Current date: 2026-07-01
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Number of records retrieved: 261
Keyword score statistics
score 6 -- 1 abstracts
score 5 -- 5 abstracts
score 4 -- 5 abstracts
score 3 -- 4 abstracts
score 2 -- 8 abstracts
in total -- 23 abstracts
Articles that appeared on 2026-07-01
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[abstract 1 / 23] Yes (score: 6)
- Title: The Lifetimes of High-redshift Quasars Suggest Magnetic Disk SupportAuthors: Jarrett Johnson, Phoebe Upton Sanderbeck, Nicole Lloyd-Ronning, Madeline Marshall, Kelcey Davis,Comments: 6 pages, 2 figures, accepted for publication in ApJSubjects: astro-ph.GA astro-ph.COCreated: 2026-06-29; Updated: 2026-07-01; Datestamp: 2026-07-01
It has recently been suggested that a variety of data on ACTIVE GALACTIC NUCLEi (AGN) can be explained if AGN disks are supported against gravitational fragmentation by MAGNETic fields that are advected into the disk from the surrounding galaxy. Here we derive the maximum timescales over which accretion onto a BLACK HOLE (BH) powering an AGN can be maintained at a given rate, both with and without MAGNETic disk support. We then compare these timescales to the lifetimes of episodes of sustained luminous accretion that are inferred from measurements of the photoionized proximity zones around high-redshift QUASARs. While some of the shortest inferred QUASAR lifetimes are consistent with pure gas pressure support, we find that some additional MAGNETic support is likely required to explain the longest inferred QUASAR lifetimes of > 10$^4$ yr. For these longest-lived AGN, we find that MAGNETic pressure in their disks can be up to a hundred times higher than the gas pressure. In addition, the lack of inferred QUASAR lifetimes that are definitively > 10$^6$ yr is consistent with gas pressure and advected MAGNETic fields being the principal sources of disk support. This adds to the body of evidence that MAGNETic fields play an important role in sustaining the rapid growth of supermassive BHs in the early universe.
[abstract 2 / 23] Yes (score: 5) - Title: Comments on the paper "Eliminating beam-induced depolarizing effects in the hydrogen JET target for high-precision proton beam polarimetry at the Electron-Ion Collider"Authors: Andrei Poblaguev,Comments: 5 pages. Comment on arXiv:2508.01366Subjects: physics.acc-phCreated: 2026-06-24; Updated: 2026-07-01; Datestamp: 2026-07-01
A critical review of the methodology used in F. Rathmann et al., Phys. Rev. Accel. Beams 29, 021001 (2026), to evaluate beam-induced dePOLARIZATION of the Atomic Polarized Hydrogen Gas Jet (HJET) target at the Electron--Ion Collider (EIC) is presented. It is shown that several key assumptions underlying that analysis -- including the introduction of a photon emission threshold, the application of FERMI's Golden Rule to coherent hyperfine transitions, the interpretation of power broadening as a physical linewidth increase, and the treatment of spatial MAGNETic fields -- are either incorrect or internally inconsistent. As a consequence, the predicted large dePOLARIZATION effects are demonstrated to be artifacts of the adopted methodology rather than genuine physical phenomena. A consistent quantum-mechanical treatment based on the time-dependent Schrödinger equation shows that beam-induced dePOLARIZATION probabilities at the EIC are negligibly small.
[abstract 3 / 23] Yes (score: 5) - Title: The MAGNETic mayhem in Abell 2199: discovery of SYNCHROTRON threads and homogeneous diffuse radio lobesAuthors: R. Timmerman, L. Rudnick, A. Botteon, G. Brunetti, R. Kale,Comments: Accepted for publication in MNRAS, 12 pages, 11 figuresSubjects: astro-ph.CO astro-ph.GACreated: 2026-06-29; Updated: 2026-07-01; Datestamp: 2026-07-01
Sensitive low-frequency radio observations have started uncovering examples of SYNCHROTRON-emitting threads, isolated from the rest of radio emission in galaxy clusters. As the bridge of radio emission previously detected between the radio lobes of 3C 338 in Abell 2199 is a candidate of such a structure, we observed this galaxy cluster using the International LOFAR Telescope. These observations revealed the presence of multiple narrow isolated SYNCHROTRON threads in 3C 338: east, west and north of the AGN and its radio lobes. Chandra X-ray observations show that these structures most likely do not reside within cavities in the intracluster medium (ICM), and are therefore considered to be distinct structures from the radio lobes. Non-detections in 1.5 GHz Very Large Array observations imply that the spectral index of these newly-discovered isolated threads is likely $α_{1500}^{144} < -3.0$ or steeper. We consider these isolated SYNCHROTRON threads to most likely display examples of MAGNETic threads within the ICM that have captured SYNCHROTRON-emitting plasma, as has recently been proposed. Furthermore, our observations reveal the radio lobes to show an almost perfectly uniform spectral index, unlike what would be expected if substantial age differences are present in the radio lobes according to standard spectral ageing models. We find that the RELATIVISTIC plasma in 3C 338 is consistent with a homogeneous COSMIC RAY electron population, with the spectral variations dependent on the local MAGNETic field strength. Finally, we explore the various models that could explain this trend in the radio lobes.
[abstract 4 / 23] Yes (score: 5) - Title: Prospects for Improving the Theoretical Uncertainty for Tests of General Relativity with the EHTAuthors: Lia Medeiros, George N. Wong, Feryal Ozel,Comments: Submitted to ApJSubjects: astro-ph.HE gr-qcCreated: 2026-06-29; Updated: 2026-07-01; Datestamp: 2026-07-01
We characterize the relationship between the size of the bright ring observed in simulated BLACK HOLE images and the size of the analytic BLACK HOLE shadow. Calibrating this relationship is crucial for mass measurements and, when independent mass measurements are available, for tests of general relativity using Event Horizon Telescope (EHT) images. We perform this calibration using a large set of high-resolution simulated images generated with different accretion-flow modeling approaches and spanning a wide range of system parameters and initial conditions. We show that the theoretical uncertainty in this relationship can be reduced significantly through future observations, improved imaging techniques, and the application of astrophysical or model-based constraints. In particular, the uncertainty decreases compared to existing measurements when (i) observing at 345 GHz, (ii) applying geometric image constraints, such as the ring width inference from the PRIMO image reconstruction algorithm, (iii) incorporating astrophysical constraints such as the BLACK HOLE spin axis in M87 being aligned (or anti-aligned) with the large-scale JET observed at longer radio wavelengths, and (iv) assuming that the accretion flow can be described by a MAGNETically arrested field configuration. Finally, we quantify how the uncertainty is expected to decrease as additional observations are obtained in subsequent years and identify dwell-time filtering, i.e., evaluating the persistence of a geometric measurement over time, as a promising avenue for improving the precision of the calibration.
[abstract 5 / 23] Yes (score: 5) - Title: Active Galactic Nuclei as high-energy neutrino sourcesAuthors: Filippo D'Ammando,Comments: Invited review article for The Astronomy and Astrophysics Review. Accepted for publication. 59 pages, 25 figuresSubjects: astro-ph.HE astro-ph.GACreated: 2026-06-29; Updated: 2026-07-01; Datestamp: 2026-07-01
Identifying the sources of the high-energy astrophysical neutrinos has been one of the main topics in astrophysics since the first observation of high-energy neutrinos by the IceCube Neutrino Observatory. Active Galactic Nuclei (AGN) are sources of high-energy gamma-rays and are considered to be promising candidates to be sources of high-energy neutrinos and ultra-high energy COSMIC RAYs as well. However, several studies suggest that the neutrino emission from the $γ$-ray BLAZAR population only accounts for a small fraction of the total astrophysical neutrino flux. We present and discuss recent results on the search for correlations between astrophysical neutrinos and both gamma-ray and radio bright AGN. The IceCube Collaboration has reported high-energy neutrino events that may come from both the radio-loud AGN TXS 0506+056 and the radio-quiet AGN NGC 1068. Other cases of possible associations between high-energy neutrino events and individual BLAZARs were claimed with controversial results. We discuss the properties of these sources together with the different neutrino production mechanisms proposed for those sources. Finally, we outline future prospects in the field, focusing on remaining open questions, the development of upcoming neutrino facilities, and the evolving multi-frequency landscape within the multi-messenger era.
[abstract 6 / 23] Yes (score: 5) - Title: Coherent and Incoherent Emission from the Ordered Magnetospheres of Low-Mass Stars, UCDs, and Massive StarsAuthors: Francesco Cavallaro, Paolo Leto, Barnali Das, Corrado Trigilio, Grazia Umana, Cristobal Bordiu, Filomena Bufano, Carla S. Buemi, Joseph R. Callingham, Laura Driessen, Adriano Ingallinera, Sara Loru, Stanley Owocki, Simone Riggi, Alan C. Ruggeri, Giovanni Sabatini, Matt E. Shultz, Alessio Traficante,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/Cavallaro01. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopesSubjects: astro-ph.SRCreated: 2026-06-29; Updated: 2026-07-01; Datestamp: 2026-07-01
Massive early-type (B/A) stars and ultracool dwarfs (UCDs) represent two distinct regimes in which ordered, large-scale MAGNETospheres are observed. In rapidly rotating massive stars, incoherent radio emission is explained by the centrifugal breakout (CBO) mechanism: plasma confined within the rigidly rotating MAGNETosphere accumulates beyond the co-rotation radius, where centrifugal forces trigger breakout events and MAGNETic RECONNECTion, generating non-thermal electrons that produce incoherent gyro-SYNCHROTRON emission. Empirically, the radio luminosity correlates with the power released by CBO events, establishing a clear link between stellar rotation, MAGNETic confinement, and radio output. In UCDs, persistent non-thermal radio emission exhibits similar luminosity trends to those of massive MAGNETic stars, despite the absence of strong stellar winds. This similarity suggests that a CBO-like process may also operate in these fully convective, low-mass objects, though the plasma source and acceleration mechanisms remain uncertain. In both classes, coherent electron cyclotron maser emission (ECME), characterized by strong POLARIZATION and rotational modulation, is observed, indicating common MAGNETospheric processes analogous to planetary auroral emission. The Square Kilometre Array (SKA) will be able to deeply observe about 70\% of the sky. We expect to observe $\sim 1000$ UCDs, enabling better statistical analysis of their emission and a test of the CBO hypothesis.
[abstract 7 / 23] Yes (score: 4) - Title: Line-Tied Flux Rope Relaxation and Reconnection: A 3D Kinetic Case StudyAuthors: Joshua Pawlak, James Juno, Jason M. TenBarge,Comments: 17 pages, 10 figures, accepted for publication to Physics of PlasmasSubjects: physics.plasm-phCreated: 2026-06-29; Updated: 2026-07-01; Datestamp: 2026-07-01
Magnetic flux ropes are ubiquitous MAGNETic structures found in plasmas ranging from astrophysical to laboratory. We employ a newly-developed parallel-kinetic-perpendicular-moment (PKPM) model to simulate the 3D interaction and evolution of two line-tied flux ropes at realistic laboratory plasma parameters, while retaining essential parallel kinetic physics in the system. We find that ropes undergo a current-dependent transition from a diaMAGNETic to paraMAGNETic regime, which we quantify with a simple analytic model. Although the macroscopic structural evolution qualitatively differs significantly between these regimes, analyzing the RECONNECTion in proper field-aligned coordinates reveals that the underlying kinetic dynamics remain similar. Using the squashing factor and quasi-potential as diagnostics of 3D MAGNETic RECONNECTion, we identify the formation of a quasi-separatrix layer and show that these quantities provide consistent metrics for RECONNECTion rate and structure.
[abstract 8 / 23] Yes (score: 4) - Title: Hunting Wandering 3[abstract 9 / 23] Yes (score: 4)Authors: Urvi Thakurdesai, Anthony J. Taylor, Steven L. Finkelstein, Gene C. K. Leung, Oscar A. Chavez Ortiz, Jonathan R. Trump, Bren E. Backhaus, Nikko J. Cleri, Francesco D'Eugenio, Fabio Pacucci, Anton M. Koekemoer, Pablo Arrabal Haro, Micaela Bagley, Mark Dickinson, Jeyhan Kartaltepe, Casey Papovich, Nor Pirzkal,Comments: 15 pages, 8 figures, 1 table. Accepted for publication in ApJSubjects: astro-ph.GACreated: 2026-06-29; Updated: 2026-07-01; Datestamp: 2026-07-01
The early growth and assembly of supermassive BLACK HOLEs (SMBHs) remain key topics of interest in galaxy evolution. One of the scenarios predicted by theoretical models is that frequent minor mergers and asymmetric gas inflows may cause SMBHs to temporarily reside off-center within their host galaxies in the early universe. To observationally test this scenario, we investigate whether spatially offset ionization signatures-which may be indicative of ACTIVE GALACTIC NUCLEi (AGN)-can be identified. Using JWST NIRSpec PRISM spectroscopy from the Cosmic Evolution Early Release Science (CEERS) survey, we analyze the 2D spectra of 90 high-redshift galaxies (3 < z < 8), including two known broad-line AGN. By measuring key emission lines such as Hα, H\b{eta}, [OIII]λ5007, [NeIII]λ3868, and [OII]λλ3727, 3729 we derive spatial flux ratio profiles, and focus on [OIII]/Hβ as a tracer of high-ionization mechanisms that may indicate AGN activity. We identify 26 galaxies (~30% of the sample) with significant localized peaks in [OIII]/Hβ. Out of these 26 galaxies, 12 sources (~46%) exhibit significant spatial offsets between the peak [OIII]/Hβ ratio and the stellar continuum center. Six of these sources show the highest amount (> 1.5) pixel spatial offsets. This spatial offset between ionization structure and stellar centers offers a promising avenue to probe early SMBH evolution and its connection to galaxy formation.
arXiv:2606.30742 [pdf, ps, other]Extended Ly$α$ emission is ubiquitous around QUASARs and traces cool circumgalactic gas, providing insight into halo gas dynamics and ACTIVE GALACTIC NUCLEi (AGN) feedback. However, its connection to the cold molecular gas of the host galaxies remains largely unexplored. We aim to characterize the molecular gas reservoirs in QUASARs at cosmic noon and investigate how they are linked to extended Ly$α$ emission. To this end, we present ALMA CO(4-3) observations of 37 QUASARs at $z\sim3$ from the QSO MUSEUM survey, previously mapped in Ly$α$ with VLT/MUSE. We derive molecular gas masses and gas fractions, explore correlations with Ly$α$ nebula and QUASAR properties, and search for CO-emitting companions. Of 37 QUASARs, 21 are detected in CO(4-3), with gas masses $M_\mathrm{gas}\approx(3-40) \times10^9\,\mathrm{M_\odot}$. Quasars with the most massive molecular gas reservoirs are associated with the centrally dimmest Ly$α$ nebulae, while those hosting the centrally brightest Ly$α$ nebulae are generally not detected in CO. This suggests that gas and dust in the hosts regulate Ly$α$ escape and consequently affect the emission from halo gas. We find evidence that QUASARs with lower Eddington ratios harbor more massive gas reservoirs, whereas strongly accreting QUASARs ($λ_\mathrm{Edd} \gtrapprox 0.9$) likely deplete their gas through QUASAR-driven outflows. Despite their higher molecular gas masses within the sample, CO-detected low-Eddington QUASARs exhibit low gas fractions, with a median $M_\mathrm{gas}/M_* \sim 0.10$, below those typical of inactive star-forming galaxies. Six QUASARs are marginally resolved in CO, with effective radii up to $\sim 8\,\mathrm{kpc}$. In addition, we detect 14 high-fidelity companion galaxies, indicating overdense QUASAR fields with a QUASAR-galaxy cross-correlation length of $9.81^{+2.22}_{-2.05}\,h^{-1}\mathrm{cMpc}$.
arXiv:2606.30839 [pdf, ps, other]We aim to characterize the post-collapse evolution of accretion-induced collapse (AIC) remnants of rapidly rotating, MAGNETized white dwarfs, focusing on their rotational, MAGNETic, and thermal structure, as well as the development of instabilities and their energy content. We perform nine axis-symmetric general-RELATIVISTIC neutrino MAGNETohydrodynamic (MHD) simulations of collapsing, rapidly rotating, MAGNETized white dwarfs. The simulations follow the system from collapse through bounce and up to $\sim$1 s post-bounce. The simulations are performed by the conformally flat general RELATIVISTIC neutrino MHD code \texttt{Gmunu}. The collapse produces a rapidly rotating proto-MAGNETar surrounded by a persistent accretion disk lasting at least $\sim 1$ s after bounce. The remnant mass and spin span 1.15--1.45 $M_{\odot}$ and 2.9--4.9 kHz, respectively, with stronger initial MAGNETic fields generally leading to lower rotation rates. During the first $\sim 10$ ms, the proto-MAGNETar exhibits global oscillations that drive both gravitational-wave emission and coherent modulation of the poloidal MAGNETic field energy. The MAGNETic energy evolution, normalized to its bounce value, follows an approximately universal behavior across all models. The remnant interior remains strongly MAGNETized ($\gtrsim 10^{13}$ G) and hot ($\gtrsim 20$ MeV) up to 1 s after bounce, with maxima of both quantities co-located in the inner $\sim 10$ km. The MAGNETic field topology shows surface poloidal fields of ${\sim}10^{12}$ G and toroidal fields of ${\sim}10^{14}$ G, with strong toroidal components extending into the equatorial region. When the MAGNETic energy exceeds the rotational energy ($\sim 10^{52}$ erg), the remnant core becomes unstable, leading to episodic MAGNETic flux expulsion, mass ejection, and flare-like activity in which MAGNETic energy is released and thermalized in the surrounding material.
arXiv:2606.30990 [pdf, ps, other]We develop a new analytical model describing the radiative and dynamical structure of an accretion-powered X-ray pulsar, including RELATIVISTIC effects and a detailed representation of the rotational and MAGNETic geometry of the neutron star and the two accretion columns. The model provides for the first time a simultaneous calculation of both the phase-averaged spectrum and the pulse profile for an accretion-powered X-ray pulsar. The X-ray continuum spectrum is calculated using the analytical model of Becker & Wolff (2022), which assumes a conical accretion column geometry. The trajectory of the radiation escaping from the two columns is tracked through the curved spacetime using the Schwarzschild metric. The angular distribution of the radiation escaping from the surfaces of the columns (the beaming pattern) is represented using a set of "LASER-like" emission directions, with associated amplitudes, called weight coefficients, that each contribute "sub-profiles" to the observed pulse profile. The sub-profiles provide basis functions that are used to fit the observed pulse profile. This yields a set of weight coefficients that determine the beaming pattern of the emission from the accretion column. We use the new model to analyze NUSTAR data for Her X-1, allowing the determination of the temperature, accretion rate, and MAGNETic field strength, as well as the rotational inclination angle and the latitudes of the two MAGNETic poles. The method also yields the beaming pattern of the emission, hence providing for the first time a self-consistent phenomenological description of the physical and radiative structures of the two accretion columns.
arXiv:2604.21759 [pdf, ps, other]We model the multi-band lightcurves of 80 SNe Ic-BL, including 11 associated with lGRBs, using a MAGNETar engine model with $^{56}$Ni decay. We find that the data are all consistent with a MAGNETar central engine, and such a model yields high-quality fits across the sample. The medians with $1σ$ regions of the key parameters are $P_{\rm{i}}\sim2.04^{+1.84}_{-0.96}\,{\rm{ms}}$, $B_{\rm{p}}\sim3.96^{+3.28}_{-1.40}\times10^{15}\,{\rm{G}}$, $M_{\rm{ej}}\sim2.30^{+1.48}_{-1.02}\,M_\odot$, and $M_{\rm{Ni}}\sim0.18^{+0.14}_{-0.09}\,M_\odot$, with strong and statistically significant correlations observed for both $M_{\rm{ej}}-P_{\rm{i}}$ (anti-correlation) and $M_{\rm{Ni}}-M_{\rm{ej}}$ (correlation). Comparing the SN Ic-BL samples with and without lGRB association using fitting parameters, we find no significant difference between them, although the GRB-associated sample is slightly brighter, possibly due to an observational bias. Relative to ordinary SNe Ic, SNe Ic-BL have similar $^{56}$Ni and ejecta masses, suggesting comparable pre-SN progenitor properties, with differences possibly arising from the presence of a MAGNETar engine. In comparison with other possible MAGNETar-powered SESNe, including SLSNe Ic and FBOTs, we confirm a strong universal $M_{\rm{ej}}-P_{\rm{i}}$ correlation, indicating a common origin. SNe Ic-BL and SLSNe Ic have similar ejecta mass distributions, typically $M_{\rm ej}\gtrsim0.5\,M_\odot$, while FBOTs mostly lie below this value. Differences between SNe Ic-BL and SLSNe Ic may arise from MAGNETar properties, with SN Ic-BL MAGNETars rotating faster and having stronger fields. Moreover, the $P_{\rm{i}}-B_{\rm{p}}$ distribution of lGRB MAGNETars largely overlaps with that of SN Ic-BL MAGNETars. In connection with binary simulation results, we propose a unified physical classification and progenitor framework for MAGNETar-powered and ordinary SESNe.
arXiv:2606.30727 [pdf, ps, other]The search for and the characterization of ultra-compact dual ACTIVE GALACTIC NUCLEi (AGN) are among the hottest topics of current extragalactic astrophysics. These systems involve two accreting massive BLACK HOLEs (MBHs) embedded within the same host galaxy, with relative projected separations from a few hundred pc down to a few pc. They are central to understanding hierarchical galaxy formation, BLACK HOLE growth and demographics, and accretion-feedback coupling in the most extreme interaction phases. Even more compellingly, such tight pairs are the most direct precursors of gravitationally bound binary MBHs (sub-pc scale separation), which are among the loudest emitters of gravitational waves (GWs) in the low-frequency ranges. SHARP will deliver the first statistical census and physical characterization of ultra-compact dual AGN up to cosmic distances, finally bridging the observational gap between kpc-scale pairs and sub-pc GW-emitting binaries, and enabling a breakthrough understanding of MBH growth, feedback and co-evolution across cosmic time.
arXiv:2606.30757 [pdf, ps, other]The advent of JWST has revealed a large population of AGN at $z>4$, which are $\sim1$ dex more abundant than previously expected, including also the enigmatic population of Little Red Dots (LRDs). Remarkably, the vast majority of JWST-discovered AGN and LRDs are not detected in X-rays, and most of them also show faint rest-frame UV continua and faint high-ionization emission lines, as well as unusually faint emission in the Mid and Far infrared. Recent studies investigating their radio properties have reported no significant detections, even in deep stacking analyses, reaching sensitivities of 0.5-0.1 $μ$Jy at $z\sim 5-6$, corresponding to $L_{R}\lesssim 10^{39}\rm \ erg\ s^{-1}$. While these non-detections may be consistent with a standard radio-quiet nature, some results suggest that the radio emission might instead be significantly suppressed by other physical phenomena. Three main scenarios have been proposed in the literature to explain the physical properties of these objects across the electroMAGNETic spectrum: Compton-thick absorption by a broad-line region with high covering-factor, intrinsically weak emission driven by high accretion rates, or the presence of a cocoon of dense ionized gas that produces strong scattering effects. The unprecedented sensitivity of SKAO will enable the detection of the radio emission of these AGN in all three cases. Because each scenario is expected to produce distinct radio signatures, future SKAO continuum surveys will be able to distinguish between them, uncovering the physical processes responsible for their peculiar properties. Observations spanning a wide range of integration times (1-1000 hours) and frequencies with SKA-Mid and SKA-Low (0.2-11 GHz) will allow us to characterize these objects from the local Universe to high redshift, investigate possible radio variability, and test alternative scenarios to BLACK HOLE accretion.
arXiv:2606.30894 [pdf, ps, other]Reflection off the companion star and its focused stellar wind is predicted to modulate the X-ray POLARIZATION of BLACK HOLE X-ray binaries at half the orbital period ($P_{\rm orb}/2$), with an energy-dependent amplitude. We test this prediction against all publicly available IXPE observations of Cygnus X-1, comprising 26 one-day bins from 12 observation IDs spanning 2022-2024. Since the normalized Stokes parameters correlate linearly with the spectral hardness ratio in all three energy bands (2-4, 4-6, and 6-8 keV), we employ a simultaneous harmonic regression that decouples spectral variability from orbital modulation at both $P_{\rm orb}/2$ and $P_{\rm orb}$, complemented by direct fitting of 3D Monte Carlo radiative transfer stellar companion and wind-scattering templates. After removing the spectral hardness trend, neither approach reveals statistically significant orbital modulation: permutation tests yield $p > 0.01$ in all bands, with 99% confidence upper limits of 0.47%, 0.67%, and 1.81% on the $P_{\rm orb}$ amplitude and 0.54%, 0.77%, and 2.13% on the $P_{\rm orb}/2$ amplitude in the 2-4 keV, 4-6 keV, and 6-8 keV bands, respectively. The best-fit stellar companion and wind-scattering amplitude scaling factors in the three bands of $A = $ 0.78$\pm$0.89, 0.96$\pm$0.62, and $-$1.02$\pm$1.11 are consistent with a null result. These non-detections are sensitivity-limited, as the predicted stellar companion and wind-scattering RMS amplitudes in the three bands of $\approx$0.10%, $\approx$0.33%, and $\approx$0.49% are at or below the statistical noise floor of $\sim$0.15%, $\sim$0.31%, and $\sim$0.84%. We quantify the additional exposure required to detect the predicted signal and constrain the wind physics.
arXiv:2602.22370 [pdf, ps, other]Ultracold neutral plasmas provide a useful system for studying extreme parameter regimes plasma physics in an accessible laboratory setting. The parameter space of plasma physics can be characterized in part by coupling strength and degree of MAGNETization. The range of achievable strong coupling is determined in part by the lowest possible temperatures that can be achieved. This work examines the early-lifetime electron heating of moderately coupled, strongly MAGNETized plasmas. This heating is dominated by disorder-induced heating and heating due to Rydberg atom formation. By using experimentally informed simulations, it is found that disorder-induced heating has a large influence in electron temperature well into the plasma lifetime. Additionally, the dependence of the minimum achievable electron temperature on MAGNETization and initial electron energy is examined. In this work, we find electron temperatures as low as $0.52^{+.10}_{-.05}\ \mathrm{K}$ (for electron density, $n_{e}$, of $6.1 \times 10^{12}\ \mathrm{m^{-3}}$), which determines the maximum coupling strength for the measured experimental conditions.
arXiv:2605.14065 [pdf, ps, other]The interaction of electrically charged particles with MAGNETic fields is a fundamental problem in several areas of physics. An example is the motion of energetic particles through a MAGNETized plasma. The most accurate and reliable way to explore theoretically the interactions between particles and fields is via test-particle simulations. In such simulations one creates the turbulent MAGNETic field and solves the Newton-Lorentz equation numerically by employing an integration scheme. In the current article we discuss exponential integrators and derive systematically from this the Rodrigues scheme as well as the famous Boris integrator. For an approach where one creates the MAGNETic field anew at each time step, both integrators are overall comparable. In theory the Rodrigues approach should be more accurate due to the fact that the occurring matrix exponential is evaluated without further approximations. Practically, both methods provide very similar results. It is argued in the current article that a Rodrigues based integrator is a very strong alternative because for the specific problem discussed here, it does not require longer computing times.
arXiv:2605.18973 [pdf, ps, other]The association of broad-lined Type Ic SUPERNOVAe with long-duration GAMMA-RAY BURSTs (GRBs) has been known for 28 years. However, only about seventy GAMMA-RAY BURST SUPERNOVAe (GRB-SNe) have been identified, of which only half have spectroscopic classifications. At $z=0.153$, GRB 260310A is the 12th spectroscopically confirmed GRB-SN discovered within 1 Gpc, offering a critical opportunity to follow one of these rare SUPERNOVAe in detail. We present optical to near-infrared imaging and spectroscopy of GRB 260310A and SN 2026fgk out to 65 d after discovery. The optical afterglow is among the brightest ever observed from a GRB. Spectra obtained more than two weeks after the explosion reveal broad absorption features that securely identify SN 2026fgk as a Type Ic-BL SUPERNOVA. Modeling of the multi-wavelength ($grizJK_s$) lightcurve shows that the SUPERNOVA is approximately half the luminosity ($k_\textrm{98bw}=0.4-0.6$) of the canonical GRB-SN 1998bw. We derive a nickel mass of $M_\textrm{Ni}=0.4-0.5$ $M_\odot$ with a total ejected mass of $M_\textrm{ej}\approx4-6 $ $M_\odot$ and kinetic energy $E_\textrm{K}=(3-8)\times10^{51}$ erg. The GRB exploded at an extremely large offset of 15 kpc from its host galaxy. Long-slit spectra reveal a ``bridge'' of nebular emission extending along the galaxy's disk to the GRB location, which has a sub-solar metallicity ($\sim$\,$0.4Z_\odot$), compared to a near solar metallicity for the host galaxy. This indicates that the large offset arises from the galaxy's extended light profile rather than an isolated environment.
arXiv:2606.30711 [pdf, ps, other]JWST's Little Red Dots (LRDs) display a unique constellation of features that do not occur simultaneously in any other class of galaxies or AGN. Here we observe that many of these features find parallels in the 19th century Great Eruption (GE) of $η$ Carinae and a sub-class of SUPERNOVAe (Type IIn). Drawing on these stellar phenomena -- outflows trapped by dense circumstellar gas envelopes -- we sketch a possible scenario for LRDs. Outflows from the central engine produce an enshrouding envelope of gas that may be thought of as a slow wind. This dense wind and its enormous extent produce an opacity so high that a pseudo-photosphere forms within the wind, obscuring the central engine and manifesting as a blackbody-like continuum. Radiation from the buried engine powers the system. The engine may also launch fast winds that crash into the existing envelope to generate shocks. Lines form within the wind above the photosphere -- electron scattering and absorption in the clumpy (ionized + neutral) medium account for broad wings and P-Cygni cores. A key implication is that inferences of ``overmassive BLACK HOLEs" may be interpreting this wind-like physics as a virial broad-line region. We propose an escape velocity argument to constrain the mass of the engine, which yields $M<10^{5} M_\odot$ for the typical LRD. The lack of variability and low surface gravity of the photosphere provide further support for intermediate mass ($M\approx10^{3-6} M_\odot$), but very luminous super-Eddington ($L_{\rm{bol}}/L_{\rm{edd}}\gtrsim5$) systems harboring a supermassive star or intermediate mass BLACK HOLE. Paralleling the evolution of IIn SNe, dust production in the envelope may mark the beginnings of classical AGN. This paper explores a possible self-consistent explanation for the entire life-cycle of LRDs, from their enshrouding in dense gas to their fates as seeds of massive BLACK HOLEs.
arXiv:2606.30726 [pdf, ps, other]While AGN feedback is a key driver of massive galaxy evolution, its physical properties and observational signatures in the dwarf regime remain poorly understood. We investigate the impact of AGN-driven outflows on the ISM of dwarf galaxies and assess whether these events can be robustly identified through emission-line diagnostics. We analysed a high-resolution cosmological MAGNETo-hydrodynamical zoom-in simulation from the AURIGA project. We focused on a dwarf galaxy with 1e9.7 M*/Msun hosting a BH of 1e7 Msun. We identified individual outflow episodes via pressure peaks in the gas surrounding the central BH, tracked the thermodynamic and kinematic history of such gas, and computed synthetic, spatially resolved nebular emission using photoionisation models to construct BPT diagnostic diagrams. We show that AGN activity in this regime produces compact, over-pressurised central bubbles reaching >1e6 K temperatures. These structures accelerate the ISM up to 600km/s, exceeding those driven by stellar feedback: the outflowing material does not escape the halo, but instead decelerates and redistributes within 10kpc from the galaxy center. Synthetic emission-line modelling reveals clear, time-dependent signatures of such AGN-driven feedback. Over its life cycle, the simulated AGN-hosting galaxy traces the locus of observed dwarf AGNs and migrates from the SF sequence in the BPT diagrams through the composite region into the AGN regime, highlighting a self-regulation mechanism in which the BH accretes its fuel supply, progressively moving towards the low-ionisation nuclear region. Our results suggest that AGN-driven outflows in dwarfs primarily regulate the central ISM through episodic heating and rapid gas recycling, rather than large-scale gas ejection. These processes generate observable spectroscopic signatures, offering a promising avenue for identifying AGN feedback in low-mass galaxies.
arXiv:2606.30886 [pdf, ps, other]We investigate the multipolar surface MAGNETic-field structure of the high-mass millisecond pulsar PSR J0740+6620 using the 32-bin bolometric NICER pulse profile of Dittmann et al. (2024). Building on the neural-network surrogate framework of Olmschenk et al. (2025), we model the emitting regions as open-field-line footpoints of an offset dipole plus axisymmetric quadrupole static vacuum field, rather than as prescribed geometric hotspots. We fix the stellar mass, radius, observer inclination, and hotspot temperature ratio to the Dittmann et al. (2024) maximum-likelihood values and explore the resulting 11-dimensional MAGNETic-field space. To make this feasible, we train convolutional neural-network surrogates on $5.12\times10^7$ synthetic bolometric light curves and use them in a parallel ensemble Markov Chain Monte Carlo calculation on 4000 CPU cores, accelerating likelihood evaluations by a factor of $\gtrsim 400$. We perform independent inferences for two calibrated temperature-weight prescriptions, Tw=1.31 and Tw=1.41, encoding the relative bolometric weight associated with the hotspot temperature difference. The posteriors, posterior-predictive light curves, and maximum-likelihood values are very similar, indicating weak sensitivity to this choice. The offset model reproduces the observed double-peaked profile and yields broad, multimodal posteriors, reflecting both the background-dominated data and degeneracies of the multipolar parameterization. The hotspot-density map shows that pulse phases constrain the approximate azimuthal placement of the emission, while latitude, surface extent, and morphology remain weakly constrained. A restricted zero offset run is disfavored within the adopted field basis. This work extends neural-network-accelerated MAGNETic-field inference to PSR J0740+6620 and motivates future energy-dependent, force-free, and joint X-ray/$γ$-ray extensions.
arXiv:2606.30969 [pdf, ps, other]We investigate the repetitive Penrose process for charged particles in an initially extremal Kerr--Newman BLACK HOLE and develop a nonlinear iterative framework in which the black-hole mass, angular momentum, electric charge, and irreducible mass are updated after every extraction event. By imposing the triple turning-point condition, we obtain an analytic solution of the conservation equations, allowing the entire extraction sequence to be followed self-consistently. The dynamics are governed by two electroMAGNETic couplings. The coupling $\hat Q\hat q_0$ determines whether the incident particle can continue to access the ergoregion and therefore controls the termination of the repetitive process, whereas $\hat Q\hat q_1$ governs the depth of the negative-energy states and the extraction efficiency. An attractive interaction ($\hat Q\hat q_1<0$) significantly enhances both the energy return on investment and the energy utilization efficiency and, above a critical charge, produces a transient increase of the dimensionless spin despite the continuous loss of angular momentum. We identify a four-region structure in the captured-particle charge parameter space. Near the critical charge $\hat q_1\simeq-54.85405$, the evolution approaches the reversible Christodoulou--Ruffini limit with the energy utilization efficiency approaching unity while the BLACK HOLE remains sub-extremal. Beyond this point the irreducible mass decreases, indicating the breakdown of the test-particle approximation. Unlike the repetitive Penrose process in the extremal Reissner--Nordström spacetime, the Kerr--Newman BLACK HOLE can evolve through the neutral state and reverse the sign of its electric charge without violating the area theorem or cosmic censorship, demonstrating that the discharge barrier found in the Reissner--Nordström case is not a generic property of charged BLACK HOLEs.
arXiv:2606.31035 [pdf, ps, other]Title: Nonlinear Landau Collisions Without Collision TensorsAuthors: R. Jorge, B. Herfray, C. Vega, V. Zhdankin,Comments: 6 pages, 3 figuresSubjects: physics.plasm-phCreated: 2026-06-30; Updated: 2026-07-01; Datestamp: 2026-07-01Far-from-equilibrium plasmas require nonlinear Coulomb collisions, but direct three-dimensional Hermite discretization of the Landau operator needs an impractical dense tensor. By porting quantum chemistry Coulomb-integral methods, we reduce the six-dimensional integrals to one-center Coulomb moments and separable exponential-sum contractions. This gives a four-order-of-magnitude working-memory reduction and enables nonlinear relaxation tests. Numerical simulations preserve invariants and show that finite-basis linearization changes relaxation and produces a fourfold angular error.
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