研究動向

astro-ph.IM2026年7月30日

Laboratory characterization of iLocater

Marcelo Tala Pinto, Marshall C. Johnson, Julia Brady, Xavier Lesley-Saldaña, Jonathan Crass, Allie Renshaw, Michael Engelman, Brian Sands et al.

iLocater is a diffraction-limited, fiber-fed spectrograph designed for the Large Binocular Telescope (LBT), which targets high-precision radial velocity measurements in the near-infrared. Prior to deployment, comprehensive laboratory characterization was essential to validate instrument performance and inform alignment strategies. This paper presents results from four key areas of lab characterization: (1) adjustment and optimization of detector orientation to optimize spectrum alignment with th…

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astro-ph.EPastro-ph.SR2026年7月30日

A Systematic Trend in the Observed vs. Predicted Radii of Transiting Brown Dwarfs

Thomas G. Beatty

Transiting brown dwarfs provide a direct empirical test of substellar evolutionary models, and with more than 50 now known we can carry out this test at the population level. We compared the observed masses and radii of 31 field-age, weakly irradiated transiting brown dwarfs to the Sonora Diamondback, Sonora Bobcat, and ATMO 2020 grids, and a subset of 23 of them to the irradiated models of Mukherjee et al. (2026). In every comparison we find a radius-dependent trend, with fits of $R_{\rm pred}$…

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physics.opticsastro-ph.IMphysics.acc-ph2026年7月30日

New techniques for high-resolution imaging and high-precision wavefront sensing via masked-aperture interferometry

Nithyanandan Thyagarajan, Bojan Nikolic, Chris Carilli, Laura Torino, Ubaldo Iriso

Achieving high-angular-resolution imaging on subarcsecond scales is fundamentally limited by wavefront aberrations imparted by the propagation medium and by optical elements along the light path. Accurate recovery of source structure at these fine angular scales therefore relies on precise, real-time sensing and correction of wavefront aberrations. Drawing inspiration from radio interferometry, we have developed different approaches using masked apertures that directly measure both the amplitude…

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hep-exastro-ph.SR2026年7月30日

First Experimental Bounds on Transverse Plasmon Solar Axions with ANAIS-112

S. J. Hollick, M. Giannotti, J. Ruz, J. K. Vogel, R. M. Alkaddah, J. Amaré, J. Apilluelo, S. Bharat et al.

Solar axion-like particles (ALPs) can be resonantly produced through the conversion of transverse plasmons in the magnetic field of the solar interior, introducing a production mechanism complementary to the conventional Primakoff process. In this Letter, we report the first experimental search for solar ALPs produced through this mechanism. Using an exposure of 625.75 kg$\times$yr from ANAIS-112, we search for the annual modulation of the flux induced by the variation of the Earth--Sun distance…

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astro-ph.HE2026年7月30日

Exploring cosmic magnetism with gamma-ray burst afterglow emission

Paolo Da Vela, Davide Miceli, Lara Nava, Giancarlo Ghirlanda

The nature and origin of magnetic fields on cosmological scales are still unclear. Magnetic fields detected in galaxies and galaxy clusters are typically interpreted as the result of the amplification of weak seed fields, but their nature remains largely unknown with two scenarios considered: the cosmological and the astrophysical origin. Signatures of magnetization in cosmic voids from observations of very high energy (VHE, E > 100 GeV) photons from extragalactic sources can provide crucial res…

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astro-ph.HE2026年7月30日

Relativistic effects of PSR~J1856--0039 double neutron star system in a 2.36-hour compact orbit

Z. L. Yang, J. L. Han, W. Q. Su, P. F. Wang, C. Wang, T. Wang, D. J. Zhou, Yi Yan et al.

Compact double neutron star (DNS) systems are unique laboratories for testing gravitational theories and studying DNS mergers. Here we report the properties of a new DNS system, PSR J1856--0039, discovered in the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The pulsar is mildly recycled with a period of 23.4~ms in a compact eccentric orbit ($e=0.106$) with an orbital period of 2.36 hours. By following up FAST observations, we measured the relativistic effects, including the orbi…

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astro-ph.IMastro-ph.EPastro-ph.SR2026年7月30日

Commissioning and on-sky performance verification of iLocater

Marshall C. Johnson, Marcelo Tala Pinto, Jonathan Crass, Brian Sands, Jackson Datkuliak, Sai Vidyud Senthil Nathan, Justin R. Crepp, Michael Engelman et al.

iLocater is a high-resolution near-infrared extreme precision radial velocity (EPRV) spectrograph that was deployed to the Large Binocular Telescope (LBT) in June 2026. iLocater operates over $λ=966-1312$ nm with a median resolving power of $R=205,000$ as measured in the laboratory. We present the commissioning and initial on-sky verification program using solar and night-time observations at the LBT. First light was achieved on 27 June 2026, and nearly 150 on-sky spectra have now been recorded.…

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astro-ph.GA2026年7月30日

An Exploratory Analysis of New Large Gaia-informed Quasar Samples in SDSS-V

Shir Aviram, Benny Trakhtenbrot, Tom Dwelly, Scott F. Anderson, Sean Morrison, Michael Eracleous, Yue Shen, Mara Salvato et al.

Quasars are luminous objects that provide insights into the physics and evolution of supermassive black holes (SMBHs) and their accretion flows, galaxy evolution, and even cosmology. In this study, we present an exploratory study based on the ongoing fifth generation of the Sloan Digital Sky Survey (SDSS-V) and its unique dual-hemisphere, wide-field, and multi-object spectroscopic capabilities, with the aim of creating a comprehensive, all-sky quasar sample. The targets were selected through two…

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astro-ph.IM2026年7月30日

The Calibration System of the iLocater Spectrograph

Sai Vidyud Senthil Nathan, Jonathan Crass, Julia E. Brady, Mark Derwent, Marcelo Tala Pinto, Brian Sands, Jackson Datkuliak, Jonathan Shover et al.

iLocater is a new near-infrared, extreme precision radial velocity (EPRV) instrument delivered to the Large Binocular Telescope in the summer of 2026. The instrument utilizes single-mode fibers (SMFs) for light transmission, including its calibration systems. We present an overview of the iLocater calibration system, detailing the specific sources and the hardware required to inject calibration light into the SMFs. Furthermore, we discuss the hardware that efficiently switches between these sour…

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astro-ph.SRastro-ph.GAastro-ph.IM2026年7月30日

PANTERA. I. Hunting for the Most Metal-Rich Stars in the Solar Neighborhood with High-Resolution Spectroscopy

Serat M. Saad, D. M. Rowan, K. Z. Stanek, Ilya Ilyin, Benjamin J. Fulton, Howard Isaacson, Jessica Lu

We present PANTERA (Project for Astrophysical Nucleosynthesis and Targeted Exploration of metal-Rich Abundances), a high-resolution spectroscopic survey of the most metal-rich stars in the solar neighborhood. In this first paper, we report iron abundances for 56 metal-rich stars, selected from Gaia DR3 XP spectrophotometric metallicities. These targets were observed with the PEPSI spectrograph on the Large Binocular Telescope (LBT), the Levy spectrograph on the Automated Planet Finder (APF) tele…

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astro-ph.HEastro-ph.COhep-ph2026年7月30日

Semi-analytic Inference of Satellite Densities in the Cold Dark Matter Model Part II. Implications for Dark Matter Indirect Detection Constraints

Kailash Raman, Dylan Folsom, Manoj Kaplinghat, Mariangela Lisanti, Benjamin R. Safdi

Dwarf galaxies provide excellent targets to search for signals of dark matter annihilation or decay. Using a calibrated semi-analytic model and the latest stellar kinematic data (presented in Part I), this paper updates the astrophysical J-factors for the Milky Way's dwarf spheroidal galaxies. We infer the probability distributions for the J-factors of 39 dwarfs by conditioning a population of subhalos, generated with the SatGen semi-analytic satellite model, on either a dwarf's kinematically de…

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astro-ph.SRastro-ph.GA2026年7月30日

The T-GEX project. I. Stealth UV-bright Sun-like stars in the Galaxy as candidate contributors to the UV upturn

M. L. L. Dantas, D. Beltrán, R. E. Giribaldi, R. Smiljanic, P. R. T. Coelho, P. B. Tissera

We constructed the Tiny Gaia-ESO + GALEX (T-GEX) catalogue by combining Gaia-ESO spectroscopy, Gaia DR3 astrometry, GALEX UV photometry, and 2MASS and AllWISE infrared measurements for 37 stars. Astrometric and spectroscopic quality cuts minimise obvious multiplicity and spectral peculiarity, although unresolved companions cannot be excluded. We classified the stars relative to the empirical FGK UV-normal locus, applied a 3-component Gaussian mixture model in the FUV-NUV versus NUV-$G$ plane, me…

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astro-ph.GA2026年7月30日

The influence of feedback on the baryonic content of haloes in the COLIBRE simulations

Jonathan J. Davies, Joop Schaye, Filip Huško, Ruby J. Wright, Evgenii Chaikin, Matthieu Schaller, Robert J. McGibbon, Alejandro Benítez-Llambay et al.

We present predictions for the relation between the halo gas mass fraction and halo mass, $f_{\rm gas}^{200}-M_{200}$, from the COLIBRE cosmological simulations of galaxy formation, and explore how the gas content of haloes is influenced by feedback from supernovae and active galactic nuclei (AGN) over time. The $f_{\rm gas}^{200}-M_{200}$ relation in COLIBRE is non-monotonic, with a peak at $M_{200}\sim 10^{11.5-12}$~M$_\odot$. Below this mass, feedback from supernovae efficiently expels gas fr…

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astro-ph.IMastro-ph.COcs.LG2026年7月30日

Emulating Cosmic Structure Formation with a Lagrangian Neural Cellular Automaton

Cooper Jacobus, Beatriz Tucci, Oliver Philcox

Field-level inference of cosmological initial conditions from galaxy surveys requires a forward model that is simultaneously accurate in the non-linear regime, computationally efficient, and fully differentiable. Traditional N-body simulations are accurate but computationally prohibitive for iterative inference, while approximate solvers like Lagrangian Perturbation Theory (LPT) fail to capture the knotty halo-forming dynamics of the cosmic web at late times. We introduce the \textit{Lagrangian…

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astro-ph.IMastro-ph.HEgr-qc2026年7月30日

Assessing the Impact of Instrumental Requirements on the Scientific Performance of the Einstein Telescope

Ulyana Dupletsa, Francesco Iacovelli, Mikhail Korobko, Valeria Sequino, Alessandro Agapito, Manuel Arca Sedda, Biswajit Banerjee, Nicolò Cibrario et al.

We investigate the relationship between instrumental requirements and the scientific performance of the Einstein Telescope (ET), a third-generation (3G) gravitational-wave (GW) observatory. Different technical design choices result in distinct noise budgets, ultimately shaping the detector's scientific capabilities. To systematically assess and compare their impact, we define a comprehensive set of performance metrics spanning compact binary coalescence (CBC) detection and parameter estimation,…

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astro-ph.GAastro-ph.COhep-ph2026年7月30日

Semi-analytic Inference of Satellite Densities in the Cold Dark Matter Model Part I. Comparison to Ultra-faint Dwarf Kinematics

Kailash Raman, Dylan Folsom, Manoj Kaplinghat, Mariangela Lisanti, Benjamin R. Safdi

Ultra-faint dwarf galaxies are critical testing grounds for probing the limits of galaxy formation in the cold dark matter (CDM) paradigm. Employing a semi-analytic cosmological satellite generator that captures the expected CDM halo population, we estimate Milky Way dwarf density profiles through two methods: a kinematic approach using stellar velocity dispersions and a separate method based on dwarf stellar masses. The kinematic approach yields a larger diversity in central dark matter densiti…

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astro-ph.GA2026年7月30日

Superdiffusion at the Galactic Centre

Pau Amaro Seoane, Kostas Tzanavaris, Reinhard Genzel, Frank Eisenhauer, Thomas Ott, Stefan Gillessen, Guillaume Bourdarot, Diogo C. Ribeiro et al.

Tracking S-star cluster orbits around Sgr A* calibrates orbital transport models for space-borne gravitational wave detectors. Standard kinetic theories model this cluster via local Fokker-Planck equations, which predict that general relativistic precession halts angular momentum diffusion at the Schwarzschild barrier. Because inverse-square gravitational encounters generate a Holtsmark torque distribution with infinite variance, resonant relaxation operates as a space-fractional process governe…

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astro-ph.EP2026年7月30日

An Inclined, Eccentric Planet and an Inner Debris Disk Could Reproduce AU Mic Structure

Arcelia Hermosillo Ruiz, Ruth Murray-Clay, Meredith A. MacGregor, Renata Frelikh

The debris disk orbiting the M star AU Microscopii has a series of large-scale clumps that move away from the star at high velocities above the mid-plane on the southeast side. Two more bright features lie on the northwest side of the disk, localized below the mid-plane and moving toward the star. These clumps are only observed in scattered light indicating that they affect small 0.2$μ$m-sized grains. We present a mechanism for emitting periodic dust clumps by appealing to stellar forces and an…

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astro-ph.COastro-ph.GA2026年7月30日

Shear-kSZ: A New Estimator for the Matter-Electron Power Spectrum from kSZ Tomography and Weak Lensing

Boryana Hadzhiyska

We propose a new estimator for the ionized gas--matter power spectrum, which correlates the kinematic Sunyaev--Zel'dovich (kSZ) field with the line-of-sight velocity field and the weak-lensing convergence map. Analogously to the standard stacked kSZ estimator, this estimator factorizes into a calibratable velocity kernel multiplying the matter--electron cross-power spectrum, $P_{me}(k)$. Because the estimator accesses $P_{me}(k)$ for the full matter distribution rather than around a specific bia…

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astro-ph.GA2026年7月30日

J-ATLAS: Javalambre Andromeda and Triangulum Legacy Astrophysical Survey

Borja Anguiano, Andres del Pino

The outskirts of nearby galaxies preserve long-lived signatures of hierarchical assembly and provide a fossil record of galaxy formation. J-ATLAS, the Javalambre Andromeda and Triangulum Legacy Astrophysical Survey, is a proposed wide-field optical photospectroscopic survey of the M31--M33 system with JST/T250 and JPCam. Using the dense J-PAS filter system, it will deliver homogeneous low-resolution optical SEDs for resolved stars, compact stellar systems, emission-line sources, and background o…

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astro-ph.IM2026年7月30日

High-speed, low-noise, multi-megapixel CCDs for next generation X-ray observatories

Haley R. Stueber, Tanmoy Chattopadhyay, Peter Orel, Steven W. Allen, Marshall W. Bautz, Michael Cooper, Kevan Donlon, Catherine E. Grant et al.

Next generation X-ray observatories require fast, low-noise, low-power, multi-megapixel imaging spectrometers. To meet these demands, the X-ray Astronomy and Observational Cosmology (XOC) Group at Stanford, in partnership with the MIT Kavli Institute and MIT Lincoln Laboratory (MIT-LL), is developing multi-channel X-ray charge-coupled devices (CCDs) and fast readout architectures. We report the energy resolution and noise performance achieved with a full-scale (1440x1440-pixel), 16-channel, fron…

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astro-ph.HE2026年7月30日

Braking indices as probes of r-mode spin-down in young pulsars

Shahram Abbassi, Armin Memarian, Evelyn Sophia Guest, S. R. Valluri

We present a timing-based framework for interpreting braking-index measurements in young pulsars using a four-channel spin-down model that includes particle-wind, magnetic-dipole, mass-quadrupole, and current-quadrupole torques. The observed braking index is a torque-weighted average of the channel exponents, enabling equation-of-state-independent constraints on the torque fraction of a possible r-mode-like current-quadrupole component from timing data alone. For positive, slowly varying secular…

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astro-ph.HEgr-qc2026年7月30日

Universality of dual mass-scaled fundamental modes in two-fluid neutron stars with mirror dark matter

Hajime Sotani, Ankit Kumar

Universal relations provide a particularly useful way to extract physical information from neutron star observables in the presence of various uncertainties by reducing the dependence on uncertain model parameters and microphysical inputs. In this study, we examine the oscillation frequencies of mirror dark matter admixed neutron stars using a two-fluid description, where the outer and inner fluids give rise to two distinct fundamental frequencies. We confirm that the universal relation between…

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astro-ph.GAastro-ph.CO2026年7月29日

Constraining the shape of dark matter haloes using only starlight II. Tests of the technique with objects of known gravitational potential

Jorge Sanchez Almeida, Angel R. Plastino, Sergio Guerra Arencibia, Nitya Kallivayalil, Jack T. Warfield

Under the collisionless cold dark matter (CDM) paradigm, galaxies with stellar masses below 10**(5-6) Msun are expected to preserve primordial cuspy dark matter (DM) profiles. Because baryonic feedback should be too weak to transform cusps into cores at these masses, such galaxies provide especially sensitive tests of DM physics. If cores are observed in these systems, they could indicate departures from CDM. To address this problem, Sanchez Almeida et al. (2025) introduced the Eddington Inversi…

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astro-ph.IMastro-ph.CO2026年7月29日

Dish Assembly Precision for HIRAX

Jennifer Studer, Devin Crichton, Alexandre Refregier, Keshav Bechoo, H. Cynthia Chiang, Chandrachud B. V. Dash, Sindhu Gaddam, Aditya Krishna Karigiri Madhusudhan et al.

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a radio interferometer array that is being deployed at the South African Radio Astronomy Observatory (SARAO) Square Kilometer Array (SKA) site in South Africa. Mapping the southern sky, its aim is to observe neutral hydrogen (HI) through intensity mapping (IM) across the redshift range of 0.78-2.55. The observation of HI makes it possible to tomographically probe large cosmological volumes, enabling constraints on, for example,…

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astro-ph.SR2026年7月29日

Constraints from parallaxes and average period spacings in the asteroseismic study of 8 DAVs

Agnès Kim, Keaton J. Bell

With space missions such as Kepler, TESS, and Gaia, we have a wealth of data on pulsating white dwarfs that can be leveraged in white dwarf asteroseismology. We address the question of the proportion of white dwarfs with thin hydrogen layers versus those with thick hydrogen layers. We also provide a mass-radius relation for carbon-oxygen core, hydrogen atmosphere white dwarfs. Such a relationship can be used in conjunction with magnitudes and distance measurements to constrain the mass and effec…

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astro-ph.IM2026年7月29日

Characterization and on-sky testing of photonic, AWG-based astronomical spectrographs

Jeronimo Calderon-Gomez, Frantz Martinache, Nick Cvetojevic, Marc-Antoine Martinod, Vincent Foriel, Nemanja Jovanovic, Pradip Gatkine, Gregory Sercel et al.

Astrophotonics is a field that intends to meet the needs of next-generation instruments at a small footprint, low cost, and high stability, compared to bulk-optics-based alternatives. Much development effort is driven by the stringent requirements of direct detection and characterization of exoplanets. Our team works in characterizing Arrayed-Waveguide Grating (AWG) chips for photonics-based, high-resolution, near infrared spectro-interferometry. AWG spectrographs allow to test the feasibility o…

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astro-ph.SR2026年7月29日

Evolutionary variations of superficial iron and calcium abundance in main sequence A stars

Yu. A. Fadeyev, R. M. Bayazitov

Main sequence stellar evolution models were computed together with solution of the equations of atomic diffusion for 16 elements from hydrogen to nickel. The grid of evolutionary tracks comprises the models with stellar masses ranged from 1.4 to $2.5M_\odot$ computed for initial helium and metal abundances $Y=0.28$ and $Z=0.02$, respectively. The calculations were done for the mass loss rates $10^{-15}M_\odot/\textrm{yr}\le\dot M\le 10^{-12}M_\odot/\textrm{yr}$ as well as for $\dot M=0$. The hig…

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astro-ph.COastro-ph.IM2026年7月29日

Impact of numerical stability in Bayesian noise wave calibration on global 21-cm experiments

Saswata Dasgupta, Adarsh Kumar Dash, Dominic Anstey, Harry T. J. Bevins, Christian Kirkham, Eloy de Lera Acedo

Detecting the global 21-cm signal from the Cosmic Dawn and Epoch of Reionization requires calibration accuracy far below the level of astrophysical foregrounds. REACH models its receiver using the noise wave formalism, with five frequency-dependent low-noise amplifier parameters fitted jointly to multiple calibration sources. We identify a numerical instability in this Bayesian calibration pipeline: the condition number of the posterior covariance matrix reaches $κ(\mathbf{V}^*) \sim 10^{9}$--$1…

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astro-ph.HE2026年7月29日

Outflow Behavior from the Transonic Advective Disks: A Hydrodynamical Simulation Study

Sanjit Denath, Indranil Chattopadhyay, Raj Kishor Joshi, Philippe Laurent, Priyesh Kumar Tripathi, M. Saleem Khan

We investigate the properties of outflows from the transonic advective accretion disk using hydrodynamical numerical simulations. We consider two different disk temperatures with an order-of-magnitude difference. For the hotter disk, we adopt initial conditions for velocity, specific angular momentum, and temperature from analytical solutions. In the colder disk case, the velocity and angular momentum profiles are kept identical, while an order of magnitude reduction in the temperature. The simu…

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