Current date: 2026-07-16
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Number of records retrieved: 698
Keyword score statistics
score 9 -- 1 abstracts
score 6 -- 3 abstracts
score 5 -- 2 abstracts
score 4 -- 2 abstracts
score 3 -- 6 abstracts
score 2 -- 12 abstracts
in total -- 26 abstracts
Articles that appeared on 2026-07-16
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[abstract 1 / 26] Wow! (score: 9)
- Title: Time-resolved leptonic modeling of the prompt emission of GRB 211211AAuthors: Maria Petropoulou, Maria Gkoni, Konstantinos Xyloportas, Stamatios I. Stathopoulos, Georgios Vasilopoulos, Apostolos Mastichiadis,Comments: 16 pages, 11 figures, submitted to A&ASubjects: astro-ph.HECreated: 2026-07-14; Updated: 2026-07-16; Datestamp: 2026-07-16
GRB 211211A is a long duration GAMMA-RAY BURST with a compact object merger origin. In this work, we model the time-resolved prompt-emission spectra of GRB 211211A within a leptonic radiation framework. Our goal is to infer the physical properties of the emitting region, study the temporal evolution of the radiating particle distribution, and make predictions for prompt emission at TeV energies. We perform Markov Chain Monte Carlo fitting of the time-resolved numerical spectral energy distribution (SED) models computed with the time-dependent non-thermal radiation code LeHaMoC. Our calculations include SYNCHROTRON emission and self-absorption, inverse Compton scattering including cooling in the Klein-Nishina regime, and photon-photon pair production. We find that the prompt emission of GRB 211211A between 10 keV and 10 MeV can be successfully reproduced by SYNCHROTRON radiation from a population of RELATIVISTIC electrons. The spectral evolution during the first minute of the burst reflects different physical conditions in the emitting region. Our best-fit models favor fast-cooling solutions for the first 8 s, followed by a transition to slow-cooling solutions at later times. The accompanying SYNCHROTRON self-Compton emission extends to TeV energies, with predicted fluxes that would be detectable by CTAO for a burst similar to GRB 211211A, provided a sufficiently rapid response to a FERMI-GBM trigger or if the burst occurs within the CTAO field of view. The observed short variability of this burst requires very high Doppler factors ($\sim1000-2500$) throughout the burst evolution. Such extreme Doppler factors are difficult to reconcile with the JET Lorentz factor inferred from afterglow modeling unless the prompt-emitting regions are themselves moving RELATIVISTICally with respect to the JET plasma.
[abstract 2 / 26] Yes (score: 6) - Title: Self-Consistent Modelling of Neutrino Production in Turbulent Black Hole CoronaeAuthors: Sébastien Le Bihan, Martin Lemoine, Frank Rieger,Comments: 15 pages, 14 figures, accepted by A&A (29 June 2026)Subjects: astro-ph.HECreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
Stochastic particle acceleration in MAGNETized turbulent plasmas has emerged as a key mechanism to explain multi-messenger signals from compact astrophysical environments. Self-consistent modelling remains challenging because it requires to treat simultaneously several non-linear kinetic processes, especially turbulence-driven acceleration and its feedback on the turbulent cascade, as well as the radiative and hadronic losses, including the reprocessing of electroMAGNETic radiation in radiatively dense environments. The present paper introduces the hybrid numerical code Turb-AM3 designed to this effect. This hybrid numerical code couples the state-of-the-art time-dependent lepto-hadronic radiative solver AM3 with a stochastic acceleration module that incorporates recent theoretical advances in turbulent acceleration and accounts for the dynamical damping of turbulence by accelerated particles. In the second part of the paper, we use this code to provide self-consistent time-dependent models of proton acceleration in the turbulent BLACK HOLE corona of NGC~1068. We find that the IceCube neutrino signal is well reproduced for a standard set of physical parameters describing the BLACK HOLE corona. The same template model accounts in a satisfactory way for IceCube observations of other ACTIVE GALACTIC NUCLEi. Furthermore, our exploration of parameter space allows us to predict detailed template spectral shapes for the TeV neutrino spectrum, which in turn help understand how future neutrino observations can constrain the properties of turbulent AGN coronae and the underlying acceleration mechanism. This Turb-AM3 framework provides a powerful tool to model multi-messenger emission in a broad variety of compact astrophysical environments.
[abstract 3 / 26] Yes (score: 6) - Title: Synchrotron Emission from Cooled Particle DistributionsAuthors: Ross Ferguson, Ben Margalit,Comments: Submitted to ApJ. Comments welcome!Subjects: astro-ph.HECreated: 2026-07-14; Updated: 2026-07-16; Datestamp: 2026-07-16
Synchrotron emitting electrons can lose energy (`cool') through various processes including radiative losses (e.g., SYNCHROTRON or inverse-Compton cooling) and adiabatic expansion. Such cooling will shift electrons in energy-space and therefore change the electron distribution function. This in turn alters the nature of SYNCHROTRON emission and absorption from these electrons. In past literature these effects have typically been considered using either simplified one-zone frameworks, or using numerical methods as part of more accurate local modeling. In this work we extend the latter `local' treatment by deriving analytic expressions that are both accurate and more computationally efficient than previous numerical approaches. Considering two concrete cases of injected power-law and thermal electron distribution functions, we derive analytic fitting functions for the resulting emission and absorption coefficients including the effects of cooling. These fitting functions can be applied to SYNCHROTRON afterglow modeling from a variety of astrophysical sources, such as GAMMA-RAY BURSTs (GRBs), luminous fast blue optical transients (LFBOTs), and JETted tidal disruption events (TDEs).
[abstract 4 / 26] Yes (score: 6) - Title: Ion-Scale Current Sheets Embedded in Reconnection Jet Shear Layer of the Near-Sun Heliospheric Current SheetAuthors: Dae-Young Lee, Dooyoung Choi, Kyung-Eun Choi, Sung Jun Noh,Comments: 9 pages, 11 figures, submitted to A&ASubjects: astro-ph.SR physics.plasm-ph physics.space-phCreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
Context. Magnetic RECONNECTion in the heliospheric current sheet (HCS) plays an important role in restructuring the solar wind MAGNETic topology and generating plasma JETs and MAGNETic islands. While large-scale signatures of HCS RECONNECTion have been reported in many observational studies, the kinetic-scale structure embedded within RECONNECTion regions remains less well understood. Aims. We investigate the ion-scale currents sheets (CSs) embedded within an HCS RECONNECTion region and their relationship to the flow-shear layer at the edge of a RECONNECTion JET. Methods. We analyzed an HCS crossing observed by the Parker Solar Probe on March 29, 2024, using high-time-resolution MAGNETic field measurements. We focused on ion-scale MAGNETic transitions within two brief intervals of flow-shear layer at the edges of the RECONNECTion JET and examined them in a local LMN coordinate system. Results. Twelve representative CSs are identified, whose duration is on average $\sim$0.06 sec, corresponding to spatial scales of only a few ion inertial lengths. They are classified into three types based on the behavior of the out-of-plane MAGNETic component $B_{M}$: (1) CSs showing clear bipolar $B_{M}$ variations without bifurcation in RECONNECTing-field ($B_{L}$), (2) CSs with both bipolar $B_{M}$ variations and bifurcated $B_{L}$ profiles characterized by a plateau structure, and (3) CSs where strong fluctuations obscure an otherwise expected bipolar signature. Conclusions. The RECONNECTion JET shear layer in the HCS may serve as an active site that hosts a chain of ion-scale CSs. This provides new insight into the multiscale structure of HCS RECONNECTion and suggests that flow shear layers may play an important role in generating secondary kinetic-scale structures.
[abstract 5 / 26] Yes (score: 5) - Title: Variability of the X-ray obscuring wind in Mrk 335 with XMM-Newton/RGSAuthors: Daniele Rogantini, Erin Kara, Luigi Gallo, S Komossa, Peter Kosec, Christos Panagiotou, Dan Wilkins, Ehud Behar, Joheen Chakraborty, Dirk Grupe, Missagh Mehdipour, Ciro Pinto, Irina Zhuravleva,Comments: 11 Figures, 4 Tables, Accepted in ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-07-14; Updated: 2026-07-16; Datestamp: 2026-07-16
Transient X-ray obscuration in Seyfert 1 galaxies likely arises from clumpy accretion-disk winds near the broad-line region (BLR), but the wind structure and short-timescale variability are difficult to measure because high-resolution spectra are often suppressed during deep low states. We analyse a coordinated XMM-Newton/NUSTAR campaign on Mrk 335 in June 2021, with long-term SWIFT monitoring, capturing the source in an intermediate-flux state with strong RGS absorption features. We model the broadband SED to determine the ionising continuum for self-consistent photoionisation modelling of the RGS spectra. The stacked RGS spectrum requires three photoionised absorbers with log xi ~ 3.69, 2.97, and 1.91, outflowing at |v_out| ~ 5800, 3200, and 2100 km/s, respectively. Their properties are consistent with the three-phase obscurer reported in 2009, indicating that a similar multi-phase obscuring wind can persist over decade timescales. Using five consecutive RGS observations, we track the wind evolution on day timescales and find strong variability in column density and ionisation in all phases, together with smaller but coherent velocity changes. During a flare, the low-ionisation phase shows a significant drop in opacity, while in the subsequent epoch all phases show increased outflow velocities, suggesting a possible connection between continuum variability and changes in the line-of-sight absorber. The high-ionisation phase responds most directly to changes in ionising luminosity, while the lowest-ionisation phase shows at most a delayed response. Order-of-magnitude constraints place the obscurer at BLR scales, ~10^3-10^5 Rg, with kinetic power potentially reaching the percent level of L_bol for plausible assumptions on geometry and clumpiness.
[abstract 6 / 26] Yes (score: 5) - Title: Assessing the sensitivity to Axion-Like-Particle Dark Matter with very-high-energy gamma-ray observations of selected AGN and galaxy cluster pairsAuthors: Cervane Grimaud, Denys Malyshev, Emmanuel Moulin,Comments: 5 pages, 3 figures. Contribution to the 2026 VHEPU session of the 60th Rencontres de MoriondSubjects: astro-ph.HE astro-ph.CO hep-phCreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
Axion-Like-Particles (ALPs) are pseudo-scalar particles actively searched as light DARK MATTER candidates. ALPs can couple to photons which give rise to the possibility of oscillations with photons in an external MAGNETic field. If sufficiently strong, this coupling can imprint distinctive spectral irregularities in the gamma ray spectrum of astrophysical sources. We present a prospective study on the sensitivity of probing ALP-photon interactions using stacked observations of selected ACTIVE GALACTIC NUCLEi (AGNs) located behind galaxy clusters. The ALP-photon conversion in cluster MAGNETic fields produces absorption-like features in AGN spectra that are difficult to predict for individual sources. To address this, we apply a stacking analysis of multiple AGN-cluster pairs, yielding a controlled prediction of the expected ALP induced spectral patterns and enhancing the sensitivity to such irregularities. Using simulated data for selected hard-spectrum FERMI/LAT AGNs that can be observed by Imaging Atmospheric Cherenkov Telescopes such as H.E.S.S., we evaluate the performance of this method. The combination of mock IACT observations with our stacking approach enable exploration of the previously uncharted ALP DARK MATTER parameter space in the neV mass range.
[abstract 7 / 26] Yes (score: 4) - Title: Fe K$α$ line from the Broad Line Region of PDS456 with XRISM/ResolveAuthors: Alfredo Luminari, Fabrizio Nicastro, Stefano Bianchi, Elias Kammoun,Comments: A&A Letter, accepted. 3 Figures, 4 main pagesSubjects: astro-ph.HECreated: 2026-07-14; Updated: 2026-07-16; Datestamp: 2026-07-16
The high-luminosity, high-mass and likely super-Eddington QUASAR PDS 456 is known for its extremely dynamic environment. A wealth of observational features from the millimetric up to the X-ray band shows energetic outflows at all scales, from accretion disc up to galaxy scales. Broad Emission Lines in the optical and UV show significant widths and line-of-sight velocities. Moreover, NIR interferometry revealed a partially outflowing Broad Line Region. Thanks to the unprecedented energy resolution of the X-ray microcalorimeter Resolve onboard XRISM, we detect a neutral Fe K$α$ line, the main tracer of cold matter around AGNs. The line blueshift ($v_{\rm out}=2700$ km s$^{-1}$) and width ($σ\leq 700$ km s$^{-1}$) are on the lower bound of the range of values of the optical-UV emission lines, possibly suggesting a stratified medium. The derived column density, $N_{\rm H} \approx 10^{22}$ cm$^{-2}$, is significantly lower than what expected for Broad Line Regions, again in agreement with a composite emission. The very small Equivalent Width (9 eV) marks one of the smallest measurements in the literature and probes the high-luminosity end of the so-called Iwasawa-Taniguchi (or X-ray Baldwin) effect.
[abstract 8 / 26] Yes (score: 4) - Title: Inverse Transfer in Non-helical 2D Collisionless Magnetic Turbulence: Island-Merger Picture with Kinetic EffectsAuthors: Yangyang Cai, Hongzhe Zhou, Yosuke Mizuno,Comments: 13 pages, 11 figures, 1 tableSubjects: astro-ph.HECreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
Magnetic inverse transfer is often invoked to connect small-scale MAGNETic-field generation to larger coherence scales in high-energy and cosmological plasmas. The underlying MAGNETohydrodynamic (MHD) arguments combine two logically distinct ingredients: a bulk quantity that is asymptotically conserved in the limit of small resistivity, and a time scale determined by the decay dynamics. In this work, we explore whether this scenario still holds in decaying nonhelical turbulence formed by collisionless plasmas using particle-in-cell simulations. The simulations approximately satisfy $B^2ξ_B^2\simeq{\rm const}$ as in the MHD case, and the fitted exponents in $B^2\propto t^{-p}$ and $ξ_B\propto t^q$ obey $p\simeq2q$. Here $B^2\equiv\langle B_x^2+B_y^2\rangle$ is the average in-plane MAGNETic energy density, and $ξ_b$ is the MAGNETic integral scale. However, the decay time scale differs from the MHD case as inferred from the decay exponents. We found $p<1$ and $q<1/2$ in all cases with different initial MAGNETization $σ_0$, with both exponents lower than the MHD values and varying systematically with $σ_0$. The spectral peak also migrates toward lower wavenumber at a rate faster than the growth of $ξ_B$, indicating a broken self-similarity. The broken self-similarity is attributed to the appearance of kinetic scales in the MAGNETic energy spectrum due to pressure anisotropy and Larmor-scale MAGNETic structures. These results indicate that in astrophysical collisionless plasmas, including but not restrict to solar wind, pulsar-wind nebulae, interstellar medium, and cosmological plasmas, MAGNETic coherence can continue to grow by inverse transfer, but extrapolations based on MHD decay-time scaling can overestimate the rate of large-scale field growth.
[abstract 9 / 26] (score: 3) - Title: Tidal disruption event rates across cosmic time: forecasts for LSST, Roman, and JWST and their constraints on the supermassive BLACK HOLE mass functionAuthors: Mitchell Karmen, Suvi Gezari, Colin Norman, Muryel Guolo,Comments: Published in ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-07-14; Updated: 2026-07-16; Datestamp: 2026-07-16
Measuring the mass distribution of supermassive BLACK HOLEs (SMBHs) over cosmic time remains particularly challenging for the low mass (M_BH<10^8 M_sun) population at z>1. This population is also the most sensitive to SMBH seeding and early growth models. In this work we construct a semi-empirical model for the redshift evolution of the TDE rate under multiple SMBH mass function prescriptions, and show that the observed redshift-dependent rate of TDEs is very sensitive to the SMBH mass function and its evolution with redshift. We further incorporate galaxy-scale processes that evolve with redshift -- namely, increasing galaxy nuclear stellar densities, enhanced galaxy-galaxy merger rates, dust obscuration, and a possible top-heavy IMF at early cosmic times -- and quantify their combined impact on the TDE rate. We find that including these effects generally results in a volumetric TDE rate that increases with redshift until a maximum near cosmic noon, before declining at higher redshift where SMBHs that can disrupt stars become increasingly scarce. We forecast TDE rates in the Rubin LSST and the Roman High Latitude Time Domain Survey, alongside expectations for serendipitous TDE rates in the JWST COSMOS-Web survey. Finally, we provide a methodology for using a flux-limited survey of TDEs in LSST to directly constrain the redshift evolution of the SMBH mass function.
[abstract 10 / 26] (score: 3) - Title: Effect of Neutron Star Jets on Common Envelope EvolutionAuthors: Deepanshu Gurjar, Luke Chamandy, Eric G. Blackman, Yangyuxin Zou, Baowei Liu, Jason Nordhaus,Comments: 11 pages, 8 figures, 1 table, submitted to ApJSubjects: astro-ph.SR astro-ph.HECreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
The common envelope (CE) phase is a key stage in binary star evolution that is still not very well understood. Once engulfed by the giant star, the binary companion may accrete envelope material. For neutron star (NS) companions, such accretion may in principle occur at mass rates several orders of magnitude above the Eddington limit and may result in outflows dominated by powerful bi-polar JETs with mass-loss rates similar to the accretion rates. Such JETs would impact the morphology of the system and the rate of envelope unbinding, which affect the duration and outcome of the CE event. Employing 3D global hydrodynamic simulations, we study the role of such NS JETs in a CE event involving a red giant branch star. The JETs eventually drill through and break out of the envelope, producing prominent low-density bi-polar lobes. The JETs cause about twice as much envelope mass to be unbound as compared to simulations of the same duration without NS JETs. However, the rate of mass unbinding due to the JETs decreases towards the ends of the simulations as the JETs break out and energetically decouple from the envelope. Moreover, JET activity leads to slightly reduced drag on the binary, decreasing the rate of orbital energy transfer to the envelope. Hence, while such powerful JETs can play an important role, negative feedback effects tend to prevent them from dominating envelope unbinding and dictating CE outcomes.
[abstract 11 / 26] (score: 3) - Title: Here, There and Everywhere: How AGN JETs affect galaxy cluster environmentsAuthors: Isaac Rosenberg, Martine Lokken, Renée Hložek, Weiguang Cui, Sara Santoni, Romeel Davé,Comments: 17 pages, 11 figures, to be submitted to A&A. Comments welcomeSubjects: astro-ph.CO astro-ph.GACreated: 2026-07-14; Updated: 2026-07-16; Datestamp: 2026-07-16
Active galactic nuclei (AGN) feedback via BLACK HOLE-driven JETs and winds plays a key role in redistributing matter across megaparsec scales. However, the implementation of JET feedback in cosmological simulations remains highly prescriptive, leading to uncertainties in the predicted state of the Warm-Hot Intergalactic Medium and other extragalactic observables. We investigate how variations in AGN JET velocity, orientation, and delayed hydrodynamic coupling impact the thermodynamic state of gas surrounding galaxy clusters. We aim to identify observational signatures in the thermal Sunyaev-Zel'dovich (tSZ) effect and galaxy properties that can constrain these models. We employ zoom-in hydrodynamic simulations centered on three galaxy clusters from The Three Hundred, utilizing the SIMBA-C model and various feedback parameters. We use filament-finding algorithms and oriented stacking to probe the effect on large-scale structure and compare our results to observational data for brightest cluster galaxies from eRASS1, BLACK HOLE-halo mass relations and baryonic mass fractions. Jet velocity is the dominant tested parameter in heating low-density environments at $z > 1$. At lower-$z$, higher velocity JETs quench STAR FORMATION, expel baryonic matter, and prevent BLACK HOLE growth. While the tSZ signal within the central cluster and surrounding filaments is only affected by $\sim10\%$, the signal in under-dense regions outside filaments is enhanced by $\sim100\%$. In this case study, high velocity AGN JETs provide the best match to galaxy properties from eRASS1 and other X-ray surveys. We find that hot gas in low-density regimes is a sensitive probe of AGN feedback. Future high-resolution tSZ surveys like the Simons Observatory and spectral-distortion experiments like FOSSIL have the potential to probe the thermal state of the gas outside clusters to distinguish between these feedback models.
[abstract 12 / 26] (score: 3) - Title: Dynamics in Nuclear Stellar Clusters: The Impact of Collisions and Disrupted BinariesAuthors: Barak Rom, Re'em Sari,Comments: 16 pages, 5 figures. Accepted for publication in ApJLSubjects: astro-ph.GA astro-ph.HECreated: 2026-07-14; Updated: 2026-07-16; Datestamp: 2026-07-16
The nuclear stellar clusters surrounding supermassive BLACK HOLEs (SMBHs) host millions of stars and stellar remnants. We study how stellar collisions and binary disruptions, alongside two-body scattering and gravitational-wave (GW) emission, shape the stellar distribution and regulate the abundance of stars on tightly bound orbits. We show the following. (a) Stars in the inner region of the cluster follow a steady-state density profile scaling as $n(r)\propto r^{-5/4}$, set by the balance between collisional depletion and binary replenishment. This profile is largely independent of whether two-body scattering or GW emission drives the orbital evolution prior to the collisions. (b) For SMBHs with $M\lesssim2 \times 10^7 M_\odot$, roughly half of the stars injected by the Hills mechanism eventually collide. The rest are tidally disrupted while on orbits with periods of order months to years. (c) For more massive SMBHs, these short-orbital-period tidal disruption events are suppressed, and most injected stars are ultimately destroyed by collisions. (d) Stellar extreme-mass-ratio inspirals (sEMRIs) can form around SMBHs with $M\gtrsim2\times10^6 M_\odot$, but are typically terminated by collisions before circularizing. Our model highlights the dynamical challenge stellar collisions pose for the formation of sEMRIs and, consequently, for stellar models of quasiperiodic eruptions. Applied to the Galactic Center, the collision-regulated density profile is consistent with the observed stellar distribution slope. Based on this profile, we estimate the stellar mass within the orbit of S2, finding it consistent with the observational upper limit, account for the recently discovered star S301, predict that most stars near Sgr$~{\rm A}^*$ follow eccentric orbits, and determine their typical eccentricities.
[abstract 13 / 26] (score: 3) - Title: DARK-HIDE: Dark matter versus hidden dimensions in BLACK HOLE imagesAuthors: Mohsen Fathi,Comments: 12 pages, 10 figures, 1 tableSubjects: gr-qc astro-ph.HECreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
Dark matter near a BLACK HOLE and effective extra-dimensional corrections can change the same horizon-scale observables. This creates a simple but important question: if an image differs from Kerr, what caused the difference? We study this problem with DARK-HIDE. The dark-matter branch is described by rotating metrics with radial mass functions, while the hidden-dimensional branch is a rotating braneworld metric with a non-electroMAGNETic tidal charge. We compare photon regions, critical curves, controlled image morphology, a shadow-size likelihood calibrated to EHT results, and local ZAMO escape cones. A strong negative tidal charge is easy to separate from Kerr and from the two benchmark dark-matter profiles. The difficult case appears after the tidal charge is continuously adjusted to mimic the dark-matter critical curve and image proxy. At $\varepsilon/M=0.025$, the best $P+I$ mimics occur at $q/M^2=-0.01917$ for Einasto and $-0.01117$ for cored cNFW, with small standardized separations of $0.084$ and $0.051$. A ray-bundle caustic test does not pass the required convergence and topology checks, so it is excluded from inference. After marginalizing over spin and isotropic inclination, current EHT shadow-size constraints leave both dark-matter amplitudes prior dominated. They mildly suppress large negative tidal charge, but remain fully compatible with $q=0$. Local escape cones retain a small, smooth, and well-resolved difference between the matched branches. Thus, present shadow size alone cannot break the DARK-HIDE degeneracy, while local photon transport keeps additional strong-field information.
[abstract 14 / 26] (score: 3) - Title: Observational Evidence for Counter-helicity Magnetic Reconnection in a Solar EruptionAuthors: Jinrui Chang, Yi Bi, Bo Yang, Junchao Hong, Jiayan Yang, Qingmei Wang,Comments: Accepted for publication in The Astrophysical JournalSubjects: astro-ph.SRCreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
Magnetic RECONNECTion between coronal MAGNETic systems carrying opposite self-helicity may play a role in solar eruptions, but observational evidence remains limited. We investigate an M7.0 flare in NOAA Active Region 13615 on 2024 March 28 using multiwavelength observations and nonlinear force-free field extrapolations. The reconstructed coronal field reveals a low-lying positive-helicity core field beneath an overlying MAGNETic system of opposite sign. During the eruption, the footpoint connectivity of these two MAGNETic systems changes markedly: field lines rooted in the western footpoint region change from positive to negative helicity, and the positive-helicity domain is substantially reduced. These changes are accompanied by a remote chromospheric brightening, intermittent EUV stripe-like brightenings extending from the source region toward the remote chromospheric brightening, the subsequent formation of large-scale coronal loops, and a weak outer hard X-ray source located at a footpoint of the core field. Together, these results suggest that the eruption was closely associated with RECONNECTion between the core field and the overlying counter-helicity system, providing observational evidence that counter-helicity RECONNECTion can contribute to the destabilization of eruptive solar MAGNETic fields.
[abstract 15 / 26] (score: 2) - Title: Stellar-like Galactic center excess challenges particle DARK MATTERAuthors: Silvia Manconi, Christopher Eckner, Francesca Calore, Fiorenza Donato,Comments: v2: matches version accepted in PRD. Description of the methods and discussion extended, results unchangedSubjects: hep-ph astro-ph.HECreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
The Galactic Center (GC) is potentially hosting the largest indirect signal from particle DARK MATTER (DM), which in many well-motivated models would produce gamma rays as their final states. However, this region has often been dismissed for DM studies because of the evidence for an unexpected gamma-ray component over astrophysical backgrounds at GeV energies, firstly discovered in the data of the \textit{FERMI} Large Area Telescope (LAT), the so-called Galactic Center Excess (GCE). While this was initially considered to hint at GeV thermal relics, recent work supports a GCE interpretation in terms of a stellar population of millisecond pulsar-like sources in the Galactic bulge. Building on this preference, we re-evaluate the GC as a powerful target for indirect DM searches via gamma rays. This is achieved by combining adaptive template fitting and photon-count statistical methods to assess the role of sub-threshold point sources in the observed \textit{FERMI}-LAT gamma-ray counts, while minimizing the mismodeling of Galactic diffuse emission backgrounds. In a fully self-consistent way, the gamma-ray data are fitted with a mixed model comprising a DM signal and a stellar bulge, both potentially contributing to the GCE. The space left for signals from weak-scale DM particle annihilations is quantified by extracting 95\% C.L. upper limits on the annihilation cross section, which, depending on the DM density profile, result in stringent limits for masses $\lesssim 300$ GeV. The robustness of our results is supported by tests on simulated data.
[abstract 16 / 26] (score: 2) - Title: OzDES Reverberation Mapping Program: CIV lags from six years of dataAuthors: A. Penton, H. McDougall, T. M. Davis, Z. Yu, U. Malik, P. Martini, B. E. Tucker, C. Lidman, G. F. Lewis, R. Sharp, M. Aguena, S. Allam, F. Andrade-Oliveira, J. Asorey, D. Bacon, S. Bocquet, D. Brooks, R. Camilleri, A. Carnero Rosell, D. Carollo, A. Carr, J. Carretero, T. Y. Cheng, L. N. da Costa, M. E. da Silva Pereira, J. De Vicente, S. Desai, S. Everett, J. García-Bellido, K. Glazebrook, D. Gruen, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, K. Kuehn, O. Lahav, S. Lee, M. March, J. L. Marshall, J. Mena-Fernández, R. Miquel, J. Myles, R. L. C. Ogando, A. A. Plazas Malagón, A. Porredon, M. Rodriguez-Monroy, A. K. Romer, E. Sanchez, D. Sanchez Cid, M. Smith, E. Suchyta, M. E. C. Swanson, V. Vikram, N. Weaverdyck,Comments: 12 pages, 8 figures; see also companion paper McDougall et al; v2 is the version accepted for publication in PASA including some figure updates and data links availableSubjects: astro-ph.GACreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
We present 29 successfully recovered CIV time lags in Active Galactic Nuclei from the complete Dark Energy Survey Reverberation Mapping campaign. The AGN in this sample span a redshift range of 1.9
[abstract 17 / 26] (score: 2) - Title: Waveforms and Fluxes of Generic Extreme-Mass-Ratio Inspirals with a Spinning SecondaryAuthors: Qiuxin Cui, Wen-Biao Han,Comments:Subjects: astro-ph.HE gr-qcCreated: 2026-07-14; Updated: 2026-07-16; Datestamp: 2026-07-16
Extreme mass-ratio inspirals (EMRIs), comprising a stellar-mass compact object (CO) orbiting a supermassive BLACK HOLE (BH), are key targets for future space-based gravitational-wave (GW) observatories. Incorporating the spin of the secondary body into waveform models not only enhances measurement precision but also offers insight into the spin distribution of stellar-mass COs. In this work, we construct the flux and waveform for an EMRI with a spinning secondary in a Kerr background under the linear-spin approximation. Using the radiative prescription (half-retarded minus half-advanced field), we calculate orbit-averaged fluxes for the fundamental constants of motion, including the energy, angular momentum, and the Carter-like constant. This framework provides a tractable route to generating waveforms that incorporate the secondary spin.
[abstract 18 / 26] (score: 2) - Title: Constraints on primordial BLACK HOLEs from the first part of LIGO-Virgo-KAGRA fourth observing runAuthors: M. Andrés-Carcasona, A. J. Iovino, E. Vallejo-Pagès, V. Vaskonen, H. Veermäe, M. Martínez, Ll. M. Mir,Comments:Subjects: astro-ph.CO astro-ph.HE gr-qcCreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
We analyse primordial BLACK HOLE (PBH) populations using state-of-the-art modelling of PBH binaries, deriving the strongest bounds on PBH abundance in the $0.6$-$100\,M_\odot$ range from LIGO-Virgo-KAGRA O4a data and demonstrating sensitivity in the $10^{-4}$-$10^4\,M_\odot$ range, for both monochromatic and log-normal mass functions. The constraints are dominated by resolvable PBH mergers, while the associated gravitational wave background provides complementary but weaker limits. To obtain limits that are agnostic about the astrophysical BLACK HOLE (ABH) population, we devise two new methods, data-driven methods for statistical inference on scenarios in which PBHs account for a subset of the catalogued events. Allowing for this possibility relaxes slightly the bounds in the solar mass range $2$-$20\, M_\odot$. Our bounds are independent of the assumptions about the astrophysical BLACK HOLEs population and represent the most stringent constraints on the PBH abundance in the solar mass range to date.
[abstract 19 / 26] (score: 2) - Title: Pitch-Angle Scattering of Cosmic Rays: Confronting Theory with ObservationsAuthors: Huirong Yan, Siqi Zhao, Ming Zhang,Comments: 9 pages, 4 figures, accepted in The Astrophysical Journal Letters (ApJL)Subjects: astro-ph.HE astro-ph.SRCreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
Cosmic ray (CR) propagation is controlled by scattering in turbulent MAGNETic fields in space. In general, diffusive propagation is governed by pitch-angle diffusion in phase space. In this study, pitch-angle diffusion in the local interstellar medium (LISM) deduced from the analysis of the CR small-scale anisotropy data from the Tibet AS$γ$ experiment is compared with theoretical predictions. While it is difficult to reconcile the inferred LISM pitch angle diffusion coefficient with conventional theoretical results of particle scattering by Alfvénic turbulence, we find remarkable agreement with the predictions of particle scattering by quasi-slab fast modes whose properties are shaped by damping in the warm ionized medium. These findings offer direct evidence that CR scattering is predominantly governed by fast-mode turbulence. Furthermore, the comparison between experimental and theoretical results imposes strong constraints on plasma and MAGNETic field parameters within the local bubble, indicating that the LISM is in a low $β$ condition. The turbulence in the LISM should be compressible with an amplitude in the range of $0.3\lesssim δB/B_0 <1$.
[abstract 20 / 26] (score: 2) - Title: A Multi-Wavelength View of the First Type Ic-BL Supernova with an Einstein Probe X-ray Shock BreakoutAuthors: Jillian C. Rastinejad, Gokul Srinivasaragavan, Nikhil Sarin, Tanner O'Dwyer, S. Bradley Cenko, James K. Leung, Anya E. Nugent, Daniel A. Perley, Genevieve Schroeder, Shreya Anand, Tomas Ahumada, Igor Andreoni, Aleksandra Bochenek, Alessandra Corsi, Christoffer Fremling, Anna Y. Q. Ho, Mansi M. Kasliwal, Geoffrey Mo, Anirudh Salgundi, Kendall I. Sippy, J. Sollerman, Eric C. Bellm, Tracy X. Chen, Michael W. Coughlin, Michael C. Davis, Fabio De Colle, Danielle Frostig, Christopher L. Fryer, Michael J. Graham, Xander J. Hall, K. -R. Hinds, Luca Izzo, Wynn Jacobson-Galan, Nathan P. Lourie, Keiichi Maeda, Josiah Purdum, Ben Rusholme, Avinash Singh, Robert Stein,Comments: Version accepted to ApJL with minor changesSubjects: astro-ph.HECreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
In March 2026, the Einstein Probe (EP) discovered its most nearby (z = 0.0343) Fast X-ray Transient (FXT), EP260321a, the first EP FXT to provide a strong match to expectations for X-ray "shock breakout'" (SBO) emission. Here, we present our multi-wavelength follow-up campaign of EP260321a and its broad-line Type Ic (Ic-BL) SUPERNOVA (SN) counterpart, SN2026gzf. We show that our radio follow-up extending over 5.8 - 54.5 days post-FXT rules out an on-axis JET counterpart of isotropic-equivalent kinetic energy $E_{K} \gtrsim 10^{49}$ erg for circumburst densities $n > 10^{-2}~{\rm cm}^{-3}$ and assuming microphysical parameters $ε_e = ε_B = 0.1$. Our radio data also constrains a median mass-loss rate of $\dot{M} \lesssim 1.2 \times 10^{-5} M_{\odot}~{\rm yr}^{-1}$ for a Wolf-Rayet progenitor. In addition, we derive SN2026gzf's properties, including $^{56}$Ni mass, diffusion timescale, and expansion velocities, from our $\sim$nightly-cadence optical data and compare them with those of optically discovered Type Ic-BL SNe, finding that SN 2026gzf is well within the 90\% confidence interval across all properties. We further fit SN2026gzf's light curve and determine that combined emission from both interaction with CSM and $^{56}$Ni radioactive decay provides the best fit with plausible model parameters. Finally, using the rate of Ic-BL SNe from the ZTF Bright Transient Survey and assuming all Type Ic-BL SNe produce EP260321a-like FXTs, we infer an expected rate of EP-detected SBOs of 4.4 - 16 year$^{-1}$. This is inconsistent at the 90% confidence level with current EP detection rates, potentially indicating that most Type Ic-BL SNe produce less luminous X-ray SBO signals compared to EP260321a.
[abstract 21 / 26] (score: 2) - Title: Assessing the large-scale angular clustering of UNIONS Lyman Break Galaxies via cross-correlationsAuthors: Constantin Payerne, Christophe Yèche, William d'Assignies Doumerg, Hendrik Hildebrandt, Martin Kilbinger, Calum Murray, Thomas de Boer, Kenneth C. Chambers, Scott Chapman, Alan W. McConnachie,Comments: 20 pages, 19 figures, to be submitted to The Open Journal of AstrophysicsSubjects: astro-ph.COCreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
Lyman-break galaxies (LBGs), selected via the strong spectral break blueward of the Lyman limit, are powerful tracers of large-scale structure at redshifts $z>2$. In this work, we assess the feasibility of using LBGs selected from the Ultraviolet Near Infrared Optical Northern Survey (UNIONS) multi-band photometric catalog as cosmological probes of the high-redshift Universe using two-point statistics. We demonstrate that spatially varying imaging systematics, driven by variations in PSF depth, seeing across the UNIONS footprint, limit robust measurements of the LBG auto-angular power spectrum on large scales, even after correcting the LBG field with linear or non-linear mitigation techniques. This study shows that clustering analyses of faint galaxy samples close to survey depth are challenging. We therefore turn to cross-correlation measurements with external tracers, in particular the \textit{Planck} CMB lensing convergence and QUASARs from DESI DR1 and \textit{Quaia}, which are less sensitive to the angular imaging systematics. Using both data and mock catalogues, we demonstrate that the LBG--CMB lensing cross-power spectrum can be measured more robustly than the auto-spectrum, with an amplitude consistent with theoretical predictions. Residual systematics primarily manifest as excess variance at large angular scales, without introducing a significant bias in the recovered signal. Taken together, these results establish UNIONS-selected LBGs as reliable tracers for cross-correlation cosmology at $z\sim 2.5$, and highlight cross-correlation techniques as a powerful and robust avenue for extracting cosmological information from photometric high-redshift galaxy samples in the presence of complex imaging systematics.
[abstract 22 / 26] (score: 2) - Title: Post-Newtonian N-Body Dynamics in Extended Theories of GravityAuthors: Antonio Tedesco,Comments: 19 pages; accepted for publication in The European Physical Journal C. This replacement only fixes the automatic LaTeX title-page date to July 12, 2026; no scientific content or body text has been changed. This replacement does not correspond to a revised scientific versionSubjects: gr-qcCreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
We derive the complete first post-Newtonian (1PN) Lagrangian and corresponding equations of motion for the RELATIVISTIC $N$-body system in Scalar-Tensor-Fourth-Order Gravity (STFOG), including the Non-Commutative Spectral Geometry (NCSG) sector as a special case. In the regime $Φ\sim Ψ$ ($γ\sim 1$), the linearized fourth-order field equations are solved in the Standard Post-Newtonian gauge, and the variational Lagrangian is built directly from the point-particle action. The resulting dynamics is governed by three Yukawa functions $ζ$, $\mathcal{W}$ and $Ξ$, which encode the scalar, gravitoMAGNETic and three-body sectors and depend on the effective masses $(m_R,m_Y,m_ϕ)$ of the additional propagating modes. In this context, we show that the nonlinear metric component ${}^{(4)}\!g_{00}$ plays no role at 1PN level. The 1PN orbital motion of the above extended theories is thus obtained in closed form, and the Einstein--Infeld--Hoffmann equations are recovered in the corresponding general-RELATIVISTIC limit. The formalism provides a common framework for the RELATIVISTIC celestial mechanics of the Solar System, binary pulsars such as PSR J0737-3039, Galactic-center stellar orbits and triple systems.
[abstract 23 / 26] (score: 2) - Title: Semi-supervised morphological classification of fast radio bursts from the second CHIME/FRB catalogueAuthors: Bo Lin Fan, Renée Hložek, Antonio Herrera Martin,Comments: 18 pages + 4 supplementary, 10 figures + 2 supplementarySubjects: astro-ph.HE astro-ph.COCreated: 2026-07-14; Updated: 2026-07-16; Datestamp: 2026-07-16
Understanding the morphology of fast radio bursts (FRB), and whether all sources repeat, are key challenges that are becoming more tractable given the increase in data from surveys such as the Canadian Hydrogen Intensity Mapping Experiment FRB project (CHIME/FRB). We present a Convolutional Autoencoder unsupervised classifier for separating the CHIME/FRB data into morphological classes. This data-driven approach is more reproducible than visual inspection, since groupings are learned from the data itself and not subject to differences between expert annotations. While most bursts occupy a similar area of morphological parameter space, we identify three classes of bursts separate from the general FRB population. While one class contains bursts with short bandwidth, and downward-drifting sub-burst structure, the characteristic bursts of other classes have very short temporal width, and occupy the entire CHIME observing band. We identify two distinct subgroups of temporally short, simple broadband bursts; one with minimal scattering and the other with higher scattering. As an additional output of our classifier, we provide a binary FRB repeatability classification, and train the classifications on simulations that mimic the first FRB catalogue from CHIME/FRB. We are able to correctly identify 86$\%$ of repeater bursts. We find that our approach is able to independently recover the downward linear drifting burst morphologies previously defined through visually inspection. Overall, we find that although there exists FRB subgroups with higher or lower proportion of repeaters, there is substantial overlap between the morphological properties of repeaters and one-off bursts consistent with previous studies.
[abstract 24 / 26] (score: 2) - Title: Towards a joint X-ray and gamma-ray analysis of Pulsar Wind Nebulae with GammapyAuthors: Katharina Egg, Alison M. W. Mitchell,Comments: 6 pages, 3 figures. Proceedings of the 8th Heidelberg International Symposium on High-Energy Gamma-Ray Astronomy (γ-2024)Subjects: astro-ph.HE astro-ph.IMCreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
For detailed studies of Pulsar Wind Nebulae (PWNe), objects that show photon emission across the entire electroMAGNETic spectrum, multiwavelength analyses are crucial. The comparison of especially X-ray and gamma-ray emission and their angular sizes can help us to constrain the properties of PWNe, such as their particle transport mechanism or their potential for the acceleration of hadronic particles. In this vein, we are working towards a joint analysis of eROSITA X-ray data and H.E.S.S. gamma-ray data. To enable this, eROSITA data is adapted into the framework of Gammapy, a Python package for gamma-ray analysis through a multi-step process of adapting the formats of not only the photon event list, but also all X-ray response functions, into open data formats compatible with Gammapy. This is accomplished using newly developed Python converter functions. In this contribution we present the first eROSITA maps of the PWN MSH 15-52 in Gammapy, compared to the associated H.E.S.S. emission.
[abstract 25 / 26] (score: 2) - Title: Multi-height Diagnosis of MHD Wave Periods and their Propagation in Solar Plages Using IRIS ObservationsAuthors: Gayathri Hegde, Pradeep Kayshap,Comments: 26 Pages, 16 figures, Accepted for Publication in Advances in Space Research JournalSubjects: astro-ph.SRCreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
This work aims to investigate MAGNETohydrodynamic (MHD) waves in solar plages at five distinct heights, spanning from photosphere to the upper chromosphere, using spectroscopic observations provided by Interface Region Imaging Spectrograph (IRIS). The dominant period is found to not change within the plages, while, in pores, the dominant period decreases linearly from 4.20 to 3.20 minutes from the photosphere to the upper chromosphere. Furthermore, in the solar plages, cross-wavelet analysis reveals that periods from 2.0 to 6.0 minutes propagate till the upper chromosphere from the photosphere. The periods beyond 6 minutes have a zero/constant phase difference in the photosphere and in the middle chromosphere. Thus, the 6.0-minute period would be considered the cutoff period at these heights. Next, the propagation speeds of MHD waves above solar plages are estimated in the photosphere and chromosphere. Within the limit of uncertainties, the propagation speed in solar plage is close to the sound speed; hence, the waves are slow MAGNEToacoustic in nature. Lastly, with the help of phase difference analysis, we found that formation heights of Mg ii k2r and Mg ii k3 are underestimated in solar plage, while the formation height of Mn i is overestimated. In case of pores, the formation heights of Mg ii k2r, Mg ii k3, and Mn i are overestimated. Interestingly, in the quiet-Sun (QS), the formation heights of Mn i and Fe i are nearly the same, and also the formation height of Mg ii k3 is similar to the formation height of Mg ii k2r. In conclusion, some important findings are reported in this work, namely, (1) dominant periods at five different heights between the photosphere and chromosphere, (2) estimation of cutoff periods in the photosphere, middle chromosphere, and the upper chromosphere in the plages, and (3) variations in the formation heights of these spectral lines in pore, plage, and QS.
[abstract 26 / 26] (score: 2) - Title: Adaptive optics imaging of the nuclei of Seyfert 2 galaxies: An unexpectedly high incidence of nuclear stellar ringsAuthors: Nina Mackensen, Jochen Heidt, Francisco Pozo Nuñez,Comments:Subjects: astro-ph.GACreated: 2026-07-15; Updated: 2026-07-16; Datestamp: 2026-07-16
High-resolution imaging of ACTIVE GALACTIC NUCLEi (AGNs) on subkiloparsec scales is essential for investigating their fueling. Observations in the near-infrared (NIR) are especially valuable as they minimize the absorption by dust. However, the inferred nuclear morphology may depend on the method used to analyze the images. We assess whether ground-based adaptive-optics observations of the cores of Seyfert 2 galaxies in the Ks band provide advantages over HST observations at shorter wavelengths (V and H bands). We also investigate whether a dedicated 2D analysis is preferable to a 1D approach. A sample of 18 Seyfert 2 galaxies was observed with the adaptive optics (AO) system in the Ks band at the Large Binocular Telescope (LBT) and compared to archival HST V- or H-band images. The analysis included a 2D modeling procedure via GALFIT as well as an unsharp masking technique. Results from different filters are consistent, showing no clear advantage of the redder filter. Using both GALFIT and unsharp masking in tandem is preferable, as the two methods provide complementary strengths. We identified nuclear stellar rings in 8 of the 18 galaxies in our sample (44 +/- 12%). This fraction is significantly higher than reported in previous studies and about a factor of two higher than reported in the most complete atlas of nuclear rings. The radii, size distribution, and inferred masses of the detected nuclear rings are similar to those observed in non-active galaxies. Low-luminosity AGNs appear to have little impact on nuclear ring formation and evolution. The high incidence of nuclear stellar rings in our study is unexpected and warrants further investigation. This could be tested further using the large number of suitable archival HST images available. If confirmed, it would imply that nuclear stellar rings are considerably more common than previously recognized.
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