研究動向

astro-ph.HE2026年8月22日

Relativistic blob signatures in the M87 jet at sub-parsec scales

Donaldo Mora, Alejandro Cruz-Osorio, Erika Benítez, Yosuke Mizuno

In this work, we present results from general-relativistic radiative-transfer calculations of black hole accretion and jet launching to reproduce the observed properties of the M\,87 jet at sub-parsec scales. For the first time, in the simulations we have included a blob component at the launching region of the jet that allowed us to reproduce the quasi-simultaneous low-energy spectral energy distribution ($10^{10} \text{ Hz} \leq ν\leq 10^{16} \text{ Hz}$). Moreover, we obtain a better fit of t…

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astro-ph.EPastro-ph.IM2026年8月22日

Assessing the Impact of High-Resolution Imaging on Statistical Validation of TESS Planet Candidates

Michael Collier, Steven Giacalone, Brian Derfer, David R. Ciardi, Catherine A. Clark, Ian J. M. Crossfield, Sarah Deveny, Sergio B. Fajardo-Acosta et al.

High-resolution imaging is widely used to constrain false-positive scenarios in exoplanet validation, but it is a finite follow-up resource that reaches only a subset of candidates, and its population-level impact on validation outcomes has not been quantified through controlled removal experiments. Using an automated pipeline built on TRICERATOPS, we compute the false-positive probability (FPP) of 443 TESS planet candidates. For the 264 planet candidates with high-resolution imaging observation…

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astro-ph.GA2026年8月22日

The Milky Way Joins the Extragalactic World: I. PHANGS

Neal J. Evans, Davide Elia, Jiayi Sun, Sophia Stuber, Adam K. Leroy

Complete catalogs of molecular clouds in the Milky Way allow analysis of the molecular medium and the star formation properties of the Milky Way that closely follows the method used for nearby galaxies, in particular in the PHANGS project. The dependencies of the depletion time on other properties of molecular gas in the Milky Way are similar to those of other galaxies when analyzed in an analogous way. They exhibit a large scatter and relatively weak correlations. The strongest correlation is a…

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astro-ph.GA2026年8月22日

Beyond orientation: Evidence for distinct physical regimes among Little Red Dots and Little Blue Dots

L. Barrufet, J. S. Dunlop, M. L. Hamadouche, M. Mezcua, D. Herrero-Carrion, M. Santos-Lleo, R. Gottumukkala, D. Spinoso et al.

Little Red Dots (LRDs) and Little Blue Dots (LBDs) may represent the same population of compact active galactic nuclei (AGN) observed along different lines of sight. We test this scenario using a spectroscopic sample from the DAWN {\it JWST} Archive, selected based on common criteria for H$α$ equivalent width, UV continuum slope, and compactness. We use the optical continuum slope to distinguish between samples of 89 LRDs and 191 LBDs spanning $1 \lesssim z \lesssim 7.5$, and compare their conti…

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astro-ph.IM2026年8月22日

On the performance of pre-trained vision transformers for supernova spectral classification using different spectral representations

J. Serrano Bell, P. Gálvez Molina, V. Contreras Rojas, W. Fox Fortino, M. Rojas, P. Protopapas, F. Bianco

The spectroscopic classification of supernovae is a key component of time-domain astronomy and plays an important role in the identification of Type Ia events. The increasing volume and diversity of spectroscopic data motivate the development of automated classification approaches. In this work, we explore the use of Transformer-based vision models for supernova spectral classification, focusing on how different visual representations of spectra and fine-tuning strategies affect classification p…

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astro-ph.EP2026年8月22日

A Highly Reflective Atmosphere on the Lava World TOI-561b Revealed by JWST/NIRSpec Phase Curve

Samuel Boucher, Lisa Dang, Alex McGinty, Johanna K. Teske, Raymond Pierrehumbert, Anjali A. A. Piette, Nicole L. Wallack, Angharad Weeks et al.

Ultra-short period (USP) rocky planets are expected to be depleted of any substantial gaseous envelope due to the intense irradiation they receive from their host star, making the recent detection of an atmosphere around TOI-561~b particularly surprising. That finding was based on the planet's bulk density and dayside emission spectrum, but full-orbit phase curve observations offer a more comprehensive way to constrain the presence and characteristics of a planet's atmosphere. In this paper, we…

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astro-ph.GA2026年8月22日

EROSE: An algorithm searching for resolved Local Group satellites. The impact of combining different photometric bands on the detectability of Milky Way satellites in the LSST

Samuel Rusterucci, Nicolas F. Martin, Else Starkenburg

Systematic searches for ultra-faint Milky Way satellite galaxies typically combine local density estimators with colour-magnitude cuts, which are usually performed in 2D and have rarely, if ever, been extended to higher-dimensional spaces. These studies generally rely on $gri$ photometry, overlooking the shallower but metal-sensitive $u$ band. Entering the era of LSST, our study explores different $ugri$ combinations to determine which provides the best performance. We injected 36,000 dwarf gala…

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astro-ph.GA2026年8月22日

On the importance of the IGM/CGM enrichment in determining chemical abundances during the first 600 Myr

Annalisa Citro, Yong-Zhong Qian, Claudia Scarlata

JWST observations show that galaxies at $z>8$ exhibit a wide range of carbon-to-oxygen (C/O) ratios at fixed metallicity and systematically elevated nitrogen-to-oxygen (N/O) ratios compared to local galaxies. Proposed explanations include finely tuned star-formation histories (SFHs), differential or pristine inflows, top- or bottom-heavy initial mass functions, or enrichment from Wolf-Rayet stars, supermassive stars (SMSs), or Population III stars. The observed abundances reflect both in situ pr…

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astro-ph.HE2026年8月22日

VLASS Discovery of a Luminous Galactic Radio Transient Evolving on Decade Timescales

Jessie M. Miller, Gregg Hallinan, Dillon Dong, Adolfo S. Carvalho, S. T. Myers, Jean Somalwar, Casey Law, B. M. Gaensler et al.

We present a multiwavelength analysis of the radio transient VT J1906+0849, discovered as a 70 mJy source in Epoch 1 of the Very Large Array Sky Survey (VLASS), 21 yr after an NRAO VLA Sky Survey (NVSS) non-detection. Radio observations reveal the source was first detected in 2005, peaking at $\gtrsim200$ mJy in 2014, then declining until a late 2025 rebrightening. The transient sits at a Galactic latitude of $\approx0.74^\circ$ and the properties of its optical-infrared counterpart support a Ga…

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astro-ph.GAastro-ph.HE2026年8月22日

The Random Magnetic Field of the Milky Way

Michael Unger, Glennys R. Farrar

We constrain the large-scale isotropic random component of the Galactic magnetic field using the Planck reconstruction of the 408 MHz synchrotron sky. Our analysis simultaneously fits the random-field structure, the synchrotron contributions of the coherent field and local foregrounds, and isotropic and dipolar offsets. A new element of the analysis is the use of excess polarized emission at 30 GHz to model local foregrounds, allowing us to retain 97% of the sky without absorbing these structure…

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astro-ph.EP2026年8月22日

Does Cumulative XUV Unify the Neptunian Desert?

Qunfeng Jiang

The architecture of close-in planetary systems includes a conspicuous scarcity of Neptune-size worlds, known as the Neptunian desert. The deficit spans roughly $2$--$10\,R_{\oplus}$ at orbital periods of a few days. Atmospheric erosion by stellar X-rays and extreme-ultraviolet (XUV) radiation may shape its lower boundary, while the strong mass dependence of stellar activity complicates comparisons across spectral type. We test whether standardized cumulative XUV exposure places the lower boundar…

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astro-ph.GA2026年8月22日

The [Ne V] AGN Diagnostic in SDSS-IV/eBOSS: An Anticorrelation Between Ionization State and AGN Luminosity in Low-Redshift Coronal-Line Galaxies

Owen S. Matthews Acuña, Christy A. Tremonti, Nikko J. Cleri, Kyle B. Westfall, Bee R. Erena, Jacob B. Stimac, Britt Lundgren, Drake Miller et al.

Traditional narrow-line diagnostics fail at high redshift, where low metallicity drives star-forming galaxies and Active Galactic Nuclei (AGN) into overlapping regions of the Baldwin-Phillips-Terlevich (BPT) diagram. Coronal lines, with ionization potentials exceeding 100 eV, offer a robust alternative: they cannot be produced by normal stellar populations, arise almost exclusively from AGN or fast shocks, and are insensitive to abundance evolution. Among these, the [Ne V] doublet is the brighte…

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astro-ph.HEhep-ph2026年8月22日

Generation of TeV Photons by PeV Neutrinos in Dense Astrophysical Environments

Jun-Chen Wang, Hanlin Song, Hao Li, Jie Zhu, Bo-Qiang Ma

Recent observations by IceCube and KM3Net of PeV-scale ultra-high-energy (UHE) neutrinos, together with detections of TeV-PeV photons from various sources such as the Crab Nebula, the Galactic Center, and gamma-ray burst by ground-based observatories including Tibet AS$γ$, MAGIC, Carpet-3, and LHAASO, point to the existence of extreme astrophysical environments capable of accelerating particles to ultra-high energies. These findings motivate investigations of possible connections between UHE neu…

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astro-ph.HE2026年8月22日

Constraining neutron-star properties with ensembles of thermonuclear bursts: application to SRGA J144459.2-604207

Duncan K. Galloway, Serena Jones, Luke Waterson, Tao Fu, Adelle J. Goodwin, Zhaosheng Li

Deducing the properties of the host neutron stars from thermonuclear (type-I) X-ray bursts remains a challenge, due to incomplete data, multidimensional parameter space, and dearth of suitable models and analysis tools. Here we describe further development of the BEANSP package, with a new "ensemble" analysis mode utilising the consistent and regular "clocked" bursting exhibited by some sources. This mode requires only one model evaluation per epoch, and so is much more efficient than the previo…

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gr-qcastro-ph.SRmath.DS2026年8月22日

Resonance crossings as entire functions of the Koopman operator

Priscilla Canizares

Astrophysical binaries formed by a stellar-mass compact object and a massive black hole are among the most promising sources for future space-based gravitational-wave detectors. These extreme mass-ratio inspiral (EMRI) systems are tracked coherently over more than $10^{5}$ orbits, encoding detailed information about strong-field gravity. Translating a detection into physical parameters requires models of comparable precision. One outstanding difficulty is the treatment of transient orbital reson…

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gr-qcastro-ph.SRmath.DS2026年8月22日

Resonance crossings as entire functions of the Koopman operator

Priscilla Canizares

Astrophysical binaries formed by a stellar-mass compact object and a massive black hole are among the most promising sources for future space-based gravitational-wave detectors. These extreme mass-ratio inspiral (EMRI) systems are tracked coherently over more than $10^{5}$ orbits, encoding detailed information about strong-field gravity. Translating a detection into physical parameters requires models of comparable precision. One outstanding difficulty is the treatment of transient orbital reson…

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astro-ph.SR2026年8月21日

alpha_theta waves in the tachoclines of Sun-like stars

T. V. Zaqarashvili, M. Dikpati, P. A. Gilman

Vertical gradient of mean turbulent electromotive force (expressed by the dynamo coefficient, alpha, caused by the penetrating convection into the tachoclines of Sun-like stars leads to the non-propagating alpha-mode patterns, which result in the periodic variations of magnetic field horizontal components. The aim of the paper is to study the influence of the latitudinal variation of the dynamo coefficient on the linear dynamics of large-scale waves in the overshoot layers of the tachoclines in…

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astro-ph.HE2026年8月21日

CtaAgnVar : a Pipeline for Variability Studies with the Cherenkov Telescope Array Observatory

G. Grolleron, J. -P. Lenain, J. Biteau, C. Boisson, M. Cerruti

Blazars are active galactic nuclei whose relativistic jet points toward the observer, accelerating particles that radiate across the electromagnetic spectrum. Characterizing their flux and spectral variability constrains the physics of the central black hole and its jet, making blazars a key science case for the Cherenkov Telescope Array Observatory (CTAO). The CTAO, with two sites and a sensitivity five to ten times better than current Imaging Atmospheric Cherenkov Telescopes, should reconstruc…

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astro-ph.GA2026年8月21日

Angular momentum in isolated disc galaxies: Insights from TNG100

A. Sorgho, L. Verdes-Montenegro, M. Baes, R. Ianjamasimanana, M. Korsaga, B. Namumba, S. Sanchez-Expósito, J. Garrido et al.

Angular momentum is a fundamental property that shapes the evolution of disc galaxies, strongly influencing the internal mechanisms that regulate star formation. Its content within disc galaxies is predicted to change over time, mainly as a result of external processes that regulate galaxy evolution. While several numerical studies paint a complex picture of angular momentum variation with environmental mechanisms, a recent observational finding suggests that galaxies are subject to angular mome…

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astro-ph.GA2026年8月21日

The curious case of HCO$^+$: Extreme abundances under extreme conditions

Katarzyna M. Dutkowska, Bin Jia, Serena Viti, Tobias M. Dijkhuis, Gijs Vermariën

Context. HCO$^+$ is widely observed in both Galactic and extragalactic environments and typically exhibits abundances of $10^{-9}-10^{-8}$. However, recent modeling studies suggest that in environments exposed to elevated cosmic-ray ionization rates and strong thermal or mechanical processing its abundance may increase by several orders of magnitude. Aims. To interpret these predictions, we need to understand the physical conditions that produce extreme HCO$^+$ abundances and the chemical pathwa…

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astro-ph.EPastro-ph.IM2026年8月21日

Transit Searches for Habitable-Zone Exoplanets with Artificial Intelligence

Qingtian Liu

Searching for Earth-sized planets in stellar habitable zones ultimately means finding a small number of very shallow, widely separated transits in noisy light curves. Around Sun-like stars, habitable-zone planets generally have long orbital periods, so a finite observing baseline may record only a few transits. At the same time, intrinsic stellar variability, instrumental systematics, and data gaps can obscure these weak events or produce transit-like brightness changes. This review examines rec…

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astro-ph.EPastro-ph.IM2026年8月21日

Transit Searches for Habitable-Zone Exoplanets with Artificial Intelligence

Qingtian Liu

Searching for Earth-sized planets in stellar habitable zones ultimately means finding a small number of very shallow, widely separated transits in noisy light curves. Around Sun-like stars, habitable-zone planets generally have long orbital periods, so a finite observing baseline may record only a few transits. At the same time, intrinsic stellar variability, instrumental systematics, and data gaps can obscure these weak events or produce transit-like brightness changes. This review examines rec…

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physics.soc-phastro-ph.GAastro-ph.HEastro-ph.IMastro-ph.SR2026年8月21日

From Timbuktu to SKA: Who owns the Astronomy knowledge Africa produces?

Rhea Koch, Amare Abebe

Africa has deep and diverse traditions of astronomical knowledge, ranging from archaeological astronomy, pharaonic stellar timekeeping, and manuscript astronomy in Timbuktu and the Sahel, to ecological seasonal astronomy in southern Africa and calendrical computation in the Ethiopian tradition. These multiple epistemic traditions form part of a long intellectual history that precedes and intersects with contemporary astronomy on the continent. In the context of this long-standing intellectual he…

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astro-ph.GA2026年8月21日

The GASKAP-HI Survey towards the Magellanic Clouds: Cold Atomic Gas Survival and Evolution in the Large Magellanic Cloud

Hongxing Chen, Sne{\vz}ana Stanimirovi{ć}, James Dempsey, Jacco Th. van Loon, Yik Ki Ma, Hiep Nguyen, Nickolas M. Pingel, John M. Dickey et al.

We use atomic hydrogen (HI) absorption detections from the GASKAP-HI survey to investigate the properties of cold atomic gas in the Large Magellanic Cloud (LMC). Using the radiative transfer method, we decompose 155 sightlines into 330 cold neutral medium (CNM), 2 thermally unstable neutral medium (UNM), and 310 warm neutral medium (WNM) components. We find that the CNM in the LMC exhibits higher optical depths (median 0.46), lower spin temperatures (median $\sim$37 K), broader linewidths (media…

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astro-ph.GA2026年8月21日

The GASKAP-HI Survey towards the Magellanic Clouds: Cold Atomic Gas Survival and Evolution in the Large Magellanic Cloud

Hongxing Chen, Snezana Stanimirovic, James Dempsey, Jacco Th. van Loon, Yik Ki Ma, Hiep Nguyen, Nickolas M. Pingel, John M. Dickey et al.

We use atomic hydrogen (HI) absorption detections from the GASKAP-HI survey to investigate the properties of cold atomic gas in the Large Magellanic Cloud (LMC). Using the radiative transfer method, we decompose 155 sightlines into 330 cold neutral medium (CNM), 2 thermally unstable neutral medium (UNM), and 310 warm neutral medium (WNM) components. We find that the CNM in the LMC exhibits higher optical depths (median 0.46), lower spin temperatures (median $\sim$37 K), broader linewidths (media…

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astro-ph.HE2026年8月21日

EWOCS VII : Unveiling the faint diffuse X-ray emission in Westerlund 1

Albacete-Colombo J. F., Andersen M., De Becker M., Mackey J., Larkin C. J. K., Guarcello M. G., Anastasopoulou K., Sciortino S. et al.

Westerlund 1 (Wd 1) is the closest supermassive star cluster to the Sun, with over 100,000 stars of all spectral types down to brown dwarfs. This population strongly heats the surrounding interstellar medium (ISM), making Wd 1 a key site to study stellar feedback on intracluster gas. We present the most detailed X-ray study to date of its diffuse emission, aiming to separate and quantify the point-source contribution to the true diffuse emission. We analysed 36 Chandra ACIS-I observations within…

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astro-ph.IMastro-ph.EPmath-phphysics.data-an2026年8月21日

NestyNet. IV. Laws Chosen by Nothing in Advance

Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis, Neil Ibata, Anirudh Shankar

Differential-equation (DE) discovery tends to break down precisely where much of physics begins. Fields are coupled, governing laws are nonlinear in the state, amplitudes, coordinates, or operators of interest, yet derivatives must remain consistent across fields, channels, and differentiation orders. NestyNet-DE addresses this via two complementary DE search strategies, both employing analytic derivatives from segmented neural surrogates: a sparse-library route linear in the outer coefficients,…

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astro-ph.IMastro-ph.EPmath-phphysics.data-an2026年8月21日

NestyNet. IV. Laws Chosen by Nothing in Advance

Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis, Neil Ibata, Anirudh Shankar

Differential-equation (DE) discovery tends to break down precisely where much of physics begins. Fields are coupled, governing laws are nonlinear in the state, amplitudes, coordinates, or operators of interest, yet derivatives must remain consistent across fields, channels, and differentiation orders. NestyNet-DE addresses this via two complementary DE search strategies, both employing analytic derivatives from segmented neural surrogates: a sparse-library route linear in the outer coefficients,…

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astro-ph.IM2026年8月21日

DOLPHIN (Device of Line Photometry in Nasmyth): A Switchable Multiband Photometer for the ISAS 1.3-m Telescope

Kohei Miyakawa, Hirokazu Kataza, Teruyuki Hirano, Hajime Kawahara, Shotaro Tada, Takehiko Wada

We present the design, construction, and commissioning of DOLPHIN (Device of Line Photometry in Nasmyth), a compact instrument for switchable broad- and narrow-band photometry at the Nasmyth focus of the ISAS 1.3-m telescope. DOLPHIN was developed as a cost-conscious platform for differential measurements of selected spectral features with modest-aperture telescopes. A motorized eight-position filter wheel provides access to Johnson-Bessell B, V, and R bands and narrow-band Na D and H$α$ filters…

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astro-ph.IMphysics.data-an2026年8月21日

NestyNet. III. Symbolic Regression from Analytic Neural Surrogates

Rodrigo Ibata, Wassim Tenachi, Foivos Diakogiannis, Neil Ibata, Anirudh Shankar

Many physical laws are simple only after the right representation, decomposition or internal coordinate has been found, but discovering that structure from data is combinatorially hard. This task is symbolic regression (SR), the search for closed-form expressions that fit data without assuming a fixed model class. Here we present NestyNet-SR. A neural surrogate with analytic derivatives is used to detect separability, recursively reducing multivariate problems to simpler neural atoms. These atom…

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