Current date: 2026-08-21
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Datestamp limit: 2026-08-21 (0 days ago)
Created/updated limit: 2026-08-14 (7 days ago)
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Scoring abstracts
Number of records retrieved: 734
Keyword score statistics
score 9 -- 1 abstracts
score 8 -- 2 abstracts
score 7 -- 1 abstracts
score 5 -- 6 abstracts
score 4 -- 2 abstracts
score 3 -- 7 abstracts
score 2 -- 14 abstracts
in total -- 33 abstracts
Articles that appeared on 2026-08-21
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[abstract 1 / 33] Wow! (score: 9)
- Title: The Total and Polarized Radio Emission from the Innermost Jets of a High-Redshift Quasar and a Candidate at Parsec-Scale ResolutionAuthors: Bence Husvéth, Krisztina É. Gabányi, Tao An, Sándor Frey, Jun Yang, Iván Agudo, Yingkang Zhang,Comments: 17 pages, 3 figures, accepted for publication in MDPI UniverseSubjects: astro-ph.GACreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
High-frequency very long baseline interferometry (VLBI) polarimetry probes SYNCHROTRON-emitting plasma closer to the central engines of radio-loud ACTIVE GALACTIC NUCLEi (AGNs), but observations above 43 GHz are technically demanding. We present 22-GHz European VLBI Network observations of the $z=4.31$ QUASAR J1510+5702 and J1606+3124, whose published spectroscopic redshift, $z=4.56$, is uncertain; a photometric estimate gives $z_{\rm phot}=0.9\pm0.1$. For the published $z>4$ redshifts, 22 GHz corresponds to rest-frame frequencies above 118 GHz. Polarized emission is detected in J1510+5702, and a low-level polarized signal is recovered from the brightest feature of J1606+3124. Adopting $z=4.56$, that feature has a brightness temperature of $T_{\mathrm{b,VLBI}}=(7.4\pm0.8)\cdot10^{10}$ K, allowing a mildly Doppler-boosted interpretation, while the young compact-source scenario also remains viable. The core of J1510+5702 has $T_{\mathrm{b,VLBI}}=(1.08\pm0.15) \cdot10^{12}$ K, implying a Doppler factor of ${\sim}22$ under the equipartition assumption. This component has a ${\sim}3.5$ % fractional POLARIZATION. These observations show that cm-wavelength VLBI can access rest-frame millimeter-band POLARIZATION in bright $z>4$ JETs.
[abstract 2 / 33] Wow! (score: 8) - Title: 2D MAGNETohydrodynamic JET simulations: properties of recollimation shocksAuthors: Stella Boula, Fabrizio Tavecchio, Gianluigi Bodo, Nektarios Vlahakis, Paolo Coppi,Comments: 18 pages, 21 figures, 2 tables, accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Recollimation shocks are a frequent outcome in overpressured RELATIVISTIC JETs and are crucial for interpreting stationary features in Active Galactic Nuclei. The precise influence of MAGNETic fields on JET stability, energy dissipation, and variability remains debated, particularly as different field configurations can significantly alter shock properties and the onset of fluid instabilities. We perform a study of 2D axisymmetric RMHD JETs to quantify how the ambient density contrast ($ν$), pressure ratio ($P$), MAGNETization ($σ$), and MAGNETic pitch parameter ($α$) govern the formation and strength of the first recollimation shock. We also assess how these parameters create the local geometric conditions favorable for the centrifugal instability (CFI), utilizing linear theory as a diagnostic. We find that the JET's global geometry is affected by the MAGNETic pressure. The recollimation distance decreases monotonically with increasing MAGNETization $σ$, as increased MAGNETic forces immediately limit JET expansion. Remarkably, in the MAGNETically dominated regime, the ratio of the MAGNETized recollimation distance ($z_{\rm MHD}$) to its purely hydrodynamic counterpart ($z_{\rm HD}$) converges onto a power-law scaling, $z_{MHD}/z_{HD} \propto (B_0^2/P_{ext})^{-1/3}$, where $B_0$ the initial MAGNETic field and $P_{ext}$ the external pressure. Jets with high density contrast relative to the ambient medium or high internal pressure further enhance field compression. Furthermore, synthetic SYNCHROTRON maps show that a dominant toroidal field yields highly boosted, localized emission knots, whereas a strong poloidal field creates a diffuse profile and shifts the recollimation zone downstream. Regions susceptible to CFI are determined primarily by the local $σ_{\text{tor}}/Γ^2$ profile and streamline curvature created during recollimation.
[abstract 3 / 33] Wow! (score: 8) - Title: Revisiting the Growth Rate of the Relativistic Tearing Instability: The Role of the Non-ideal MHD StructureAuthors: Kaoru Sugimoto, Kunihito Ioka, Masaru Shibata,Comments:Subjects: physics.plasm-ph astro-ph.HECreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Magnetic RECONNECTion in MAGNETically dominated pair plasmas is a key process in high-energy astrophysical systems. We revisit the RELATIVISTIC tearing instability in a Harris current sheet and derive an improved analytical expression for its linear growth rate and the most unstable wavenumber. The key modification is the treatment of the vector potential perturbation in the non-ideal MAGNETohydrodynamic (MHD) region. Instead of the conventional constant-A approximation, we use an extrapolated-A approximation, in which the ideal-MHD solution is linearly extrapolated into the non-ideal region. Comparison with two-dimensional particle-in-cell simulations shows that the revised theory improves the prediction of the most unstable wavenumber. The improvement is most pronounced at low particle drift velocities, where the particle gyroradius is smaller than the current-sheet thickness and the fastest-growing mode shifts to longer wavelength. The resulting analytical expressions provide an updated benchmark for MAGNETically dominated RECONNECTion and its applications to high-energy astrophysical plasmas, including GAMMA-RAY BURSTs and fast radio bursts.
[abstract 4 / 33] Wow! (score: 7) - Title: The intrinsic luminosity-decay correlation in subsamples of GRB X-ray afterglowsAuthors: S. P. R. Shilling, S. R. Oates, J. L. Racusin, B. Cenko, R. Gupta, P. Nuessle, M. Smith, G. P. Lamb, C. Turnbull,Comments: 21 pages, 24 figures, accepted for publication in MNRASSubjects: astro-ph.HECreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
The intrinsic luminosity-decay correlation in GAMMA-RAY BURST (GRB) afterglows, between the early-time luminosity and the average rate of decay past this time, has previously been observed in the radio, optical/UV, X-ray and GeV wavebands and quantitatively shows that more luminous afterglows tend to have higher average rates of decay. We have compiled an updated sample of 427 X-ray afterglows with measured redshifts, observed with SWIFT/XRT over 20 years. For each GRB, we measure the luminosity at 200 seconds in the rest frame, $L_{\mathrm{X,200s}}$, and the average rate of decay from this time, $α_{X,>200s}$. We find these parameters are correlated with a Spearman's rank coefficient ($R_\mathrm{sp}$) of $0.54\pm0.04$ at a significance of $\geq3σ$ and a linear regression slope of $0.18\pm0.02$. We separate our sample into subsamples, including 395 long GRBs (LGRBs) and 32 short GRBs (SGRBs) and find evidence of the $L_{\mathrm{X,200s}}$-$α_{X,>200s}$ correlation at a significance of $\geq3σ$ in LGRBs but not in SGRBs, consistent with previous studies. In a subsample of 102 LGRBs with well-sampled light curves and late end times, we find that scatter in the correlation is significantly reduced and the strength increases to $R_\mathrm{sp}=0.80\pm0.04$ whilst the slope remains consistent with the full sample. We discuss our results and, briefly, their potential implications on constraining the cause of the correlation. Possible causes include geometric effects due to the angle between the observer and the JET-axis, or some mechanism that regulates the rate at which energy is released by the GRB central engine.
[abstract 5 / 33] Yes (score: 5) - Title: High-energy neutrino emission associated with gravitational-wave signals: effects of cocoon photons and constraints on late-time emissionAuthors: Riki Matsui, Shigeo S. Kimura, Kenji Toma, Kohta Murase,Comments:Subjects: astro-ph.HE gr-qc hep-phCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
We investigate prospects for the detection of high-energy neutrinos produced in the prolonged JETs of short GAMMA-RAY BURSTs (sGRBs). The X-ray lightcurves of sGRBs show extended emission components lasting for 100-1000 seconds, which are considered to be produced by prolonged engine activity. Jets by prolonged engine activity should interact with photons in the cocoon formed by the JET propagation inside the ejecta of neutron star mergers. We calculate neutrino emission from JETs by prolonged engine activity, taking account of the interaction between photons provided from the cocoon and COSMIC RAYs accelerated in the JETs. We find that IceCube-Gen2, a future neutrino telescope, with the second-generation gravitational wave detectors will probably be able to observe neutrino signals associated with gravitational waves with around 10 years of operation, regardless of the assumed value of the Lorentz factor of the JETs. Neutrino observations may enable us to constrain the dissipation region of the JETs. We apply this model to GRB 211211A, a peculiar long GRB whose origin may be a binary neutron-star merger. Our model predicts that IceCube is unlikely to detect any associated neutrino, but a few similar events will be able to put a meaningful constraint on the physical quantities of the prolonged engine activities.
[abstract 6 / 33] Yes (score: 5) - Title: High-energy neutrinos from late-time JETs of GAMMA-RAY BURSTs seeded with cocoon photonsAuthors: Riki Matsui, Shigeo S Kimura, Hamid Hamidani,Comments: 18 pages, 7 figures, and 1 table, accepted to ApJSubjects: astro-ph.HE hep-phCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
In GAMMA-RAY BURSTs (GRBs), $\sim$ 100 - 1000 s after the prompt emission, afterglow observations have consistently shown X-ray excesses detected in the form of flares (XFs; in long GRBs) or extended emission (EEs; in short GRBs). These observations are interpreted as emissions from JETs launched by late central engine activity. However, the characteristics of these late-time JETs, particularly the dissipation radius ($r_{\rm diss}$), Lorentz factor ($Γ$), and cosmic-ray loading factor ($ξ_p$), remain unknown despite their importance. Here, in order to understand the properties of the late-time JETs with future multi-messenger observations, we estimate the detectability of neutrinos associated with late-time emissions for a wide range of $r_{\rm diss}$ and $Γ$, assuming $ξ_p=10$. We take into account external seed photons from the cocoon around the JETs, which can enhance the neutrino production through photohadronic interaction in the JET dissipation region. Our results are still consistent with the upper limit obtained by IceCube. Our calculations indicate a promising prospect for neutrino detection with IceCube-Gen2 through the stacking of $\sim 1000-2000$ events, for a wide range of $r_{\rm diss}$ and $Γ$. We found that setting an optimal energy threshold of 10 TeV can significantly reduce noise without negatively affecting neutrino detection. Furthermore, even in the case of non-detection, we show that meaningful constraints on the characteristics of the late-time JETs can be obtained.
[abstract 7 / 33] Yes (score: 5) - Title: Systematic Error in Approximate Models of the GRB Early AfterglowAuthors: Benjamin Amend, Eric R. Coughlin, Jonathan Zrake,Comments: 16 pages, 7 figuresSubjects: astro-ph.HECreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
Gamma-ray burst (GRB) afterglows are thought to arise when RELATIVISTIC ejecta launched by a compact central engine drive a blast wave into the surrounding circumburst medium, producing broadband SYNCHROTRON emission. We present a rigorous assessment, based on high-resolution special RELATIVISTIC hydrodynamics simulations, of a widely adopted `two-zone model' for approximating the dynamics of the early afterglow phase. Before the onset of the Blandford-McKee (BMK) self-similar solution, the outflow generally produces two emission components, associated with the forward-shocked circumburst medium and the reverse-shocked ejecta. The subsequent evolution depends on whether the reverse shock significantly decelerates the ejecta as it crosses the shell, separating the so-called RELATIVISTIC and Newtonian reverse shock regimes. We show that when the reverse shock is Newtonian, it crosses the ejecta shell long before BMK self-similarity is established, leaving a prolonged interval that can span $\sim$ hours in observer time in which the true hydrodynamic evolution is not captured by standard semi-analytic prescriptions. We demonstrate that this mismatch can, for representative afterglow parameters, substantially overpredict the reverse-shock emission from radio through ultraviolet frequencies, or overpredict the forward-shock emission at X-ray frequencies, depending on how the transition away from the two-zone model is prescribed.
[abstract 8 / 33] Yes (score: 5) - Title: The second Arcminute Microkelvin Imager - Large Array Gamma-ray burst radio afterglow catalogAuthors: L. Rhodes, D. Ibrahim, N. Sqalli, G. E. Anderson, R. Fender, A. J. van der Horst, J. S. Bright, A. K. Hughes, D. R. A. Williams-Baldwin, D. A. Green, D. Haggard, A. Horesh, Y. Perrott, P. Scott, T. Staley, D. Titterington,Comments: 25 pages and 20 figures (included appendices). Submitted to ApJSubjects: astro-ph.HECreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
Radio observations of GAMMA-RAY BURST afterglows provide insight in to the different emitting regions within the JET, its hydrodynamics and burst environment. In this paper, we present the second iteration of the Arcminute Microkelvin Imager - Large Array (AMI-LA) Gamma-ray burst (GRB) radio afterglow catalog. The catalog consists of 1035 observations of 210 bursts. Our observations range from 0.04 to 900days post-burst. We detect radio emission associated with 19 events with flux densities spanning 0.1-40mJy, and present a detailed analysis of six events whose light curves have not been published elsewhere. In our individual afterglow analyses, we find that our radio counterparts show evidence of reverse shock emission 60% of the time. Two of the detected afterglows show evidence of scintillation which we use to place source size limits at tens of days. Of the whole catalog, 50 events have redshift measurements which we use to find the radio afterglow luminosity distribution for our sample. Our luminosity distribution spans five orders of magnitude, a larger range than seen in optical and X-ray bands, indicative of the strong dependence of the radio counterparts on the GRB's physical parameters.
[abstract 9 / 33] Yes (score: 5) - Title: First Observational Evidence for QPO-like Coevolution between Characteristic Damping Timescales and X-ray Time Lags among AGNsAuthors: Haoyang Zhang, Li Zhang,Comments: 14 pages, 6 figures, 2 tablesSubjects: astro-ph.HECreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Quasi-periodic oscillations (QPOs) and stochastic variability provide complementary probes of the inner accretion flow around supermassive BLACK HOLEs in ACTIVE GALACTIC NUCLEi (AGNs). Previous multi-epoch studies of narrow-line Seyfert 1 galaxy RE~J1034+396 revealed a coevolution between the QPO frequency and the X-ray time lag, but whether the stochastic variability participates in the same structural evolution has remained unclear. We analyze the multi-epoch XMM-Newton observations of RE~J1034+396 and model the soft (0.3--1~keV) and hard (1--4~keV) light curves separately using a damped random walk process. We obtain reliable characteristic damping timescales (CDTs) for 17 observations, with the soft-band CDT consistently longer than its hard-band counterpart. When combined with the X-ray time lag, the hard-band CDT traces a counterclockwise closed loop that closely resembles the previously reported QPO-frequency--time-lag loop, whereas the soft-band CDT exhibits more complex trajectory. Under plausible dynamical, thermal, and viscous interpretations, the hard-band CDT is associated with characteristic scales in the inner hot accretion flow/corona. The observed loops may represent different projections of a common cyclic evolution of the inner accretion flow/corona, as the three timing observables may respond to its dynamical, stochastic, and radiative properties on different timescales. These results provide the first observational support among AGNs for the physical picture in which changes in the spatial extent of the hot inner flow/corona simultaneously affect QPO and stochastic variability.
[abstract 10 / 33] Yes (score: 5) - Title: Quasi-periodic Eruptions from Recurrent Satellite Black Hole Transits through Magnetized Galactic Nucleus Accretion DisksAuthors: Na Wang, Jing-Tong Xing, Tong Liu, Ya-Ping Li, Shuang-Liang Li,Comments: 9 pages, 1 figureSubjects: astro-ph.HE astro-ph.GACreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Quasi-periodic eruptions (QPEs) are recurrent soft X-ray flares from galactic nuclei, but their origin remains uncertain. The delayed ultraviolet (UV) counterpart detected in Ansky provides a new constraint on viable models. We present a two-channel model in which a satellite BLACK HOLE (sBH) repeatedly crosses a nuclear accretion disk threaded by a large-scale MAGNETic field. Gravitational focusing and dynamical drag generate hot, optically thick ejecta whose expansion and photon diffusion power the soft X-ray QPE. For fiducial Bondi-scale parameters, the model yields a characteristic X-ray duration of $\sim10^3\ \mathrm{s}$ and luminosity of $\sim10^{42}\ \mathrm{erg\,s^{-1}}$; at lower orbital inclinations, the duration extends to the day-long scale observed in Ansky. Simultaneously, the sBH motion compresses and bends the background MAGNETic field, triggering in-disk RECONNECTion. The dissipated energy then emerges after photon diffusion as a broader, delayed UV response. The resulting thermal power is comparable to the variable UV luminosity of Ansky. Unfavorable MAGNETic fields or diffusion times longer than the QPE recurrence period can weaken or smear out the UV signal, potentially explaining the lack of clear UV counterparts in other QPE sources.
[abstract 11 / 33] Yes (score: 4) - Title: A Comprehensive JWST/NIRSpec Census of Broad-Line Active Galactic Nuclei: Faint, Tiny, but Highly Accreting Sources in the Remote UniverseAuthors: Caroline Baccus, Xinfeng Xu,Comments: Submitted to the Astrophysical Journal, 19 pages, 7 figuresSubjects: astro-ph.GACreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
We present a sample of 252 broad-line Active Galactic Nuclei (BLAGNs), incorporating 171 newly identified sources, spanning a redshift interval from $z$ = 0.8 to 7.2. We have analyzed spectroscopic data from the NIRSpec instrument aboard the James Webb Space Telescope, using the G140H, G140M, G235H, G235M, G395H, and G395M gratings to survey N $\sim$ 80,000 galaxies for BLAGNs. Through emission-line fitting, using a sum of Gaussian models for {H$α$}, {H$β$}, [N II] $λ\lambda6548, 6584$, and [O III] $ λ\lambda4959, 5007$, we separate AGN broad-line components from narrow-line emission. We find the detection rate of BLAGNs to be relatively consistent across our redshift range. Compared to typical low-$z$ AGNs ($z$ $\lesssim$ 1), the high-$z$ BLAGNs are systematically fainter and less massive, yet they accrete more efficiently, with most showing Eddington ratios between 0.1 and 1.0. This confirms the rapid BLACK HOLE growth during the early cosmic epochs. The detection of faint, low-mass BLAGNs at high redshift also helps bridge the observational gap between local supermassive BLACK HOLEs and remote luminous QUASARs, providing a more complete view of BLACK HOLE-galaxy coevolution across cosmic time.
[abstract 12 / 33] Yes (score: 4) - Title: Collisionless Resonances Set the Size of a Weyl Exceptional RingAuthors: Xianhao Rao, Hong Li, Xuan Sun,Comments: 6 pages, 2 figures; Supplemental Material appended. Data and code are available at https://doi.org/10.5281/zenodo.22020911Subjects: physics.plasm-phCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Eliminating continuum degrees of freedom converts conservative dynamics into a dispersive, non-Hermitian response whose topology need not represent the causally selected kinetic dynamics. In collisionless MAGNETized plasma, retarded Landau and cyclotron resonances damp two Weyl modes differently and replace a cold Weyl point by an exceptional ring. Axial roots and root-normalized POLARIZATION mixing predict its off-axis radius, $R_{\rm EP}^{\rm pred}=|ΔΓ|/(2|v_{\rm mix}|)$, before any double root is computed. Across five nonRELATIVISTIC scans spanning a 310-fold range of differential damping, $R_{\rm EP}^{\rm pred}$ agrees with the nonlinear double-root radius $R_{\rm EP}^{\rm full}$ within $0.12\%$. The selected retarded kinetic-response bundle is a continuous graph over the electric root line bundle and has the same first Chern class under stated conditions. The cold interface mode continues to a localized Keldysh pole with one oriented crossing in the tested line-gap window, consistent with the inherited charge.
[abstract 13 / 33] (score: 3) - Title: Modeling Relativistic Tidal Disruptions of MESA StarsAuthors: Liam M. Wang, Giovanni Maria Tomaselli, Zihan Zhou,Comments: 9 pages, 5 figuresSubjects: astro-ph.HE astro-ph.GA astro-ph.SR gr-qcCreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
Tidal disruption events (TDEs) occur when a star passes so close to a BLACK HOLE that its self-gravity is overcome by the external tidal field. As the star passes, it initially deforms, then is ripped apart, and some of its material eventually falls back on bound orbits, forming an accretion disk around the BLACK HOLE. A Newtonian model of TDEs, based on stellar perturbation theory of MESA stars, was recently introduced as an alternative to computationally intensive hydrodynamical simulations. In this work, we add RELATIVISTIC corrections to the model, incorporating equatorial Kerr geodesics, RELATIVISTIC tidal fields, and RELATIVISTIC fallback times. Compared to the Newtonian case, we find that stars are disrupted earlier in their orbit, which gives them less time to accumulate physical deformations. Additionally, we find that the increased distance from the BLACK HOLE at the time of disruption makes the fallback time longer. However, the BLACK HOLE spin has a negligible impact on fallback time, except for orbits with exceptionally close pericenter. Our results allow for a more accurate calculation of fallback rates than the Newtonian model, while also remaining computationally cheap. The code is available on GitHub.
[abstract 14 / 33] (score: 3) - Title: Non-ideal MHD and protostellar feedback effects on disc formation and evolution in numerical simulations of star cluster formationAuthors: Nina Filippova, Stella S. R. Offner, Michael Y. Grudic, Philip F. Hopkins,Comments: 35 pages, 39 figures. Accepted for publication in MNRAS. Published version available at https://doi.org/10.1093/mnras/stag1501Subjects: astro-ph.SR astro-ph.GACreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
While recent surveys have resolved hundreds of nearby protostellar discs, numerical simulations assuming ideal MAGNETohydrodynamics (MHD) have historically struggled to achieve disc formation due to efficient angular momentum removal by MAGNETic torques. Non-ideal MHD effects, relevant at the low ionization fractions typical of molecular clouds, have been shown to reduce the effectiveness of MAGNETic braking and promote disc formation. In this work, we present the results from a suite of calculations following the gravitational collapse of 50 $M_{\odot}$ turbulent molecular cloud cores down to the formation and evolution of stellar systems and protostellar discs. We use the radiation-MHD code GIZMO including non-ideal MHD (Ohmic resistivity, ambipolar diffusion, and the Hall effect) and the STARFORGE numerical framework for modeling STAR FORMATION and stellar feedback. We compare the effects of assuming ideal vs. non-ideal MHD and including sub-grid protostellar JET feedback on disc formation and evolution. Discs form in all of our models but are least massive in the model with ideal MHD and sub-grid JET feedback. Apart from the ideal MHD$+$JETs model, we do not observe any significant differences in disc properties between the ideal and non-ideal MHD models; however, ideal MHD discs are embedded in smaller rotating envelopes. Disc sizes are in general agreement with those of observed discs. Jet feedback increases core fragmentation and reduces final stellar masses. Our results suggest that MAGNETic braking does not efficiently suppress disc formation, regardless of whether ideal or non-ideal MHD is assumed, under the dynamical conditions in which multiple stellar systems form.
[abstract 15 / 33] (score: 3) - Title: The VariableTNG project: mass-dependent regulation of galaxy morphology by baryonic feedbackAuthors: Yikai Liu, Hong Guo, Volker Springel, Kexin Liu, Luis C. Ho, BoCheng Zhu,Comments:Subjects: astro-ph.GACreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Galaxy morphology is shaped by both assembly history and baryonic processes, but their relative roles remain uncertain. We use the VariableTNG (VTNG) simulation suite to investigate how variations in baryonic feedback regulate galaxy morphology while keeping the initial conditions fixed. VTNG consists of cosmological MAGNETohydrodynamic simulations performed with the moving-mesh code {\sc AREPO}, varying eight parameters governing stellar and AGN feedback. At $z=1$, we characterize morphology using $κ_{\rm co}$, $v/σ$, and the axis ratio $c/a$. We find substantial morphological diversity across feedback models, with the dominant mechanism strongly dependent on stellar mass. For $M_\ast \lesssim 10^{11}\,{\rm M_\odot}$, morphology is primarily controlled by the SUPERNOVA temperature $T_{\rm SN}$: larger $T_{\rm SN}$ delays early STAR FORMATION, promotes a denser and more rotationally supported gas reservoir, and favours subsequent disc growth through in-situ STAR FORMATION. At higher masses, morphology becomes increasingly sensitive to AGN feedback, particularly the QUASAR-mode coupling efficiency $ε_{\rm f,high}$. Higher $ε_{\rm f,high}$ suppresses early BLACK HOLE growth, thereby weakening subsequent radio-mode feedback associated with gas depletion and loss of rotational support. The resulting morphology--mass relation is non-monotonic, with maximum rotational support at intermediate stellar masses. Our results demonstrate that baryonic feedback regulates galaxy morphology through distinct mass-dependent pathways, with stellar feedback dominating at lower masses and AGN self-regulation becoming increasingly important at the massive end.
[abstract 16 / 33] (score: 3) - Title: Characterizing the temporal evolution of Biermann-battery-driven MAGNETic RECONNECTion in LASER-ablated plasmasAuthors: T. Morita, Y. Muramoto, S. Isayama, M. Edamoto, M. Hanano, R. Ishikawa, Y. Kanesada, K. Koba, H. Kondo, S. Kurimaru, K. Maeda, Y. Maenosono, S. Matsukiyo, A. Morita, Y. Nagamatsu, G. Nakayama, T. Ogawa, K. Oshida, Y. Pan, K. Sakai, T. Sano, Y. Sato, N. Shimoda, J. Shiota, Y. Sudo, Y. Suzuki, T. Takezaki, S. J. Tanaka, K. Tomita, S. Ueno, S. Yakura, R. Yamazaki, Y. Sakawa,Comments: Accepted for publication in Physical Review E. The paper is 12 pages long with 10 figuresSubjects: physics.plasm-phCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
This paper presents an experimental investigation of MAGNETic RECONNECTion between two LASER-produced expanding plasmas, focusing on the quantitative evaluation of the RECONNECTion rate and energy conversion under varying initial conditions. By changing the separation distance between the drive LASER focal spots (1 mm and 2 mm), we systematically controlled the inflow parameters. The RECONNECTion region was probed using a two-directional LASER Thomson scattering (LTS) system, which simultaneously measured the local plasma parameters parallel to the outflows and along the current sheet. Based on our established method incorporating macroscopic energy and mass conservation laws to derive the upstream MAGNETic field directly from LTS spectra, we characterized the temporal evolution of the current sheet and the RECONNECTion rate. The larger spot separation allows the plasma bubbles to expand for a substantially longer time before the formation of a RECONNECTion current sheet, resulting in different upstream conditions. Nevertheless, both configurations yielded comparable upstream MAGNETic fields and RECONNECTion rates. These results suggest that the RECONNECTion rate is relatively insensitive to the global inflow conditions and is primarily controlled by the local physics of the RECONNECTion layer once a current sheet is formed.
[abstract 17 / 33] (score: 3) - Title: J0011+3443: a GPS compact symmetric object, gravitational lens, or dual AGN?Authors: Efthalia Traianou, Tingting Liu, Roman Gold, Richard Mushotzky,Comments: 8 pages, 3 figures, 3 tables. Accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
We present new multi-frequency VLBA observations of \object{J0011+3443} (TXS\,0008+344, $z=0.89$) at 2.3, 4.9, 8.5, and, for the first time, 23.6\,GHz. The source consists of two compact components A and B at a projected separation of $314\pm2$\,pc, plus a third feature C detected at 23.6\,GHz at $0.6$\,mas from A. Archival low-resolution radio measurements confirm an integrated gigahertz-peaked spectrum, with an observed-frame peak frequency of $ν_\mathrm{peak}=0.73\pm0.08$\,GHz and a peak flux density of $S_\mathrm{peak}=879\pm125$\,mJy. Comparison with nearly frequency-matched low-resolution measurements shows that the VLBA recovers $0.85\pm0.11$ of the 4.85\,GHz flux density and $0.50\pm0.06$ of the 8.46\,GHz flux density. The lower recovered fraction at 8.5\,GHz suggests that low-surface-brightness emission is resolved out or falls below the VLBA surface-brightness sensitivity. We therefore interpret the VLBA component spectra as spectra of the compact recovered emission only. The 23.6\,GHz morphology, the absence of a detected flat-spectrum core, the similar compact spectra of A and B, and the steep integrated GHz spectrum favor an interpretation of \object{J0011+3443} as a GPS-class compact symmetric object, possibly in a short-lived or relic phase, although a dual-AGN origin cannot be excluded without multi-epoch astrometry.
[abstract 18 / 33] (score: 3) - Title: Chromospheric heating and MAGNETic topology above the shared penumbra of a delta-spot: Multi-line inversions and multi-height MAGNETic-field extrapolationsAuthors: M. Kriginsky, J. Leenaarts, J. de la Cruz Rodríguez, A. Pastor Yabar,Comments:Subjects: astro-ph.SRCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
We analysed observations of the Fe I 617.3 nm, Ca II 854.2 nm, and Ca II H lines obtained with CRISP and CHROMIS at the SST. Spatially coupled non-LTE inversions constrained the chromospheric atmosphere, while the WFA provided estimates of the chromospheric line-of-sight MAGNETic field. We combined these photospheric and chromospheric constraints with an HMI MAGNETogram as input to a multi-height field extrapolation. We characterised the reconstructed topology using the twist number, squashing factor, current density, and field-line connectivity. Results. The Ca II H MAGNETic signal is concentrated mainly above the strongest photospheric field concentrations, whereas Ca II 854.2 nm yields stronger and more spatially extended line-of-sight fields. The chromosphere above the shared penumbra is approximately 300 K hotter than nearby quiet regions. The selected brightening follows a chromospheric loop, with enhanced temperature and a transition from blueshift to redshift along the structure. The extrapolation recovers field strengths broadly consistent with the inversions and reveals a left-handed, flux-rope-like core following the polarity inversion line. Enhanced currents and connectivity gradients occur near parts of its boundary, where field lines connect the twisted structure to overarching loops. Conclusions. The temperature and velocity patterns and MAGNETic topology are consistent with RECONNECTion between the twisted polarity-inversion-line field and the surrounding loops, depositing energy in the chromosphere and driving plasma along reconfigured field lines. These signatures do not uniquely establish RECONNECTion, but show that combining high-resolution spectropolarimetric inversions with multi-height extrapolations can relate chromospheric energy release to the local three-dimensional MAGNETic structure.
[abstract 19 / 33] (score: 3) - Title: Excitation of the lower-hybrid drift instability in the outflow of electron-only MAGNETic RECONNECTionAuthors: B. K. Russell, K. Sakai, Y. Zhang, L. Gao, E. G. Blackman, W. Daughton, C. Dong, J. Katz, S. R. Klein, C. C. Kuranz, X. Li, X. M. Li, A. L. Milder, J. Ng, K. Orr, G. Pomraning, J. P. Schell, A. Stanier, J. Yoo, H. Ji,Comments: 8 pages, 4 figuresSubjects: physics.plasm-phCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
We report experimental evidence for the lower-hybrid drift instability in the current sheet normal direction of electron-only MAGNETic RECONNECTion. In our LASER-driven capacitor-coil experiment, the system size ($\sim$3 ion skin depths) places it in the electron-only regime. Yet, Thomson scattering reveals out-of-plane electron drift oscillations at the local lower-hybrid frequency, with kinetic energy density reaching $\sim$18% of the local MAGNETic energy density. Linear theory with the measured parameters predicts more than ten e-folding times of growth, indicating that the instability reaches the nonlinear regime within the measurement window. Supported by particle-in-cell simulations, these results demonstrate the importance of ions in the dissipation and energy transfer in electron-only RECONNECTion where their significance has not been previously recognized.
[abstract 20 / 33] (score: 2) - Title: The effects on CMB power spectra and bispectra from the POLARIZATION rotation and its correlations with temperature and E-POLARIZATIONAuthors: Hua Zhai, Si-Yu Li, Mingzhe Li, Hong Li, Xinmin Zhang,Comments: 24 pages, 5 figuresSubjects: astro-ph.COCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
The Chern-Simons term, through which the cosmic Axion-like field couples to the electroMAGNETic field, has the effect to rotate CMB POLARIZATION directions and to break the CPT symmetry. This rotation will change the CMB power spectra, no matter isotropic or anisotropic the rotation angle is. In this paper we revisit this issue by further considering the correlations between the (anisotropic) rotation angle $α$ and the CMB temperature and (unrotated) $E$ POLARIZATION fields. These correlations could be generated in the Axion-like models with nonzero potential under the adiabatic initial condition. We first investigate how these correlations contribute further modifications to the CMB power spectra, then calculate the CMB bispectra for the temperature and rotated POLARIZATION fields. These bispectra would vanish if the $Tα$ and $Eα$ correlations are absent. So, they are useful in searching for CPT violation and the $Tα$ and $Eα$ correlations arisen in the Axion-like models.
[abstract 21 / 33] (score: 2) - Title: Probing Intrinsic Ellipticity in Compact Star BinariesAuthors: Zhiqiang Miao, Huan Yang,Comments: 17 pages, 14 figures, updated to publishing versionSubjects: astro-ph.HE astro-ph.SR gr-qcCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
We present a novel resonance mechanism that can occur in {compact-star} binaries: a spin-orbit resonance. This resonance locks the binary into a unique state where {the spin of one component} evolves alongside the orbit. The resonance requires this component to possess a finite ellipticity $ε$, and we find that the locking probability is proportional to $\sqrtε$. We show that resonance locking and its subsequent breaking produce a characteristic phase signature in the gravitational waveform, opening a new observational channel for probing intrinsic ellipticity in compact-star binaries, including exotic compact objects. In addition, as an illustrative astrophysical scenario, we discuss MAGNETars, whose strong internal fields can source the required ellipticity and may place the signal in the ground-based low-frequency band, although their abundance at merger remains uncertain. We have also conducted a search in all neutron star binaries up to the O4a gravitational-wave catalog, with no positive event found so far.
[abstract 22 / 33] (score: 2) - Title: MMS Observations of Kinetic Alfvén Wave Turbulence and Steep Kinetic-Range Spectra in the Outer Plasma Sheet Boundary LayerAuthors: Mani K Chettri, Rupak Mukherjee, Hemam D. Singh,Comments: 20 pages, 6 figures. Published in the Journal of Atmospheric and Solar-Terrestrial PhysicsSubjects: physics.plasm-ph astro-ph.EPCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Energy dissipation and particle acceleration in the collisionless MAGNETotail plasma remain incompletely understood. We report observations of Kinetic Alfvén Wave (KAW) turbulence and parallel electric fields ($E_{\parallel}$) in the outer Plasma Sheet Boundary Layer (PSBL) using high-resolution burst-mode data from the Magnetospheric Multiscale (MMS) mission. For a crossing on May 31, 2017, we identify broadband KAW turbulence characterized by a normalized electric-to-MAGNETic field ratio $\mathcal{R}=|δE_{\perp}|/(v_A|δB_{\perp}|)=2.5\pm1.2$ exceeding the MHD limit, a spectral break near ion scales, a steep kinetic-range spectral slope ($α=-3.48\pm0.13$), and low MAGNETic compressibility ($C_{\parallel}\approx0.03$). We observe impulsive $E_{\parallel}$ structures up to 15 mV/m and ion density fluctuations up to 68% during enhanced wave activity. The steep spectrum, compared with undamped KAW predictions ($-7/3$ to $-8/3$), is consistent with substantial energy removal at kinetic scales. The near-zero correlation between the KAW-band filtered $E_{\parallel}$ waveform (0.18 to 2.0 Hz) and ion density fluctuations ($r\approx0.04$) indicates no simple linear, zero-lag correspondence under the adopted processing. Together with bursty energy-conversion proxies, the observations are consistent with localized field-particle energy exchange and collisionless damping of KAW turbulence in the intermediate-beta outer PSBL. A specific damping channel, such as Landau damping, is not uniquely constrained by the present diagnostics.
[abstract 23 / 33] (score: 2) - Title: Population synthesis of Be X-ray binaries in the Small Magellanic Cloud: Angular momentum recycling and stable mass transferAuthors: Víctor López Oller, Boyuan Liu, Michela Mapelli, Stefano Rinaldi, Cecilia Sgalletta, Julia Bodensteiner, Giuliano Iorio, Rebekka Schupp,Comments: 13 + 8 pages, 5 + 13 figures. Accepted for publication in A&ASubjects: astro-ph.SR astro-ph.HECreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Be X-ray binaries (BeXRBs) are key laboratories to constrain binary interaction processes such as mass transfer, angular-momentum transport, and natal kicks. The Small Magellanic Cloud (SMC), hosting a nearly complete and well-characterized BeXRB population, offers a unique opportunity to test these physical processes at low metallicity. We aim to identify the combination of binary-evolution parameters that simultaneously reproduces the observed number and the joint distribution of orbital period and optical magnitude of SMC BeXRBs. We performed an extensive grid analysis of binary population-synthesis models exploring different mass transfer efficiencies, angular-momentum transport prescriptions and Roche-lobe overflow stability criteria. We also considered the impact of natal kicks, and that of the propeller effect of rotating MAGNETic fields of neutron stars. Synthetic populations obtained with the binary population synthesis code $\texttt{sevn}$ are statistically compared to observations using likelihood-based methods applied to the orbital period and $V$-band magnitude distributions, together with requirements on the total number of systems. We find that models in which mass transfer via Roche-lobe overflow is assumed to be always stable and angular momentum is recycled back into the orbit through tides when the accretor approaches critical rotation provide the best match to observations. Our best-fitting models favor low natal kicks ($\lesssim 100\ \rm km\ s^{-1}$), a moderate mass transfer efficiency ($f_{\rm MT} \simeq 0.6$), a minimum Be threshold spin close to critical rotation, and a strong suppression of accretion onto neutron stars due to the propeller effect. Specifically, the observable population is highly sensitive to the treatment of the propeller effect, which regulates the X-ray luminosity of wide, low-accretion-rate systems.
[abstract 24 / 33] (score: 2) - Title: Evidence for Intermediate-Mass Black Holes From Microlensing Signatures in CHIME/FRB catalog 2Authors: Huan Zhou, Zhengxiang Li, Cheng-Gang Shao, Xi-Jing Wang, Kai Liao, He Gao, Zong-Hong Zhu,Comments: 12 pages, 5 figures, 1 table, accepted by ApJLSubjects: astro-ph.HE astro-ph.CO gr-qcCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Intermediate-mass BLACK HOLEs (IMBHs) are the missing link in the cosmic hierarchy of BLACK HOLEs, bridging the gap between stellar-mass BLACK HOLEs and supermassive ones. They also serve as unique laboratories for testing strong-field gravity and are prime targets for future multi-messenger observations. However, IMBHs are a population that has remained notoriously difficult to detect. The microlensing effect of fast radio bursts (FRBs) can serve as a clean and powerful method to probe IMBHs. In this work, we develop a pipeline to search for microlensed FRBs based on their dynamic spectra and apply it to the CHIME/FRB Catalog 2. Two microlensing signatures have been identified in two separate sources, i.e. FRB~20190131D and FRB~20211115A. The inferred lens masses for these two signatures are $\sim[280-467]~M_{\odot}$ and $\sim[539-609]~M_{\odot}$, respectively. Here we interpret them as evidence for IMBHs. If there are no intervening structures-such as galaxies or clusters-along the line of sights for these two sources, the two identified IMBHs might be isolated and of primordial origins. In that case, we obtain primordial BLACK HOLEs (PBHs) within these two mass ranges would constitute $\sim4\%$ of DARK MATTER. Moreover, if these two candidates are not genuine lensing signatures, the abundance of intermediate-mass PBHs with masses $>300,M_{\odot}$ is constrained to be $\sim13\%$ at $95\%$ confidence level. Therefore, more comprehensive observational information for FRBs, together with a deeper understanding of whether the intrinsic emission mechanisms of FRBs can produce lensing-like signals, will be crucial for establishing this effect as a powerful tool for probing (primordial) IMBHs.
[abstract 25 / 33] (score: 2) - Title: Astrophysical Signature and Optical Appearance of Weyl--Corrected Einstein--Maxwell Black HolesAuthors: Hassan Hassanabadi, Mrinnoy M. Gohain, Kalyan Bhuyan, Farokhnaz Hosseinifar,Comments: 27 pages, 20 figures and 1 table. Corrections and modifications incorporatedSubjects: gr-qc hep-thCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
In this work, we investigate the physics of charged BLACK HOLEs modified by Weyl corrections, which emerge from the non-minimal coupling between spacetime curvature and electroMAGNETism. We begin by revisiting the thermodynamics of these systems, deriving the Hawking temperature, Wald entropy, and heat capacity to examine how the Weyl correction parameter reshapes the landscape of thermal stability and phase transitions. Then, we apply a topological method to classify the thermodynamic states and reveal the impact of the Weyl modifications on this classification. To explore astrophysical signatures, we analyze the null trajectories and shadow cast by photons under two-photon POLARIZATION modes, deriving observational constraints on the BLACK HOLE parameters. Finally, we model the accretion disk around these BLACK HOLEs. By calculating the energy flux, spectral luminosity, and differential luminosity, we show how these corrections leave a detectable trace on the emitted radiation.
[abstract 26 / 33] (score: 2) - Title: Kinetic structure of the intracluster medium across nearby clusters observed with XRISMAuthors: Naomi Ota, Erwin T. Lau, Satoshi Yamada, Yuki Omiya, Hiroya Yamaguchi,Comments: 7 pages, 2 figures, PASJ Letter acceptedSubjects: astro-ph.CO astro-ph.GA astro-ph.HECreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
XRISM/Resolve is building a sample of galaxy clusters with directly measured ICM gas motions, revealing diverse projected dynamical states. We compile 45 XRISM/Resolve measurements in 19 nearby galaxy clusters and place them on a common, emission-weighted effective line-of-sight scale, $\ell_{\rm eff}$. We compare the line-of-sight velocity dispersion $σ_v$, bulk velocity amplitude $|v_{\rm bulk}|$, their ratio $R_v \equiv |v_{\rm bulk}|/σ_v$, and non-thermal pressure proxies. Disturbed non-cool-core systems are not simply higher-dispersion counterparts of relaxed cool-core regions. Instead, differences among cool-core centers, cool-core outer regions, and non-cool-core systems are driven mainly by coherent line-of-sight motion relative to unresolved line broadening: $R_v$ tends to remain below unity in cool-core regions but often exceeds unity in non-cool-core systems, with the mean $R_v$ rising from 0.45 in cool-core centers to 1.6 in non-cool-core systems. These diagnostics help separate local central line broadening, likely associated with AGN feedback in some cool cores, from larger-scale coherent motions associated with sloshing, mergers, and halo assembly. Comparison with forward-modeled TNG-Cluster predictions suggests that many cool-core measurements occupy the lower part of the predicted non-thermal pressure range, consistent with small hydrostatic-mass corrections in relaxed systems and larger corrections in disturbed ones. XRISM is thus beginning to resolve the projected kinetic structure of the ICM across cluster environments, rather than tracing a single sequence of increasing turbulence.
[abstract 27 / 33] (score: 2) - Title: Thermodynamics, topology and non-Abelian instability of the five-dimensional Einstein--Yang--Mills BLACK HOLE with exponential entropy correctionAuthors: Aram Bahroz Brzo, Peshwaz Abdulkareem Abdoul, Behnam Pourhassan, Izzet Skalli,Comments:Subjects: gr-qcCreated: 2026-08-18; Updated: 2026-08-21; Datestamp: 2026-08-21
The five-dimensional Einstein--Yang--Mills BLACK HOLE obtained from the higher-dimensional Wu--Yang ansatz carries a logarithmic non-Abelian contribution to the metric function, making it an analytically tractable setting for studying how gauge charge reshapes horizon thermodynamics beyond four dimensions. We derive expressions for the mass--radius relation, the Hawking temperature, the entropy, the Yang--Mills potential and the first law, and record the curvature invariants, which show that the logarithm sharpens the central singularity rather than smoothing it. A non-perturbative exponential entropy correction is then added, and the corrected heat capacity and free energies are obtained analytically. The geometry is extremal at $r_h=|Q|$ and the heat capacity diverges at $r_h=\sqrt{3}\,|Q|$, a Davies-type point. The correction moves that point inward, $r_{\rm tr}/|Q|\simeq\sqrt{3}-9λαη\,e^{-3\sqrt{3}λ}$. Using the generalized off-shell free energy we find a conserved topological charge $W=0$ carried by a stable--unstable defect pair whose inner member alone responds to the correction. We then solve the spherically symmetric MAGNETic Yang--Mills perturbation sector, which probes the gauge field itself rather than a test scalar. Two independent numerical schemes agree to better than $1.2\times10^{-7}$ and give a purely imaginary unstable mode whose growth rate falls monotonically from $Γ_{0}r_h=0.414753$ at $Q/r_h\to0$ to $0.317520$ at $Q/r_h=0.99$, passing through the Davies scale without any feature. Because the effective potential decays as $-9/(4r_{*}^{2})$, with a coefficient above the critical value $1/4$, the sector supports an infinite geometric tower of unstable modes accumulating at $Γ\to0$ with the charge-independent ratio $Γ_{n+1}/Γ_{n}\to e^{-π/\sqrt{2}}\simeq0.108453$, which we confirm numerically.
[abstract 28 / 33] (score: 2) - Title: On trace invariance and energy-dependent entanglement in muon decayAuthors: Saulo Carneiro, Fernando César Sobrinho,Comments: 6 pages, 4 figuresSubjects: hep-ph quant-phCreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
We revisit a proposed correction to the muon MAGNETic anomaly measurement and compare it with energy-binned scans reported by the FERMIlab $g-2$ collaboration. The central point is that, for a RELATIVISTIC three-body decay inferred from an ensemble of detected positrons, the relevant neutrino partial trace is defined on the asymptotic state at the detector, not on an idealised state at the decay vertex. Because the fitted positron sample mixes events with different decay times, flight times, energies and acceptances, tracing over the unobserved neutrino helicities leaves a time-dependent mixed state in the observed sector. Using angular-momentum balance, we obtain an energy-dependent correction in the positron energy interval $E_p \in (1.5,2.9)$ GeV. The corrected experimental interval for the muon anomaly moves towards the BaBar- and $τ$-based determinations, while remaining compatible at the $1σ$ level with both data-driven and lattice-based Standard Model evaluations. We then fit digitised public $R(E_p)$ scans for FERMIlab's runs $1$ to $6$, with two one-parameter hypotheses: a constant shift and the entanglement-motivated energy-dependent shift. Within digitisation accuracy, the differences in $χ^2$ remain modest and the current binned data do not provide decisive discrimination between them.
[abstract 29 / 33] (score: 2) - Title: Multi-lane type II radio bursts: Insights into shock propagation in the coronaAuthors: Nadiya K., Divya Paliwal, Anshu Kumari,Comments: Accepted for Publication in Solar Physics Journal, 14 Pages, 7 Figures, 2 TablesSubjects: astro-ph.SRCreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
Type II solar radio bursts are considered as the signatures of the coronal shocks. These bursts are generated from plasma waves excited by MAGNETohydrodynamic (MHD) shocks, and then converted into radio waves at the local plasma frequency and/or its harmonics. Hence, these bursts often have fundamental-harmonic (FH) and band-splitting (SB) structures, which provide insights into shock generation and propagation in the corona, hence, in turn, the corresponding coronal conditions. In the present study, we analysed an unusual multi-lane type II burst observed with ground-based solar radio spectrographs on May 29, 2024, between 14:24 and 14:43 UT. The start and end frequencies of the type II burst were 450 MHz and 25 MHz, respectively. By combining spectral information with radio imaging data, we found that radio waves were escaping from the corona via emissions from distinct shock regions. In addition, along with the traditional FH and SB, there were multi-lane structures in the type II bursts. Our analysis suggests complex, inhomogeneous shock dynamics near the leading edge (LE) of the coronal mass ejection (CME). This indicates that the plasma material compresses more strongly in these forefront regions. This was confirmed by radio imaging observations, which showed that the higher-frequency emission occurred at a higher altitude than the lower-frequency emission. Our results suggest that the shock geometry and plasma inhomogeneity play an important role in the generation of type II bursts, leading to traditional fundamental-harmonic split-band (FH-SB) pairs with additional splitting in the type II bands.
[abstract 30 / 33] (score: 2) - Title: Scalar-Longitudinal Radiation in Extended Electrodynamics with Multipole Theory and a Compensated Source ModelAuthors: Natan Rentzber,Comments: Apologies to the arXiv team, this was marked 'processing', but I noticed there was an accidental intend which shifted the positioning of the affiliations with respect to my name. I've corrected and centered it now. | 30 pages, 5 figuresSubjects: physics.class-phCreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
Extended electrodynamics (EED) leaves the Lorenz gauge condition unimposed and treats the scalar combination $C=\nabla\cdot\mathbf{A}+c^{-2}\partialΦ/\partial t$ as a dynamical field. For a conserved source with no scalar initial field, $C=0$ and the theory reduces to classical electrodynamics. A source with a nonzero local continuity anomaly has no Maxwell solution, but EED remains well posed and can support a scalar-longitudinal sector. For each radiating frequency of a localized source, the far field separates into the usual transverse Maxwell channel and a scalar-longitudinal channel with a longitudinal electric field, no MAGNETic field of its own, and a co-propagating $C$ field. Under the field-only energy balance used here, the time-averaged fluxes add without interference. The scalar channel depends only on $Λ=\partialρ/\partial t+\nabla\cdot\mathbf{J}$ and radiates when its moments at $k=ω/c$ are nonzero. An all-orders multipole formula is derived for this flux. Bound POLARIZATION and MAGNETization sources conserve charge identically and cannot excite the scalar channel. A compensated polarized carrier with a globally neutral anomalous surface layer isolates the channel and gives its dipole flux in closed form. The connection between the adopted flux and a physical stress-energy tensor remains unresolved. These results are conditional predictions of EED and do not imply a failure of charge conservation in classical electrodynamics.
[abstract 31 / 33] (score: 2) - Title: Determining neutral fueling response to RMPs in MAST using a multi-reservoir particle balance model and EMC3 EIRENEAuthors: Kurt Flesch, James Harrison, Andrew Kirk, Ian Waters, Heinke Frerichs, Oliver Schmitz, Livia Casali,Comments: 26 pages, 15 figures, submitted to Nuclear FusionSubjects: physics.plasm-phCreated: 2026-08-19; Updated: 2026-08-21; Datestamp: 2026-08-21
The application of certain configurations of resonant MAGNETic perturbations (RMPs) has been shown to cause a plasma pump-out in both L- and H-mode discharges at MAST. In this paper we discuss the impact of neutral fueling on this density reduction. The neutral fueling and average particle confinement time $τ_p$ of the main ion species were calculated using a 0-D particle balance analysis. When the RMPs were applied, it was found that there was an increase in ionizations and a 15$\%$ reduction in $τ_p$ for L-mode discharges and a similar result for inter-ELM (edge localized modes) periods of H-mode discharges. A time-dependent global multi-reservoir particle balance (MRPB) was developed, which included atomic and molecular reservoirs, to further investigate the role neutrals had on the density change. We discuss how this model was able to accurately reproduce the experimentally measured density reduction and ionization increase due to either a reduction in $τ_p$ or a reduction in particle fueling efficiency. Results from EMC3-EIRENE modeling indicate this change could be attributed to neutral particle fueling occurring in locations with now-opened field lines due to the chaotic edge-region from RMP applications.
[abstract 32 / 33] (score: 2) - Title: Multi-scale Memory and Regime Shift in the Hyperactive Repeating FRB 20240114AAuthors: We-Long Zhang, Sheng-Lun Xie, Jun-Jie Wei, Di Xiao, Long-Xuan Zhang, Shuang-Xi Yi, Fa-Yin Wang, Xue-Feng Wu,Comments: 12 pages, 6 figures, 1 table. Comments are welcome!Subjects: astro-ph.HECreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
We present a statistical analysis of FRB~20240114A, a hyperactive repeating fast radio burst, based on 11,553 bursts detected by FAST over 214 days. Our main findings are fourfold. (1) On the most active day (MJD~60381, 3,197 bursts in 4.38 hr), event-rate coherence analysis reveals persistent correlated activity extending up to 3600~s, the longest reported for any repeating FRB, showing memory persists even in intense bursting epochs. (2) The waiting-time distribution on this day is well described by three exponentials, whereas the full 214-day sample develops a threshold power-law tail, indicating burst statistics depend on the observational baseline, with long-range correlations emerging only over longer timescales, a hallmark of self-organized criticality. (3) Rescaled range (R/S) analysis of waiting times reveals a broken power law, with Hurst exponents $H_1=0.63\pm0.02$ (short-lag weak memory) and $H_2=1.04\pm0.02$ (long-lag non-stationary drift). The break corresponds to $\sim$1 hour, consistent with the 3600~s coherence limit. R/S analysis of energies similarly exhibits a break ($H_1=0.60\pm0.01$, $H_2=1.10\pm0.05$) at a different lag, reinforcing that non-stationarity affects both temporal and energetic properties. (4) Energy distributions exhibit waiting-time-dependent slopes that are consistent with the full and daily samples, and the high-energy cutoff remains constant across waiting-time groups, suggesting that the maximum energy scale is an intrinsic source property. Together, these results establish a multi-scale memory framework: the source behaves stochastically on short timescales but exhibits systemic non-stationarity over months, providing benchmarks for burst models and highlighting the need for long-term, high-cadence monitoring to capture temporal complexity.
[abstract 33 / 33] (score: 2) - Title: Probabilistic kilonova prediction from gravitational wave inferred binary neutron star parametersAuthors: Xiao-Fei Dong, Ik Siong Heng, Gavin P. Lamb, Chris Messenger, Nikhil Sarin, Benjamin Rayson, Nial R. Tanvir, Jessica Irwin, Thomas Wallace, Skye Rosetti, Bo Milvang-Jensen, Andrew J. Levan, Jens Hjorth,Comments:Subjects: astro-ph.HE gr-qcCreated: 2026-08-20; Updated: 2026-08-21; Datestamp: 2026-08-21
Kilonovae provide a key electroMAGNETic window into binary neutron star mergers, revealing the properties of the merging system while probing r-process nucleosynthesis of the Universe. However, only a few kilonova candidates have been detected to date, with AT2017gfo being the only one associated with a gravitational wave event, GW170817. In this work, we present \textsc{Genova}, a probabilistic framework for predicting kilonova spectra and light curves directly from gravitational wave posterior samples of binary neutron star mergers. This method uses a conditional normalising flow to learn the distribution of rest-frame spectra conditioned on the source-frame component masses, tidal deformabilities, viewing angle and time since merger. Other kilonova model parameters, such as ejecta opacities, are marginalised over during training, so that their effects are propagated into the predicted spectra as predictive uncertainty. In the self-consistency test, the flow model reproduces the median light curves with residuals typically below $\sim 0.1$ mag, and the ratio of the predicted central 68\% interval widths remains predominantly between $0.8$ and $1.4$ over $\sim 0.4$--$8.0$ days. Comparisons with a physically distinct kilonova model show that the probabilistic prediction can remain informative beyond the model used for training. We apply \textsc{Genova} to GW170817/AT2017gfo using multi-band observations, including newly re-reduced $Y$-, $J$-, $K_s$-band photometry from the Visible and Infrared Survey Telescope for Astronomy, which we present in this work. The resulting predictive intervals broadly encompass the observations while capturing both gravitational wave posterior uncertainty and the variation induced by marginalised kilonova model parameters.
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