研究動向

astro-ph.HEastro-ph.IMgr-qc2026年9月9日

Hierarchical Inference of the Supermassive Black Hole Binary Merger Rates from Joint Searches using Pulsar Timing Arrays

Sharon Mary Tomson, Rutger van Haasteren, Boris Goncharov

Gravitational-wave searches do more than identify individual sources - they provide a way to infer the underlying astrophysical populations that produce them. Currently, Pulsar Timing Arrays (PTAs) constrain the supermassive black-hole binary (SMBHB) merger-rate density through both the stochastic gravitational-wave background (SGWB) and searches for individual SMBHB signals. The latter implies converting source upper limits into rate upper limits using detection efficiencies estimated empirical…

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astro-ph.SR2026年9月9日

Exploring pulsational instabilities in the O-type supergiant HD 152249

Subharthi Dasgupta, Abhay Pratap Yadav, Sugyan Parida, Santosh Joshi

Variability in O-type supergiants is a well known phenomena although their origin is not fully understood. In very massive, luminous stars, strange mode pulsations have been suggested to play a role in the variability. Here, we present a preliminary theoretical study of O-type supergiant models corresponding to the observed parameters of the star HD 152249, which shows line profile variability. Non-adiabatic linear stability analysis with respect to radial perturbations is carried out for the co…

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astro-ph.GAastro-ph.COgr-qchep-ph2026年9月9日

Small-Scale Clustering of Primordial Black Holes: The Little Red Dot Mass Function and the High-Redshift Galaxy Tension

Borui Zhang, Wei-Xiang Feng, Haipeng An

Supermassive black holes (SMBHs) in "little red dots" (LRDs) discovered the James Webb Space Telescope (JWST) may result from runaway mergers of primordial black holes (PBHs) in clusters---through long--short mode coupling on small scales in the early Universe. In this framework, we derive the SMBH mass function, together with the compactness and overmassive features of LRDs. We also estimate that the dense gas residing in PBH clusters is consistent with LRD observations. In addition, SMBHs form…

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astro-ph.EP2026年9月9日

The Discovery of K2-232c: Divergent Formation Histories for Hot and Warm Jupiters Based on Outer Companion Eccentricity

Jessica A. Ranshaw, Xian-Yu Wang, Jennifer A. Burt, Juan I. Espinoza-Retamal, Brandon T. Radzom, R. Paul Butler, Bradford P. Holden, Steven S. Vogt et al.

Ever since their discovery, hot Jupiters have been one of the most studied types of exoplanets to exist thanks to their significant size, their proximity to their host star, and their significant departure from anything present in our solar system. Yet, the details of their formation and evolution remain unclear, including their connection, if any, to the wider-orbiting warm Jupiter population. In this work, we present the discovery of K2-232c, an eccentric cold Jupiter ($P = 1950 ^{+140}_{-120}…

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astro-ph.EP2026年9月9日

The size and mass distribution of cold classical TNOs for $5<H<13$

Gary M. Bernstein, Wesley C. Fraser, Marielle R. Eduardo, William M. Grundy, Bryan Hilbert, Matthew J. Holman, Anastasia N. Morgan, Kevin J. Napier et al.

The cold classical trans-Neptunian objects (CCs) are the only observable \textit{in situ} population of planetesimal remnants believed to have escaped collisional grinding. Recent JWST observations make it possible to fit the differential absolute magnitude distribution $dN/dH$ of the CCs from $5 13$ is unwise, as the different analytic forms diverge. It remains unclear if $dN/dH$ turns over at faint $H.$ The uncertainty in the total mass of the CC belt is dominated by uncertainty in the relatio…

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astro-ph.GA2026年9月9日

Active galactic nucleus activity in brightest cluster galaxies at intermediate redshifts in Sunyaev-Zel'dovich--selected clusters

N. Hatamkhani, R. E. Skelton, J. Delhaize, M. Hilton, S. I. Loubser, N. Gupta, K. M. Mogotsi

Context. Brightest cluster galaxies (BCGs) host powerful active galactic nuclei (AGNs) and help regulate the heating--cooling balance of the intracluster medium. While radio-mode feedback is well established locally, its prevalence at intermediate redshifts remains poorly constrained. Aims. We investigate the incidence, accretion state, and host-galaxy properties of AGNs in BCGs in Sunyaev--Zel'dovich (SZ)-selected clusters at $0.3 < z < 0.8$, testing dependences on cosmic epoch, cluster mass, a…

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astro-ph.EP2026年9月9日

The Luminosity Function of Ultra-Faint Trans-Neptunian Objects Detected by JWST

Marielle R. Eduardo, Anastasia N. Morgan, Wesley C. Fraser, David E. Trilling, Gary M. Bernstein, John A. Stansberry, Bryan Hilbert, Matthew J. Holman et al.

We present a definitive discovery of 27 trans-Neptunian objects (TNOs) using the Near-Infrared Camera (NIRCam) aboard the James Webb Space Telescope (JWST). By employing a shift-and-stack technique and a machine learning network geared specifically to identifying false-positive detections in JWST images produced through the shift-and-stack process, we achieved a 40\% detection threshold of $m_{F150W2}=28.8$ mag (corresponding to $m_r\sim29.8$ mag) across a sky area of $0.05 \ \text{deg}^2$. This…

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physics.plasm-phastro-ph.SR2026年9月9日

On the modeling of oblique firehose instabilities in regularized Kappa plasmas using ALPS

D. L. Schröder, M. Lazar, H. Fichtner, K. G. Klein, D. Verscharen

In-situ measurements in space plasmas indicate that the velocity distributions of charged particles are not in thermal equilibrium, deviating from a standard Maxwellian mainly due to anisotropies and suprathermal populations which enhance high-energy tails. Although the Standard \k{appa}-Distribution (SKD) is well established in modeling these non-equilibrium distributions, its application is often viewed controversially due to certain unphysical implications, in particular divergent velocity mo…

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astro-ph.HE2026年9月9日

Wolf-Rayet stars and black holes: mass distributions and evolutionary connection

I. A. Shaposhnikov, K. A. Postnov, A. M. Cherepashchuk

The form and relationship between the mass distributions of Wolf-Rayet stars and black holes are analyzed using a direct method for estimating the distribution function from a sample of mass values with individual distributions obtained from current observations. It is shown that, taking into account the mass loss of WR stars by the end of this evolutionary stage, the mass distribution of black holes is close to that of the CO-cores of WR stars before gravitational collapse, $M_\mathrm{BH}\simeq…

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astro-ph.HEastro-ph.GA2026年9月9日

Detection of episodic Ultra-fast Outflows in the Low-luminosity quasar Mrk 205 using XMM-Newton data

César Ivan Victoria-Ceballos, Anna Lia Longinotti, Yair Krongold, Giorgio Lanzuisi, Miriam Gudiño, Armando Lara-DI

Ultra-fast outflows (UFOs) from Active Galactic Nuclei (AGN) are winds which reach velocities up to 0.3c, and show mass outflow rates of 0.01-1 $M_{\odot} yr^{-1}$ and kinetic energies of $10^{42-45}$ erg/s. Their extreme properties allow UFOs to carry substantial kinetic power, sufficient to drive AGN feedback by injecting energy and momentum into the interstellar medium, regulating the host galaxy evolution and the supermassive black hole growth. In this work, we present a detailed analysis of…

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astro-ph.SRastro-ph.GA2026年9月9日

Open Clusters as Laboratories for Cool Star Evolution: Highlights from the Cool Stars 23 Splinter Session

Deepak Chahal, Beatrice Caccherano, Edward Gillen, Dario J. Fritzewski, Robin D. Jeffries, Kevin R. Covey, Andrew Boyle, Lyra Cao et al.

Open clusters remain among the most powerful laboratories for calibrating how fundamental stellar properties such as rotation, magnetic activity, surface chemistry, and internal structure evolve over the pre-main-sequence to main-sequence and post-main-sequence stellar lifetime. Because cluster members share a common age, galactic environment, and initial composition, they provide empirical anchors upon which age-dating techniques such as gyrochronology, activity-age relations, and chemical cloc…

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astro-ph.SRastro-ph.GA2026年9月9日

Open Clusters as Laboratories for Cool Star Evolution: Highlights from the Cool Stars 23 Splinter Session

Deepak Chahal, Beatrice Caccherano, Edward Gillen, Dario J. Fritzewski, Robin D. Jeffries, Kevin R. Covey, Andrew Boyle, Lyra Cao et al.

Open clusters remain among the most powerful laboratories for calibrating how fundamental stellar properties such as rotation, magnetic activity, surface chemistry, and internal structure evolve over the pre-main-sequence to main-sequence and post-main-sequence stellar lifetime. Because cluster members share a common age, galactic environment, and initial composition, they provide empirical anchors upon which age-dating techniques such as gyrochronology, activity-age relations, and chemical cloc…

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astro-ph.GAastro-ph.IMcs.LG2026年9月9日

Closed-Form of the Local Galactic Potential and Stellar Distribution Function from Gaia DR3

Indranil Das, Adam Kamoski, Dora Demiri, Brianna Isola, Hanieh Karimi, Dmitrii S. Zagorulia

The local dark matter density determines the strength of the signal expected in direct-detection experiments, yet published estimates from stellar motions disagree by more than their errors, and the most recent machine-learning analysis of Gaia data finds a local density consistent with zero. According to Jeans' theorem, a distribution function built from integrals of motion satisfies the collisionless Boltzmann equation (CBE) trivially for any choice of potential, so a search that simultaneousl…

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astro-ph.EP2026年9月9日

Combined JWST and HST Deep Imaging to Characterize the Smallest Known Trans-Neptunian Objects

Anastasia N. Morgan, Marielle R. Eduardo, David E. Trilling, Wesley C. Fraser, John A. Stansberry, Gary M. Bernstein, Bryan Hilbert, Matthew J. Holman et al.

We present optical-near-infrared (NIR) color measurements for small ($\leq 40$ km) Trans-Neptunian Objects (TNOs) using coordinated and nearly simultaneous observations from the James Webb Space Telescope (JWST) and the Hubble Space Telescope (HST). JWST/NIRCam data provided detections and NIR photometry for faint TNOs, while HST/ACS and WFC3 imaging enabled recovery in the optical, together yielding optical-NIR colors spanning 0.35-3.2 $μ$m. Thirteen JWST-detected TNOs were recovered in the HST…

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hep-phastro-ph.COastro-ph.HEhep-ex2026年9月9日

A Vector-Like Lepton Interpretation of the High-Energy Nuclear Recoil Candidate in LUX-ZEPLIN

Fatemeh Elahi, Pedro Schwaller

The LUX-ZEPLIN (LZ) experiment has recently reported a nuclear-recoil candidate at $E_R=248\pm23_{\rm stat}\pm23_{\rm sys}\,{\rm keV}$ in an exposure of $2.84\,{\rm tonne\,yr}$. At this unusually high recoil energy, the spin-independent (SI) xenon response is strongly suppressed, motivating dark matter interactions with a harder recoil spectrum. We show that elastic spin-dependent (SD) scattering through the nonrelativistic operator $\mathcal O_4=\mathbf S_{\rm DM}\cdot\mathbf S_N$ provides a si…

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gr-qcastro-ph.IM2026年9月9日

TARTARUS: A High-Performance Python Code for Ray Tracing in Curved Spacetimes

David F. Bambague, Alexis Larrañaga

The recent observations of the supermassive black holes M87* and Sagittarius A* by the Event Horizon Telescope collaboration (EHT) have shown the need for robust, efficient, and accessible numerical tools to model light propagation in strongly curved spacetimes. Comparing theoretical accretion models with observational data relies heavily on ray-tracing algorithms that calculate the trajectories of photons traveling from a source plasma to a distant observer. In this paper, we present TARTARUS (…

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astro-ph.GA2026年9月9日

Triaxiality of the Milky Way dark matter halo and the microlensing optical depth towards the Large Magellanic Cloud

J. García-Bellido, M. R. S. Hawkins

The microlensing optical depth towards the Large Magellanic Cloud (LMC), $τ_{\rm LMC}$, bounds the compact-object fraction of the Galactic dark matter halo, but is almost always evaluated for a spherical halo. We compute it for triaxial haloes and show that the shape dependence is carried entirely by the projection of the line of sight onto the halo principal axes: for a scale-free halo $ρ\propto R^{-α}$ at fixed local density it factorises exactly as $τ/τ_{\rm sph}=S_\odot^α\langle S^{-α}\rangl…

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astro-ph.EP2026年9月9日

TEMPUS: Relativistic coordinate time scales for any solar-system body from arbitrary ephemerides

Yan Seyffert, Agnès Fienga

Precise time-scale transformations between solar-system bodies are an essential requirement for deep-space science and solar system navigation. The post-Newtonian relativistic expression relating a body-centered coordinate time TCX to the Barycentric Coordinate Time TCB depends on the gravitational environment and velocity of the target body, and must be evaluated consistently with the chosen planetary ephemerides. So far only INPOP has provided such a solution as part of its ephemerides release…

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astro-ph.EP2026年9月9日

TEMPUS: Relativistic coordinate time scales for any solar-system body from arbitrary ephemerides

Yan Seyffert, Agnès Fienga

Precise time-scale transformations between solar-system bodies are an essential requirement for deep-space science and solar system navigation. The post-Newtonian relativistic expression relating a body-centered coordinate time TCX to the Barycentric Coordinate Time TCB depends on the gravitational environment and velocity of the target body, and must be evaluated consistently with the chosen planetary ephemerides. So far only INPOP has provided such a solution as part of its ephemerides release…

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astro-ph.GA2026年9月9日

Euclid: Quick Data Release (Q1) -- Exploring the detailed visual morphology of galaxies in clusters

P. Mas-Buitrago, S. Kruk, D. O'Ryan, M. T. Nardone, A. La Marca, P. Awad, M. Baes, M. Fossati et al.

Galaxy clusters provide unique laboratories for studying environmental effects on galaxy evolution. The morphology--density ($T$--$Σ$) and morphology--cluster-centric radius ($T$--$R$) relations trace how galaxy morphology is influenced by the environment, but previous studies at intermediate redshifts have been limited in both sample size and radial coverage. We use the Euclid Quick Data Release 1 (Q1) visual morphology catalogue to measure the $T$--$Σ$ and $T$--$R$ relations for smooth, featur…

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astro-ph.EP2026年9月9日

Interplanetary Dust Ablation Seeds Silicate Clouds in Exoplanet Atmospheres

Sven Kiefer, Gregory J. Gosselin, Caroline V. Morley, Sean P. S. Gulick

Interplanetary dust particles (IDPs) are present throughout the Solar System, with Earth experiencing a mass flux of roughly 100 tonnes of IDPs per day. These particles ablate in the upper atmosphere, delivering aerosols that form noctilucent and stratospheric clouds. Since IDPs are present in exoplanet systems as exozodiacal dust disks (exozodis), it is likely that exoplanets experience a constant infall of IDPs as well. In this work, we investigate the effect of IDPs on the cloud structure of…

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astro-ph.SRastro-ph.GA2026年9月9日

An analysis of four stellar rings

E. Paunzen, J. Florian, A. Gütl-Wallner, A. Herdin, E. Kralofsky, K. Leschinski, M. Mach, H. M. Maitzen et al.

About 50 years ago, one thousand ring-like structures (called stellar-rings) were discovered by Isserstedt (1968). They were believed to be groups of young stars formed by shell-like triggered star formation, which would make them excellent tracers of spiral arms, for example. Neglected for 40 years, we used highly accurate kinematic, astrometric, and photometric data to investigate the four most prominent stellar rings. The aim is to investigate if those structures are indeed physically related…

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astro-ph.SR2026年9月9日

Now you see me, now you don't: Deep, long-lived obscuration events of white dwarfs by dust and debris from disintegrating planetesimals

J. van Roestel, S. Bhattacharjee, J. A. Guidry, I. Caiazzo, T. Cunningham, J. J. Hermes, S. Torres, Z. Vanderbosch et al.

Transiting dust and debris around white dwarfs provide a direct view of planetary disruption. We report six previously non-variable white dwarfs that underwent single, deep obscuration events, including ZTF~J2327+0019, which fully disappeared for more than a year. These discoveries raise the number of confirmed debris-transit white dwarfs to 20. In addition, the systematic search of negative alerts from the Zwicky Transient Facility (ZTF), followed by photometric and spectroscopic observations,…

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astro-ph.HE2026年9月9日

Resolving structure within the iron line profile of Serpens X-1 with XRISM and NuSTAR

Hayden Hall, Renee M. Ludlam, Edward Cackett, Jon M. Miller, Javier A. García

We present the first simultaneous XRISM and NuSTAR observations of the neutron star low mass X-ray binary Serpens X-1. We perform spectral modeling on the joint observations of XRISM/Resolve, XRISM/Xtend, and NuSTAR, testing Comptonization and double thermal continuum model prescriptions. We find that a hybrid double thermal model adequately describes the underlying continuum of the source while the Comptonization models predict largely unphysical parameter values. We perform reflection modeling…

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astro-ph.HE2026年9月9日

Strong Polarization Signatures from Magnetically Stabilized Luminous Thin Accretion Disks

P. Chris Fragile, Peter Anninos, Madeline Breiling, Derrick Pickrel, Gabrielle Ruminski

We utilize the Monte Carlo radiation transport capabilities of Cosmos++ to explore the polarization and Faraday rotation of radiation emitted from a set of general relativistic radiation magnetohydrodynamic simulations of magnetically stabilized, thin, black hole accretion disks. The guiding question is whether or not the Faraday rotation depolarizes the radiation to such a degree as to be inconsistent with the relatively high polarization measurements coming from the Imaging X-ray Polarimetry E…

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astro-ph.GA2026年9月9日

Turbulence Cascade in Cygnus X Revealed by Multi-point VDF Method

Junjie Huang, Yangjun Pu, Keping Qiu, Junhao Liu, Yingxi Li, Mengke Zhao

Turbulence plays a crucial role in regulating star formation activities within molecular clouds, yet few methods can directly reveal its properties and underlying processes. We use molecular line data from the Nobeyama 45m Cygnus X CO Survey to study the turbulence properties and their relationships with star-forming activities and/or other non-thermal motions. In this work, we apply the multi-point velocity dispersion function (VDF), rather than direct linewidth measurements, to investigate the…

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nucl-thastro-ph.HEhep-ph2026年9月9日

How strange: Phase diagrams with 3 critical points

Mateus Reinke Pelicer, Nikolas Cruz Camacho, Rajesh Kumar, Veronica Dexheimer, Jacquelyn Noronha-Hostler

We show that the Chiral Mean-Field model (CMF) can produce a phase diagram with three critical points: the nuclear liquid-gas transition, quark deconfinement, and a strangeness driven transition. The strangeness driven transition separates a mainly nucleonic phase from one dominated by hyperons and baryon resonances. We discuss the compositional change in these transitions and their possible signatures in heavy-ion collisions and neutron star mergers.

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astro-ph.SR2026年9月9日

The role of specific entropy in the onset of the luminosity bump

S. Hekker

During their evolution, stars follow a distinct path in luminosity--temperature space. Low-mass stars that have exhausted hydrogen in their core follow the so-called red-giant branch which is predominantly in the direction of increasing luminosity and decreasing surface temperature. The luminosity bump is a temporary decrease in luminosity against this otherwise increasing trend. The bump is present in both observations and stellar evolution models. However, with canonical physics included in th…

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hep-phastro-ph.HE2026年9月8日

Axion Hair and Pulsar Electrodynamics: modelling, discharge dynamics, and particle-in-cell simulations

Samuel J. Witte, Andrea Caputo, Stefan Stelzl, Alexander Chernoglazov, Alexander A. Philippov, Surjeet Rajendran

In a companion paper, we demonstrated that static axion field gradients sourced by dense nuclear matter (\emph{axion hair}) can dominate the near-field electrodynamics of old rotation-powered pulsars, leading to new constraints on light QCD axions and on CP-violating axion-nucleon interactions. This article provides the extended theoretical and numerical framework underlying those results. We begin by providing a detailed description of the sourcing of axion hair from dense nuclear matter, compu…

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astro-ph.COastro-ph.GA2026年9月8日

Why Azimuthal Averaging Works in Halo Lensing: Symmetry and Power Counting for Nonlinear Shear and Magnification

Keiichi Umetsu

Cluster weak-lensing analyses often compress two-dimensional lensing fields into azimuthally averaged radial profiles and evaluate nonlinear observables from the averaged convergence and shear. However, the ring average of a nonlinear observable generally differs from the mean-field prediction formed from the averaged fields. This difference, divided by the mean-field prediction, defines the fractional residual. For a complete ring, the difference begins at second order in angular fluctuations.…

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