Current date: 2026-08-05
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Number of records retrieved: 718
Keyword score statistics
score 8 -- 2 abstracts
score 7 -- 5 abstracts
score 5 -- 1 abstracts
score 4 -- 6 abstracts
score 3 -- 3 abstracts
score 2 -- 21 abstracts
in total -- 38 abstracts
Articles that appeared on 2026-08-05
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[abstract 1 / 38] Wow! (score: 8)
- Title: One year of broadband radio monitoring of the enigmatic transient GRB 250702B reveals the evolution of the RELATIVISTIC JETAuthors: A. J. Goodwin, James C. A. Miller-Jones, Itai Sfaradi, Andrew Mummery, Raffaella Margutti, Tanmoy Laskar, K. D. Alexander, Yuhan Yao, Arvind Balasubramanian, G. C. Anupama, Edo Berger, Varun Bhalerao, Yvette Cendes, Ryan Chornock, C. T. Christy, D. Eappachen, Tarraneh Eftekhari, Miguel Pérez-Torres, Enrico Ramirez-Ruiz, D. K. Sahu, Sjoert van Velzen,Comments: 29 pages, 15 figures, submitted to MNRAS. All data in Table D1 available in machine readable format upon request. Comments welcomeSubjects: astro-ph.HECreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We present an extensive radio monitoring campaign of the unique extragalactic transient GRB 250702B, with observations spanning 0.65-233 GHz from 6-356 d (observer frame) post-discovery. The radio emission shows a smoothly evolving peaked SYNCHROTRON spectrum consistent with an adiabatic shock expanding into a stratified ambient medium ($n_e\propto R^{-k}$; $k= 1.5-2$). We detect significant variability in the low frequency ($\leq3$ GHz) light curves which we interpret as interstellar scintillation, placing an approximate bound on the blast wave image size of $1.2\times10^{16}\lesssim R_{\perp} \lesssim 5\times10^{17}$ cm. The temporal evolution of the flux density and critical SYNCHROTRON frequencies suggest the shock that powers the radio emission is potentially a wide-angle $θ_j\gtrsim15$ deg, low Lorentz factor ($Γ\lesssim10$) JET, or a narrow $θ_j\lesssim2$ deg highly RELATIVISTIC JET. A narrow JET is expected for a stellar-mass BLACK HOLE engine, such as a helium star merger, and the beaming-corrected kinetic energy in this scenario is consistent with the known distribution for long GRBs ($E_K\sim10^{51}$ erg). The wide-angle JET scenario would instead require a progenitor involving prolonged accretion. We derive and show an intermediate or stellar-mass BLACK HOLE tidal disruption event are viable possibilities. The beaming-corrected kinetic energy in this scenario is on the low end of the known distribution for RELATIVISTIC SMBH TDEs ($E_K\sim10^{50}$ erg). We disfavour an SMBH TDE due to lack of compatibility with the observed timescales. The detection of a JET shut off within the next year would favour a WD-IMBH TDE due to the shorter theoretical duration of super-Eddington accretion than the main-sequence TDE channels.
[abstract 2 / 38] Wow! (score: 8) - Title: Revisiting the XMM-Newton Observations of the Galactic MicroQUASAR SS 433: Implications for the Origin of the Ultrahigh-Energy Emission Detected by LHAASOAuthors: Chao-Nan Tong, Hong-Bin Tan, Ruo-Yu Liu,Comments: 18 pages, 13 figures; submitted to The Astrophysical Journal (currently under review)Subjects: astro-ph.HECreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Recently, the Large High Altitude Air Shower Observatory (LHAASO) detected ultrahigh-energy (UHE; photon energy E>100TeV) $γ$-ray emission toward SS 433, the microQUASAR embedded in the W50 nebula, making it a promising Galactic PeVatron candidate. We reanalyze the archival XMM-Newton observations covering the bipolar JETs and the thermal X-ray shell north of SS 433, and derive spatially resolved profiles of the nonthermal X-ray intensity and photon index along both JETs. The JET emission softens with distance from the source, implying a correspondingly evolving electron population. In particular, a hard electron component appears close to the JET bases, which can account for the UHE emission from SS 433 via inverse Compton radiation if the MAGNETic field remains approximately uniform along the JETs. The result, however, is highly sensitive to the MAGNETic field profile. For flux-conserving configurations in which the field decreases as the JET expands, the stronger field required in the inner regions may reduce the number of X-ray-emitting electrons and suppress their inverse Compton emission. Furthermore, electron transport calculations show that injection only at the JET bases cannot reproduce the observed intensity and spectral evolution, particularly the downstream re-brightening features, indicating additional particle injection and/or re-acceleration within the JETs.
[abstract 3 / 38] Wow! (score: 7) - Title: Physical origin of very-high-energy gamma rays from the low-luminosity ACTIVE GALACTIC NUCLEus NGC 4278 and implications for neutrino observationsAuthors: Shilong Chen, Abhishek Das, B. Theodore Zhang, Shigeo S. Kimura, Kohta Murase, Yunfeng Liang,Comments: 10 pages, 8 figures, 5 tables, Published in The Astrophysical JournalSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Relativistic JETs in ACTIVE GALACTIC NUCLEi (AGNs) are known to accelerate particles to extreme energies, yet the physical origin of very-high-energy (VHE) emission from low-luminosity (LL) AGNs remains unclear. NGC 4278, a nearby LL AGN, has recently been identified as a VHE source following detections by LHAASO. In this work, we present a multiwavelength and multimessenger analysis to investigate the origin of this emission. SWIFT X-Ray Telescope monitoring reveals a quasi-quiescent state characterized by the low X-ray flux. Modeling the broadband spectral energy distribution with the leptohadronic code AMES, we find that a standard one-zone SYNCHROTRON self-Compton model underpredicts the VHE flux, unless a relatively high Doppler factor ($δ\gtrsim 6$) is invoked. Alternatively, an external inverse-Compton (EIC) scenario-scattering seed photons from a radiatively inefficient accretion flow-provides a good description of the broadband emission with modest JET power and Doppler factor. We further explore neutrino production within a leptohadronic framework. The EIC model in the quasi-quiescent state yields the largest predicted number of muon neutrinos, reaching $N_{ν_μ} \sim 0.001$ over 15 yr of IceCube observations (assuming that 0.1\% of the Eddington luminosity is converted into high-energy protons). Future multimessenger observations are essential to unveil the details of the high-energy processes of NGC 4278.
[abstract 4 / 38] Wow! (score: 7) - Title: Relativistic Magnetohydrodynamic Simulations of Giant Magnetar BurstsAuthors: Koushik Chatterjee, Alexander Philippov, Andrei M. Beloborodov, Kyle Parfrey, Bart Ripperda, Elias R. Most,Comments: ApJL accepted versionSubjects: astro-ph.HECreated: 2026-08-03; Updated: 2026-08-05; Datestamp: 2026-08-05
Gradual crustal deformation can generate strongly twisted MAGNETic fields around MAGNETars, potentially triggering giant flares with total energies exceeding $10^{44}\,\mathrm{erg}$. In this Letter, we present the first RELATIVISTIC MAGNETohydrodynamic simulation of a surface shear-driven MAGNETar eruption, capturing RECONNECTion-driven plasma heating, the ejection of RELATIVISTICally hot plasma, and the formation of a hot fireball confined within the inner MAGNETosphere. We find that MAGNETic RECONNECTion in the equatorial current sheet launches a hot trailing outflow capable of powering the initial spike observed in giant flares, while simultaneously leaving behind a thermally stratified fireball with sufficient thermal energy to produce the pulsating, decaying tail. Together, these features provide a self-consistent physical framework for understanding the observed energetics of MAGNETar giant flares. The eruption also expels a MAGNETically dominated giant plasmoid carrying up to $\sim 9\%$ of the MAGNETosphere's total MAGNETic energy. Furthermore, our simulation demonstrates how the plasmoid drives the formation of a blast wave---an important ingredient in models linking MAGNETar eruptions to fast radio bursts.
[abstract 5 / 38] Wow! (score: 7) - Title: Modelling the delayed shock-breakout emission following JET-launching binary neutron star mergers via RELATIVISTIC MAGNETohydrodynamic simulations simulationsAuthors: Matteo Pais, Riccardo Ciolfi, Andrea Pavan,Comments: 20 pages, 16 figures, accepted for publication on Astronomy & Astrophysics, figures in the journal version are color blind friendlySubjects: astro-ph.HE astro-ph.SR gr-qcCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
In binary neutron star (BNS) mergers launching a RELATIVISTIC JET, an electroMAGNETic (EM) signal is produced when the JET-driven shock breaks out of the merger ejecta. The observed time delay of this shock-breakout (SBO) emission with respect to the gravitational-wave (GW) signal from the merger provides a powerful probe of the physical conditions governing JET launching and early-time JET propagation. Considering different models of JET propagation in realistic post-merger environments, we investigate the SBO emission and corresponding GW-EM delay that would be observed depending on the viewing angle and the assumed ejecta opacity. We performed RELATIVISTIC MHD simulations of JETs propagating through a post-merger environment directly imported from the outcome of a previous BNS merger simulation. We also introduced a specific procedure to faithfully reconstruct the early dynamical ejecta up to their natural front. The evolution was followed in 3D up to 0.6 s and then we continued imposing axisymmetry and an eight times higher resolution. Varying JET launching time and luminosity, we identified three representative models spanning regimes from early breakout to extended JET choking. For each case, we tracked the JET-driven forward shock up to the photosphere and computed the angle-dependent bolometric SBO luminosity, and taking into account non-radial photon propagation, RELATIVISTIC Doppler shifts, and light-travel-time effects. We considered two opacity values spanning a factor of ten. We find that the GW-EM delay depends only weakly on both the viewing angle and the ejecta opacity, making it, at least for the limited set of configurations considered here, a robust diagnostic for constraining models. Comparing our three cases with GRB 170817A, we find smaller GW-EM delays. Reproducing the same delay will require a broader exploration of the parameter space.
[abstract 6 / 38] Wow! (score: 7) - Title: A refined method for measuring cosmological distances using variability and proper motions in AGN with VLBI-detected counter-JETsAuthors: Jeffrey A. Hodgson, Anthony Carr, David Parkinson, Matteo Statti, Jaehyeon Myeong, Benjamin L'Huillier, Arman Shafieloo, Ioannis Liodakis, Se Heon Oh,Comments: 6 pages, 2 figures. Accepted to A&A. Fixed typo in abstractSubjects: astro-ph.CO astro-ph.HECreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
In a previous paper, we described a `standard speed-gun' (SSG) distance that uses the speed of light to standardize a ruler under the assumption that the radio variability seen in BLAZARs is causally limited. The apparent size is then measured with Very Long Baseline Interferometry in order to derive the angular diameter distance. A key limitation of this method is that it requires knowledge of the RELATIVISTIC Doppler factor. Previously, we estimated the distance to the bright radio source, 3C 84 at the center of the Perseus cluster assuming a Doppler factor of δ~ 1. In this paper, we aim to describe how a detected counter-JET and approaching JET proper motions can be used to remove the need for knowledge of the Doppler factor when measuring cosmological distances in this way. Under the assumption of a disk (or spherical) geometry and parameterizing the relationship between the physical emitting region and the variability timescale via a causality correction factor (kappa), we estimate a refined angular diameter distance to 3C 84 (z=0.0178) with statistical errors. Assuming kappa=1, we derive distances of D_A,disk = 78.9(-9.8+11.0) Mpc (or D_A,sphere = 71.2(-8.8+9.7) Mpc). Comparing these results to literature benchmarks, we find that the spherical assumption yields a distance consistent with local Type Ia SUPERNOVAe calibrated to the SH0ES H0, while a disk-like geometry aligns with expectations from a lower H0 cosmology. Ultimately, this demonstrates that utilizing JET and counter-JET kinematics successfully removes the Doppler-factor dependence from the standard speed-gun method, providing a viable independent distance estimate once the geometric structure of the JET is resolved.
[abstract 7 / 38] Wow! (score: 7) - Title: EP241113a: dissipative photospheric emission from a dirty fireballAuthors: Cui-Yuan Dai, Xiang-Yu Wang, Bing Zhang,Comments: 12 pages, 5 figures; published in ApJLSubjects: astro-ph.HECreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
EP241113a, a soft X-ray transient detected by the Einstein Probe (EP), has an isotropic-equivalent energy ($E_{γ,\rm{iso}}\sim 10^{51}{\, \rm erg}$) comparable to classical GAMMA-RAY BURSTs (GRBs) but an exceptionally low peak energy ($E_{\rm{p}} \lesssim 1 \, {\rm keV}$), placing it off the canonical $E_{\rm{p}}$--$E_{γ,\rm{iso}}$ (Amati) relation at $>3σ$ confidence. The afterglow of EP241113a is also unusual, with an extremely low plateau luminosity and no JET break up to the latest observation. Such properties have been interpreted as arising from an energetic ``dirty fireball,'' i.e., a RELATIVISTIC JET with energy comparable to classical GRBs but much higher baryon loading, leading to a bulk Lorentz factor of $Γ\sim 20$. In this {\it Letter}, we propose that low $E_{\rm{p}}$ arises from dissipative photospheric emission in such a low-$Γ$ JET. As $Γ$ decreases, the photosphere shifts outward while the internal shock radius moves inward, causing dissipation to occur well below the photosphere and making the prompt emission photosphere-dominated. Meanwhile, the thermalization radius also moves outward, reducing the comoving radiation temperature where the spectral peak is established. Combined with weaker Lorentz boosting, these effects naturally shift the observed $E_{\rm{p}}$ into the soft X-ray band. We further suggest that such a low-$Γ$ JET may be powered by neutrino--antineutrino ($ν\barν$) annihilation in a hyperaccreting disk formed during the core collapse of a massive star. Compared with the Blandford--Znajek process, neutrino annihilation can produce a dirtier JET through baryon entrainment from a neutrino-driven wind. EP241113a-like events therefore offer new insight into the dissipation physics and launching mechanisms of JETs from collapsing massive stars.
[abstract 8 / 38] Yes (score: 5) - Title: Profile Analysis of the Multiwavelength 2.1-year Oscillations of PG 1553+113Authors: P. Peñil, N. Torres-Albà, A. Rico, L. Marcotulli, A. Domínguez, M. Ajello, S. Buson, S. Adhikari,Comments: 21 pages, 10 figues, 5 tablesSubjects: astro-ph.GACreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We investigate the morphology of the oscillation profiles of the BLAZAR PG~1553+113 in relation to its well-known $\sim$2.1 yr periodicity. We identify individual cycles in the $γ$-ray, X-ray, UV, and optical light curves and characterize their temporal profiles using analytical models for single- and multi-peaked events. We find that the oscillations are generally described by a broad activity envelope with shorter-timescale substructure, showing that the $\sim$2.1 yr signal is not a strictly sinusoidal or self-similar modulation. The internal morphology varies across cycles and energy bands. This is particularly evident in X-rays, where all analyzed cycles show a strong formal preference for multi-component profiles, unlike the $γ$-ray band, where several cycles admit statistically comparable empirical descriptions. The contemporaneous MWL oscillations show broadly aligned activity episodes, but the timing and relative amplitudes of secondary components are not systematically repeated. This suggests that a common long-term modulation affects the broadband emission, while additional local or energy-dependent processes shape individual cycles. Such a picture is compatible with a geometric, JET-related contribution to the broad recurrent envelope, with intrinsic variability superimposed on it. We also identify new cycles with a dominant peak accompanied by weaker twin-peak-like features, similar to structures previously discussed in a supermassive BLACK HOLE binary scenario for PG~1553+113. Although our results do not provide definitive evidence for this interpretation, the recurrence of comparable morphologies in newly analyzed cycles keeps this scenario viable.
[abstract 9 / 38] Yes (score: 4) - Title: Spin Constraints on 4U 1630-47 via combined Continuum Fitting and Reflection methods: a comparative study using Frequentist and Bayesian statisticsAuthors: Debtroy Das, Honghui Liu, Zuobin Zhang, Cosimo Bambi, Jiachen Jiang, Johannes Buchner, Andrea Santangelo, Menglei Zhou,Comments: 31 pages, 13 figures. v2: refereed versionSubjects: astro-ph.HECreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We present a comprehensive Bayesian spectral analysis of the BLACK HOLE X-ray binary 4U 1630-47 during its 2022 outburst, using simultaneous NICER and NUSTAR observations. Using the traditional frequentist approach, we build our model combining reflection spectroscopy with continuum fitting techniques and analyze the data. In the Bayesian framework, we jointly constrain the BLACK HOLE's spin, mass, and inclination within a unified framework. Employing nested sampling, we capture parameter degeneracies and rigorously propagate both statistical and systematic uncertainties. Our results yield robust evidence for a high spin, with the exact value still subject to model-dependent systematic uncertainties from both approaches. Our Bayesian analysis infers spin $a^* = 0.96_{-0.03}^{+0.02}$, mass $M_{\rm BH} = 12.19_{-1.46}^{+1.22} \, M_\odot$, and inclination angle $i = 55.75_{-1.37}^{+1.60}$ degrees, obtained via relxillNS flavor of our model. It also demonstrates the power of Bayesian inference in fetching valuable insights into the complex physics of BLACK HOLE accretion and enabling high-confidence measurements of fundamental parameters.
[abstract 10 / 38] Yes (score: 4) - Title: A Comprehensive Study of Morphology and Kinematics in Extended Nebulae Around UV Luminous Quasars at $z\approx1$Authors: Zhuoqi Liu, Sean D. Johnson, Eric F. Bell, Zhijie Qu, Benoît Epinat, Hsiao-Wen Chen, Marc Rafelski, Jennifer I-Hsiu Li, Alexander Beckett, Mandy C. Chen, Sayak Dutta, David DePalma, Gwen C. Rudie, Joop Schaye, Patrick Petitjean, Sebastiano Cantalupo, Elise Fuller, Wolfram Kollatschny, Sebastián López, Nishant Mishra, Sowgat Muzahid, Andrea Travascio, Fakhri S. Zahedy,Comments: Accepted by ApJ; 28 pages, 9 figuresSubjects: astro-ph.GACreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Gas flows between galaxies and the circumgalactic medium (CGM) play a central role in galaxy evolution and can become observable as giant nebulae when illuminated by the QUASARs. We present an ensemble study of nebulae around 30 UV-luminous QUASARs at z=0.4-1.4 from the CUBS and MUSEQuBES surveys, 27 of which are detected in extended [O II] and/or [O III] emission. Based on a joint analysis of nebular morphology and surrounding galaxy environments, we introduce three morpho-kinematic classifications. We identify eleven irregular, large-scale (>50 kpc) systems, many of which are likely interaction-related; twelve compact host-galaxy-scale nebula, likely tracing CGM/ISM gas; and four systems with complex morphologies of uncertain origin. We introduce a quantitative measure of the spatial and kinematic association between nebulae and QUASAR-host group galaxies, finding a statistically significant association for ten nebulae, most of which are irregular, large-scale nebulae, consistent with qualitative analysis. Radio JETs are detected in six systems, with no strong correlation found between radio activity and nebular emission. The [O II] nebulae are more asymmetric than their Ly$α$ counterparts at $z>2$, but bear more similarity to H I gas observed in 21 cm around local elliptical galaxies. Blueshifted-redshifted patterns, likely tracing gas rotation, are observed in roughly 30% of the systems, though disturbed kinematics suggest that feedback may also be important. These results show that giant QUASAR nebulae are not a uniform class of objects, but instead arise through multiple pathways shaped by host-galaxy gas, galaxy interactions, group environments, and QUASAR activity, with the most striking cases associated with galaxy interactions.
[abstract 11 / 38] Yes (score: 4) - Title: Nebular_AGN: A CIGALE module for fitting ACTIVE GALACTIC NUCLEus emission linesAuthors: Hao Zhang, Patrice Theule, Veronique Buat, Denis Burgarella, Estelle Pons, Mederic Boquien,Comments:Subjects: astro-ph.GACreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Aims. The increasing discovery of high-redshift AGNs in recent years imposes more stringent requirements on spectral analysis tools for deriving the properties of AGNs and their host galaxies from emission-line diagnostics. To address this need, we develop a new module for the popular SED-fitting tool Code Investigating GALaxy Emission (CIGALE), the [nebular_AGN] module, which enables the efficient and flexible simulation and fitting of emission lines originating from the broad-line regions (BLRs) and narrow-line regions (NLRs) of AGNs, and allows the estimation of the physical properties of these regions. Methods. We use the spectral synthesis code Cloudy to construct the database for the new module. Based on the X-ray and accretion disk continua implemented in CIGALE, we generate the incident radiation fields of the models. We then adopt the AGN geometry and dust settings implemented in CIGALE to define a flexible set of physical parameters for the gas clouds, thereby producing a comprehensive database for the [nebular_AGN] module. Results. We benchmark the [nebular_AGN] module using a QUASAR composite spectrum, an empirical metallicity calibration, and observational data from X-ray-selected AGNs. Our module can approximately reproduce the majority of QUASAR emission-line profiles, cover the key emission-line ratios observed in AGN samples, and provide an assessment of their physical properties. For specific combinations of parameters, the metallicity derived by our module is consistent with the empirical formula. We further compare our models with other photoionization models used to simulate AGN NLR emission, and perform a line-sensitivity study to identify the most effective diagnostic lines for each parameter in our module. Finally, we confirm that the dust attenuation law plays an important role in SED fitting.
[abstract 12 / 38] Yes (score: 4) - Title: Tilted thin accretion disks in the full Kerr spacetime and their implicationsAuthors: K. S. Sruthy, Chandrachur Chakraborty, Sudip Bhattacharyya,Comments: 25 pages, 17 figures, 2 tables, matches published versionSubjects: astro-ph.HE gr-qcCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We derive a steady-state warped-disk equation in the full Kerr spacetime to study the tilt dynamics of a thin, viscous accretion disk around a spinning collapsed object. The formulation, based on Pringle's framework, remains valid for all values of the Kerr parameter $a$, thereby encompassing both Kerr BLACK HOLEs (BHs; $0 < a \le 1$) and Kerr naked singularities ($a > 1$). By incorporating the exact Keplerian and Lense-Thirring precession frequencies, we analytically obtain the radial tilt equations of the disk without invoking slow-spin or weak-field approximations. Numerical solutions of the resulting equations, obtained under realistic boundary conditions, reveal significant deviations from slow-spin approximations, particularly in the inner disk where the RELATIVISTIC effects dominate. In the diffusive regime, we find that for Kerr naked singularities the tilt profile exhibits distinct inner hump(s) near the radius where the specific angular momentum vanishes -- a feature absent for Kerr BHs. Consideration of a tilt in the inner disk could significantly influence the interpretations from observed X-ray spectral, timing, and POLARIZATION features, which are crucial to probe the strong gravity regime and to infer the spin of the central object. While such a distinct hump feature alone does not uniquely distinguish Kerr BHs from Kerr naked singularities, their interpretation in conjunction with constraints on the disk regime may provide a potential observational handle on the nature of the accreting collapsed object.
[abstract 13 / 38] Yes (score: 4) - Title: AT 2022csn: A Photometrically Peculiar Optical/UV Tidal Disruption Event in a Type II AGNAuthors: Yael Dgany, Iair Arcavi, Grisha Zeltyn, Sebastian Gomez, Daichi Hiramatsu, Benny Trakhtenbrot, Megan Newsome, Dalya Baron, Craig Pellegrino, Jamison Burke, Nadejda Blagorodnova, David Jones, Gerard-Garcia Moreno, Erez A. Zimmerman, Asaf Horowicz, Avishay Gal-Yam, Mariusz Gromadzki, Edo Berger, Sara Faris, D. Andrew Howell, Harsh Kumar,Comments: Accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-08-03; Updated: 2026-08-05; Datestamp: 2026-08-05
The emission mechanism and host galaxy preference of optical/UV tidal disruption events (TDEs) are still not entirely understood. We present observations of the TDE AT 2022csn, which is one of the most distant (d_L~726 Mpc) and luminous (L_peak=2.487^(+0.073)_(-0.067)*10^(44) erg/s) optical/UV TDEs observed to date. Although it is a spectroscopically normal H+He TDE, it shows some photometric peculiarities, exhibiting a pronounced double-peaked light curve (with peaks separated by 18.30 pm 2.84 days in the g-band), and lying in the low-temperature and large-radius end of the optical/UV TDE population. The host galaxy of AT 2022csn shows evidence for a significant starburst within the last ~Gyr consistent with other optical/UV TDEs, but also narrow emission lines that place it within the Type II AGN region of the BPT diagram. Interaction between the TDE and a pre-existing AGN accretion disk might explain the peculiar photometric properties. However, it is puzzling that a TDE would be visible in a Type II AGN, where according to the AGN unification picture the central region around the supermassive BLACK HOLE is obscured. We suggest a few scenarios to reconcile this. AT 2022csn together with AT 2019ahk, which shows similar properties, may belong to a new subset of low-temperature, high-radius TDEs in galaxies with Type II AGN emission features.
[abstract 14 / 38] Yes (score: 4) - Title: Radiation reaction in the classical RELATIVISTIC Størmer problemAuthors: Francisco S. N. Lobo, Tiberiu Harko,Comments: 16 pages, 2 figuresSubjects: physics.plasm-ph astro-ph.HE gr-qcCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We extend the classical RELATIVISTIC Størmer problem by incorporating radiation reaction through the Landau--Lifshitz formulation, thereby providing a self-consistent description of dissipative charged-particle motion in a static dipole MAGNETic field. We derive the complete dimensionless equations and distinguish them from a reduced drag-only model that preserves the exact energy-loss law while omitting directional effects associated with MAGNETic field gradients. For planar motion, the reduced system yields exact instantaneous evolution laws for the particle energy and canonical angular momentum, together with averaged transport equations for regular bound librations. When the motion is constrained to the instantaneous circular branch, the secular evolution can be integrated in closed form and approaches a simple large-radius power law. This analytical solution provides a useful benchmark, although the circular branch is radially unstable and therefore does not describe generic nearby trajectories. Numerical integrations further illustrate the nonuniform dissipative deformation of planar rosette-like orbits. In three dimensions, the complete Landau--Lifshitz force produces local exponential damping of small vertical perturbations, with the leading contribution arising from the field-gradient term absent from the reduced model. These exact, averaged, conditional, and local results establish a controlled analytical framework for studying radiation-driven phase-space transport in strongly inhomogeneous MAGNETic fields and provide a foundation for future global simulations, kinetic descriptions, and calculations of the associated electroMAGNETic emission.
[abstract 15 / 38] (score: 3) - Title: Solar Orbiter SEP Dropout during a Magnetic Cloud with Evidence for Strong Connectivity GradientsAuthors: Radoslav Bucik, Raul Gomez-Herrero, Samuel T. Hart, Maher A. Dayeh, Nariaki V. Nitta,Comments: 10 pages, 5 figures. Accepted version of the paper. Publisher typeset PDF is provided as ancillary fileSubjects: astro-ph.SR physics.space-phCreated: 2026-08-01; Updated: 2026-08-05; Datestamp: 2026-08-05
We analyze an impulsive solar energetic particle (SEP) event observed by Solar Orbiter at 0.93 au on 2022 December 24 that exhibits a pronounced intensity dropout between approximately 07:15 and 10:00 UT. Pitch-angle distributions show a near-field-aligned beam before the dropout, which disappears abruptly at the dropout onset. At the same time, a weak 100--200 keV component appears at pitch angles of about 90--180 degrees; no comparable enhancement over this pitch-angle range is present at MeV energies. The dropout onset is not accompanied by an abrupt change in the in situ MAGNETic field or solar wind plasma. Solar imaging associates the SEP event with a JET from a compact source. Ballistic back mapping, together with Potential Field Source Surface extrapolations and quasi-separatrix-layer proxy diagnostics, indicates that Solar Orbiter nominally connects to the source region, but lies close to strong connectivity gradients where small displacement may shift the connection to neighboring open field lines. The in situ measurements show that the event occurs during a MAGNETic-cloud passage and that additional dropouts occur later in the event. These results favor an interpretation in which the dropout reflects rapid changes in particle access between adjacent flux tubes, while the MAGNETic cloud may help preserve the sharp SEP intensity gradients between them.
[abstract 16 / 38] (score: 3) - Title: The mass-dependent interplay of active galacitc nuclei and SUPERNOVA feedback in shaping the $L_{\rm X}$--$T$ relation of early-type galaxiesAuthors: Haojie Xia, Feng Yuan, Bocheng Zhu, Haoen Zhang, Tingfang Su, Aoyun He, Suoqing Ji,Comments: 14 pages, 8 figures, published in A&ASubjects: astro-ph.GACreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
The observed X-ray luminosity--temperature ($L_{\rm X}$--$T$) relation of hot gas in early-type galaxies deviates significantly from the prediction of purely gravitational heating, providing a key constraint on non-gravitational processes such as SUPERNOVA (SN) and ACTIVE GALACTIC NUCLEus (AGN) feedback. We investigate the physical origin of this relation using high-resolution 3D hydrodynamical simulations with the multiscale AGN-regulated cosmic ecosystem resolver in 3D (MACER3D) framework, which we applied to a dwarf elliptical, a massive elliptical, and a cluster-central galaxy. For comparison, we performed controlled simulations that included AGN winds and SN feedback in isolation, excluding cosmological inflow and environmental effects. The dominant regulation mechanism depends strongly on the halo mass. In the cluster-central case, neither AGN winds nor SN feedback alone can sufficiently suppress the gas density and $L_{\rm X}$. When both are included, their nonlinear coupling suppresses the X-ray emission, producing ($L_{\rm X}$, $T$) values below the observed relation; this discrepancy can be resolved by incorporating AGN JET feedback. In massive elliptical galaxies, the inclusion of AGN feedback brings the model predictions into broad agreement with the observed $L_{\rm X}$--$T$ relation, indicating that AGN feedback dominates SN feedback. At the low-mass end, dwarf galaxy models also follow the observed trend. In this regime, models with either SN or AGN feedback alone predict low $L_{\rm X}$. When both are included, AGN wind-driven transport of SN-enriched gas to intermediate radii enhances the metallicity and radiative cooling, thereby increasing $L_{\rm X}$. This coupled process establishes a fountain-like circulation, in which gas is repeatedly lifted and recycled within the galaxy.
[abstract 17 / 38] (score: 3) - Title: Statistical Study of Solar Prominence Plumes Based on NVST H$α$ ObservationsAuthors: Yangrui Chen, Yijun Hou, Jincheng Wang, Ting Li, Shuo Yang, Yilin Guo, Junyi Zhang, Haitang Li, Feiyang Sha, Qing Zhou, Yu Liu, Xiaoli Yan,Comments: 15 pages, 9 figures, 1 table, accepted for publication in ApJSubjects: astro-ph.SRCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Plumes are one of the most representative dynamic features observed in prominences and play a key role in mass and MAGNETic transport within them. However, their physical nature and triggering processes remain actively debated. Based on limb H$α$ observations from the New Vacuum Solar Telescope (NVST) during 2013--2025, we statistically investigated 34 plumes with clear and complete evolutions by developing an automated image-processing pipeline. It is revealed that plume lifetimes mainly range from 300 s to 700 s, with vertical displacements between 3--7 Mm. The mean widths and velocities are concentrated in the range of 0.5--1.5 Mm and 10--20 km s$^{-1}$, respectively. Besides wide distribution ranges, plume parameters exhibit irregular evolution fluctuations, indicating that the formation and evolution of various plumes may exhibit different physical patterns. Correlation analysis among the parameters further reveals that: (1) Positive correlations were found among lifetime, vertical displacement, and mean width, indicating an intrinsic coupling between the temporal and spatial scales of plumes. (2) Trajectory curvature is negatively correlated with lifetime, vertical displacement, and velocity. Accelerating and width-contracting plumes typically have lower curvature, suggesting that curvature may reflect environmental influences and the stability of plumes. (3) Plumes with higher initial velocities were more likely to be accompanied by precursor brightening, suggesting that these plumes may be triggered by MAGNETic RECONNECTion. Furthermore, we infer that some plumes in non-bubble regions may be inherently driven by mini-filament eruptions. These results establish a statistical framework for prominence plumes and reveal diversity in their dynamical evolution and triggering mechanisms.
[abstract 18 / 38] (score: 2) - Title: Suppression of boosted relic neutrinos by photon backgrounds during ultra-high-energy COSMIC RAY propagationAuthors: Gabriel Azeredo, Vitor de Souza,Comments: 18 pages, 5 figuresSubjects: astro-ph.HE hep-phCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Constraining the cosmic neutrino background (C$ν$B) represents a major experimental challenge in cosmology. Recent studies have suggested that relic neutrinos boosted by ultra-high-energy COSMIC RAYs (UHECRs) may generate observable diffuse neutrino fluxes. Previous estimates have not effectively propagated the primary COSMIC RAYs, often neglecting crucial energy losses and the unavoidable, competing interactions with diffuse photon backgrounds. Here we revisit these expectations using a realistic Monte Carlo propagation framework. This approach allows us to consistently incorporate COSMIC RAY energy losses, nuclear photodisintegration, and production of secondary neutrinos. We show that interactions with diffuse photon backgrounds strongly suppress the boosted relic neutrino flux predicted in simplified propagation scenarios. Furthermore, we demonstrate that to produce any observable suppression on the UHECR energy spectrum at Earth, or for the boosted C$ν$B component to become comparable to the cosmogenic neutrino flux, the C$ν$B density must be enhanced by a factor, the so-called overdensity, of extreme magnitude ($η\gtrsim 10^{8}$).
[abstract 19 / 38] (score: 2) - Title: Beyond Plane Waves: Coherent Network Response to Collimated Gravitational-Wave WavepacketsAuthors: S. D. Campos,Comments: Several improvements, including reorganization of the sections and the inclusion of considerations regarding Pulsar Timing ArraysSubjects: gr-qc astro-ph.HECreated: 2026-08-03; Updated: 2026-08-05; Datestamp: 2026-08-05
We present a paraxial wavepacket model for structured, collimated gravitational-wave bursts and derive the coherent response of detector networks to these signals. For current terrestrial baselines such as LIGO-Virgo, analytic mismatch estimates confirm that the paraxial wavepacket model waveforms are effectively indistinguishable from standard sine-Gaussian bursts, validating the robustness of the plane-wave approximation in this regime. However, we identify a physical scaling regime relevant to third-generation networks and galactic-scale Pulsar Timing Arrays in which finite transverse structure-motivated by wave-optics lensing or ultra-RELATIVISTIC beaming induces non-negligible geometric phase shifts. A toy event-level Monte Carlo study compares a standard burst-search ranking with a paraxial wavepacket model-constrained statistic that penalizes geometric inconsistencies across detectors. In this controlled setup, the model prior yields an illustrative factor of $\sim 3$-$4$ gain in detection efficiency at a fixed false-alarm rate, while maintaining performance on plane-wave-like signals. These results suggest that paraxial corrections may provide a necessary metrological framework for signal discrimination and unbiased parameter estimation in future cosmic-scale observations.
[abstract 20 / 38] (score: 2) - Title: Finite-Field QED Corrections to Vacuum Birefringence and Magnetar Polarization TransportAuthors: S. Abbassi, F. A. Chishtie, S. R. Valluri,Comments: e.g. 25 pages, 5 figures, Accepted for Publication in the European Physical Journal CSubjects: astro-ph.HE hep-phCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We study low-energy photon propagation in a constant MAGNETic field within the finite-field one-loop Heisenberg--Euler framework and apply the resulting mode-dependent refractive indices to MAGNETar POLARIZATION transport. In a centered-dipole model, the POLARIZATION-limiting radius is unchanged to better than $10^{-12}$ because mode decoupling occurs at $\sim10^2R_{\rm NS}$, where $B\ll B_{\rm cr}$. Near the surface, however, the weak-field Cotton--Mouton expression overestimates the accumulated birefringent phase by up to a factor $2.9$ at $10^{15}$~G. At the plasma--vacuum resonance, finite-field corrections reduce the resonance density by $32\%$ and raise the adiabatic conversion energy by $14\%$ for 1E~1547.0$-$5408; the corresponding changes are factors $2.6$ and $1.37$ for 1RXS~J1708$-$4009, and factors $9.7$ and $2.13$ for SGR~1806$-$20, the latter controlled by the strong-field asymptote. The parallel-mode MAGNETic response remains positive and exhibits a broad maximum near $17B_{\rm cr}$. Its strict $\mathcal O(α)$ expansion is monotonic, indicating that the detailed position and profile of the maximum are not controlled beyond the present approximation and require higher-loop assessment. These results identify vacuum-resonance observables as the most sensitive channel for testing finite-field QED in MAGNETars.
[abstract 21 / 38] (score: 2) - Title: Validation of the DESI DR2 Ly$α$ forest full-shape analysisAuthors: M. Herbold, A. Cuceu, P. Martini, H. K. Herrera-Alcantar, J. Guy, C. Gordon, O. Manasoiu, J. Aguilar, S. Ahlen, O. Alves, U. Andrade, E. Armengaud, S. Avila, A. Aviles, A. Bault, F. Beutler, D. Bianchi, M. Bonici, A. Brodzeller, D. Brooks, A. Carnero Rosell, E. Chaussidon, J. Chaves-Montero, Z. Chen, T. Claybaugh, K. S. Dawson, A. de la Macorra, A. Dey, W. Elbers, V. A. Fawcett, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, G. Gambardella, S. Gontcho A Gontcho, D. Gonzalez, A. X. Gonzalez-Morales, R. Gsponer, G. Gutierrez, B. Hadzhiyska, C. Hahn, K. Honscheid, D. Huterer, M. Ishak, S. Jos, S. Juneau, N. V. Kamble, N. G. Karaçaylı, T. Karim, R. Kehoe, D. Kirkby, F. -S. Kitaura, A. Kremin, O. Lahav, M. Landriau, J. Lasker, L. Le Guillou, A. Leauthaud, M. E. Levi, Q. Li, W. Liu, K. Lodha, M. Manera, A. Meisner, R. Miquel, J. Morawetz, J. Moustakas, P. Mukherjee, A. Muñoz-Gutiérrez, S. Nadathur, G. Niz, H. E. Noriega, E. Paillas, N. Palanque-Delabrouille, J. Pan, M. P. Ibanez, W. J. Percival, F. Prada, H. Pulido-Hernández, A. Pérez-Fernández, I. Pérez-Ràfols, C. Ravoux, J. Rohlf, G. Rossi, R. Ruggeri, M. F. Ruiz-Herrera Bernal, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, H. Seo, J. Silber, T. Simon, F. Sinigaglia, M. Siudek, G. Tarlé, W. Turner, R. Vaisakh, M. Vargas-Magaña, B. A. Weaver, M. Wolfson, H. Yang, H. Zhang,Comments:Subjects: astro-ph.COCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We present the validation of the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2) Lyman-$α$ (Ly$α$) forest full-shape analysis. This analysis combines three-dimensional Ly$α$ forest auto-correlations and cross-correlations with QUASARs to extract information from both the baryon acoustic oscillation (BAO) feature and the broadband clustering signal, with primary emphasis on the Alcock-Paczynski (AP) measurement. Compared to the DESI DR1 analysis, the DR2 validation uses substantially larger and more realistic mock datasets, including CoLoRe 2LPT and AbacusSummit Ly$α$ forest simulations. The modeling framework is also improved through analytic marginalization over small scales ($<10$ $h^{-1}$Mpc) and the impact of ultraviolet background fluctuations. The validation program was completed prior to unblinding and defines quantitative requirements for the cosmological parameters of interest, which are evaluated using hundreds of mock realizations. We further test the analysis through independent fits to the auto- and cross-correlations, multiple catalog splits, and a broad suite of analysis and modeling variations applied to both mocks and blinded observational data. We find that the BAO and AP parameters satisfy all validation requirements and remain stable across all tests. In contrast, mock studies reveal a significant bias in the inferred growth-rate parameter $fσ_8$, leading us to exclude this measurement from the final analysis. The consistency across mocks, data splits, and robustness tests demonstrates that the DR2 Ly$α$ full-shape analysis provides a reliable and substantially improved broadband AP measurement over previous Ly$α$ forest studies.
[abstract 22 / 38] (score: 2) - Title: Radial transport of electric current by electroMAGNETic microturbulence in tokamaksAuthors: Haomin Sun, Toby Adkins, Justin Ball, Yann Camenen,Comments:Subjects: physics.plasm-phCreated: 2026-08-03; Updated: 2026-08-05; Datestamp: 2026-08-05
The turbulent transport of toroidal angular momentum helps determine the rotation profiles of tokamak plasmas, and thereby their confinement and stability. The electron contribution therein has an additional consequence: even a modest electron momentum flux can correspond to a substantial turbulent flux of toroidal current, whose divergence could in principle modify the safety-factor profile. Here, using nonlinear gyrokinetic simulations, we show that electroMAGNETic fluctuations qualitatively alter turbulent momentum transport. In microtearing-mode-driven turbulence, the total momentum transport is inefficient relative to that of heat, yet an electron contribution associated with the turbulent Maxwell stress dominates the momentum flux. We show that this contribution exceeds an estimated scale required for turbulent current redistribution to compete with the collisional processes maintaining the bootstrap current. In the case of kinetic-ballooning-mode-driven turbulence considered, the momentum transport is found to be stronger and remains dominated by the electrostatic ion contribution; nevertheless, retaining the Maxwell stress is essential for the electron momentum flux to exceed this bootstrap-based reference scale. To enable this study, we independently implemented complete electroMAGNETic momentum-flux diagnostics in the gyrokinetic codes GENE and CGYRO, and verified them through linear and nonlinear cross-code benchmarks. Taken together, these results suggest that electroMAGNETic momentum transport may potentially be important for the coupled evolution of the rotation, current, and safety-factor profiles in high-beta tokamak plasmas.
[abstract 23 / 38] (score: 2) - Title: Gamma-ray and radio populations of millisecond pulsars in globular clustersAuthors: Hannah Lawson, Duncan R. Lorimer,Comments: 16 pages, 6 figures, 2 tables. Submitted to JHEAPSubjects: astro-ph.HECreated: 2026-08-03; Updated: 2026-08-05; Datestamp: 2026-08-05
The populations of millisecond pulsars (MSPs) across the Milky Way's globular cluster (GC) system serve as powerful diagnostics of neutron star evolution in a variety of dense stellar environments. Using properties of 118 Galactic GCs, we performed Monte Carlo simulations of their gamma-ray fluxes observed by FERMI. We compared two luminosity models: a 3D fundamental plane (model A) and a lognormal distribution (model B). Both models reproduce the observed gamma-ray fluxes and mirror the scaling law with the GC stellar encounter rate established for low-mass X-ray binaries and radio MSPs. Due to its lower average gamma-ray luminosities, model B predicts a 6-7 times larger MSP population ($5150^{+720}_{-710}$) than model A ($770\pm60$). Furthermore, both models accurately predict a population-wide expectation of roughly three clusters whose aggregate gamma-ray emission is dominated by a single bright MSP. Invoking a radio-to-gamma-ray luminosity scaling ($L_r \sim 3.5 \times 10^{-7} L_γ$), we find that model B predicts a mean radio pseudoluminosity ($\log L_{\rm pseudo} \sim -1.6$) that is fainter than canonical pulsars. This result is consistent with recent evidence attributing the apparent faintness of Galactic MSPs to geometric effects. In contrast, model A implies an intrinsically brighter population ($\log L_{\rm pseudo} \sim -0.3$) that lacks a clear physical basis and is inconsistent with the results found for Galactic pulsars. The larger underlying population of faint millisecond pulsars predicted by model B could be probed by sensitive surveys with emerging radio facilities to further constrain the evolutionary pathways of MSPs.
[abstract 24 / 38] (score: 2) - Title: Elliptic flow of $π^0$ mesons in Cu$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV and U$+$U at $\sqrt{s_{_{NN}}}=193$ GeVAuthors: PHENIX Collaboration, N. J. Abdulameer, U. Acharya, C. Aidala, N. N. Ajitanand, Y. Akiba, R. Akimoto, J. Alexander, D. Anderson, S. Antsupov, K. Aoki, N. Apadula, H. Asano, E. T. Atomssa, T. C. Awes, B. Azmoun, V. Babintsev, M. Bai, X. Bai, B. Bannier, E. Bannikov, K. N. Barish, S. Bathe, V. Baublis, C. Baumann, S. Baumgart, A. Bazilevsky, M. Beaumier, R. Belmont, A. Berdnikov, Y. Berdnikov, L. Bichon, D. Black, B. Blankenship, D. S. Blau, J. S. Bok, V. Borisov, K. Boyle, M. L. Brooks, J. Bryslawskyj, H. Buesching, V. Bumazhnov, S. Butsyk, S. Campbell, P. Chaitanya, C. -H. Chen, D. Chen, M. Chiu, C. Y. Chi, I. J. Choi, J. B. Choi, S. Choi, P. Christiansen, T. Chujo, V. Cianciolo, B. A. Cole, M. Connors, R. Corliss, N. Cronin, N. Crossette, M. Csanád, T. Csörgő, L. D'Orazio, A. Datta, M. S. Daugherity, G. David, K. Dehmelt, A. Denisov, A. Deshpande, E. J. Desmond, L. Ding, V. Doomra, J. H. Do, O. Drapier, A. Drees, K. A. Drees, J. M. Durham, A. Durum, T. Engelmore, A. Enokizono, R. Esha, K. O. Eyser, B. Fadem, D. E. Fields, M. Finger, M. Finger, D. Firak, D. Fitzgerald, F. Fleuret, S. L. Fokin, J. E. Frantz, A. Franz, A. D. Frawley, Y. Fukao, T. Fusayasu, K. Gainey, C. Gal, P. Garg, A. Garishvili, I. Garishvili, F. Giordano, A. Glenn, X. Gong, M. Gonin, Y. Goto, R. Granier de Cassagnac, N. Grau, S. V. Greene, M. Grosse Perdekamp, T. Gunji, T. Guo, H. Guragain, Y. Gu, J. S. Haggerty, K. I. Hahn, H. Hamagaki, J. Hanks, K. Hashimoto, R. Hayano, T. K. Hemmick, T. Hester, X. He, J. C. Hill, A. Hodges, R. S. Hollis, K. Homma, B. Hong, T. Hoshino, J. Huang, T. Ichihara, Y. Ikeda, K. Imai, Y. Imazu, M. Inaba, A. Iordanova, D. Isenhower, A. Isinhue, D. Ivanishchev, B. V. Jacak, S. J. Jeon, M. Jezghani, X. Jiang, Z. Ji, B. M. Johnson, K. S. Joo, D. Jouan, D. S. Jumper, J. Kamin, S. Kanda, B. H. Kang, J. H. Kang, J. S. Kang, J. Kapustinsky, G. Kasza, D. Kawall, A. V. Kazantsev, J. A. Key, V. Khachatryan, P. K. Khandai, A. Khanzadeev, K. M. Kijima, C. Kim, D. J. Kim, E. -J. Kim, Y. -J. Kim, Y. K. Kim, E. Kistenev, J. Klatsky, D. Kleinjan, P. Kline, T. Koblesky, M. Kofarago, B. Komkov, J. Koster, D. Kotchetkov, D. Kotov, L. Kovacs, F. Krizek, K. Kurita, M. Kurosawa, Y. Kwon, Y. S. Lai, J. G. Lajoie, A. Lebedev, D. M. Lee, G. H. Lee, J. Lee, K. B. Lee, K. S. Lee, S. H. Lee, M. J. Leitch, M. Leitgab, B. Lewis, X. Li, X. Li, S. H. Lim, M. X. Liu, D. A. Loomis, D. Lynch, S. Lökös, C. F. Maguire, Y. I. Makdisi, M. Makek, A. Manion, V. I. Manko, E. Mannel, M. McCumber, P. L. McGaughey, D. McGlinchey, C. McKinney, A. Meles, M. Mendoza, B. Meredith, Y. Miake, T. Mibe, A. C. Mignerey, A. Milov, D. K. Mishra, J. T. Mitchell, M. Mitrankova, Iu. Mitrankov, S. Miyasaka, S. Mizuno, A. K. Mohanty, S. Mohapatra, D. P. Morrison, M. Moskowitz, T. V. Moukhanova, B. Mulilo, T. Murakami, J. Murata, A. Mwai, T. Nagae, S. Nagamiya, J. L. Nagle, M. I. Nagy, I. Nakagawa, Y. Nakamiya, K. R. Nakamura, T. Nakamura, K. Nakano, C. Nattrass, P. K. Netrakanti, M. Nihashi, T. Niida, R. Nouicer, N. Novitzky, T. Novák, G. Nukazuka, A. S. Nyanin, E. O'Brien, C. A. Ogilvie, H. Oide, K. Okada, M. Orosz, A. Oskarsson, K. Ozawa, R. Pak, V. Pantuev, V. Papavassiliou, I. H. Park, J. S. Park, S. Park, S. K. Park, L. Patel, S. F. Pate, J. -C. Peng, D. V. Perepelitsa, G. D. N. Perera, D. Yu. Peressounko, J. Perry, R. Petti, C. Pinkenburg, R. P. Pisani, M. Potekhin, M. L. Purschke, H. Qu, J. Rak, I. Ravinovich, K. F. Read, D. Reynolds, V. Riabov, Y. Riabov, E. Richardson, D. Richford, N. Riveli, D. Roach, S. D. Rolnick, M. Rosati, M. S. Ryu, B. Sahlmueller, N. Saito, T. Sakaguchi, H. Sako, V. Samsonov, M. Sarsour, S. Sato, S. Sawada, K. Sedgwick, J. Seele, R. Seidl, Y. Sekiguchi, A. Seleznev, A. Sen, R. Seto, P. Sett, D. Sharma, A. Shaver, I. Shein, T. -A. Shibata, K. Shigaki, M. Shimomura, K. Shoji, P. Shukla, A. Sickles, C. L. Silva, D. Silvermyr, B. K. Singh, C. P. Singh, V. Singh, M. Skolnik, M. Slunečka, K. L. Smith, S. Solano, R. A. Soltz, W. E. Sondheim, S. P. Sorensen, I. V. Sourikova, P. W. Stankus, P. Steinberg, E. Stenlund, M. Stepanov, A. Ster, S. P. Stoll, M. R. Stone, T. Sugitate, A. Sukhanov, J. Sun, Z. Sun, A. Takahara, A. Taketani, Y. Tanaka, K. Tanida, M. J. Tannenbaum, S. Tarafdar, A. Taranenko, E. Tennant, A. Timilsina, T. Todoroki, M. Tomášek, H. Torii, R. S. Towell, I. Tserruya, B. Ujvari, H. W. van Hecke, M. Vargyas, E. Vazquez-Zambrano, A. Veicht, J. Velkovska, M. Virius, V. Vrba, E. Vznuzdaev, R. Vértesi, X. R. Wang, D. Watanabe, K. Watanabe, Y. Watanabe, Y. S. Watanabe, F. Wei, S. Whitaker, S. Wolin, C. L. Woody, M. Wysocki, B. Xia, Y. L. Yamaguchi, A. Yanovich, S. Yokkaichi, I. Yoon, I. Younus, Z. You, I. E. Yushmanov, W. A. Zajc, A. Zelenski, S. Zhou,Comments: 325 authors from 74 institutions, 14 pages, 10 figures, 3 tables. v1 is version submitted to Physical Review C. HEPdata tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htmlSubjects: nucl-exCreated: 2026-08-03; Updated: 2026-08-05; Datestamp: 2026-08-05
The second-order azimuthal anisotropy coefficients ($v_2$) of neutral $π$ mesons ($π^0$) have been measured as a function of the transverse momentum ($p_T$) and centrality of Cu$+$Au collisions at $\sqrt{s_{_{NN}}}=200$~GeV and U$+$U at $\sqrt{s_{_{NN}}}=193$ GeV at the Relativistic Heavy Ion Collider. The analysis used experimental data collected by the PHENIX experiment at midrapidity $|η|<0.35$ over a broad $p_T$ range up to $\approx10$~GeV/$c$, and the obtained results are compared with previous PHENIX measurements in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$~GeV. In all three collision systems, the $π^0$~$v_2$ values follow the scaling with the second-order participant eccentricity and the cube root of the number of participating nucleons ($\varepsilon_2 N_{\rm part}^{1/3}$) up to $\approx4$~GeV/$c$. Furthermore, the behavior of the azimuthal-dependent $π^0$ nuclear-modification factors and associated fractional parton-energy losses are evaluated from measured nonzero $v_2$ values of $π^0$ at $p_T>5$ GeV/$c$ and found to be approximately the same for similar values of $N_{\rm part}^{1/3}$ in these collision systems. These findings demonstrate that the mechanism of $π^0$ $v_2$ generation exhibits a high degree of universality across different initial geometries of heavy-ion collisions.
[abstract 25 / 38] (score: 2) - Title: The Indian Pulsar Timing Array Data Release 2: III. Search for a Stochastic Gravitational Wave BackgroundAuthors: Hemanga Tahbildar, Kunjal Vara, Mayuresh Surnis, Churchil Dwivedi, Bhal Chandra Joshi, Sharika Dhakappa, Aman Srivastava, Shantanu Desai, Abhimanyu Susobhanan, Adya Shukla, Himanshu Grover, P. Arumugam, Manjari Bagchi, Neelam Dhanda Batra, Manoneeta Chakraborty, Shaswata Chowdhury, Debabrata Deb, A. Gopakumar, Sushovan Mondal, Kuldeep Meena, K Nobleson, Avinash Kumar Paladi, Arul Pandian B, Kaustubh Rai, Prerna Rana, Shubhit Sardana, Vidit Singh, Jaikhomba Singha, Keitaro Takahashi, Pratik Tarafdar, Zenia Zuraiq,Comments:Subjects: astro-ph.HECreated: 2026-08-03; Updated: 2026-08-05; Datestamp: 2026-08-05
We present the first independent search for an isotropic stochastic gravitational wave background in the second data release of the Indian Pulsar Timing Array, comprising of 27 millisecond pulsars monitored simultaneously in two frequency bands with the upgraded Giant Metrewave Radio Telescope over a maximum 7.2 year baseline. Building on a comprehensive single pulsar noise analysis, we search for a common uncorrelated red noise process within a Bayesian inference framework and with the noise-marginalized optimal statistics, and we test the robustness of the result through per-pulsar dropout analyses and solar-wind exclusion cuts. Leaving the spectral index free, we recover a broad amplitude posterior, $\log_{10} A_{\rm CURN} = -13.71^{+1.06}_{-3.28}$, with an unconstrained spectral index $γ_{\rm CURN} = 2.98^{+3.62}_{-2.70}$ and a Savage-Dickey Bayes factor of $2.5$ for a common red process over the no signal model. The optimal-statistic signal to noise ratios for the monopole, dipole, and Hellings-Downs correlations are all consistent with zero. Fixing the spectral index to $γ= 13/3$, the value predicted by an idealized toy model in which the background is sourced by a population of supermassive BLACK HOLE binaries in circular orbits evolving purely under leading-order gravitational radiation reaction, we place a $95\%$ upper limit on the common-process amplitude of $A_{\rm GWB} < 3.4\times10^{-14}$, stable across solar elongation cuts of $10^\circ$, $20^\circ$, and $30^\circ$. This limit lies approximately an order of magnitude above the amplitudes reported by other, longer-running pulsar timing array experiments. We also demonstrate through simulated datasets with the addition of simple chromatic and achromatic noise components that it will take at least a 10 year baseline to start recovering the common red noise signal.
[abstract 26 / 38] (score: 2) - Title: Structural quasi-universality in highly MAGNETized differentially rotating neutron starsAuthors: Pratul Manna, Surajit Kalita,Comments: 10 pages with 6 figures and 3 tables; comments welcomeSubjects: astro-ph.HE astro-ph.SR gr-qcCreated: 2026-08-03; Updated: 2026-08-05; Datestamp: 2026-08-05
Universal relations among macroscopic properties of neutron stars provide a powerful framework to probe their internal structures while minimizing uncertainties associated with the equation of state (EoS). Although such relations have been extensively studied for uniformly rotating stars, their extension to differentially rotating and strongly MAGNETized configurations remains largely unexplored. We systematically investigate equilibrium configurations for a wide range of EoSs, rotation profiles, and MAGNETic field strengths. We establish a generalized quasi-universal relation between the moment of inertia and compactness that remains remarkably insensitive to the underlying EoS across uniformly rotating, differentially rotating, and strongly MAGNETized configurations. For sequences with fixed angular momentum, the normalized moment of inertia exhibits a quasi-universal dependence on compactness, with deviations primarily due to MAGNETic field strength and degree of differential rotation. We derive analytic expressions for these dependencies, enabling a unified phenomenological model applicable over a wide range of stellar configurations. As astrophysical applications, we quantify the systematic bias in MAGNETar luminosity estimates and the rotational kinetic energy of post-merger remnant of GW170817. These results extend quasi-universal relations beyond the standard assumptions of uniform rotation and weak MAGNETization, providing a robust framework for interpreting observations of highly MAGNETized and differentially rotating neutron stars, and enabling more reliable constraints on their astrophysical properties.
[abstract 27 / 38] (score: 2) - Title: Statistical Analysis of Droplet Size Distributions in Liquid-Jet-in-Crossflow AtomizationAuthors: Tom Johny, Bharat Bhatia, Zafar Alam, Ashoke De,Comments:Subjects: physics.flu-dynCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
This study investigates the droplet size distribution (DSD) and atomization characteristics of a liquid JET injected into a crossflow (LJICF) under varied momentum flux ratios, Weber numbers, and flow conditions. Numerical simulations are performed using the validated compressible Volume of Fluid-Lagrangian Particle Tracking (VOF-LPT) coupled framework to capture both the primary and secondary atomization processes. Key parameters, including momentum flux ratio, Weber number, crossflow pressure, and velocity, were analyzed to assess their impact on droplet size characteristics, including Sauter mean diameter (SMD) and standard deviation (STD) in the downstream region. The discrete size distribution of droplets comprising probability density and cumulative distribution reveals a shift toward finer, more uniform droplets under enhanced breakup conditions. The findings emphasize the critical role of aerodynamic forces and instabilities in driving efficient atomization, with higher momentum flux ratios and Weber numbers leading to finer and more uniform droplets. Increased crossflow pressure promotes finer droplet formation but is found to reduce droplet density in the downstream domain due to a confined spray plume, delayed particle conversion, and reduced droplet residence time. The log-normal and Rosin-Rammler distributions effectively capture droplet size trends, with the former closely representing the skewness and tail behavior and the latter accurately representing intermediate and larger droplets. However, both have limitations in replicating sharp peaks and the smallest droplet sizes, respectively.
[abstract 28 / 38] (score: 2) - Title: Quasi-single-stage optimization for advanced stellaratorsAuthors: Guodong Yu, Yidong Xie, Hengqian Liu, Caoxiang Zhu,Comments:Subjects: physics.plasm-phCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Advanced stellarator design requires a balance between plasma performance and the manufacturability of three-dimensional modular coils. In conventional two-stage optimization, the coils required to realize an optimized equilibrium can be limited by engineering feasibility. Here, we develop a quasi-single-stage (QSS) framework that incorporates coil feasibility directly into plasma-boundary optimization. QSS uses the maximum normalized normal-field error, evaluated rapidly from surface currents on a uniformly offset winding surface, as a coil-feasibility surrogate. We apply this method to optimize configurations targeting quasi-axisymmetry, quasi-helical symmetry, quasi-isodynamicity, and a combination of omnigenity with piecewise omnigenity. The QSS-optimized configurations exhibit smoother plasma boundaries and winding surfaces, lower normal-field reconstruction errors, and reduced coil complexity, while preserving favourable MAGNETic-symmetry and transport properties. QSS provides a practical proof-of-principle strategy for co-optimizing plasma physics and coil engineering in stellarator design.
[abstract 29 / 38] (score: 2) - Title: Generation of dense RELATIVISTIC electron beams via vortex LASER-driven self-generated MAGNETic pinchingAuthors: Mingxuan Wei, Fengyu Sun, Zhongpeng Li, Xichen Hu, Huiting Ma, Guangwei Lu, Zhuofan Zhang, Lijie Cui, Qijin Zhang, Mengjiao Wang, Weijun Zhou, Qian Zhao, Wenqing Wei, Yi Xu, Zongxin Zhang, Jiayi Qian, Jiacheng Zhu, Xiaoyan Liang, Min Chen, Wenpeng Wang, Jian-Xing Li, Wenchao Yan, Yuxin Leng, Jie Zhang,Comments:Subjects: physics.plasm-ph physics.acc-phCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
In multi-petawatt LASER plasma accelerators, achieving high-density RELATIVISTIC electron beams is typically accompanied by large transverse divergence, limiting the attainable effective electron density needed for high-flux interaction regimes relevant to laboratory astrophysics. Here we report experimental demonstration of self-generated MAGNETic pinching (SMP), a collective mechanism that actively regulates transverse beam dynamics using a Laguerre-Gaussian LASER at strong RELATIVISTIC intensity (~8 x 10^19 W/cm^2) interacting with an underdense plasma. The electron beam evolves from a two-lobe high-charge injection structure into a compressed, high-density profile, yielding a threefold reduction in divergence and nearly an order-of-magnitude enhancement in effective beam density compared with a Gaussian driver. Particle-in-cell simulations agree with the experimental observations and reveal that a self-generated azimuthal MAGNETic field governs the electron dynamics within the SMP regime, which is defined by the forming condition S = 0.717 l a0 [ne(10^18 cm^-3)]^-3/4 = 1, where l, a0, and ne are topological charge, LASER amplitude, and plasma density, respectively. A transient kick from a dense inner sheath electron population drives collective MAGNETic pinching, transforming an initially separated electron distribution into a compressed and well-collimated beam. For higher-power LASER systems, the forming condition can be extended to higher plasma densities and larger orbital angular momentum modes, potentially enabling electron beams with charges exceeding several nC and effective densities above 10^19 cm^-3. This mechanism provides a route to overcoming transverse expansion and enhancing rare interaction processes relevant to high-flux particle sources.
[abstract 30 / 38] (score: 2) - Title: Electron transport in a radiation-dominated plasma Application to solar corona brighteningsAuthors: Roland Duclous, Vladimir Tikhonchuk, Marina Leboulanger, Xavier Blanc, Allan-Sacha Brun, Antoine Strugarek,Comments:Subjects: astro-ph.SRCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Bremsstrahlung scattering of fast electrons on ions can be enhanced by the microwave radiation present in the solar corona. It can account for the electron diffusive transport along MAGNETic loops and high precipitation rates. This process can also dominate the transport of thermal electrons confined in such loops. The influence of stimulated Bremsstrahlung scattering on the electron transport is studied, with focus on the return current induced by the fast electron population trapped in MAGNETic loops. Overall, transport coefficients are reevaluated in the radiation-dominated plasma, characterized by the stimulated action of radiation on the Bremsstrahlung electron-ion collision, down to thermal velocities. We develop a theoretical framework for electron transport driven by a large bandwidth, bright low-frequency part of the photon spectrum and compute a set of radiation-enhanced transport coefficients. UV, XEUV and hard X-ray signals from flares, evidencing anomalous resistivity, thermal conduction inhibition and high precipitation rates of fast electrons, are reinterpreted. The anomalous resistivity due to stimulated Bremsstrahlung scattering is found to dominate the classical resistivity in flares. The runaway effect due to Coulomb collisions is suppressed. Thermal conduction is inhibited compared to the Spitzer conduction, in agreement with coronal seismology of slow-mode waves. Stimulated Bremsstrahlung scattering is found to be a key collisional process in flaring events. It can explain the above loop-top hard X-ray signal due to the fast electrons, and the measured electrical conductivity due to the thermal electrons. As a perspective, the corresponding transport coefficients can be used in radiation MHD codes. The radiation model could also be applied to stimulate large-angle electron scattering in the kinetic or hybrid models used to study the solar corona.
[abstract 31 / 38] (score: 2) - Title: From Størmer to Schwarzschild: Analytical Dynamics of Charged Particles in a Dipole MagnetosphereAuthors: Francisco S. N. Lobo, Tiberiu Harko,Comments: 29 pages, 2 figuresSubjects: gr-qc astro-ph.HE hep-thCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We investigate the conservative dynamics of RELATIVISTIC charged particles in a Schwarzschild spacetime threaded by an externally supported dipolar MAGNETic field. The gravitational sector is treated exactly in isotropic coordinates, while the electroMAGNETic field is described by the leading asymptotic term of the RELATIVISTIC exterior dipole solution. This formulation provides an analytically tractable RELATIVISTIC extension of the classical Størmer problem and allows the circular-orbit and stability structure to be studied explicitly. For the outward-Lorentz branch, characterized by a positive signed MAGNETic coupling for positive azimuthal motion, we find a non-trivial competition between radial and vertical stability. Weak MAGNETic coupling shifts the radially marginal orbit inward, whereas at stronger coupling vertical instability becomes the limiting mechanism and the inner boundary of stable circular motion moves outward. The associated vertical epicyclic mode progressively softens and vanishes at the vertical stability boundary. The marginally bound sequence exhibits a distinct strong-coupling behaviour, illustrating that energetic and stability boundaries need not evolve together. The radial and vertical epicyclic frequencies also generate characteristic commensurabilities that may provide natural sites for nonlinear orbital coupling. Because the MAGNETic field is treated as a test field, these charged-particle effects leave the vacuum Schwarzschild null-geodesic structure unchanged. Magnetic signatures in compact-object observations must therefore arise through the dynamics and radiation of charged matter, plasma propagation effects, or physics beyond the test-field approximation. The framework developed here provides an analytical basis for studying nonlinear dynamics, radiation reaction, and more realistic compact-object MAGNETospheres.
[abstract 32 / 38] (score: 2) - Title: Generation-Resolved Signatures in QED Cascades: Diagnostics for Ultraintense Laser ParametersAuthors: Ke-Jia Wei, Feng Wan, Hao-Tian Wang, Yan-Xi Wu, He Yuan, Jian-Xing Li,Comments:Subjects: physics.plasm-phCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We present a generation-resolved analysis of shower-type, spin- and POLARIZATION-dependent quantum electrodynamics (QED) cascades initiated by head-on collisions of ultraintense LASER pulses ($a_0 = 200$--$1000$) with $10$~GeV electron bunches. Using a Monte Carlo model that tracks cascade evolution across distinct generations, we shows that radiation reaction strongly suppresses high-generation yields. The positron energy spectrum exhibits a systematic softening with increasing $a_0$, and the average photon POLARIZATION $\overlineξ_3$ increases with pulse duration $τ$ due to POLARIZATION-selective depletion in nonlinear Breit--Wheeler pair production. We identify a scaling relation $a_0^2τ$ that governs both the maximum cascade generation $G_{\max}$ and the fraction of backward-emitted photons $F_r$, thereby establishing experimentally accessible diagnostics for LASER intensity and pulse duration using two observables: $F_r$ and the positron peak energy $\varepsilon_+^{\rm peak}$. These generation-dependent signatures suggest a potential shot-resolved, post-interaction approach for characterization of ultraintense LASER parameters in the strong-field QED regime.
[abstract 33 / 38] (score: 2) - Title: Wave excitation by a collapsing granule: insights from IFU observations and high-resolution RMHD simulationsAuthors: J. Buttler, G. Vigeesh, I. Milić, M. van Noort, S. M. Díaz Castillo, C. J. Díaz Baso, F. Riva, O. Steiner,Comments: 11 pages, 13 figuresSubjects: astro-ph.SRCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Context. Granular collapse is an ubiquitous process of granular evolution on the solar surface, but it is hard to analyze in sufficient spatial, temporal, and spectral detail. Aims. We analyze the change in physical conditions in the photosphere during a specific granular collapse event and the subsequent atmospheric response. Methods. We contrast a high-resolution radiative MAGNETo-hydrodynamic simulation of a granular collapse performed using the CO5BOLD code with the recent integral field unit observations carried out using the MiHI instrument at the Swedish 1-m Solar Telescope. Results. Our analysis shows that the observed and simulated granular collapse show remarkable similarity. Specifically, they both exhibit the signature of a wave pulse excited in the deep photosphere and visible up to the temperature minimum. This wave is detectable through a blue-wing emission in the observed and synthetic Na i D1 line. We also estimate the acoustic energy flux carried by the wave and analyze its initiation. Conclusions. Combining high-resolution IFU spectropolarimetry and state-of-the-art simulations of the solar lower atmosphere, this study showcases our current capabilities in identifying specific physical processes taking place during the granular collapse and their impact on the atmosphere above.
[abstract 34 / 38] (score: 2) - Title: A JWST redshift for the host galaxy of EP250207b of z=3.2: a collapsar origin is viableAuthors: Agnes P. C. van Hoof, Peter G. Jonker, Andrew J. Levan, Nial R. Tanvir, Franz E. Bauer, Joe Bright, Francesco Carotenuto, Ting-Wan Chen, Ashley Chrimes, Gregory Corcoran, Laura Cotter, Joyce N. D. van Dalen, Rob A. J. Eyles-Ferris, Morgan Fraser, Daniele B. Malesani, Daniel Mata Sánchez, Antonio Martin-Carrillo, Paul O'Brien, Francesca Onori, Jonathan Quirola-Vásquez, Maria E. Ravasio, Andrea Rossi, Javi Sánchez-Sierras, Nikhil Sarin, Steve Schulze, Hui Sun, Manuel A. P. Torres,Comments: 7 pages, 6 figures, 1 table. Version submitted to MNRASSubjects: astro-ph.HECreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We present James Webb Space Telescope (JWST) and Hubble Space Telescope (HST) observations of the field of the fast X-ray transient (FXT) detected by Einstein Probe, EP250207b, to resolve any ambiguity about the host galaxy and redshift of the FXT. EP250207b was originally associated with a nearby galaxy at z=0.082, based on its low chance alignment probability, and a binary neutron star merger origin was proposed. However, we report the detection of a background galaxy at z=3.2 at the location of EP250207b. Assuming this galaxy is the actual host galaxy, the rest-frame energetics and timescales of the event change. Furthermore, the available data are not able to rule out the presence of a SUPERNOVA associated with EP250207b if at this redshift. We model the X-ray, optical, near-infrared and radio light curves using a tophat JET model implemented in Redback and find that they are consistent with an on-axis gamma ray burst afterglow. The energetics and host galaxy properties do not allow us to distinguish between a collapsar and a merger driven event.
[abstract 35 / 38] (score: 2) - Title: General-RELATIVISTIC structure of two-component quantum dark fermion starsAuthors: Ilídio Lopes,Comments: 19 pages, 10 figures and 3 tables. Accepted for publication in Physical Review DSubjects: astro-ph.HE astro-ph.GA gr-qc hep-ph hep-thCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
We develop a general-RELATIVISTIC framework for two-component quantum dark fermion stars: equilibrium configurations of two degenerate fermion species governed by gravity, a Yukawa-mediated dark fifth force and a globally relevant Bohm quantum-pressure correction. The treatment retains the full covariant form of the nonlinear Klein--Gordon equation in the Schwarzschild interior, with closure relations valid at arbitrary compactness, from the ultralight baseline up to densities of order $0.16\,\mathrm{fm}^{-3}$ at which RELATIVISTIC scalar densities and self-consistent effective fermion masses become unavoidable. Two Lagrangian parameters, the dark-fermion mass and the dimensionless ratio between the Yukawa channel and gravity, together fix the equilibrium structure; a joint measurement of mass and radius therefore constrains the dark-sector microphysics directly from gravitational-wave observables. For particle masses in the band $10^{-11}$--$10^{-10}$ eV, the configurations exhibit radii of $3$--$24\,\mathrm{km}$ and compactness in the range $0.14$--$0.34$, behaving as dual mimickers: at moderate compactness they overlap with neutron stars in mass, radius, and inspiral frequency; at the most compact end ($κ\sim 0.34$, $R_T/R_S\simeq 1.5$) they cross the photon sphere and could masquerade as low-mass BLACK HOLEs in the mass-gap region. Tidal-deformability measurements discriminate against both populations: the dimensionless tidal deformability is measurably smaller than the neutron-star value yet remains non-zero, unlike that of a genuine BLACK HOLE. These objects populate the sensitivity bands of LISA, the Einstein Telescope, and Cosmic Explorer, producing astrometric microlensing signatures individually resolvable by \textit{Gaia}. The framework thus provides a reproducible and falsifiable template for constraining dark-sector properties through multi-messenger observations.
[abstract 36 / 38] (score: 2) - Title: Iron K$α$ signatures from accretion disks around fermionic DARK MATTER coresAuthors: V. Crespi, F. L. Vieyro, C. R. Argüelles, J. A. Rueda,Comments: Submitted to Astronomy & Astrophysics. Comments are welcomeSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
The fluorescent iron line and its broadening due to RELATIVISTIC effects are excellent probes to study the inner part of an accretion disk and the space-time geometry near the compact object. We investigate the iron K$α$ line profile within the extended RAR model, which describes a fermionic DARK MATTER distribution on galaxy scales. The most general solutions are characterized by a compact and highly degenerate core able to mimic the central BLACK HOLE, transitioning into an extended halo composed of the same particles. We aim to contrast the resulting line morphologies in this scenario with those predicted by the standard Kerr BLACK HOLE paradigm. Special attention will be given to MCG-06-30-15 galaxy. We compute the line profile using the numerical ray-tracing code, Skylight. We consider two distinct configurations for the emissivity of the cold accretion disk: an irradiation profile based on the lamp-post corona prescription, and a phenomenological power-law profile. The resulting profiles exhibit a diverse phenomenology. In particular, the most compact fermion cores produce a line broadening comparable to that observed in rapidly rotating BLACK HOLEs. The presence of emitting matter at radii smaller than a gravitational radius yields distinctive spectral features that are entirely absent in the BLACK HOLE scenario. For MCG-06-30-15 galaxy, we find a good agreement with the observed broad features of the iron line profile, provided the compactness of the fermion core is close to critical. These results reinforce the need for independent BLACK HOLE spin measurements. Combined with such constraints, iron-line spectroscopy may provide a powerful observational tool to distinguish BLACK HOLEs from alternative compact solutions, in particular compact fermionic dark-matter cores.
[abstract 37 / 38] (score: 2) - Title: Probing Axion Like Particle-Proton Interactions through the Interplay of Dark Matter and Cosmic Rays in Large-Scale StructureAuthors: Wen-Qing Guo,Comments: 16 pages, 3 figuresSubjects: astro-ph.HECreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Axion-like particles (ALPs) provide a well-motivated DARK MATTER candidate whose interactions with Standard Model particles may generate observable cosmological signatures. We investigate the diffuse $γ$-ray emission produced by the scattering process between ALP DARK MATTER and cosmic-ray (CR) protons inside DARK MATTER halos, and explore its detectability through the cross-correlation between the unresolved $γ$-ray background (UGRB) measured by \textit{FERMI} Large Area Telescope (LAT) and the Two Micron All Sky Survey Redshift Survey (2MRS) galaxy catalog in the local Universe ($z\leq0.1$). To model the cosmological $\mathrm{GeV}$-$\mathrm{PeV}$ CR proton population, we develop a phenomenological bottom-up prescription that links CR injection to the STAR FORMATION rate through the SUPERNOVA rate, while the steady-state CR density is determined by diffusive escape. Our forecasts indicate that UGRB-galaxy cross-correlation measurements can probe previously unexplored regions of the ALP parameter space over a broad range of ALP masses. More generally, this work presents a general framework for cosmological observables generated by interactions between DARK MATTER and an additional astrophysical field, opening a new avenue for indirect DARK MATTER searches using large-scale structure observations.
[abstract 38 / 38] (score: 2) - Title: First fast radio burst search campaign at the Argentine Institute of Radio AstronomyAuthors: Carlos O. Lousto, Harsh Prajapati, Ezequiel Zubieta, Susana B. Araujo Furlan, Guillermo Gancio, Joaquín Pelle, Gustavo E. Romero, Federico García, Santiago del Palacio, Nathan Cahill,Comments: 8 pages, 2 figuresSubjects: astro-ph.HE astro-ph.IMCreated: 2026-08-04; Updated: 2026-08-05; Datestamp: 2026-08-05
Fast radio bursts (FRBs) are intense millisecond-duration radio transients of extragalactic origin whose physical nature remains under active investigation, and which also serve as probes of the intergalactic medium. We report on the first FRB search campaign carried out at the Argentine Institute of Radio Astronomy (IAR) between December 2024 and March 2026, targeting nearby galaxy superclusters in the southern sky. We observed fields in the Ophiuchus, Shapley, and Sculptor/Phoenix supercluster regions with one of the two 30~m antennas of the IAR, using a ROACH-based backend with 400~MHz of bandwidth centred at 1400~MHz and a time resolution of 41--82~$μ$s, for a total net observing time of 212~h. The data were searched for dispersed single pulses with \texttt{PRESTO} in the dispersion measure range $100 \leq \mathrm{DM} \leq 500$, and candidates were classified with the FETCH machine learning classifier. The pipeline was validated on archival Parkes data containing known FRBs and on synthetic bursts injected into IAR observations. One FRB candidate, FRB~20251018, was identified on 18 October 2025 in an observation pointed towards the galaxy cluster A2870, in the Phoenix supercluster, with a dispersion measure of $243$, a signal-to-noise ratio of 8.2, and a FETCH probability of $p=0.99$. To the best of our knowledge, this would be the first FRB detected from South America. A set of more marginal candidates is also presented. These results demonstrate the capability of the IAR antennas to detect FRBs and support the continuation and extension of the monitoring campaign, including coincident dual-antenna observations and cross-matches with gravitational-wave events and electroMAGNETic transients.
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