jie Su, Jiancheng Wang et al.

The alignment and stacking of astronomical images are fundamental steps for detecting faint objects and performing high?precision astrometry. In traditional alignment workflows, the extraction of source lists is critically dependent on key parameters such as the Full Width at Half Maximum (FWHM) and the Signal-to-Noise Ratio (SNR) threshold. These parameters are often selected manually through an inefficient trial-error process that lacks objectivity and does not guarantee optimal results. We pr…

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astro-ph.IMastro-ph.SR2026年9月7日

Filter and baffle design for the short-wavelength camera on SOLAR-C EUVST

James McKevitt, Duncan Rust, Berend Winter, David Walton, Sarah Matthews, Ted Pyne, Yukio Katsukawa, Ryohko Ishikawa et al.

SOLAR-C, which is scheduled to launch in the late 2020s with the Extreme Ultraviolet High-Throughput Spectroscopic Telescope (EUVST), will deliver EUV spectroscopy of the solar atmosphere with unprecedented temperature coverage and resolution. We present the optical design and mechanical impacts for the short-wavelength camera, and how our design choices affect scientific performance using complete forward modelling. We discuss the design and optical impact of the thin-film aluminium filter and…

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astro-ph.HEastro-ph.CO2026年9月7日

NEXUS: Transient Searches and First Results from Year One Observations

Ming-Yang Zhuang, Lei Hu, Justin D. R. Pierel, Zhiwei Pan, Yue Shen, Adam J. Burgasser, Xiaohui Fan, Luis C. Ho et al.

We describe ongoing efforts of high-redshift transient searches using multi-epoch NIRCam imaging (F200W+F444W) and NIRSpec MSA/PRISM spectroscopy from the NEXUS JWST multi-cycle Treasury program targeting the north ecliptic pole region. The transient search area covers $\sim 61.5\,{\rm arcmin^2}$ between the reference epoch and each subsequent NEXUS-Deep epoch at a cadence of $\sim2$~months. In the first year of observations from NEXUS, we detect 68 robust transients, with the host photometric r…

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gr-qcastro-ph.HEhep-th2026年9月7日

A New Window for Testing the PPN in the Strong-Field Regime: Stellar Rotation of S301

Mohsen Khodadi, Salvatore Capozziello

The recently discovered S301 star, with an orbital period of 8.7 years and eccentricity $e = 0.982$, reaches a pericenter of just $140\,R_{\mathrm{s}}$ --- approximately nine times closer than S2's $\sim 1200R_{\mathrm{s}}$ --- offering an unprecedented laboratory for testing strong-field gravity. We demonstrate that S301's stellar spin precession provides a novel probe of the PPN parameter $γ$, scaling as $(2γ_{\mathrm{PPN}} + 1)/3$ relative to general relativity (GR). For maximum projected vel…

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astro-ph.GAastro-ph.SR2026年9月7日

Catching Up with the Fastest Star in the Galaxy: A Two-Passage GRAVITY+ Campaign to Detect S301's Schwarzschild Precession

Joseph Catanzarite

S301 is the fastest known star in the Galaxy. It orbits Sgr A* every 8.68 yr on an e = 0.9832 orbit that carries it within 136 Schwarzschild radii at 25,600 km/s (GRAVITY Collaboration 2026). An orbit like that must precess, by the same Schwarzschild effect that turns Mercury's perihelion, whatever the spin of the black hole. We ask whether an astrometry-only GRAVITY+ campaign covering the 2031.8 and 2040.5 periapsis passages can catch it. We validate a relativistic light-curve model, design a 1…

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astro-ph.COastro-ph.GA2026年9月7日

Little Red Dot Cosmology: A Matter-Era Baryon Acoustic Oscillations Probe of $Λ$CDM

Jessica A. Zebrowski, Rohan P. Naidu

The discovery of Little Red Dots (LRDs) with JWST provides a new source population for cosmology in a largely unmapped period of cosmic history. LRDs are most numerous at $4\lesssim z\lesssim9$, thereby bridging existing low-redshift large-scale-structure measurements and the cosmic microwave background. In this epoch, the Universe is deep in the matter-dominated era, where dark energy is dynamically negligible and the expansion history is tightly predicted in $Λ$CDM, making these redshifts a cl…

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astro-ph.GA2026年9月7日

A Unified Magnetohydrodynamic Scaling Relation for the Multiphase Interstellar Medium

Mengke Zhao, Guang-Xing Li, Keping Qiu

The interplay of magnetic fields, turbulence, and gravity governs the structural evolution of the interstellar medium (ISM) and the initial conditions of star formation, yet observational gaps have long enforced a broken power-law description of the magnetic field--density relation. Here we assemble a unified dataset spanning ten orders of magnitude in density ($10^{-26}$--$10^{-16}\,\mathrm{g\,cm^{-3}}$) by combining pulsar and Zeeman observations. The unified data are consistent with a continu…

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astro-ph.EP2026年9月7日

Constraining the orbit of the retrograde planet in the $ν$ Octantis system

Alan Cefali Signor, Alexandre C. M. Correia, Maria Helena Moreira Morais, Timothée Vaillant, Ho Wan Cheng, Man Hoi Lee, Trifon Trifonov

The $ν$ Octantis system is composed of a compact stellar binary and a retrograde S-type planet orbiting near the edge of stability. Here, we investigate the dynamically viable architectures of this system by exploring the planetary orbital elements with a Monte Carlo method. To handle the large number of free parameters, we employed a novel approach in which all relevant orbital parameters were varied simultaneously, which we refer to as corner stability maps. Furthermore, since the osculating o…

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astro-ph.EPastro-ph.SR2026年9月7日

The Effect of X-Ray and Accretion Variability on Mid-Infrared Lines in the Young Disk-Bearing Binary DQ Tau

Bayron Portilla-Revelo, Konstantin V. Getman, Ágnes Kóspál, Dmitry Semenov, Vitaly Akimkin, Lis Zwicky, Jan Forbrich, Sierk van Terwisga et al.

A star's radiation field is the main energy source of a planet-forming disk. Stellar photons---from X-rays to optical---are reprocessed in the inner protoplanetary disk enabling mid-IR diagnostics of the disk's physical conditions. Most pre-main-sequence stars accrete at moderate rates and emit X-rays efficiently. Such activity is expected to drive stochastic variability in the stellar spectrum. It is not clear to what extent such variability affects the thermochemical structure of protoplanetar…

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astro-ph.IMastro-ph.HEastro-ph.SR2026年9月7日

Multimessenger Spectroscopy

Kristen Lackeos

A multimessenger method is developed for scheduling optical spectroscopy of ultracompact double white dwarf binaries from Laser Interferometer Space Antenna (LISA) data. The orbital parameters inferred from the gravitational wave (GW) signal are used to predict the argument of latitude $u(t)$, which sets the phase dependence of the radial velocity. With $u(t)$ known in advance, spectra can be taken at selected orbital phases. The GW and spectroscopic descriptions are linked by $u(t)=Φ_{\rm GW}(t…

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