Current date: 2026-08-10

Setting default datestamp limit: 0

Datestamp limit: 2026-08-10 (0 days ago)

Created/updated limit: 2026-08-03 (7 days ago)

Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics

Setting default set: physics

OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-08-10&until=2026-08-10&set=physics&metadataPrefix=arXiv

Scoring abstracts

Number of records retrieved: 624

Keyword score statistics

score 10 -- 2 abstracts

score 7 -- 2 abstracts

score 6 -- 1 abstracts

score 5 -- 2 abstracts

score 4 -- 6 abstracts

score 3 -- 5 abstracts

score 2 -- 20 abstracts

in total -- 38 abstracts

Articles that appeared on 2026-08-10

[abstract 1 / 38] Wow! (score: 10)
arXiv:2511.01361 [pdf, ps, other]

Title: Search for neutrino emission from BLAZAR $γ$-ray flares accounting for possible neutrino time delays

Authors: Egor Podlesnyi, Foteini Oikonomou,

Comments: 16 pages (11+5), 12 figures (9+3), 7 tables (2+5); published in the Open Journal of Astrophysics

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

We report the results of the search for the high-energy neutrino emission associated with BLAZAR flares, accounting for a possible lag of neutrinos with respect to the electroMAGNETic emission, either due to the slowness of the proton energy losses in $pγ$ collisions and/or proton acceleration. We perform two tests, cross-matching neutrinos with energies $E_ν \gtrsim 100$ TeV from the public catalogue of neutrino alerts IceCat-1 with ACTIVE GALACTIC NUCLEi from two source samples based on 1) the MOJAVE database and 2) the CGRaBS catalogue, and utilising FERMI-LAT light curves from the public light curve repository. We scan over a wide range of values of the JET-frame time delay $t^{\prime}_{\mathrm{delay}}$ between the neutrino arrival and the time of the prior major $γ$-ray flare and find a pre-trial $\sim 2σ$ correlation at $t^{\prime}_{\mathrm{delay}} \sim 10^{3}$ d, which is consistent ($p_{\mathrm{post-trial}} \sim 0.1$) with expectations under the null hypothesis after trial correction.

[abstract 2 / 38] Wow! (score: 10)
arXiv:2511.16556 [pdf, ps, other]

Title: Bayesian POLARIZATION calibration and imaging in very long baseline interferometry

Authors: Jong-Seo Kim, Jakob Roth, Jongho Park, Jack D. Livingston, Philipp Arras, Torsten A. Enßlin, Michael Janssen, J. Anton Zensus, Andrei P. Lobanov,

Comments: Accepted for publication in A&A

Subjects: astro-ph.IM

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Extracting polarimetric information from very long baseline interferometry (VLBI) data is demanding but vital for understanding the SYNCHROTRON radiation process and the MAGNETic fields of celestial objects, such as ACTIVE GALACTIC NUCLEi (AGNs). However, conventional CLEAN-based calibration and imaging methods provide suboptimal resolution without uncertainty estimation of calibration solutions, while requiring manual steering from an experienced user. We present a Bayesian POLARIZATION calibration and imaging method using Bayesian imaging software resolve for VLBI data sets, that explores the posterior distribution of antenna-based gains, POLARIZATION leakages, and polarimetric images jointly from pre-calibrated data. We demonstrate our calibration and imaging method with observations of the QUASAR 3C273 with the VLBA at 15 GHz and the BLAZAR OJ287 with the GMVA+ALMA at 86 GHz. Compared to the CLEAN method, our approach provides physically realistic images that satisfy positivity of flux and POLARIZATION constraints and can reconstruct complex source structures composed of various spatial scales. Our method systematically accounts for calibration uncertainties in the final images and provides uncertainties of Stokes images and calibration solutions. The automated Bayesian approach for calibration and imaging will be able to obtain high-fidelity polarimetric images using high-quality data from next-generation radio arrays. The pipeline developed for this work is publicly available.

[abstract 3 / 38] Wow! (score: 7)
arXiv:2608.06527 [pdf, ps, other]

Title: A Search for GeV Emission from Magnetar Giant Flare Candidates with FERMI-LAT

Authors: Vikas Chand, Michela Negro, Nicola Omodei, Niccol`o Di Lalla, Eric Burns, Soebur Razzaque, Aaron C. Trigg, Giacomo Principe,

Comments: Accepted for publication in the Astrophysical Journal

Subjects: astro-ph.HE

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

The discovery of delayed GeV emission from the extragalactic MAGNETar giant flare (MGF) GRB 200415A, located in the nearby Sculptor galaxy, revealed for the first time that these rare transients can launch RELATIVISTIC outflows that power high-energy afterglows. Motivated by the recent identification of additional nearby MGF candidates in the archival data of the FERMI Gamma-ray Burst Monitor, we conduct a search for GeV counterparts with the FERMI Large Area Telescope (LAT). We analysed post-trigger time intervals taken in the range $10^{2}$--$10^{4}$\,s using a maximum-likelihood approach and performed a stacking analysis of all candidates with LAT coverage. In addition, we searched for photon triplets through \chng{a waiting time} analysis to identify events potentially associated with MGFs. We recover the known delayed signal from GRB\,200415A but find no GeV emission from the remaining six candidates. For three events, the earliest emission is unconstrained because the $10^{2}$\,s interval contains zero exposure after standard selections. For the events with LAT coverage, we obtain upper limits at 95\% confidence level of order $F_E \sim 10^{-9}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$ for the individual events, and a stacked population-averaged limit of $\approx2\times10^{-10}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$. We interpret these upper limits within the RELATIVISTIC fireball framework, where the prompt spectral peaks favor a baryonic-poor regime ($η> η_*$). For the candidates with hard prompt spectrum and early LAT coverage, the baryonic-poor condition restricts the mass of RELATIVISTIC ejecta to $M_b \lesssim 1\text{--}4 \times 10^{22}$\,g; the LAT upper limits confirm that the predicted GeV afterglow from such clean outflows falls below current instrumental sensitivity.

[abstract 4 / 38] Wow! (score: 7)
arXiv:2608.07060 [pdf, ps, other]

Title: Constraining Circum-burst Environments of GRBs with Jet Break Features in X-ray Afterglows

Authors: Si-Ji Xin, Yu-Qi Zhou, Sheng-Jin Sun, Cheng-Jie Sun, Shuang-Xi Yi, Yuan-Chuan Zou, Yu-Peng Yang, Yan-Kun Qu, Fa-Yin Wang,

Comments: Accepted for publication in ApJ; 28 pages, 7 figures and 2 tables

Subjects: astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

The nature of the circum-burst medium serves as a key diagnostic for probing the progenitor systems and the physics of RELATIVISTIC JET propagation in GAMMA-RAY BURSTs (GRBs). In this work, we systematically infer the density profile index $k$ (where $n \propto r^{-k}$) from the change in the temporal decay index at the JET break ($Δα$). Within the framework of the uniform JET model, the two quantities are linked by the relation $Δα= (3 - k)/(4 - k)$. We apply this diagnostic to a substantial and uniformly selected sample of 170 GRBs with clear JET breaks, identified from over 1,400 SWIFT/XRT X-ray afterglows observed from 2004 to 2024. By fitting the light curves with a broken power-law model, we obtain $Δα$ for each burst and subsequently derive the corresponding $k$ value. We then use the derived $k$ values to classify the circum-burst environment of each GRB. Our results reveal a near-even split: 82 bursts ($\sim48\%$) are consistent with a constant-density interstellar medium (ISM, $k \approx 0$), while 88 bursts ($\sim52\%$) favor a wind environment ($k \approx 2$). For the 35 bursts with optical data, our X-ray-based classifications are generally consistent with independent multi-band analyses. Additionally, we derive JET opening angles and true beaming-corrected energies for bursts with known redshifts.

[abstract 5 / 38] Yes (score: 6)
arXiv:2605.07255 [pdf, ps, other]

Title: Resonant Inverse Compton Scattering and Hard X-ray Emission in Magnetar Magnetospheres

Authors: Kun Hu, Nicholas Rackers, Alexander Y. Chen,

Comments: 22 pages, 13 figures. Accepted for publication in ApJ. Revised following referee comments

Subjects: astro-ph.HE

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

Magnetars are a subclass of neutron stars with ultra-strong surface MAGNETic fields. Some MAGNETars exhibit persistent hard X-ray emission, characterized by power-law tails with photon indices around 1--1.5, extending from ${\sim}$10 keV to several hundred keV. The leading explanation for this hard X-ray component is resonant Compton scattering, in which the thermal seed photons are upscattered by RELATIVISTIC electron-positron pairs flowing along MAGNETic field lines in the MAGNETosphere. In this work, we adopt the pair outflow framework of the MAGNETar MAGNETosphere and calculate the resonant Compton scattering opacity, as well as the spectrum and POLARIZATION of the upscattered emission. We find that resonant cooling can substantially modify the MAGNETospheric plasma density and impose strong optical depth constraints on the hard X-ray emission regions. Under the viewing geometry inferred from IXPE, an equatorial twist near the stellar surface provides a viable configuration for the NUSTAR hard X-ray spectrum of 4U 0142+61, while a polar-twist geometry is disfavored. Joint spectral, timing, and polarimetric modeling will be essential for distinguishing between the MAGNETospheric scattering geometries and understanding the physical properties of the pair plasma.

[abstract 6 / 38] Yes (score: 5)
arXiv:2607.17971 [pdf, ps, other]

Title: The Complete Catalog of Gamma-Ray Transients Observed by GRBAlpha & VZLUSAT-2 CubeSat Missions

Authors: Marianna Dafcikova, Jakub Ripa, Andras Pal, Norbert Werner, Michaela Duriskova, Yasushi Fukazawa, Martin Kolar, Laszlo Meszaros, Filip Munz, Masanori Ohno, Lea Szakszonova, Hiromitsu Takahashi, Masato Yokota, Jean-Paul Breuer, Hsiang-Kuang Chang, Balazs Csak, Vladimir Daniel, Juraj Dudas, Marcel Frajt, Gabor Galgoczi, Peter Hanak, Filip Hroch, Chin-Ping Hu, Jan Hudec, Nikola Husarikova, Yuto Ichinohe, Jakub Kapus, Miroslav Kasal, Martin Koleda, Robert Laszlo, Chih-Hsun Lin, Tsung-Che Liu, Tsunefumi Mizuno, Kazuhiro Nakazawa, Hirokazu Odaka, Michal Pazderka, Ales Povalac, Maksim Rezenov, Martin Sabol, Kaustubha Sen, Miroslav Smelko, Petr Svoboda, Martin Topinka, Che-Chih Tsao, Tomas Urbanec, Ivo Vertat, Tomas Vitek, Chih-En Wu,

Comments: accepted for publication in ApJ Supplement

Subjects: astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

We present the largest sample of gamma-ray transients observed by any CubeSat mission so far. Observations were acquired by a 1U CubeSat GRBAlpha, the smallest astrophysical space observatory, and a 3U CubeSat VZLUSAT-2. Both missions were technological pathfinders and carried a novel CsI scintillator-based detector read-out by silicon photomultipliers. They operated on Sun-synchronous low Earth orbits below 550 km for about four years; GRBAlpha between March 2021 and June 2025 while VZLUSAT-2 between January 2022 and November 2025. Despite being technological experiments, they observed over 300 gamma-ray transients including GAMMA-RAY BURSTs (GRBs), solar flares, soft gamma repeaters and one outburst from an X-ray binary. Among these are the two brightest GRBs ever observed, GRB 221009A and GRB 230307A, without saturation and GRBs at redshifts up to z=4.2. GRBAlpha also contributed to the InterPlanetary Network. Regular monitoring of transients was demonstrated by a detection rate of two transients or one GRB a week and the shortest time between two subsequent detections of only 42 minutes. We show that a constellation of nanosatellites around the Earth would observe at least 60% of FERMI/GBM GRBs with 5$σ$ significance and over 90% at 3$σ$ level. GRBAlpha and VZLUSAT-2 prove that routine monitoring of the gamma-ray sky can also be done by low-cost and quickly developed nanosatellite missions.

[abstract 7 / 38] Yes (score: 5)
arXiv:2608.07234 [pdf, ps, other]

Title: Search for gamma-ray spectral lines from DARK MATTER annihilation with the H.E.S.S. Inner Galaxy Survey

Authors: H. E. S. S. Collaboration, F. Aharonian, H. Ashkar, V. Barbosa Martins, R. Batzofin, Y. Becherini, D. Berge, K. Bernlohr, M. Bottcher, C. Boisson, J. Bolmont, F. Brun, B. Bruno, T. Bulik, C. Burger-Scheidlin, S. Casanova, J. Celic, M. Cerruti, A. Chen, M. Chernyakova, J. O. Chibueze, O. Chibueze, B. Cornejo, G. Cotter, J. de Assis Scarpin, M. de Bony de Lavergne, M. de Naurois, E. de Ona Wilhelmi, A. G. Delgado Giler, J. Djuvsland, A. Dmytriiev, K. Egberts, K. Egg, C. Escanuela Nieves, M. D. Filipovic, G. Fontaine, S. Funk, S. Gabici, J. F. Glicenstein, J. Glombitza, P. Goswami, B. Hess, J. A. Hinton, W. Hofmann, T. L. Holch, M. Holler, M. Jamrozy, F. Jankowsky, I. Jaroschewski, I. Jung-Richardt, K. Kasprzak, K. Katarzynski, D. Kerszberg, B. Khelifi, N. Komin, K. Kosack, D. Kostunin, R. G. Lang, S. Lazarevic, A. Lemiere, J. -P. Lenain, P. Liniewicz, A. Luashvili, J. Mackey, D. Malyshev, D. Malyshev, V. Marandon, M. Meyer, A. Mehta, A. M. W. Mitchell, R. Moderski, L. Mohrmann, A. Montanari, E. Moulin, J. Niemiec, L. Olivera-Nieto, M. O. Moghadam, S. Panny, R. D. Parsons, U. Pensec, G. Puhlhofer, A. Quirrenbach, M. Regeard, A. Reimer, O. Reimer, I. Reis, H. Ren, B. Reville, F. Rieger, G. Roellinghoff, G. Rowell, B. Rudak, K. Sabri, V. Sahakian, H. Salzmann, A. Santangelo, M. Sasaki, F. Schussler, J. N. S. Shapopi, W. Si Said, S. Spencer, L. Stawarz, S. Steinmassl, T. Takahashi, T. Tanaka, A. M. Taylor, G. L. Taylor, T. Unbehaun, C. van Eldik, M. Vecchi, C. Venter, J. Vink, T. Wach, S. J. Wagner, A. Wierzcholska, M. Zacharias, A. Zech, W. Zhong, F. Bradascio,

Comments: Accepted in Phys. Rev. Lett., includes Supplemental materials. 6+7 pages, 2+1 figures, 0+2 tables

Subjects: astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Spectral gamma-ray line features are expected as key signatures from DARK MATTER (DM) annihilations of TeV-scale particle DM. Observations of the Galactic Centre with atmospheric Cherenkov telescopes are unique to probe thermal-relic TeV particle DM, well beyond the reach of direct detection and COLLIDER searches. We report here on the search for line signals in very-high-energy gamma rays using data from the Inner Galaxy Survey, consisting of 546 hours of H.E.S.S. observations of the inner few degrees of the Galactic Centre. No significant signal is detected. We then compute the exclusion limits on the annihilation line cross section $\langle σv \rangle_{\rm line}$, with a two-dimensional log-likelihood ratio test statistics, exploiting spectral and spatial features of the DM signal. Assuming an Einasto DM density profile for the Milky Way, our results provide the most constraining limits so far, reaching $\langle σv \rangle_{\rm line} = 2.3$ $\times$ $10^{-28}$ and $2.4 \times$ $10^{-27}$ cm$^3$s$^{-1}$ for DM masses of 1 and 10 TeV, respectively. The present limits are used to constrain the widely searched Wino, Higgsino and Quintuplet models. For the first time, thermal Higgsino DM is probed for DM Milky Way models.

[abstract 8 / 38] Yes (score: 4)
arXiv:2512.11207 [pdf, ps, other]

Title: Synthetic POLARIZATION observations of MAGNETized pillars in HII regions: Assessing the reliability of the Davis-Chandrasekhar-FERMI method

Authors: Luis Andrés Hernández-Cruz, Manuel Zamora-Avilés, Abraham Luna, Raúl Naranjo-Romero, José Franco, Aina Palau, Alejandro García-Pérez, Javier Ballesteros-Paredes, Marcial Becerril-Tapia,

Comments:

Subjects: astro-ph.GA

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

We investigated the morphology and strength of MAGNETic fields in pillar-shaped structures at the boundaries of HII regions by combining three-dimensional radiation-MAGNETohydrodynamic (R-MHD) simulations with synthetic polarimetric and molecular-line observations. Our analysis focuses on a self-consistently formed pillar as a proof of concept to test the Davis-Chandrasekhar-FERMI (DCF) method under externally driven conditions. The pillar arises as an ionization front compresses a dense clump, producing a MAGNETically aligned, elongated structure whose morphology and field configuration resemble systems such as the pillars in M16. Synthetic 850 μm dust-POLARIZATION maps reproduce the pillar's large-scale MAGNETic-field morphology, confirming polarimetry as a reliable tracer of MAGNETic-field geometry. To evaluate DCF-based methods, we extract local density and velocity dispersion self-consistently from synthetic 13CO observations and measure POLARIZATION-angle dispersion using single-Gaussian fits to the synthetic POLARIZATION-angle distributions. We find that DCF-based methods systematically overestimate the intrinsic plane-of-sky MAGNETic-field strength by average factors of ~7 for the classical DCF method and ~5 for the modified Skalidis & Tassis formulation. This overestimation is already present in the full-pillar measurement and is not removed by applying polarimetric S/N cuts or by excluding the dynamically complex head. We attribute the discrepancy to external compression by the expanding H II region, which organizes the MAGNETic field on pillar scales while driving non-thermal gas motions. Consequently, the measured velocity and POLARIZATION-angle dispersions no longer trace the same turbulence-driven perturbation field assumed by DCF. Our results highlight the need for caution when applying DCF-based analyses to pillars or other externally compressed structures.

[abstract 9 / 38] Yes (score: 4)
arXiv:2603.19721 [pdf, ps, other]

Title: HAWC Study on the Ultra-High-Energy Gamma-Ray Emissions from the Pulsar Wind Nebula G32.64+0.53

Authors: R. Alfaro, C. Alvarez, E. Anita-Rangel, M. Araya, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, R. Babu, P. Bangale, E. Belmont-Moreno, A. Bernal, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, F. Carreón, S. Casanova, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, P. Desiati, N. Di Lalla, R. Diaz Hernandez, M. A. DuVernois, J. C. Díaz-Vélez, K. Engel, T. Ergin, C. Espinoza, N. Fraija, S. Fraija, J. A. García-González, F. Garfias, N. Ghosh, M. M. González, J. A. González, J. A. Goodman, D. Guevel, J. Gyeong, J. P. Harding, I. Herzog, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, S. Kaufmann, D. Kieda, K. Leavitt, W. H. Lee, J. Lee, H. León Vargas, A. L. Longinotti, G. Luis-Raya, K. Malone, O. Martinez, J. Martínez-Castro, J. A. Matthews, P. Miranda-Romagnoli, J. A. Morales-Soto, E. Moreno, M. Mostafá, M. Najafi, A. Nayerhoda, L. Nellen, R. Noriega-Papaqui, N. Omodei, E. Ponce, Y. Pérez Araujo, E. G. Pérez-Pérez, C. D. Rho, A. Rodriguez Parra, D. Rosa-González, M. Roth, H. Salazar, D. Salazar-Gallegos, A. Sandoval, M. Schneider, J. Serna-Franco, M. Shin, A. J. Smith, Y. Son, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, E. Varela, L. Villaseñor, X. Wang, Z. Wang, I. J. Watson, S. Yu, X. Zhang, H. Zhou, C. de León,

Comments: ApJ Accepted, Submitted 11 February 2026

Subjects: astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Multi-TeV gamma-ray emission around eHWC J1850+001 (a source from the first HAWC catalog of gamma-ray sources emitting above 56 TeV) is spatially coincident with the pulsar wind nebula (PWN) G32.64+0.53, powered by PSR J1849-0001. The absence of counterparts in radio, optical, and GeV energy ranges, contrasted with clear detections in X-rays and very-high-energy (VHE) gamma-rays, is indicative of a non-thermal leptonic origin for the nebula. We apply a systematic analysis pipeline, including a sophisticated model for the Galactic diffuse emission, to 2860 days of data from the HAWC Observatory. Our detailed analysis confirms that the ultra-high-energy (UHE) emission originates from G32.64+0.53, and we measure its spectrum up to 270 TeV with significant emission well beyond 100 TeV. We fit the multi-wavelength observations with a time-dependent leptonic model powered by the pulsar's rotational energy, and the results establish the nebula as a leptonic PeV accelerator, capable of accelerating electrons to a maximum energy of $E_{\mathrm{cut}}\geq2.9~\mathrm{PeV}$ (95\% one-sided lower bound). The model also constrains the nebular MAGNETic field to $4.28 ~\mathrm{μG}$, supporting a leptonic PWN origin for the observed UHE emission.

[abstract 10 / 38] Yes (score: 4)
arXiv:2605.02219 [pdf, ps, other]

Title: Distributions of particles accelerated by strong Alfvénic turbulence

Authors: Stanislav Boldyrev, Daniel Humphrey, Vadim Roytershteyn, Cristian Vega,

Comments: 8 pages, 1 figure; edited to match the published version

Subjects: physics.plasm-ph astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

This work presents a model for generating nonthermal power-law tails of particles' energy probability density functions in turbulent collisionless plasmas, applicable to both non-RELATIVISTIC and RELATIVISTIC scenarios. We propose that strong Alfvénic turbulence energizes plasma particles through curvature acceleration, particularly for particles with Larmor radii comparable to the scales of turbulence. When the energy density of the energized particles increases, the efficiency of the energy exchange process diminishes. As a result, the acceleration process saturates, leading to power-law distributions of particle momentum and energy. In the non-RELATIVISTIC case, the momentum probability density function scales as $f(p) dp \propto p^{-3} dp $, while in the ultraRELATIVISTIC case, the energy probability density function scales as $ f(γ) dγ\propto γ^{-3} dγ$, where $γ$ is the Lorentz factor. This model provides a unified framework for understanding particle acceleration in both energy regimes, complementing existing analytical approaches. The predicted scalings are consistent with available observations of energetic ion distributions in the heliosphere and with the findings from numerical simulations of ultraRELATIVISTIC particle acceleration in MAGNETically dominated plasma turbulence.

[abstract 11 / 38] Yes (score: 4)
arXiv:2605.22323 [pdf, ps, other]

Title: Magnetar Fireballs and Short Bursts: Curved Spacetime Lensing, QED Effects, Spectra, Polarization, and Impulse Responses

Authors: Zorawar Wadiasingh, Hoa Dinh Thi, Constantinos Kalapotharakos, Kun Hu, Matthew G. Baring, Alice K. Harding, George Younes, Sebastien Guillot, Andrea Sanna, Michela Negro, Jeremy D. Schnittman, Oliver J. Roberts, Eric Burns, Chin-Ping Hu, Ersin Göğüş,

Comments: Accepted for publication in ApJS

Subjects: astro-ph.HE astro-ph.SR

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

Magnetar short bursts (SBs) are hard X-ray transients of durations $0.01-1$ s peaking at $\sim 10-100$ keV, and are prime targets for new high-energy missions and polarimeters. The recent association of SBs with bright radio bursts in SGR 1935+2154 has broadened interest in SB physics. We present new advanced fireball models combining general RELATIVISTIC light bending, polarized transport in MAGNETized photospheres, MAGNETic photon splitting attenuation, and MAGNETospheric vacuum birefringence. These models also have relevance to trapped fireballs in MAGNETar giant flare pulsating tails. We adopt confined flux tube geometries consistent with adiabatic fireballs, and anisotropic/polarized emergent intensities to produce spectra and POLARIZATIONs, and energy-time Stokes impulse responses. We predict that most fireballs are highly linearly polarized, especially when vacuum birefringence is important. There is rich potential for diagnostics: coexisting direct and lensed delayed images, gaps by occultation of the neutron star surface, and Shapiro+Rømer delay with temporal caustics. These effects can imprint spin phase dependence of the spectral and POLARIZATION character of bursts. Predicted signatures depend strongly on viewing geometry, fireball configuration, and photon splitting assumptions, yielding large variance in model high-energy spectral shapes and cutoffs, and energy-dependent POLARIZATION. The models can reproduce established double-blackbody SB spectral phenomenology, and we find that the unusual April 2020 radio-associated SB from SGR 1935+2154 is broadly consistent with a footpoint close to the MAGNETic pole, and possibly near pole-on viewing geometry. Our models motivate reverberation-style analyses for SBs and suggest that high-quality data might constrain source geometry, burst crustal footpoints, and, potentially, neutron star masses and radii.

[abstract 12 / 38] Yes (score: 4)
arXiv:2608.06462 [pdf, ps, other]

Title: AT2021yky: A Fast-Rising Optical Transient with Evolving Broad Hydrogen Emission Consistent with an Ambiguous Nuclear Transient

Authors: Paarmita Pandey, Jason T. Hinkle, Christopher Kochanek, Michael A. Tucker, Mark T. Reynolds, Katie Auchettl, C. Ashall, Dhvanil D. Desai, Aaron Do, Willem B. Hoogendam, M. E. Huber, T. de Jaeger, Thomas B. Lowe, Anna V. Payne, Benjamin J. Shappee, Todd A. Thompson, Daniel R. Wilkins,

Comments: Comments are welcome. 16 pages, 14 figures, 5 tables

Subjects: astro-ph.HE

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

Nuclear transients are powerful probes of supermassive BLACK HOLE properties, offering insight into BLACK HOLE mass, accretion physics, and the structure of galactic nuclei. Among these, a growing class of events cannot be classified as either tidal disruption events (TDEs) or ACTIVE GALACTIC NUCLEi (AGN) flares, and their physical origins remain poorly understood. We present a multi-wavelength photometric and spectroscopic analysis of AT2021yky (ZTF21abzciqh), an ambiguous nuclear transient (ANT) at a redshift of $z = 0.076$. AT2021yky reached a peak bolometric luminosity of $L_{\rm peak} = (4.1 \pm 1.1) \times 10^{43}~\mathrm{erg~s^{-1}}$, with a rise-time of $18.2 \pm 0.7$ days. The early-time UV/optical emission is well described by a blackbody with a temperature of $T \simeq 1.4 \times 10^{4}$ K, cooler than most optically selected TDEs. No X-ray emission from the transient is detected, with a $3σ$ limit of $L_X \lesssim 3.4 \times 10^{41}$ erg s$^{-1}$ near peak. Spectroscopic observations reveal a largely featureless blue continuum with broad (FWHM$\sim 11,000$ km s$^{-1}$) H$α$ emission line that appears around 20$-$40 days post-peak. The host-galaxy emission-line ratios indicate the presence of an AGN, though the absence of optical or mid-IR variability and a non-AGN mid-IR color suggest it is weak. AT2021yky exhibits a rapid rise time comparable to that of luminous fast blue optical transients (LFBOTs), while its decay timescale and late-time broad H$α$ emission resemble those observed in TDEs. However, its cooler blackbody temperature and the absence of He II and Balmer emission lines other than H$α$ instead favour its classification as an ANT.

[abstract 13 / 38] Yes (score: 4)
arXiv:2608.06478 [pdf, ps, other]

Title: Multi-wavelength synthesis of a flux rope-trapped mini-prominence eruption and post-flare coronal rain

Authors: Samrat Sen, Alexander G. M. Pietrow, Veronika Jer{\vc}i{ć}, Patrick Antolin,

Comments: Accepted for publication in Astronomy & Astrophysics journal. The animations corresponding to the figures 3, 4 and 7 are available from the lead author on reasonable request

Subjects: astro-ph.SR physics.plasm-ph

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

Small-scale eruptive phenomena in the solar corona including miniature flux ropes and associated cool plasma condensations are not fully understood despite increasing high-resolution observations. We perform forward modeling based on a 2.5D MHD simulation capturing homologous flux rope eruptions, in-situ condensation leading to a mini-prominence, and subsequent post-flare coronal rain. Synthetic diagnostics are obtained using optically-thin EUV and UV emissions, and non-LTE radiative transfer treatment for the H$α$ line. The synthetic EUV emission reveals the flux ropes as bright rim-like structures. The corresponding UV diagnostic shows bright region, which is co-spatial with the dark core due to embedded cool plasma ($\sim$ tens of kK) inside the flux rope, identifying an erupting mini-prominence. Spectral synthesis of Si IV 1402.77 A indicates an upward motion of the mini-filament, and reveals the presence of two predominant velocity components during eruption. At a later stage, thermal instability in post-flare arcades produces coronal rain with temperatures of $\approx 10^4$ K. The EUV diagnostics reveal brightening at the downstream of the rain blob, indicating localized heating associated with compressional effects. The H$α$ spectral synthesis shows enhanced absorption signatures and red-shifted profiles corresponding to downflows of the coronal rain blobs up to $\approx 23$ km s$^{-1}$, whereas the Si IV 1402.77 A spectral profile shows the maximum downflow velocity of $\approx50$ km s$^{-1}$, highlighting the evidence of thermodynamic and kinematic structuring within the falling rain blobs. The synthetic diagnostics provide clear, multi-wavelength signatures that can guide future high-resolution observations, and highlight the importance of small-scale RECONNECTion-driven processes in shaping the multi-thermal structure (between MK to kK) of the solar corona.

[abstract 14 / 38] (score: 3)
arXiv:2511.18821 [pdf, ps, other]

Title: Off-Equatorial Orbits around Magnetically Charged Black Holes

Authors: Xilai Li, Loris Del Grosso, David E. Kaplan,

Comments: 16 pages, 10 figures. v2: matches version submitted to PRD. v3: matches version accepted in PRD

Subjects: gr-qc

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

We present a complete characterization of stable, off-equatorial circular orbits around MAGNETically charged BLACK HOLEs (MBHs). For a static, spherically symmetric MBH, we derive an exact analytic expression for the orbital latitude $θ$ as a function of radius $r$ and we analyze the effect of SYNCHROTRON radiation. We show that charged particles such as electrons and protons can exhibit $\mathcal{O}(1)$ latitude deviations at the innermost stable circular orbit (ISCO) radius and remain stable under SYNCHROTRON emission even for extremely small values of the BLACK HOLE MAGNETic charge. We then extend the analysis to rotating MBHs, numerically computing the prograde and retrograde orbital branches and demonstrating how frame-dragging modifies their structure and stability regions. We show that these off-equatorial orbits are a unique feature of the MAGNETic charge, being forbidden in the analogous electrically charged Kerr-Newman spacetime. Our results suggest that environments surrounding MAGNETically charged BLACK HOLEs can exhibit distinctive phenomenological signatures, potentially offering a way to constrain the MAGNETic charge of astrophysical BLACK HOLEs.

[abstract 15 / 38] (score: 3)
arXiv:2606.21193 [pdf, ps, other]

Title: Rankine-Hugoniot conditions in Q-variables: a wave-aligned formulation of MHD discontinuities

Authors: Anna Krupka, Tijs Van Hoof, Tom Van Doorsselaere,

Comments: 32 pages, 2 figures. Published in Physics of Plasmas

Subjects: physics.plasm-ph

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

The recently developed Q-variable formalism generalises the Elsässer representation by providing a wave-aligned representation applicable to a broad class of MAGNETohydrodynamic disturbances, including Alfvénic, fast, slow, and kink waves. While this framework has proven useful for the study of wave dynamics and turbulence, its behaviour in the presence of plasma discontinuities has not yet been established. In this work, we derive the complete set of Rankine-Hugoniot jump conditions in terms of the Q-variables by rewriting the ideal MHD equations in a form suitable for shock-frame jump analysis. This yields explicit jump relations for mass, momentum, MAGNETic flux, and energy. We then demonstrate analytically that these relations are exactly equivalent to the classical MHD Rankine-Hugoniot conditions. This reformulation provides a wave-aligned representation of MHD discontinuities and offers a natural framework for discussing directional wave content and branch-restricted limits when $α$, the wave-branch parameter entering the Q-variable definition, is chosen consistently with the relevant characteristic speed. The resulting formulation is well suited for the analysis of wave-shock interactions in MAGNETised plasmas, with potential applications to the solar wind, MAGNETospheric systems, and large-scale models of structured plasma environments such as UAWSOM.

[abstract 16 / 38] (score: 3)
arXiv:2608.06617 [pdf, ps, other]

Title: The Equations of Reduced Magnetohydrodynamics in Dipole Coordinates

Authors: Ian M. DesJardin, Christopher Bard, Natalia Y. Buzulukova, John C. Dorelli,

Comments: 23 pages, 3 figures, 1 supplementary material (pdf), and 4 Python scripts

Subjects: physics.plasm-ph physics.space-ph

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

The equations of reduced MAGNETohydrodynamics (RMHD) isolate the Alfvénic energy transfer and turbulence dynamics from MHD in a computationally tractable way. In this study, we derive the equations of RMHD for a low $β$ plasma in a dipole coordinate system aligned with the background MAGNETic field using a multiscale analysis. The Kreiss theorem is used to derive the equilibrium conditions that the background conditions must satisfy on the time scale of MHD turbulence. From these, we find a connection between plasma flow along flux tubes and changes in the Alfvén speed that may drive nonlinear wave effects. The final equations demonstrate an intimate coupling between field aligned currents and plasma vorticity including the effects of nonuniform flux tube area and realistic plasma density profiles. This work has immediate application to the MAGNETosphere-ionosphere coupling problem in the Earth's MAGNETosphere as it provides a way to link dynamically evolving field aligned currents from the MAGNETosphere, especially important during geoMAGNETic storms and substorms, with the development of MAGNETohydrodynamic turbulence at low altitudes in a self-consistent manner. This also clarifies the role of Alfvén waves as a transfer mechanism of energy under these inhomogeneous circumstances while remaining simple enough to make predictions. Furthermore, this study makes use of a novel methodology, a computer algebra system, in performing the brunt of algebraic work under complicated coordinate systems. We hope this approach serves as a template for performing reproducible and verifiable multiscale perturbation analysis under arbitrarily complex geometries.

[abstract 17 / 38] (score: 3)
arXiv:2608.06944 [pdf, ps, other]

Title: Parameter Estimation for Eccentric Supermassive Black Hole Binaries with Pulsar Timing Arrays

Authors: Sara Manzini, Stanislav Babak,

Comments:

Subjects: astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Pulsar timing array (PTA) experiments are searching for gravitational waves (GWs) in the nanohertz band. The primary GW sources targeted by PTAs include populations of inspiralling supermassive BLACK HOLE binaries (SMBHBs) in the local Universe, some of which may emit detectable continuous gravitational-wave (CGW) signals. In this paper, we focus on the detection strategy for individual binaries on eccentric orbits. Using simulated datasets based on the EPTA DR2new configuration, we perform injection-recovery studies across the parameter space. We demonstrate that individual component masses can be measured when an eccentric SMBHB is detected at high GW frequencies. We further show a correlation between the CGW signal and the stochastic gravitational-wave background (SGWB) at low frequencies, which makes CGW identification challenging. Finally, the developed software is GPU-compatible, enabling efficient Bayesian inference. This work lays the groundwork for future applications to real PTA data.

[abstract 18 / 38] (score: 3)
arXiv:2608.06978 [pdf, ps, other]

Title: Smoothed particle MAGNETohydrodynamics for simulations of galaxy and cosmic structure formation

Authors: Orestis A. Karapiperis, Matthieu Schaller, Nikyta Shchutskyi, Federico A. Stasyszyn, Maarten Elion,

Comments: 64 pages, 33 figures, submitted for publication in MNRAS

Subjects: astro-ph.GA astro-ph.CO astro-ph.IM

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

We introduce a novel formulation of cosmological smoothed particle MAGNETohydrodynamics (SPMHD), designed to model MAGNETic field physics in a vast array of nonlinear astrophysical systems, and which we have implemented in the highly-parallel, entirely modular, and open-source simulation code SWIFT. Our numerical scheme is designed to offer optimal performance at a minimal computational cost, keep a low memory footprint, and most notably couple robustly to effective sub-resolution recipes of galaxy formation. This is achieved through expressing our evolution equations in a density-energy conservative form, and augmenting them with discontinuity-capturing terms tailored to high dynamic range simulations, which are further modulated by adaptive switches that drastically improve coupling to sub-grid models and limit spurious dissipation. We moreover present novel suggestions for the two major regularisation techniques used in modern SPMHD, namely a tensile instability correction and mixed hyperbolic/parabolic divergence-cleaning scheme, to ensure code stability in highly dynamical scenarios. We evaluate the performance of our method on a series of problems of increasing complexity, culminating in three astrophysical applications which have historically proven challenging for mesh-less methods: we study JET launching from a forming proto-stellar core, dynamo amplification in a massive galaxy cluster and MAGNETic field evolution in a Milky Way-like disk galaxy; the latter constitutes the first reported coupling of the EAGLE galaxy formation model to a MAGNETohydrodynamics solver. Keeping model hyperparameters fixed across our test suite to provide a transparent picture of our method's capabilities in production, we demonstrate sound performance and convergence with resolution on standard `laboratory' numerical experiments, as well as competitive capabilities in realistic applications.

[abstract 19 / 38] (score: 2)
arXiv:2507.09722 [pdf, ps, other]

Title: Compression and Reconnection Investigations of the MagnetoPause (CRIMP): A Mission Concept to Uncover the Impact of Mesoscale Reconnection and Plasma Outflow Processes at the Dayside Magnetopause

Authors: Jason M. H. Beedle, Bryan C. Cline, Samuel T. Badman, Humberto Caldelas, Kelly Cantwell, Alex Hoffmann, Christian Hofmann, India Jackson, Tre'Shunda James, Miguel Martinez-Ledesma, Bruno Mattos, Brett A. McCuen, Sophie R. Phillips, Bryan Reynolds, Julie Rolla, Orlando M. Romeo, Frances A. Staples, Michael J. Starkey, Olga P. Verkhoglyadova, Andres Romero-Wolf, Alfred E. Nash,

Comments: Updated to address reviewer comments and reflect the manuscript in its accepted, and now published, form

Subjects: physics.space-ph astro-ph.EP astro-ph.IM astro-ph.SR physics.plasm-ph

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

The Compression and Reconnection Investigations of the Magnetopause (CRIMP) mission is a hypothesis-driven, Heliophysics Medium-Class Explorer (MIDEX) Announcement of Opportunity (AO) mission concept designed to study mesoscale structures and particle outflow along Earth's MAGNETopause using two identical spacecraft. CRIMP is designed to uncover the impact of MAGNETosheath mesoscale drivers, dayside MAGNETopause mesoscale phenomenological processes and structures, and localized plasma outflows on MAGNETic RECONNECTion and the energy transfer process in the dayside MAGNETosphere. CRIMP accomplishes this through uniquely phased spacecraft configurations that allow multipoint, contemporaneous measurements at the MAGNETopause. This enables an unparalleled look at mesoscale spatial differences along the dayside MAGNETopause on the scale of 1-3 Earth Radii (Re). Through these measurements, CRIMP will uncover how local mass density enhancements affect global RECONNECTion, how mesoscale structures drive MAGNETopause dynamics, and if the MAGNETopause acts as a perfectly absorbing boundary for radiation belt electrons. This allows CRIMP to determine the spatial scale size, extent, and temporal evolution of energy and mass transfer processes at the MAGNETopause - crucial measurements to determine how the solar wind energy input to the MAGNETosphere is transmitted between regions and across scales.

[abstract 20 / 38] (score: 2)
arXiv:2509.18253 [pdf, ps, other]

Title: Small Progenitors, Large Couplings: Type Ic Supernova Constraints on Radiatively Decaying Particles

Authors: Francisco R. Candón, Damiano F. G. Fiorillo, Hans-Thomas Janka, Bart F. A. van Baal, Edoardo Vitagliano,

Comments: 8 pages, 3 figures; Supplemental Material: 8 pages, 5 figures. Updated to match the published version

Subjects: hep-ph astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Supernova (SN) 1987A provides classic bounds on gamma-ray flashes from the radiative decay of sub-GeV particles, but the latter may decay so rapidly as to be shielded by the stellar envelope. Using axionlike particles with photon coupling as a benchmark, we show that Type Ic core-collapse SUPERNOVAe largely evade this attenuation due to their compact progenitors. We identify two regimes. At small couplings, while individual flashes may be missed by FERMI-LAT, the high Type Ic rate enables a stacking analysis of nondetections. At larger couplings, decay photons trigger fireball formation; the absence of a signal from the rare broad-lined Type Ic SN 1998bw excludes this scenario. The resulting bounds significantly exceed those from SN 1987A for short decay lengths.

[abstract 21 / 38] (score: 2)
arXiv:2511.03035 [pdf, ps, other]

Title: Significant Evidence of an AGN Contribution in GHZ2 at z = 12.34

Authors: Oscar A. Chavez Ortiz, Steven L. Finkelstein, Adele Plat, Maddie Silcock, Emma Curtis Lake, Anthony Taylor, Ansh R. Gupta, Lorenzo Napolitano, Marco Castellano, Volker Bromm, Ikki Mitsuhashi, Stephane Charlot, Adriano Fontana, Jorge A. Zavala, Jacopo Chevallard, Denis Burgarella, Michaela Hirschmann, Tom Bakx, Alba Vidal-Garcia, Antonello Calabro, Anna Feltre,

Comments:

Subjects: astro-ph.GA

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

GHZ2 is among the highest-redshift galaxies discovered to date, exhibiting a spectrum rich with prominent emission lines in the rest-frame ultraviolet (UV) and optical. These features raise critical questions about the mechanism powering this nebular emission, in particular the extremely strong C IV1548 emission (rest-frame EW = 45 Angstrom). Here we aim to quantify the AGN contribution within this system using the BEAGLE-AGN tool to simultaneously fit the spectrum and photometry of GHZ2. We consider a range of models with and without AGN components, allowing us to disentangle the stellar and AGN contribution of GHZ2 for the first time. We conclude that a partial contribution by an AGN is significantly favored based on the Bayes factor comparison to models without an AGN component, measuring an AGN contribution of 54$^{+1}_{-1}$% and 26$^{+4}_{-2}$% for the C IV$λ$1548 and C III]$λ$1908 emission lines, respectively. We obtain an estimate for the BLACK HOLE mass using the accretion luminosity ($L_{acc}$) from the best fit BEAGLE-AGN model, computing a value of log$_{10}$(M$_{BH}$/M$_{\odot}$) = 7.20$^{+0.04}_{-0.04}$, for an Eddington ratio of $η$ = 0.5 (with a systematic uncertainty of $\sim$1 dex). The inferred BLACK HOLE mass to stellar mass ratio is 0.05$^{+0.02}_{-0.02}$, consistent with other high redshift AGN systems. If the BLACK HOLE interpretation is confirmed, GHZ2 would represent the most distant BLACK HOLE identified to date, making it an ideal laboratory to study AGN growth and their role in shaping high-redshift galactic evolution.

[abstract 22 / 38] (score: 2)
arXiv:2604.24908 [pdf, ps, other]

Title: TDCOSMO XXVI: Uniform lens modeling of eight doubly imaged QUASARs

Authors: Ryan Brady, Xiang-Yu Huang, Simon Birrer, Anowar J. Shajib, Nafis Sadik Nihal, Cameron Lemon, Martin Millon, Veronica Motta, Dominique Sluse, Frederic Courbin,

Comments: Published in the Open Journal of Astrophysics

Subjects: astro-ph.CO astro-ph.GA

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

We present the first uniform gravitational lens modeling analysis of eight doubly imaged QUASARs from multi-band observations with the Hubble Space Telescope. Previous time-delay cosmography analyses by the TDCOSMO Collaboration have primarily relied on quadruply imaged QUASARs, while doubly imaged systems, despite being more abundant, remain underutilized due to their fewer geometric constraints. Using an open-source $\texttt{Lenstronomy}$ framework, we reconstruct the lensing systems with a pipeline tailored for doubles. Comparing our results to the literature, the modeled Einstein radii agree at an average of 1.5$σ$, which is expected given data and modeling heterogeneity, while modeled image separations differ from Gaia DR2 measurements with an r.m.s of only 3.6 mas. We find a strong correlation between Fermat potential precision and the surface brightness of the spatially extended host arcs, establishing that arc surface brightness is the primary driver of mass model precision in doubly imaged systems. To further quantify the information contributed by the lensed arcs, we performed a conjugate point analysis that uses only the QUASAR image positions to constrain the lens mass profiles. The resulting posteriors are substantially broader than those from full image modeling, and a strong anti-correlation between mass parameter hypervolume and arc magnitude additionally confirms that arc brightness determines the degree to which the lens mass profile can be constrained in doubles. A hierarchical cosmographic analysis incorporating time-delay measurements and stellar kinematics to infer $\text{H}_0$ will be presented in a subsequent publication. The uniform pipeline and arc surface brightness trends established here will significantly accelerate the construction of time-delay cosmography samples from the large lens populations expected from LSST, Roman, and Euclid.

[abstract 23 / 38] (score: 2)
arXiv:2606.01915 [pdf, ps, other]

Title: The gravitational wave-BLACK HOLE imaging correspondence for modified BLACK HOLEs

Authors: David Díaz-Guerra, Ángel Rincón, Diego Rubiera-Garcia, Diego Saez-Chillon Gomez,

Comments: v2: minor corrections, accepted for publication in Phys. Rev. D; 14 pages, 2 figures, revtex4-2 style

Subjects: gr-qc

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Black holes (BHs) can be studied via fundamentally different observational channels that probe complementary aspects of their physics. While BH imaging provides access to the quasi-static space-time geometry via the strong bending of light rays, gravitational wave (GW) observations probe the dynamical response of the space-time to time-dependent processes in the inspiral, merger and ringdown phases. Both messengers -- electroMAGNETic imaging probes and ringdown GW spectroscopy --, provide access to essentially the same region -- the one between the BH event horizon and the photon region --, but they do it via conceptually different methods, encoding different physical information. However, it has been shown in the literature that physical quantities supposedly exclusive of each such messenger are actually tightly related to each another via a correspondence that occurs in the eikonal limit (i.e. large values of the multipole number $\ell$) of the geometric-optics approximation. In this paper we clarify the actual identification of observables within such a correspondence and test its accuracy for modified spherically symmetric BH geometries proposed in the literature. We find that even for low values of $\ell$ the correspondence is surprisingly accurate in relating the real and imaginary parts of quasi-normal modes in the GW ringdown phase with the critical impact parameter and Lyapunov exponent of nearly-bound light trajectories for every such model analyzed. We discuss the applicability of such a result both for each messenger individually, and also for foreseeable tests of BHs combining both messengers.

[abstract 24 / 38] (score: 2)
arXiv:2608.06455 [pdf, ps, other]

Title: Beyond Feedback: Disentangling Baryonic Effects with tSZ$\times$FRB Cross-Correlations

Authors: Isabel Medlock, Daisuke Nagai,

Comments: 17 pages, 6 figures, submitted to ApJ

Subjects: astro-ph.GA

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

Standard observational probes lack the sensitivity to characterize the interplay between feedback-driven gas ejection and non-thermal pressure support in groups and clusters, and current models lack the framework to disentangle it. Recent first detections of the tSZ$\times$FRB cross-power spectrum (Takahashi et al, 2025; Sharma et al 2026) have been interpreted as constraining AGN feedback and $σ_8$, but the baryon models used do not independently parameterize non-thermal pressure support, leaving feedback efficiency and gas thermodynamics degenerate. We demonstrate that this cross-correlation provides sensitivity to the thermal and non-thermal structure of cluster gas that neither observable alone can achieve, because the tSZ effect traces electron pressure while FRBs trace solely electron density. Using the Baryon Pasting (BP) framework, which separately parameterizes feedback efficiency $ε_f$ and non-thermal pressure amplitude $A_{\rm nt}$, we show that their joint constraint breaks this degeneracy. In the noise-free limit, adding the cross-power spectrum reduces $r_{\rm cond}$ from $0.96$ to $0.08$ (a 12-fold reduction) and improves the joint figure of merit by a factor of 19, with the constraining power concentrated at cluster interior scales ($\ell \gtrsim 3000$). Recent detections are consistent with our fiducial model and disfavor weak feedback ($ε_f^{95\%} \gtrsim 2.40\text{--}3.67 \times 10^{-6}$ across datasets). With $5\times10^4$ FRBs from DSA-2000 combined with SO, we forecast $3.8\%$ fractional precision on $A_{\rm nt}$, improving to $2.3\%$ with CMB-HD. These constraints directly inform the hydrostatic mass bias, with immediate implications for cluster-based cosmological inference from eROSITA, SO, and CMB-HD.

[abstract 25 / 38] (score: 2)
arXiv:2608.06458 [pdf, ps, other]

Title: Dipole Anisotropy in Newly Sampled AGN Population: Still in Tension with CMB Dipole

Authors: Dahee Lee, Minji Oh, Gayathri Asok, Tsutomu T. Takeuchi, Kyungjin Ahn,

Comments: Submitted to ApJ; 12 pages, 7 figures; Comments welcome

Subjects: astro-ph.CO

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

We revisit the all-sky survey data, the Wide-field Infrared Survey Explorer (WISE) catalog, with an improved galaxy-selection criterion to investigate the inconsistency between the dipole anisotropy in the galaxy number count and the kinematic CMB dipole anisotropy. We apply a set of ACTIVE GALACTIC NUCLEi (AGN) selection criteria composed of a flux cut and multiple color cuts, and formulate an appropriate adaptation of the original Ellis & Baldwin (1984) formalism for our photometric survey samples whose spectral energy distributions deviate from a pure power-law form. We find that the newly sampled AGNs from the WISE catalog still bears an anomalous number-count dipole anisotropy, whose amplitude is ~ 2.5 times as large as that of the purely kinematic origin at a 5.3 sigma confidence level. We also find that the direction of our WISE-AGN dipole is ~ 3 sigma away from that of the CMB dipole. We discuss its possible cosmological implications: nonlinearity of the nearby universe and mismatch of matter-rest frame and the CMB-rest frame.

[abstract 26 / 38] (score: 2)
arXiv:2608.06561 [pdf, ps, other]

Title: Effect of Chordwise Flexibility Distribution on Wave-Assisted Flapping Foil Performance

Authors: Lokesh Silwal, Neel Karani, Anchal Sareen,

Comments:

Subjects: physics.flu-dyn

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

This study investigates the influence of the spatial distribution of flexibility along a propulsor on thrust generation and propulsive efficiency in wave-assisted flapping foils. While flexibility is known to enhance propulsive performance, the role of its chordwise placement remains poorly understood. Here, the effective flexible length is systematically varied by shifting the flexure location along the tail while maintaining constant flexural rigidity and total chord length. Experiments are conducted in quiescent flow at heave frequencies of 0.8 Hz and 1.25 Hz, and non-dimensional heave amplitudes of h* = 0.13 and 0.22. Simultaneous measurements of hydrodynamic forces, flow fields, and tail kinematics are used to quantify performance and elucidate the underlying fluid-structure and fluid-particle interactions. The fully flexible configuration consistently achieves higher propulsive efficiency (up to approximately 164%) across all conditions, which is attributed to enhanced JET persistence and increased streamwise vortex spacing, indicative of a more coherent and sustained momentum JET. In contrast, the mid-flexible configuration yields substantially higher thrust (up to approximately 66%) at the largest heave frequency and amplitude, driven by a pronounced increase in near-wake JET velocity and momentum flux. These results demonstrate that the chordwise distribution of flexibility governs the trade-off between thrust and propulsive efficiency by modulating wake coherence and momentum transfer. The findings establish flexibility placement as a key design parameter in flapping propulsion and provide physics-based guidelines for enhancing the performance and endurance of wave-driven unmanned surface vehicles.

[abstract 27 / 38] (score: 2)
arXiv:2608.06593 [pdf, ps, other]

Title: Measuring the electric dipole moment of the neutron using neutron star spin-down

Authors: Abriana Lyda,

Comments: 131 pages, 17 figures

Subjects: astro-ph.HE

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

The neutron electric dipole moment (nEDM) is a sensitive probe of CP violation beyond the Standard Model. We develop a source-specific framework for constraining CP-odd neutron structure using the nearby millisecond pulsar PSR J0437-4715. Mass and radius measurements are used to construct a stellar-structure model and estimate the polarized inner-crust neutron reservoir. Wideband radio polarimetry provides a propagation-informed surface-field posterior that is not obtained from the conventional $P\dot P$ MAGNETic-field estimate, while published NICER hot-region constraints are used to test low-order surface-field geometries and isolate the dipolar component entering the electroMAGNETic torque. These inputs are propagated through a present-day spin-down budget including electroMAGNETic and gravitational-wave losses. The remaining positive residual is first interpreted as an unscreened electric-dipole-radiation benchmark. Crustal and MAGNETospheric screening then motivate an effective CP-odd MAGNETic-quadrupole channel. Conditional on the adopted screening, coherence, and effective-mode-frequency prescriptions, the positive-residual branch gives a 90th-percentile bound $|M_n^0|<7.47\times10^{-38}$ e cm$^2$. With the adopted QCD conversion coefficients, this corresponds to $|\barθ|<2.99\times10^{-9}$ and an equivalent $|d_n|<4.42\times10^{-25}$ e cm. Although weaker than laboratory nEDM limits, the result demonstrates how source-specific neutron-star structure, radio propagation, MAGNETic geometry, and spin-down energetics can be combined to test nonstandard CP-odd radiation channels.

[abstract 28 / 38] (score: 2)
arXiv:2608.06619 [pdf, ps, other]

Title: Average soft X-ray surface brightness profile of massive galaxy clusters in Magneticum simulations

Authors: A. Kruglov, N. Lyskova, I. Khabibullin, V. Biffi, K. Dolag,

Comments: Submitted to JHEAP

Subjects: astro-ph.CO astro-ph.HE

Created: 2026-08-06; Updated: 2026-08-10; Datestamp: 2026-08-10

The self-similar growth of massive galaxy clusters suggests that radial profiles of their key thermodynamic properties should have identical shapes after proper mass- and redshift-dependent re-scaling. This property, tested within the virial radius on samples of well-studied individual objects, together with clear and robust observational characteristics such as sensitivity and background accounting, enables the possibility of stacking observations that can be confronted with identically-derived population-averaged predictions from theory or numerical simulations at large radii. Such a comparison not only eliminates effects of inevitable stochasticity in properties of individual objects, but also allows one to reach higher sensitivity for the faintest regions on the outskirts of the clusters. In this study, we conduct a one-to-one comparison of the observed and simulated average soft X-ray surface brightness profiles of several dozen massive galaxy clusters at low redshift. We find a very good out-of-the-box agreement between the 0.3 - 2.3 keV surface brightness profile of stacked galaxy clusters recently measured by SRG/eROSITA and the corresponding predictions from the Magneticum cosmological hydrodynamical simulations, which are known to reproduce other scaling relations observed for massive galaxy clusters. A significant difference between the observed and simulated profiles is present in the very central region, where effective implementation of the AGN feedback likely results in excessive gas redistribution within the core. The simulations predict a very noisy surface brightness profile beyond several times the virial radius of the cluster, with the mean signal being orders of magnitude lower than the local radially-flat but strongly fluctuating emission background, meaning that a proper detection of this component would be very challenging even with larger samples in the future.

[abstract 29 / 38] (score: 2)
arXiv:2608.06666 [pdf, ps, other]

Title: Detailed Abundance Determination of Metal-Poor Stars with X-Shooter II. - Chemically Disentangling the Halo, Disk and GSE

Authors: Benjamin D. C. Lowe, Luca Casagrande, Thomas Nordlander, Gary S. Da Costa, Norbert Christlieb,

Comments: 20 pages, 16 figures. Accepted in MNRAS

Subjects: astro-ph.GA astro-ph.SR

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

We present a detailed chemical analysis of seven extremely metal-poor (EMP) star candidates observed with X-Shooter, combining them with 16 EMP candidates from Paper I. We measured abundances for 16 elements, showing excellent agreement with previously published results. The sample was further extended using high-resolution literature data for 315 metal-poor stars. The full sample was then kinematically separated into prograde disk, retrograde disk, Gaia-Sausage Enceladus (GSE) and halo classifications. Combining dynamics with chemistry, we demonstrate that the prograde disk exhibits a distinct negative linear trend in [Sc/Mg] with increasing metallicity, with a slope of -0.6 dex per dex. This contrasts with the halo trend at -0.04 dex per dex, a difference significant at the 3.95$σ$ level. Within the metallicity range -4.2 $\leq$ [Fe/H] $\leq$ -1.9, the prograde disk trend is driven by low [Mg/Fe] at lower metallicities, along with low [Sc/Fe] at higher metallicities. This could be due to reduced early Mg enrichment in the progenitor prograde disk, followed by subsequent Mg enrichment, possibly associated with a later gas accretion event. However, the physical origin of the higher-metallicity Sc depletion remains unexplained by current nucleosynthesis models. The result remains significant at the >3$σ$ level across kinematic classifications derived from a different Galactic potential. Additionally, we also identified an r-I star with enhanced Ti, moderately-enhanced Sc, and depleted in C (unrelated to its evolutionary state). These abundances suggest a massive JET-induced hypernova progenitor, though a measurement of Zn is needed to verify this.

[abstract 30 / 38] (score: 2)
arXiv:2608.06716 [pdf, ps, other]

Title: Radio Constraints on the Circumstellar Environment of the Type IIb Supernova SN 2024iss

Authors: Yuhei Iwata, Tomoki Matsuoka, Masanori Akimoto, Keiichi Maeda, Nozomu Tominaga, Yoshinori Yonekura, Takashi J. Moriya, Kotaro Niinuma, Kenta Fujisawa,

Comments: 6 pages, 3 figures, accepted for publication in PASJ

Subjects: astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Type~IIb SUPERNOVAe exhibit diverse progenitor properties, and radio observations offer a unique probe of their mass-loss histories shortly before the explosion. We present Japanese VLBI Network single-baseline monitoring of the nearby Type IIb SN 2024iss at 6.9 and 8.4 GHz, spanning approximately one year after its discovery. Our radio observations have detected its emission at 10 and 23 days after the explosion, with subsequent epochs yielding non-detections. Based on the peak radio luminosity and peak time, SN 2024iss exhibits radio properties highly comparable to those of compact-envelope events. Using a SYNCHROTRON self-absorption (SSA) modeling, we estimate a progenitor mass-loss rate of $\dot{M} \approx 2.5 \times 10^{-6}\>M_{\odot}\>{\rm yr^{-1}}$ for a compact progenitor wind velocity of $100 \>{\rm km\>s^{-1}}$. Furthermore, our SSA analysis yields a mean expansion velocity of $V_{\rm sh} \approx 3.3 \times 10^4\>{\rm km\>s^{-1}}$, which exceeds the theoretical shock velocity derived from the self-similar solution by a factor of $\sim 2.4$. Even for the conservative upper-bound peak time, the SSA-derived velocity remains larger than the theoretical expectation by a factor of $\gtrsim 1.7$. To explain this velocity excess, we propose the presence of a confined, dense circumstellar matter (CSM) surrounding the progenitor. The shock emergence from this confined CSM may have accelerated the forward shock, pointing to a highly complex and non-steady mass-loss history shortly before the explosion.

[abstract 31 / 38] (score: 2)
arXiv:2608.06764 [pdf, ps, other]

Title: Linear and nonlinear benchmark of gyrokinetic simulation of energetic particle driven toroidal Alfven eigenmodes in ITPA TAE benchmark case

Authors: Youjun Hu, Yang Chen, Lei Ye, Zhiyong Qiu, Youwen Sun,

Comments:

Subjects: physics.plasm-ph

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

A new gyrokinetic code, TEK, was benchmarked in simulating energetic particle (EP) driven toroidal Alfven eigenmodes (TAEs) in the simple tokamak configuration chosen by the ITPA-EP group for code benchmarking purpose. Linear benchmark has been well established by other codes, whereas nonlinear benchmark for this case is lacking. This paper presents, besides the linear benchmark, nonlinear results for both single-n and multiple-n simulations (n is the toroidal mode number). The nonlinear results are in good agreement with an analytical theory on zonal field beat-driven by Alfven eigenmodes, partially verifying correctness of the nonlinear simulations. The saturation level and the resulting EP transport are examined. This provides data for future inter-code nonlinear benchmarking. In TEK, all species (electrons, thermal ions, EPs) are treated on the same footing using the gyrokinetic model (with electrons in the zero Larmor radius limit). The electroMAGNETic cancellation problem is mitigated by using the mixed-variable pullback method. Numerical details related to electroMAGNETic gyrokinetic simulation are discussed.

[abstract 32 / 38] (score: 2)
arXiv:2608.06787 [pdf, ps, other]

Title: Symmetry Classification of Non-Relativistic Hidden Spin Polarization in Noncollinear Magnets

Authors: Yuzhong Hu, Pan Zhou, Baoru Pan, PengBo Lyu, Lizhong Sun,

Comments:

Subjects: cond-mat.mtrl-sci

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Hidden spin POLARIZATION (HSP), in which spin-polarized states exist locally while the total spin POLARIZATION are hidden in momentum space, has been extensively studied in nonMAGNETic and collinear MAGNETic systems, but remains largely unexplored in noncollinear MAGNETs. Here we establish a unified symmetry framework for HSP in noncollinear MAGNETic materials based on spin-group theory. We show that spin symmetries systematically constrain nonRELATIVISTIC spin POLARIZATION, giving rise to four distinct split spin-texture (SST) types for each local sector, denoted as SST-1, SST-2, SST-3, and SST-4. Based on these splitting forms, together with the dimensionality of the associated local spin textures and the symmetry relations between different local sectors, we further classify HSP into three categories: HSP-1, HSP-2, and HSP-3. We illustrate these categories using tight-binding models and representative material examples, including SrFe$_2$Se$_2$O, USb, Sr$_2$Mn$_3$Sb$_2$O$_2$, PrFeAsO, and GdMn$_2$Si$_2$. A survey of the MAGNDATA database further identifies 133, 7, and 139 candidate noncollinear MAGNETic materials hosting HSP-1, HSP-2, and HSP-3, respectively. In addition, our symmetry analysis and first-principles calculation show that many of these materials can exhibit nonzero spin-related response tensors. These results establish a general framework for understanding HSP in noncollinear MAGNETs and highlight their potential for spin-dependent functionalities.

[abstract 33 / 38] (score: 2)
arXiv:2608.07150 [pdf, ps, other]

Title: Colored Black Holes in Logarithmic Nonlinear Yang--Mills Theory

Authors: Celio R. Muniz,

Comments: 24 pages, 5 figures

Subjects: gr-qc

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

We construct static, spherically symmetric, and asymptotically flat colored BLACK HOLEs in four-dimensional Einstein gravity coupled to a logarithmic nonlinear Yang--Mills field with gauge group SU(2). Unlike solutions based on the Wu--Yang ansatz, the gauge sector contains a dynamical radial amplitude, and the configurations arise from a genuinely coupled nonlinear boundary-value problem. An integral identity excludes nontrivial sign-definite solutions approaching a MAGNETically neutral Yang--Mills vacuum, implying that colored configurations must be nodal. We numerically construct the fundamental one-node branch and verify its convergence to the ordinary Einstein--Yang--Mills colored BLACK HOLE in the linear limit. Increasing the logarithmic nonlinearity lowers the ADM mass, raises the Hawking temperature, and displaces the gauge-field node toward larger radii. Branch termination is not detected over the full range of parameters investigated. Instead, the exterior geometry approaches Schwarzschild on fixed radial domains, while the colored structure develops an increasingly extended tail. Although no independent asymptotic Yang--Mills charge is present, the non-Abelian hair leaves a subleading imprint on the far-field geometry. Inside the event horizon, the representative nonlinear solutions possess no Cauchy horizon and approach a Schwarzschild-type spacelike curvature singularity, with a finite limiting mass and no oscillary mass inflation. The recovery of the linear theory is therefore nonuniform near the cetonter: solutions that are nearly linear in the exterior eventually enter the strongly logarithmic regime in the deep interior. Finally, turning points of the Hawking temperature produce divergences and sign changes in heat capacity, indicating transitions of local thermodynamic stability.

[abstract 34 / 38] (score: 2)
arXiv:2608.07165 [pdf, ps, other]

Title: Electron-Scale-Driven Turbulence by Negative-Density-Gradient in NSTX

Authors: C. Clauser, J. Candy, J. Parisi, T. Rafiq, W. Guttenfelder, G. Avdeeva, E. Belli, J. Berkery, I. Sfiligoi, E. Schuster,

Comments:

Subjects: physics.plasm-ph

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Gyrokinetic simulations of an NSTX spherical-tokamak plasma reveal novel negative-density-gradient (NDG) drift waves at electron-gyroradius-scale that drive turbulent transport comparable to the experimental power flow. Linear simulations indicate that the dominant instability is a trapped-electron electron-scale tearing-parity mode driven mainly by negative electron density gradient, $a/L_{ne} \equiv - a/n_e \, (dn_e/dr) < 0$. Although thermal transport is mainly carried by transverse MAGNETic, $δA_{\parallel}$, fluctuations, the growth rate is sensitive to compressional MAGNETic fluctuations, $δB_{\parallel}$, differentiating these from standard microtearing modes (MTMs). Linear sensitivity analysis also reveals that the modes are most unstable at lower collisionality, consistent with the trapped-electron character. Electron-scale and multi-scale nonlinear simulations show that these modes can account for several megawatts of experimental power, with the latter suggesting that experimental gradients may lie at a bifurcation between distinct turbulence regimes.

[abstract 35 / 38] (score: 2)
arXiv:2608.07172 [pdf, ps, other]

Title: New Universal Relations for Magnetized Neutron Stars

Authors: Byon N. Jayawiguna, Siddarth Ajith, Takuya Katagiri, Kent Yagi, Piyabut Burikham,

Comments: 15 pages, 4 figures

Subjects: gr-qc astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

Unlike the neutron-star mass--radius relation, which depends sensitively on the internal stellar structure through the equation of state of dense nuclear matter, certain neutron-star properties obey approximately universal relations that exhibit only weak dependence on the equation of state. In this paper, we explore new universal relations for MAGNETized neutron stars. We focus on a purely poloidal dipolar MAGNETic-field configuration and treat the effects of the MAGNETic field perturbatively to second order in the field strength. After appropriately normalizing the relevant quantities by the stellar mass and the MAGNETic-field strength at the pole, we first identify an exact universal relation between the MAGNETic dipole moment and stellar compactness. We then find approximate universal relations among the MAGNETic dipole moment, MAGNETically-induced stellar quadrupole moment, and ellipticity, with fractional variations due to the equation of state at the level of O(10%). We support these numerical findings with analytic estimates for Newtonian polytropes, which reproduce the observed behavior. Among the newly discovered relations, the one connecting the MAGNETic dipole moment and stellar quadrupole moment may be particularly useful for the analysis of gravitational-wave signals from binaries containing MAGNETized neutron stars.

[abstract 36 / 38] (score: 2)
arXiv:2608.07237 [pdf, ps, other]

Title: Testing the spin-induced multipole moments of compact binary coalescences using the flexible theory-independent framework

Authors: Elise M. Sänger, Alessandra Buonanno, Ajit Kumar Mehta, Jan Steinhoff,

Comments: 19 pages, 18 figures

Subjects: gr-qc astro-ph.HE

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

According to the no-hair theorem, the multipole moments of an electrically neutral BLACK HOLE in general relativity are entirely determined by its mass and spin. However, this is not in general true for compact objects: The multipole moments of neutron stars or exotic compact objects can depend on their formation history and internal processes, which are encoded in an equation of state. Furthermore, their spin-induced multipole moments differ from those of BLACK HOLEs of the same mass and spin, leaving an imprint on the dynamics and emitted gravitational waves of the binary. Gravitational waves can thus be used to test the nature of compact binary coalescences. Here, we present a test of the spin-induced quadrupole and octupole moments of compact objects based on the flexible theory-independent (FTI) framework. FTI is a parameterized inspiral test of general relativity which enables the addition of post-Newtonian coefficient deviations to the gravitational-wave phase of a generic aligned-spin frequency-domain waveform model. We use this test on synthetic signals to study the measurability of spin-induced quadrupole and octupole moments. Next, we apply the test to a subset of signals observed by the LIGO-Virgo-KAGRA Collaboration. Lastly, we present forecasts for next-generation ground-based detectors, such as Einstein Telescope and Cosmic Explorer. Our estimates suggest that these detectors will be capable of placing stringent constraints on the spin-induced quadrupole and octupole moments of $\mathcal{O}(10^{-2})$ and $\mathcal{O}(10^{-1})$ respectively, which is two orders of magnitude tighter than current constraints, and thus on the nature of BLACK HOLEs in a compact binary coalescence.

[abstract 37 / 38] (score: 2)
arXiv:2608.07466 [pdf, ps, other]

Title: Characterization of a prototype parallel-plate $^{238}$U fission chamber with DD and DT fusion neutron sources

Authors: V. Hagenlocker, R. A. Tinguely, X. Wang, J. L. Ball, B. Buschmann, M. Gatu-Johnson, R. Gocht, P. Raj,

Comments:

Subjects: physics.plasm-ph

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

The SPARC tokamak will employ $^{238}$U-based fission chambers (FCs) to monitor high-performance deuterium-tritium (DT) plasma operations, spanning neutron yield rates from ${\sim}10^{15}$ to ${>}10^{19}$ n/s. This work validates the $^{238}$U FC design, which utilizes a parallel-plate detector geometry and borated polyethylene collimation to prioritize unscattered DD and DT fusion neutrons. Experimental testing with both DD and DT neutron generators corroborates vendor-specified efficiencies and demonstrates excellent detector linearity, with measured count rates showing good agreement with OpenMC neutronics simulations. Further characterization confirms the $^{238}$U FC's robustness against SPARC-relevant environmental challenges, including stray MAGNETic fields up to 14 mT and possible signal degradation risks associated with $\sim$30 m long cable runs. These results confirm that the $^{238}$U FC, supported by indirect neutron shielding as well as appropriate pulse height thresholds, provides a reliable solution for fusion power measurements as part of the SPARC neutron diagnostics suite.

[abstract 38 / 38] (score: 2)
arXiv:2608.07470 [pdf, ps, other]

Title: HST imaging, pipeline modeling, and time-delay predictions of 2 triply-imaged and 15 quadruply-imaged lensed QUASARs

Authors: William Sheu, Tommaso Treu, Adriano Agnello, Timo Anguita, Simon Birrer, Daniel Gilman, Xiaosheng Huang, Richard G. McMahon, Nicholas D. Morgan, Veronica Motta, Anna Nierenberg, Ioana Zelko,

Comments: 18 pages, 6 figures, submitted to Physical Review D

Subjects: astro-ph.CO astro-ph.GA

Created: 2026-08-07; Updated: 2026-08-10; Datestamp: 2026-08-10

The Hubble-Lema\^ıtre tension remains a significant challenge in modern cosmology, exhibiting a discrepancy between early-Universe cosmic microwave background measurements and local distance ladder observations. Strong lensing time-delay cosmography provides an independent, geometric probe of $H_0$ that can help resolve this discrepancy. Although hundreds of lensed QUASARs have been discovered, only a handful have been analyzed due to the resource-intensive follow-up required to measure precise time delays and break degeneracies. We present uniform gravitational lens modeling of 17 recently discovered lensed QUASAR systems (2 triply-imaged and 15 quadruply-imaged) to identify and prioritize the most promising candidates for future cosmological study. Using high-resolution near-infrared Hubble Space Telescope WFC3/IR F160W imaging (PID: 17916, PI: T. Treu), we perform uniform pipeline modeling with Lenstronomy. We constrain the mass and light profiles of the deflector galaxies, and assuming a fiducial cosmology, we predict their Fermat potential differences and expected time delays. Our pipeline successfully yields models and time-delay predictions for all 17 systems. Assuming ideal monitoring conditions, we estimate the total contribution from time-delay and Fermat potential modeling errors to the time-delay distance. From this, we classify the systems by estimated time-delay distance uncertainties: six "excellent" ($\leq 3\%$), five "good" ($3\%$--$7\%$), three "suitable" ($7\%$--$12\%$), and three "impractical" ($>12\%$). We recommend prioritizing follow-up campaigns on the 11 "excellent" and "good" systems, which have the potential to deliver high-precision, independent constraints on $H_0$ to help resolve the Hubble-Lema\^ıtre tension.