Current date: 2026-08-03
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Datestamp limit: 2026-08-03 (0 days ago)
Created/updated limit: 2026-07-27 (7 days ago)
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Scoring abstracts
Number of records retrieved: 665
Keyword score statistics
score 6 -- 3 abstracts
score 5 -- 2 abstracts
score 4 -- 4 abstracts
score 3 -- 8 abstracts
score 2 -- 14 abstracts
in total -- 31 abstracts
Articles that appeared on 2026-08-03
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[abstract 1 / 31] Yes (score: 6)
- Title: XRF 241001A/SN 2024aiiq: A faint soft X-ray transient detected by SVOM with a broad-line type Ic SUPERNOVA revealed by JWSTAuthors: B. Schneider, M. Brunet, B. P. Gompertz, D. Turpin, D. B. Malesani, O. Godet, A. J. Levan, F. Daigne, N. Sarin, N. A. Rakotondrainibe, A. Martin-Carrillo, J. T. Palmerio, C. C. Thöne, H. L. Li, A. Saccardi, A. de Ugarte Postigo, S. Antier, V. Buat, D. Ďurovčíková, L. Izzo, J. K. Leung, G. Mo, Y. L. Qiu, S. D. Vergani, J. Wang, J. Y. Wei, L. P. Xin, R. Mochkovitch, B. Zhang, H. B. Cai, S. Campana, A. Coleiro, B. Cordier, P. D'Avanzo, N. Dagoneau, V. D'Elia, Y. W. Dong, D. Götz, S. Guillot, X. H. Han, D. H. Hartmann, L. Huang, Y. F. Huang, P. Jakobsson, A. Klotz, C. Lachaud, E. Le Floc'h, X. M. Lu, P. Maggi, M. De Pasquale, F. Piron, R. Salvaterra, S. Schanne, J. Sollerman, N. R. Tanvir, Z. Vidadi, P. Wang, C. Wu, S. L. Xiong, Y. Xu, T. Zafar, P. P. Zhang, S. N. Zhang, S. J. Zheng,Comments: 24 pages, 16 figures. Accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
X-ray flashes (XRFs) are a type of GAMMA-RAY BURST (GRB) with prompt emission predominantly below 30 keV and have been poorly detected by previous missions. The advent of the SVOM mission, with its wide-field instrument ECLAIRs, provides a new way to detect soft X-ray transients. We present photometric and spectroscopic observations of XRF 241001A detected by SVOM, a soft, subluminous, and low-energetic burst located in a poorly populated region of the Amati relation. We investigated the origin of its faint, soft high-energy emission to assess its connection to the long GRB population. We analyzed the SVOM/ECLAIRs prompt emission and modeled its afterglow emission from X-ray to-radio. We present JWST/NIRSpec and SVOM/VT observations of the associated SUPERNOVA (SN 2024aiiq), and we compared its properties with previously detected GRB/SNe. The event XRF 241001A is located at z = 0.573 and has a prompt emission dominated by photons below 20 keV with a duration of T90 = 3.14 seconds. Its spectrum is consistent with both thermal and nonthermal models, each implying a low Epeak < 10 keV and Eiso ~ 8x10^49 erg. The X-ray-to-radio afterglow modeling favors an origin from a RELATIVISTIC JET viewed on-axis. In the optical, XRF 241001A exhibits an early blue emission, similar to that detected in some eFXTs and inconsistent with SYNCHROTRON emission. The JWST/NIRSpec observations firmly established its collapsar origin by revealing a SN Type Ic with broad lines, comparable to SN 1998bw and SN 2025kg-like events. The event XRF 241001A is a soft low-luminosity collapsar event produced by a weak RELATIVISTIC JET observed on-axis, supporting the view that part of the XRF population forms the low-energy soft tail of the long GRB population. Its observation demonstrates the potential of SVOM/ECLAIRs to probe the soft regime of the high-energy transient population that remains largely unexplored.
[abstract 2 / 31] Yes (score: 6) - Title: Peering through the dip: IXPE unveils the extended scattering environment of GX 13+1Authors: Alessandro Di Marco, Fabio La Monaca, Luigi Stella, Anagha P. Nitindala, Alexandra Veledina, Anna Bobrikova, Eleonora Veronica Lai, Alessandro Papitto, Maura Pilia, Juri Poutanen, Daniele Rogantini, Matteo Bachetti, Maria Cristina Baglio, Caterina Ballocco, Ettore Del Monte, Wei Deng, Giulia Illiano, Vladislav Loktev, Sara Motta, Fei Xie,Comments: Submitted on A&ASubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-08-03; Datestamp: 2026-08-03
Neutron star low-mass X-ray binaries feature complex accretion geometries, often including an accretion disk corona or disk winds. Here, a study of the highly inclined dipping source GX 13+1, using coordinated observations from the IXPE, NUSTAR, and SWIFT-XRT, is presented; this is the first time that such a campaign was conducted to monitor its periodic dip. Our analysis reveals significant variations in polarimetric properties tracking the dip. At the center of the dip, the POLARIZATION degree reaches a maximum of ${\sim}$9% (at more than $8σ$ confidence level). This is accompanied by a highly significant POLARIZATION angle rotation of roughly 60$^\circ$ when passing from the dip to the subsequent off-dip state. Furthermore, the dip state exhibits energy-dependent POLARIZATION. By modeling the POLARIZATION during the periodic dip, we constrain the geometry of the scattering medium. In the scenario of an oblate extended accretion disk corona (ADC), an equatorial radius at least 1.5 times its polar radius is needed with $τ{\sim}0.3$. Alternatively, the results can be modeled as scattering in a disk wind with a most probable electron density of $1.3\times10^{14}$ cm$^{-3}$ and an opening angle near 40$^\circ$, corresponding to an optical depth of ${\sim}0.2$. The obtained results highlight the crucial role of X-ray polarimetric data to unveil the geometry of the extended scattering environment surrounding the accretion disks, advancing our understanding of neutron star low-mass X-ray binaries.
[abstract 3 / 31] Yes (score: 6) - Title: Strongly Magnetized Super-Eddington Accretion: How Spin and Accretion Rate Regulate Energy Output and Mass LossAuthors: Tom Man Kwan, Lixin Dai, Cheuk Kwan Kan, Zepei Xing, Tassos Fragos, Matthew Middleton, Tao Ji, Feng Yuan,Comments: 15 main figures, 4 tables, submittedSubjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
Strongly MAGNETized super-Eddington accretion flows power many important astrophysical systems, but how BLACK HOLE parameters control their output is unclear. We present 32 general RELATIVISTIC radiation MAGNETohydrodynamics simulations of super-Eddington MAGNETically arrested disks onto stellar-mass BLACK HOLEs, varying mass ($M_{\rm BH}= 5, 15, 30\,M_{\odot}$), spin ($a=0,0.9$), and accretion rate ($\dot{M}_{\rm acc} \approx 1-2000\,\dot{M}_{\rm Edd}$). We find that BLACK HOLE spin and accretion rate jointly regulate wind loss rates and energy output efficiencies, while BLACK HOLE mass has no effect over the mass range studied here. The BH accretes only $10-40\%$ of the mass supplied to the accretion flow, while the rest is expelled in winds. This accretion fraction decreases with mass supply rate and is lower for high-spin systems. Both spin states produce strong MAGNETically driven outflows. For $a = 0$, the wind kinetic, radiative, and electroMAGNETic efficiencies are modest and show little variation across the full simulated range of accretion rates. For $a = 0.9$, both wind power and JET power increase super-linearly with $\dot{M}_{\rm acc}$, with the JET power saturating beyond $\dot{M}_{\rm acc} \sim 100\,\dot{M}_{\rm Edd}$. Radiation is strongly beamed along the funnel, with inverse beaming factors exceeding $100$ for high-spin, high-$\dot{m}$ models viewed face-on. Our results establish that rapid BH spin boosts energy-extraction efficiency, while high accretion rate amplifies total power. We provide scaling relations for luminosities, JET power, accretion ratio, and beaming, offering a framework for interpreting observations of ULXs and other super-Eddington systems.
[abstract 4 / 31] Yes (score: 5) - Title: Extending the Comisso-Asenjo Energy Extraction Mechanism to Pure Lovelock GravityAuthors: Chen Zhou, Ikhtiyor Eshtursunov, Sanjar Shaymatov, Chengxun Yuan,Comments: 13 pages, 7 captioned figuresSubjects: gr-qcCreated: 2026-07-30; Updated: 2026-08-03; Datestamp: 2026-08-03
In this paper, we extend the Comisso-Asenjo MAGNETic RECONNECTion (MR) mechanism to rotating BLACK HOLEs (BHs) in pure Lovelock/Gauss-Bonnet (GB) gravity in dimension $2N+2\leq D\leq 4N+1$ (where $N$ is the Lovelock polynomial degree of $N$th order term in the action). We perform a comprehensive analysis of the efficiency and power of extracted energy by exploring the effects of the spin parameter, plasma MAGNETization, MAGNETic field orientation, and RECONNECTion location. Our results reveal distinctive energetic features of pure Lovelock BHs relative to their Einstein counterparts, except in the special case of $D=3N+1$, where the two theories coincide. Our results demonstrate that MAGNETic RECONNECTion becomes increasingly efficient in extracting rotational energy from rapidly rotating pure Lovelock BHs with single rotation configuration as the spacetime dimension increases from $D=6$ to $9$. Furthermore, the Comisso-Asenjo MR mechanism can produce higher extraction power than the Blandford-Znajek (BZ) process in certain regions of parameter space because of its enhanced energy extraction rate. These results show that MAGNETic RECONNECTion is an efficient mechanism for extracting rotational energy from rapidly rotating pure Lovelock/GB BHs, highlighting their relevance to high-energy astrophysical phenomena.
[abstract 5 / 31] Yes (score: 5) - Title: Gamma-ray emission from particle illumination and shock-cloud interaction in the W51 ComplexAuthors: Alan Sunny, Martina Cardillo,Comments:Subjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
In the current era of very-high-energy (VHE) and ultra-high-energy (UHE) $γ$-ray astronomy, understanding Galactic PeVatrons and their acceleration mechanisms remains a primary objective. Recent LHAASO observations of the W51 Complex make it an ideal laboratory for investigating the origin of UHE emission, particularly due to the presence of massive and dense molecular environment surrounding multiple potential particle accelerators. In this work, we study two hadronic scenarios for the W51 Complex. First, we model the direct interaction between the SNR W51C and the nearby clouds in W51B, incorporating fresh particle acceleration, shock-driven adiabatic compression, and reacceleration of permeating Galactic COSMIC RAYs. Second, we explore an accelerator-independent illumination scenario in which the W51B cloud acts as a long-term confinement region for high-energy particles injected during an earlier epoch. We find that the direct shock-cloud interaction scenario successfully reproduces the GeV emission observed by FERMI-LAT, but fails to account for the UHE emission detected by LHAASO. In contrast, the illumination scenario naturally explains the UHE spectrum, indicating that dense molecular clouds can efficiently confine and sustain energetic hadronic populations over long timescales. Although the inferred injection history is compatible with a young SNR origin, the source-independent nature of the illumination framework also permits other accelerators within the W51 Complex. Our results therefore identify dense molecular environments as the key structures sustaining historical PeVatron activity and shaping the observed UHE $γ$-ray emission.
[abstract 6 / 31] Yes (score: 4) - Title: Spectral Evidence of Heavy Nuclei from the Neutron Star Crust in Magnetar BurstsAuthors: Sheng-Lun Xie, Yun-Wei Yu, Shao-Lin Xiong, Wang-Chen Xue,Comments: Minor correctionsSubjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
The crust of a neutron star (NS) provides a unique laboratory for studying matter under extreme density and MAGNETic field conditions that cannot be realized in terrestrial experiments. However, direct observational constraints on its composition have remained very limited. Magnetar bursts provide a promising means to probe the nuclear composition of the outer crust, as their energy release may be associated with stress-driven yielding of the crustal Coulomb lattice (including plastic deformation) and MAGNETic RECONNECTion in the surrounding MAGNETosphere. We develop a general-purpose radiative transfer framework for a strongly MAGNETized electron--ion thermal plasma (MEITP) and apply it to the observed X-ray burst spectra. The spectral fits disfavor light-ion compositions and instead favor plasmas characterized by effective charge numbers around $Z \sim 37$. These results provide spectral evidence for the participation of heavy nuclei in MAGNETar bursts, offer new observational constraints on the baryonic content and the location of the emitting fireballs, and further imply a crustal origin of the heavy ions.
[abstract 7 / 31] Yes (score: 4) - Title: Deep Learning-Based Classification and Analysis of Pulsar Candidates in FERMI-LAT Unassociated SourcesAuthors: C. Pozo González, R. López-Coto, J. Méndez-Gallego, E. de Oña Wilhelm,Comments: Accepted in Astronomy & Astrophysics (A&A)Subjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-08-03; Datestamp: 2026-08-03
The Large Area Telescope (LAT) has revolutionized our understanding of the high-energy sky, yet approximately one-third of the sources in the Fourth FERMI-LAT Source Catalog (4FGL) remain unassociated. Conventional machine learning, such as Decision Trees, often treat spectral features as independent tabular entries, neglecting the sequential topological information inherent in the Spectral Energy Distribution (SED). We aim to classify unassociated FERMI-LAT sources by exploiting the intrinsic shape of their spectra and variability features, avoiding the use of galactic coordinates as training features. Our primary objective is to generate a high-confidence list of PSRs candidates, further distinguishing between Young Pulsars (YPs) and Millisecond Pulsars (MSPs). We developed a hierarchical deep learning framework based on a 1D Convolutional Neural Network (1D-CNN), named TabularResCNN. This architecture treats the spectral data from the 4FGL catalog, allowing the model spectral shape. The classification is performed in two stages: first discriminating between AGNs and PSRs, and subsequently categorizing PSRs into YPs and MSPs. We implemented a cost-sensitive learning strategy to handle class imbalance and utilized Grad-CAM techniques to ensure the physical interpretability of the model's decisions. Applying this framework to 2563 unassociated sources, we identified 1136 AGNs and 202 high-confidence PSR candidates (166 YPs, 36 MSPs), increasing the pulsar population by more than 60%. They exhibit strong astrophysical consistency: YPs are confined to the Galactic plane, MSPs show a broader vertical distribution, and AGNs are isotropic. Furthermore, we identified 5 out of 5 PSRs recently confirmed by FAST. The proposed 1D-CNN framework isolates PSRs candidates based on intrinsic spectral and temporal properties, minimizing spatial bias.
[abstract 8 / 31] Yes (score: 4) - Title: Energy-dependent Optical/Near-infrared and X-ray Correlations in SWIFT J1727.8-1613Authors: Ruican Ma, Federico Vincentelli, Diego Altamirano, Alexandra Veledina, Poshak Gandhi, Piergiorgio Casella, Tariq Shahbaz, Sian Woahene-Demehin,Comments: 9 pages, 9 figures. Accepted for publication in MNRASSubjects: astro-ph.HE hep-phCreated: 2026-07-30; Updated: 2026-08-03; Datestamp: 2026-08-03
We present a timing analysis of the BLACK HOLE transient SWIFT J1727.8-1613 during its intermediate state. We use coordinated broadband X-ray observations from Insight-HXMT (2-150 keV), together with optical data from ULTRACAM (g_s and i_s bands) and near-infrared data from HAWK-I (K_s band), obtained on 2023 September 9. As shown by previous studies, the Fourier power spectrum shows a strong quasi-periodic oscillation (QPO) in the K_s, i_s and X-ray bands. Cross-correlation analysis reveals a complex coupling between the optical/near-infrared (OIR) and X-ray emission, including a delayed optical anti-correlation, a strong infrared correlation, and a pronounced dependence of these features on X-ray energy, suggesting multiple Comptonisation regions. In contrast, the lag properties do not change at the QPO frequency, displaying an OIR lag of ~60-80 ms up to 150 keV. We discuss these results in the context of small-scale JET and hot accretion flow scenarios.
[abstract 9 / 31] Yes (score: 4) - Title: Polar cap plasma loading and the morphology of pulsar $γ$-ray light curvesAuthors: Jérôme Pétri,Comments: Submitted to A&ASubjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
The discovery of more than 300 $γ$-ray pulsars by the FERMI Large Area Telescope (FERMI-LAT) has revealed a rich diversity of light-curve morphologies that remains challenging to reproduce within purely MAGNETospheric emission models, suggesting that particle acceleration and radiation may occur, at least in part, in the striped-wind current sheet. We compute a comprehensive atlas of pulsar $γ$-ray light curves based on the split-monopole current sheet geometry, with the goal of quantifying the role of pair plasma loading in shaping the observed pulse morphology. The current-sheet surface is described analytically and assumed to be the dominant site of high-energy photon emission. Spatially dependent emissivity prescriptions are introduced through a minimal set of parameters that explicitly break the north-south and azimuthal symmetries of the emitting plasma. With only a few physically motivated parameters, the model is able to reproduce a broad range of the observed $γ$-ray light-curve morphologies, including asymmetric, multi-peaked, and highly structured profiles. The results show that asymmetric emissivity, possibly related to pair-plasma loading, provides a natural and economical mechanism capable of reproducing a substantial fraction of the observed diversity of $γ$-ray pulse profiles. The current-sheet scenario therefore appears to provide a promising and physically motivated framework for high-energy pulsar emission.
[abstract 10 / 31] (score: 3) - Title: Long-term monitoring of repeating FRB 20220912A with the uGMRT at low radio frequenciesAuthors: Ajay Kumar, Yogesh Maan, Banshi Lal, Yash Bhusare, Shriharsh P. Tendulkar, Visweshwar Ram Marthi, Puja Majee,Comments: 22 Pages, 16 Figures, 1 Table, Accepted for publication in ApJSubjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
Some repeating FRBs exhibit occasional extreme repetition rates, but very few show a sustained high activity level. One such hyperactive repeater is FRB 20220912A, which was discovered by CHIME/FRB Collaboration on 2022 September 12. Here, we present results from a long-term monitoring campaign of FRB 20220912A using the upgraded Giant Metrewave Radio Telescope (uGMRT) in the frequency range from 300 to 750 MHz. Over the course of nearly two years, we detected a total of 643 bursts in this frequency range. The source exhibited extreme activity for a few months after its discovery and sustained its active phase for more than 1.5 years, with unsystematic modulations in the activity during this phase. The cumulative energy distributions in both bands show a break, consistent with other active repeaters like FRB 20121102A, FRB 202011124A, etc., suggesting common underlying emission mechanisms. Moreover, we show that the energy distribution shape for FRB 20220912A remains broadly same across a large range of frequencies and over time. Overall, the extended high activity, estimated total energy output, persistent power-law tails in the energy distributions, and the lack of detectable short timescale periodicity favor progenitor models invoking young dynamic MAGNETars, potentially emitting pulses across large rotation phase ranges.
[abstract 11 / 31] (score: 3) - Title: A quasi-star is born: formation and evolution of accreting quasi-stars as a pathway to Little Red Dots at non-zero metallicityAuthors: J. Roman-Garza, C. Charbonnel, D. Schaerer, T. Fragos, E. Cenci, R. Marques-Chaves, P. Oesch, M. Xiao,Comments: 10 pages, 6 figures, 1 tableSubjects: astro-ph.SR astro-ph.GA astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
The recently discovered Little Red Dots identified by the James Webb Space Telescope are compact high-redshift sources whose properties have motivated models involving BLACK HOLEs embedded within optically thick gaseous envelopes. We investigate their rest-frame optical emission by modeling quasi-stars, i.e. stellar envelopes powered by accretion onto a central BLACK HOLE, formed from rapidly accreting proto-stars that reach the supermassive star regime ($>10^4$~\Msun) before undergoing general RELATIVISTIC instability. We compute stellar evolution models with mass gain rates of 0.01, 0.1, and 1~\Msun/yr and metallicities $Z=0$-$0.01$. For accretion rates $\ge0.1$~\Msun/yr, stars remain nearly fully convective with $T_\mathrm{eff}\sim4000$-$9000$~K. General RELATIVISTIC instability occurs at $M_\star\sim3.5\times10^4$~\Msun\ ($6.8\times10^4$~\Msun) for $\dot{m}=0.1$~\Msun/yr (1~\Msun/yr), at $L\sim10^9$~\Lsun. Assuming the BLACK HOLE supports the envelope until complete accretion ($M_{\rm BH,max}/M_{\rm QS}=1$), quasi-stars reach maximum lifetimes of $10^7$-$10^8$~yr, $\sim100$-$1000$ times longer than their progenitors. Their formation and evolution are nearly independent of metallicity. Matching our models to Little Red Dots at $z<4.5$ ($L_\mathrm{bol}\sim10^{9.5}$-$10^{11.5}$~\Lsun) implies quasi-star masses of $10^{4.5}$-$10^{6.5}$~\Msun, while the minimum observed luminosity requires progenitor accretion rates $\gtrsim0.1$~\Msun/yr. Our models support quasi-stars as the origin of Little Red Dot optical emission and constrain their masses, lifetimes, progenitor environments, and luminosities. Our models offer a framework supporting quasi-stars as the source of Little Red Dot optical emission, and provide insights into their lifetimes, composition, progenitor's environment as well on their minimum and maximum observed luminosities.
[abstract 12 / 31] (score: 3) - Title: A new Chandra look at the globular cluster NGC 6540 and its peculiar X-ray flaring sourceAuthors: A. Sacchi, S. Mereghetti, R. Di Stefano, J. A. Irwin, M. Rigoselli, A. De Luca, N. Sims,Comments: 7 pages, 5 figures, 2 tables. Accepted for publication on A&ASubjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
We report the results of a deep ($\approx65$ ks) Chandra exposure of the globular cluster NGC 6540, obtained by combining three observations carried out in 2023-2024 to investigate the nature of the peculiar X-ray source 3XMM J180608.9-274553. This source was previously observed with XMM-Newton to exhibit a short ($\approx300$ s) and intense X-ray flare whose luminosity and duration are inconsistent with both typical type I X-ray bursts from low-mass X-ray binaries and stellar flares. Our new data indicate three faint X-ray sources near the position of the flare seen by XMM-Newton, only one of which was detected in a previous, much shorter Chandra observation. Based on the properties of these sources, localized at sub-arc-second precision, and of their optical counterparts, we discuss their possible nature and association with 3XMM J180608.9-274553: only one of these newly detected sources is compatible with the position of the flare. We also discuss a few scenarios, such as microlensing-induced amplification and BLACK HOLE flaring activity analogous to that observed in Sgr A$^\ast$, to explain the X-ray flare. Although these scenarios are intriguing, current observational evidence makes them both unlikely to be the origin of the XMM-Newton flare.
[abstract 13 / 31] (score: 3) - Title: Quiescent Host Galaxies of Extended Quasars Revealed by Spectrophotometric DecompositionAuthors: Shengxiu Sun, Linhua Jiang, Zhiwei Pan, Małgorzata Siudek, Mar Mezcua, Gaocheng Yin, Swayamtrupta Panda, Wei-Jian Guo, Steven Ahlen, David Brooks, Todd Claybaugh, Axel de la Macorra, Peter Doel, Enrique Gaztañaga, Gaston Gutierrez, Theodore Kisner, Andrew Lambert, Martin Landriau, Aaron Meisner, Ramon Miquel, John Moustakas, Ignasi Pérez-Ráfols, Eusebio Sanchez, David Schlegel, Michael Schubnell, Hee-Jong Seo, David Sprayberry, Gregory Tarlé, Benjamin Alan Weaver, Rongpu Zhou,Comments: Published in The Astrophysical Journal, 1004, 13 (2026), 20 pages, 20 figuresSubjects: astro-ph.GA astro-ph.IMCreated: 2026-07-30; Updated: 2026-08-03; Datestamp: 2026-08-03
Previous works of low-redshift QUASAR host galaxies have focused on compact QUASARs and found that their host galaxies are mainly star-forming galaxies. Here we present a study of host galaxies for QUASARs with extended morphologies in ground-based optical images. We select a sample of more than 1000 type 1 QUASARs at redshift $0.1
[abstract 14 / 31] (score: 3) - Title: Changing-Look AGNs from DESI. VI. Host GalaxiesAuthors: Shengxiu Sun, Linhua Jiang, Wei-Jian Guo, Sarah E. I. Bosman, Zhiwei Pan,Comments: Submitted to The Astrophysical Journal; 20 pages, 12 figuresSubjects: astro-ph.GA physics.data-anCreated: 2026-07-30; Updated: 2026-08-03; Datestamp: 2026-08-03
Changing-look (CL) AGNs trace rapid changes in nuclear activity, but their connection to host galaxy properties remains unclear. We present a study of the host galaxies of 105 CL AGNs previously selected by comparing DESI and SDSS data. We apply a two-epoch spectrophotometric decomposition to the DESI and SDSS spectra of the 105 objects. Meanwhile, HSC images are used to constrain their varying AGN components and non-varying stellar population components. We find that 79 of the 105 (75.2%) CL AGN hosts are quiescent galaxies, and 31/105 (29.5%) also show post-starburst signatures. We focus on 82 CL AGNs with extended host emission in the HSC images and compare them with extended QUASARs at similar redshift and stellar mass. Their STAR FORMATION activity, Balmer absorption, and quiescent fractions are broadly consistent with those of the comparison QUASARs, although post-starburst hosts are more common among the CL AGNs. Our CL AGNs with extended host emission are more often quiescent than those with compact morphology, but this difference is not apparent after matching in redshift and stellar mass. The $\mathrm{O\, \small II}$ and $\mathrm{O\, \small III}$ narrow lines show no population-wide response to the continuum and broad line changes, consistent with the slower response expected from the narrow line region. Together, these results favor changes in the central supermassive BLACK HOLE accretion rate as the main origin of the CL transitions.
[abstract 15 / 31] (score: 3) - Title: Reincarnations of massive stars in ACTIVE GALACTIC NUCLEus discsAuthors: Jing-Tong Xing, Tong Liu, Jiao-Zhen She,Comments: 14 pages, 7 figures, 5 tables, accepted for publication in MNRASSubjects: astro-ph.GA astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
The origin and evolution of massive stars in ACTIVE GALACTIC NUCLEus (AGN) discs remain uncertain. We develop a semi-analytical model that follows the evolution of an embedded core-collapse SUPERNOVA (CCSN) remnant and the subsequent formation and growth of a compact gas cloud. In the dense disc environment, efficient radiative cooling can strongly compress or bypass the Sedov-Taylor stage and drive the remnant rapidly into radiative snowplow evolution. After the remnant loses its interior pressure support, partial backflow of cooled shell fragments and refilling gas may initialize a pressure-confined and tidally limited seed cloud. The cloud then grows through shear-limited Hill capture until the gravitational, tidal, shear, photoionization, and MAGNETic conditions for collapse are simultaneously satisfied. The outcome depends strongly on the supermassive black-hole (SMBH) mass and explosion radius. Models with the lowest SMBH mass yield fewer than one massive star per event on average, whereas the most massive SMBH models can produce from several to several hundred. For a top-heavy initial mass function, massive stars dominate the resulting stellar mass and feedback budget. Embedded SUPERNOVAe may therefore provide a localized gas-recycling channel for second-generation massive-STAR FORMATION in AGN discs.
[abstract 16 / 31] (score: 3) - Title: Joint X-ray and gamma-ray analysis at the photon level: Application to MSH 15-52Authors: Katharina Egg, Alison M. W. Mitchell,Comments: 15 pages, 18 figures, 5 tables. Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.HE astro-ph.IMCreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
Joint analysis of multi-wavelength (MWL) data at the level of photon events is challenging, but it provides a statistically preferable method of fitting the data, in contrast to fitting derived flux points. Data from X-ray and gamma-ray instruments are well-suited for a joint description, due to their common physical origin (same particle population and non-thermal processes) and incidentally also due to the high similarity of their formats. Such a description is especially desirable for objects such as pulsar wind nebulae (PWNe), diffuse sources that originate from outflows of particles that have been accelerated by pulsars. Photon emission is generated by particle interactions with the surrounding MAGNETic and radiation fields. The rich MWL emission from PWNe renders MWL studies essential to obtain a comprehensive picture of their physical properties. We demonstrate a joint MWL analysis of 3D X-ray and gamma-ray data at the photon event level by importing eROSITA X-ray data into the Gammapy software framework. We present our pipeline for converting eROSITA 3D (two spatial and one spectral dimension) event data into a Gammapy-readable format. We validated the approach through comparison with standard X-ray data products and analysis. Furthermore a 3D eROSITA data analysis as well as a joint fit with 3D H.E.S.S. data and FERMI 4FGL catalogue flux points was performed. We show through the analysis of data from the PWN MSH\,15-52 that 1D fits of Gammapy-extracted eROSITA spectra agree with the results of the native X-ray tool PyXspec. We demonstrate that 3D analyses on X-ray data can be conducted, with both background subtraction and background modelling. Furthermore, we show that joint analyses at event level between 3D X-ray and gamma-ray data can be conducted in Gammapy. This opens up exciting new possibilities for joint analyses of PWNe and other objects.
[abstract 17 / 31] (score: 3) - Title: Rates of tidal disruption events from constrained cosmological simulations of the local Universe: population properties and implications for transient surveysAuthors: Julian S. Sommer, Ildar Khabibullin, Klaus Dolag, Luca Sala, Benjamin Seidel, Jenny G. Sorce, Alice Damiano,Comments:Subjects: astro-ph.HE astro-ph.GACreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
(abridged) Motivated by upcoming surveys like LSST, we estimate tidal disruption event (TDE) rates using the constrained cosmological Simulation of the LOcal Web (SLOW) to test the limitations of traditional 2D analytical extrapolations within a fully 3D framework. We aim to provide reliable TDE budgets extracted from the simulated zoom-in volumes of the digital counterparts of the Coma, Hercules, Shapley, Virgo, and Perseus supercluster environments, and the Fornax galaxy cluster. From the zoom-in boundary volumes of the six environments, reaching radial extents of $55-92\,$Mpc, we extracted BLACK HOLE demographics (including spin) and their host galaxy properties to establish a filter scheme that strictly preserves dynamically stable "main-sequence" BLACK HOLEs. We further classified host galaxies as cuspy or cored based on the slope of their 3D stellar density profile measured within $1\,$kpc as a proxy for unresolved nuclear structure and applied the RELATIVISTIC Kesden efficiency correction to the filtered sample. We find an average volumetric and per BLACK HOLE TDE rate of $\approx 600\,$Gpc$^{-3}\,$yr$^{-1}$ and $\approx 4.5\times 10^{-5}\,$yr$^{-1}$ across all six environments, respectively. Although our absolute TDE rates match early literature estimates, the underlying spatial distribution fundamentally differs. Central core rates are heavily reduced by dynamical depletion and direct capture constraints, meaning the total TDE budget is overwhelmingly dominated by cuspy satellite galaxies in the extended cluster halos. TDE yields are driven by BLACK HOLE demographics and spatial concentration rather than total cluster mass. Actively assembling superclusters (e.g., Hercules) reduce per-black-hole TDE efficiencies via merger-driven BLACK HOLE mass growth, whereas low-mass environments (e.g., Fornax) are highly efficient due to unmerged, low-mass BLACK HOLEs.
[abstract 18 / 31] (score: 2) - Title: Sco X-1 as a continuous gravitational waves source: modelling the secular evolution using MESAAuthors: Gianluca Pagliaro, Maria Alessandra Papa, Jing Ming, Devina Misra,Comments:Subjects: astro-ph.HE gr-qcCreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
We study the prospects for detecting continuous gravitational waves (GWs) from Sco X-1 and evaluate the most likely waveform and progenitor parameters. We model the spin of the neutron star by the accretion torque and the gravitational-wave torque, considering two mechanisms for generating the non-axisymmetry responsible for the latter: MAGNETic mountains and crustal breakage deformation. Both torques are intertwined with the binary evolution, which we trace from the formation of the NS in a binary system with a main-sequence companion. We do this with MESA, starting from a set of initial binary configurations. At current sensitivity, a MAGNETic ellipticity of $\varepsilon\gtrsim 10^{-6}$ is necessary for detection. The highest frequency at which we have detectable signals increases with the accretion efficiency $η$, and it can be as high as 360Hz. At 3G (Cosmic Explorer/Einstein telescope) sensitivity, less deformed Sco X-1 NSs, with ellipticities as small as $6\cdot 10^{-9}$, are detectable, but the waveform highly depends on the binary system: the highest frequency of detectable signals spans the very broad range 600-1700Hz, strongly depending on $η$ and mass of the progenitor donor star $M^d$. If $η\leq$30%, the crust does not break. For $η\in$[40%,60%] only progenitors with $M^d\geq[1.1,1.5]M_{\odot}$ present crustal breakage, while if $η\geq$70% all crusts break. In some systems, the crust breaks during their Sco X-1 phase. If Sco X-1 were one of those systems, it would be emitting a very loud GW signal sweeping from O(1000)Hz down to torque-balance frequencies in $\approx 150000[\varepsilon /10^{-5}]^{-2/5}$ years. We estimate the current detection probability for this signal to be under 1%; this probability increases substantially - to around 41% - with 3G detectors.
[abstract 19 / 31] (score: 2) - Title: Resonant electroMAGNETic leptogenesis with coherent heavy-neutrino evolutionAuthors: Rin Takada,Comments: 7 pages, 3 figuresSubjects: hep-phCreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
We study TeV-scale electroMAGNETic leptogenesis generated by the gauge-invariant neutrino-dipole operators $O_{NB}$ and $O_{NW}$. The benchmark Wilson coefficients are specified at the renormalization scale $κ_N=M_1=1\,\mathrm{TeV}$ and related to their values at $κ_{\rm match}=3\,\mathrm{TeV}$ through the coupled one-loop $ν$SMEFT evolution. The collision network contains the symmetric-phase $1\leftrightarrow3$ and crossed $2\leftrightarrow2$ processes generated by the linear field-strength vertices and the VEV-induced two-body $γ$, $Z$, and $W$ channels through the electroweak crossover. We use a factorized leading-moment, momentum-averaged Markovian treatment for two $2\times2$ heavy-flavor density matrices, one for each helicity. Pole-resummed two-state effective couplings enter the lepton and antilepton collision tensors, while the off-diagonal density matrices describe coherent evolution and collision damping. Three resolved flavor charges are coupled to a finite-rate sphaleron equation, yielding the frozen baryon yield $Y_B^{\rm FO}$. For the benchmark $\tilde m^{\rm EM}_1=3.97\times10^{-2}\,\mathrm{eV}$, the decay-only pole prescription, in which only decay contributions enter the absorptive pole matrix, gives the locally optimized positive near-resonant maximum $Y_B^{\rm FO}=+5.50\times10^{-5}$ at $ΔM=1.29\times10^{-11}\,\mathrm{GeV}$. Adding the thermally averaged crossed-scattering moment to the pole matrix defines the decay-plus-scattering prescription and shifts the maximum to $Y_B^{\rm FO}=+8.44\times10^{-5}$ at $ΔM=1.83\times10^{-11}\,\mathrm{GeV}$. The corresponding signed mass-splitting curves cross the observed value $Y_B^{\rm obs}$ at $ΔM=1.68\times10^{-5}\,\mathrm{GeV}$ and $2.34\times10^{-5}\,\mathrm{GeV}$.
[abstract 20 / 31] (score: 2) - Title: From reflection to scattering: Polarimetric signatures of funnel-type outflows. Modeling obscured ultraluminous X-ray sourcesAuthors: Varpu Ahlberg, Alexandra Veledina, Eugene Churazov, Ildar Khabibullin,Comments: 13 pages, 10 figures. Accepted for publication in A&ASubjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
Super-Eddington accretion onto compact objects is expected to produce optically thick outflows with a funnel-shaped cavity that may collimate the emission. At inclinations higher than the grazing angle of the funnel, the central source is obscured. Accordingly, the observed emission is dominated by scattered and reflected radiation, which can therefore be strongly polarized. The detection of strong X-ray POLARIZATION in the Galactic X-ray binary Cygnus X-3 provides the first direct probe of this geometry. In this work, we present a systematic study of the inclination-dependent radiative signatures of such systems using a combination of semi-analytical methods and Monte Carlo simulations. Our treatment explicitly accounts for multiple scatterings and demonstrates that both the POLARIZATION degree and the degree of collimation are highly sensitive to the albedo of the funnel surface. We find that a low albedo (significant absorption) is essential for producing high POLARIZATION, yet it simultaneously suppresses the collimation of the emission. Conversely, a high-albedo medium (nearly pure scattering) can modestly collimate radiation, but at the cost of substantially reducing the POLARIZATION degree. We discuss our results in the context of Imaging X-ray Polarimetry Explorer observations of Cygnus X-3 and propose a physical scenario for its spectral state transitions, considering a combination of reflection from the funnel surface and scattering by a diffuse medium above the funnel. Our model provides a general framework for interpreting X-ray polarimetric signatures of obscured accretors.
[abstract 21 / 31] (score: 2) - Title: Fast gravitational waveform models for quasi-circular coalescences of neutron star--BLACK HOLE binariesAuthors: Felip A. Ramis Vidal, Adrian Abac, Marta Colleoni, Tim Dietrich, Pierre Mourier, Alejandra Gonzalez, Ivan Markin, Anna Puecher,Comments: 27 pages, 13 figuresSubjects: gr-qc astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
We present IMRPhenomXHM_NSBH and SEOBNRv5HM_ROM_NRTidalv3_NSBH, the first two frequency-domain models for gravitational-wave signals from quasi-circular, aligned-spin neutron star--BLACK HOLE (NSBH) binaries including higher-order modes beyond the dominant quadrupole. We also present IMRPhenomXPHM_NSBH, an extension of the former model to the spin-precessing case. These models incorporate tidal effects in the gravitational-wave phasing and amplitude using a higher-mode extension of the NRTidalv3 model, as well as dedicated amplitude models calibrated to numerical relativity (NR) simulations of NSBH mergers. We test the performance and validity of the new models by comparing them to NR simulations and other existing models for these systems. Finally, we perform parameter estimation studies. The new models show clear improvements over their predecessors in analyses of simulated signals, while yielding results consistent with the literature when applied to real events from the GWTC-3 and GWTC-4 catalogs.
[abstract 22 / 31] (score: 2) - Title: Faraday Complexity and Depolarisation in a High-Rotation-Measure Radio Galaxy from the Spectra and Polarisation In Cutouts of Extragalactic Sources (SPICE-RACS) DR2Authors: Debajyoti Mondal, Abhik Ghosh, Dipanjan Banerjee,Comments: 16 pages, 7 figures, 4 tables. Accepted for publication in The Astrophysical Journal (ApJ)Subjects: astro-ph.COCreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
We present a broadband spectro-polarimetric analysis of the extragalactic radio source \texttt{RACS\_0900-28\_7036} using SPICE-RACS DR2 observations with the Australian Square Kilometre Array Pathfinder (ASKAP). The source was selected for its large rotation measure (${\rm RM}=345.7\pm0.2~{\rm rad~m^{-2}}$), substantial excess relative to the local foreground ($Δ{\rm RM}\approx171~{\rm rad~m^{-2}}$), and strong evidence of Faraday complexity ($σ_{\rm add}/δσ_{\rm add}\approx8.6$). Observations span 803--1083~MHz in 36 spectral channels, enabling detailed characterization of Faraday rotation and wavelength-dependent dePOLARIZATION. One-dimensional QU-fitting and Bayesian model selection identify a multi-component model comprising one Burn-slab component and two external Faraday dispersion components (1 Slab + 2 EFD) as the preferred description. The dominant astrophysical component exhibits ${\rm RM}\approx345.5~{\rm rad~m^{-2}}$ with modest Faraday dispersion ($σ_{\rm RM}\approx3~{\rm rad~m^{-2}}$), consistent with the Galactic foreground rotation measure at the source position (${\rm RM}_{\rm Gal}=331.9\pm33.1~{\rm rad~m^{-2}}$). A secondary broader component at ${\rm RM}\approx131.5~{\rm rad~m^{-2}}$ shows strong dePOLARIZATION ($σ_{\rm RM}\approx19.5~{\rm rad~m^{-2}}$), indicating an additional turbulent Faraday-active medium along the line of sight. The fractional POLARIZATION spectrum and $q$--$u$ plane evolution further confirm multiple Faraday-active regions along the line of sight. These results demonstrate that ASKAP broadband spectropolarimetry can resolve complex Faraday structures and probe turbulent MAGNETized environments, providing a framework for systematic dePOLARIZATION studies across the full SPICE-RACS catalog and enabling statistical investigations of Faraday complexity in diverse extragalactic radio sources.
[abstract 23 / 31] (score: 2) - Title: Post-Newtonian N-Body Dynamics in Extended Theories of GravityAuthors: Antonio Tedesco,Comments: 19 pages; published in The European Physical Journal C, 86, 885 (2026). This replacement corrects only misprints and the ORCID link to reflect the published article; it does not constitute a revised scientific version. v1 is the manuscript accepted by EPJ C and submitted to arXiv on July 12, 2026; v2 only fixed the automatic LaTeX title-page dateSubjects: gr-qcCreated: 2026-07-30; Updated: 2026-08-03; Datestamp: 2026-08-03
We derive the complete first post-Newtonian (1PN) Lagrangian and corresponding equations of motion for the RELATIVISTIC $N$-body system in Scalar-Tensor-Fourth-Order Gravity (STFOG), including the Non-Commutative Spectral Geometry (NCSG) sector as a special case. In the regime $Φ\sim Ψ$ ($γ\sim 1$), the linearized fourth-order field equations are solved in the Standard Post-Newtonian gauge, and the variational Lagrangian is built directly from the point-particle action. The resulting dynamics is governed by three Yukawa functions $ζ$, $\mathcal{W}$ and $Ξ$, which encode the scalar, gravitoMAGNETic and three-body sectors and depend on the effective masses $(m_R,m_Y,m_ϕ)$ of the additional propagating modes. In this context, we show that the nonlinear metric component ${}^{(4)}\!g_{00}$ plays no role at 1PN level. The 1PN orbital motion of the above extended theories is thus obtained in closed form, and the Einstein--Infeld--Hoffmann equations are recovered in the corresponding general-RELATIVISTIC limit. The formalism provides a common framework for RELATIVISTIC celestial mechanics and applies to Solar System, binary pulsars such as PSR J0737-3039, Galactic-center stellar orbits and triple systems.
[abstract 24 / 31] (score: 2) - Title: Impact of eccentricity and higher-modes on neutron star-BLACK HOLE parameter estimationAuthors: Snehal Tibrewal, Aasim Jan, Aaron Zimmerman, Hsin-Yu Chen,Comments:Subjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
Detections of gravitational waves from neutron star-BLACK HOLE systems provide avenues for studying extreme matter, constraining binary formation channels, and testing the nature of compact objects in strong gravity. Eccentric signatures in the signal further enhance this potential by improving parameter estimation and offering clues about binary formation. Because eccentricity is primarily imprinted during the inspiral phase, it is often weakly constrained or missed entirely in binary BLACK HOLE observations; in contrast, neutron star-BLACK HOLE systems produce longer in-band signals, enabling more precise measurements of eccentricity and leaving a distinct imprint on parameter inference. In this work, we present a systematic parameter-estimation study exploring the impact of eccentricity on inference using injections simulated with the state-of-the-art eccentric waveform model SEOBNRv5EHM. We find that for systems like GW200105_162426, the measurement precision of eccentricity and correlated parameters improves as eccentricity increases, yielding tighter constraints at larger eccentricities. For the highest eccentricity considered in this study, $e=0.25$, we recover eccentricity with $1σ$ uncertainty as low as $4\times10^{-4}$. In addition, the constraints on effective spin $χ_\mathrm{eff}$ and mass ratio $q$ improve relative to the quasi-circular case by factors of $\sim13$ and $\sim20$, respectively. On the other hand, we find no significant improvement in extrinsic parameters such as luminosity distance and sky localization, suggesting that for systems like GW200105_162426, the additional information provided by eccentricity in this sector is either negligible or degenerate with the information provided by higher-order modes.
[abstract 25 / 31] (score: 2) - Title: Light propagation and intensity transport in metric-affine geometryAuthors: Antonio De Felice, Lavinia Heisenberg, Gonzalo J. Olmo, Carlos Pastor-Marcos,Comments: 10 pagesSubjects: gr-qcCreated: 2026-07-28; Updated: 2026-08-03; Datestamp: 2026-08-03
We study electroMAGNETic wave propagation in metric--affine geometries, where torsion and non-metricity may be present and the coupling between electroMAGNETism and spacetime is no longer unique. Rather than choosing a particular coupling prescription a priori, we construct electroMAGNETic sectors that preserve standard $U(1)$ gauge invariance and projective invariance of the affine connection as guiding symmetry principles. We introduce two representative models, one in which the Maxwell term is dressed by a scalar prefactor built from non-Riemannian invariants, and another in which the kinetic term is modified by a rank--four constitutive tensor acting as an anisotropic medium. We derive their geometric--optics limits and show that their couplings can modify the effective light cone, change the relation between field amplitude and intensity, induce POLARIZATION-dependent propagation, and generate birefringence and mode mixing. These results thus provide the formal basis for a broader phenomenological study connecting torsion and non-metricity with electroMAGNETic observables in concrete metric--affine backgrounds, including black-hole imaging, birefringent lensing, POLARIZATION observables, and departures from photon-number conservation.
[abstract 26 / 31] (score: 2) - Title: Understanding constraints on primordial mass BLACK HOLEs made of DARK MATTER using fast radio burstsAuthors: Surajit Kalita, Shruti Bhatporia, Amanda Weltman,Comments: 3 pages with 1 figure; based on poster in IAU XXXII General Assembly, August 2024, Cape TownSubjects: astro-ph.CO astro-ph.HE gr-qcCreated: 2026-07-30; Updated: 2026-08-03; Datestamp: 2026-08-03
In recent decades, a multitude of modified gravity theories have been proposed to address a variety of cosmological and astrophysical problems. While many of these theories remain viable, observational constraints on their parameters are increasingly stringent. Fast Radio Bursts (FRBs), in particular, have emerged as powerful probes of cosmology and fundamental physics. This study investigates the implications of a generic modified gravity theory for gravitational lensing by FRBs. By analyzing the dataset of CHIME/FRBs, we constrain the fraction of DARK MATTER composed of primordial BLACK HOLEs within this theoretical framework. Furthermore, we demonstrate that modified gravity introduces a screening effect on gravitational lensing, analogous to the scattering effect of plasma on light rays.
[abstract 27 / 31] (score: 2) - Title: Misaligned or chaotic? A strong break of axial symmetry in the local LRD J1025 revealed with VLT/FORS2 spectropolarimetryAuthors: Francesco D'Eugenio, Gabriele Pezzulli, Roberto Maiolino, Alessandro Marconi, Xihan Ji, Cristina Ramos Almeida, Andrea Ferrara, Piero Madau, Xiaojing Lin, José A. Acosta-Pulido, Fuyan Bian, Matilde Brazzini, Zheng Cai, Stefano Carniani, Xiaohui Fan, Ignas Juodžbalis, Robert G. Pascalau, Jan Scholtz, Charlotte Simmonds, Fengwu Sun, Sandro Tacchella,Comments: 21 pages, 12 figures. Submitted to MNRAS, comments welcomeSubjects: astro-ph.GACreated: 2026-07-30; Updated: 2026-08-03; Datestamp: 2026-08-03
Little Red Dots (LRDs) are compact ACTIVE GALACTIC NUCLEi (AGN) with unusual spectral energy distributions and broad Balmer emission, candidate signposts of rapid black-hole growth. We present VLT/FORS2 optical linear spectropolarimetry of the closest known LRD, SDSS J102530.29+140207.3, at z=0.1. In total light, we detect spatially extended narrow-H$α$ emission, probably tracing the host galaxy. We measure a nearly grey continuum polarisation $p_{\rm cont}=1.53\pm0.04$(rand.)$\pm$0.20(syst.) per cent, while broad H$α$ is less polarised, $p_{\rm Hα}=0.58-0.84$ per cent. We rule out polarisation by Milky Way dust and dilution by an unpolarised line. The polarised continuum with a depolarised line resembles local Seyfert-1 nuclei and favours a single dominant source over multi-source explanations. After Stokes-continuum subtraction, broad H$α$ shows no blue-to-red swing, but there is a significant (48$\pm$4)$^\circ$ continuum-to-line offset in polarisation angle. This implies a break of axial symmetry inside this object, posing interesting geometrical challenges to all existing LRD models and frameworks. We discuss different possible origins of this symmetry break and possible paths to discriminate between them with future observations.
[abstract 28 / 31] (score: 2) - Title: Pulse Shaping Increases Efficiency in Pulsed Plasma AcceleratorsAuthors: Patrick W. Schools, Mammadbaghir Baghirzade, Ryan Heiser, Adrian Woodley, Laxminarayan L. Raja, Thomas C. Underwood,Comments:Subjects: physics.plasm-phCreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
The performance of a gas-fed pulsed electroMAGNETic thruster is governed by the ability to deposit electrical energy while propellant is available for acceleration. Current pulsed-power systems require tradeoffs between high-current discharges that produce high exhaust velocities and longer pulses that overlap the energy deposition with more of the gas injection. This limited control restricts the specific impulse and mass utilization of these thrusters. This work introduces programmable pulse shaping as a method to increase control over energy deposition and expand the accessible operating space. We use solid-state integrated power modules to vary the discharge delay, pulse width, peak current, and the shape of the current waveform as propellant is injected. Experiments varying pulse widths from 30 to 500 $μ$s and peak currents from 3 kA to 16 kA show that short, high-current pulses produce higher exhaust velocities and greater impulse bits than longer, lower-current pulses at comparable discharge energy. The switches also enable multiple discharges of arbitrary positioning and duration during a single gas injection. This micro-burst operation is shown to increase specific impulse in air by 278\% from 840 to 3177 s through improved propellant utilization. This same pulse shaping ability is found to increase thrust efficiency from 0.2\% in single-shot operation to 3.3\% in micro-burst operation while operating with air.
[abstract 29 / 31] (score: 2) - Title: Optical Images of the Braneworld Black Hole Surrounded by an Optically Thin Accretion DiskAuthors: Wen-Hao Deng, Sen Guo, Qing-Quan Jiang, Kai Lin, Pei Wang,Comments:Subjects: astro-ph.HECreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
This work examines the observational signatures of rotating BLACK HOLEs with tidal charge in the Randall--Sundrum braneworld scenario. Combining an elliptic-integral-based analytical treatment with numerical ray tracing, we characterize photon motion around braneworld BLACK HOLEs in detail. For small observer inclinations, secondary images remain embedded inside the primary emission rings. As the inclination becomes larger, the primary and secondary images gradually separate and produce a strongly asymmetric image morphology. We show that the image asymmetry and the deformation of the inner shadow are jointly controlled by the BLACK HOLE spin, the tidal charge, and the observer inclination. To analyze the frequency shifts across the accretion disk, we extend the emitting region from the ISCO down to the event horizon by including the plunging flow. The results indicate that the observer inclination is the dominant factor governing the frequency-shift distribution. In addition, we reconstruct braneworld BLACK HOLE images using a fisheye-lens ray-tracing model. The optical morphology and brightness distribution show a clear dependence on the observing frequency, especially when comparing 230~GHz with 86~GHz. We also contrast the brightness distributions of prograde and retrograde disks, finding that both the total intensity and the peak intensity at 86~GHz are higher than those at 230~GHz. For negative values of the tidal charge, we further investigate the corresponding frequency-shift behavior and 230~GHz intensity profiles, which may provide useful theoretical guidance for future studies of extra-dimensional gravity models.
[abstract 30 / 31] (score: 2) - Title: Nonlinear POLARIZATION effects on plasma screening for thermonuclear reactionsAuthors: Hanxiang Huang, Binbing Wu, Zhengfeng Fan, Congzhang Gao, Jie Liu, Baisong Xie,Comments:Subjects: physics.plasm-ph nucl-thCreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
We investigate two-center plasma screening effects on thermonuclear reactions of D-T, p-$^{11}$B, and $^{12}$C-$^{12}$C, spanning from classical to degenerate regimes. The two-center screening potential is obtained within a finite-temperature Thomas-FERMI-Dirac framework, capturing two-ion correlations as the leading-order many-body effect. Combining the resulting screened Coulomb potential with a complex Woods-Saxon nuclear potential, we solve the stationary Schrödinger equation to obtain the fusion tunneling probabilities and the corresponding reaction rates. Compared to Debye-Hückel results, the present screening potential is stronger in weakly coupled and weakly degenerate regimes but weaker in strongly coupled and strongly degenerate regimes. Consequently, the fusion enhancement factors are amplified in the former but suppressed in the latter. An underlying interplay between two mechanisms is identified: the nonlinear POLARIZATION of ions tends to reduce the screening effect, whereas the nonlinear POLARIZATION of electrons tends to enhance it. This subtle competition is governed by the plasma coupling strength and degeneracy. These findings highlight that a two-center treatment is important for predicting fusion rates in dense plasmas.
[abstract 31 / 31] (score: 2) - Title: Runaway Electrons in Stellarators: Unlikely or Unavoidable?Authors: Ida Ekmark, Matt Landreman,Comments: 11 pages, 11 figuresSubjects: physics.plasm-phCreated: 2026-07-31; Updated: 2026-08-03; Datestamp: 2026-08-03
Generation of RELATIVISTIC runaway electrons has historically not been considered a possible problem in stellarators, but this may not hold in reactor-scale stellarators despite the lack of an externally driven plasma current. The magnitude of the plasma current governs the exponential generation of runaways, and even if there is no externally driven plasma current, the bootstrap current could be considerable in reactor-relevant stellarators. In this paper, we present a pilot study on the generation of runaway electrons in stellarator temperature collapse scenarios. To reliably study runaway electrons in stellarators, we implemented a stellarator plasma model in the runaway electron simulation tool DREAM. The model is used to explore when runaway electrons can be generated with regard to combinations of initial plasma current, temperature decay time scale, and post-decay temperature. Special consideration is given to runaway generation through avalanche multiplication in stellarators, and how it compares to tokamaks. We find that significant runaway electron generation is possible also in stellarators, and demonstrate under which conditions it could be a concern. However, our findings support the conception that runaway electrons will be less of a concern in reactor-scale stellarators compared to tokamaks.
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