Current date: 2026-09-04

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Datestamp limit: 2026-09-04 (0 days ago)

Created/updated limit: 2026-08-28 (7 days ago)

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OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-09-04&until=2026-09-04&set=physics&metadataPrefix=arXiv

Scoring abstracts

Number of records retrieved: 351

Keyword score statistics

score 11 -- 1 abstracts

score 7 -- 1 abstracts

score 6 -- 2 abstracts

score 5 -- 3 abstracts

score 4 -- 2 abstracts

score 3 -- 5 abstracts

score 2 -- 9 abstracts

in total -- 23 abstracts

Articles that appeared on 2026-09-04

[abstract 1 / 23] Wow! (score: 11)
arXiv:2609.03435 [pdf, ps, other]

Title: The Jet Properties and Accretion Regime for the Blazar Sequence

Authors: Qingchen Long,

Comments: 19 pages, 4 figures, and 3 tables; accepted for publication in ApJ. Comments are welcome

Subjects: astro-ph.HE

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

The puzzling bimodality displayed by BLAZARs on the broad-band spectral indices ($α_{\rm ro}-α_{\rm ox}$) plane is still an open question. To investigate its physical origin, we compiled a sample comprising 136 flat-spectrum radio QUASARs (FSRQs), 64 low-SYNCHROTRON-peaked BL Lac objects (LBLs), 39 intermediate-SYNCHROTRON-peaked BL Lac objects (IBLs), and 105 high-SYNCHROTRON-peaked BL Lac objects (HBLs). Our results show that (FSRQs+LBLs)$\rightarrow$IBLs$\rightarrow$HBLs follow a \reflectbox{$\angle$}-shaped evolutionary sequence on the $α_{\rm ro}-α_{\rm ox}$ plane, with the average 5\,GHz radio Doppler factor, JET power, and accretion Eddington ratio decreasing along this \reflectbox{$\angle$}-shaped track. Additionally, the distributions of $α_{\rm ox}$ exhibit only slight differences among BLAZAR subclasses, whereas those of $α_{\rm ro}$ and $α_{\rm rx}$ differ significantly. Our results can be naturally explained if the distribution of BLAZARs on the $α_{\rm ro}-α_{\rm ox}$ plane is regulated by the accretion rates and the Doppler beaming effect across different bands ($δ_i^{q_i}/δ_j^{q_j}$). However, $δ_i/δ_j$ plays a pivotal role in the distribution, while JET shape ($q=2(3)+α_ν$) and spectral indices ($α_ν$) play a minor role. Our results suggest that FSRQs+LBLs are strong-JET sources coupled with radiatively efficient accretion, and their JETs are accelerated to a larger distance from the core and still maintain RELATIVISTIC speeds down to the radio region; HBLs are weak-JET sources coupled with radiatively inefficient accretion, and their JETs may begin to decelerate in the optical region and exhibit sub-RELATIVISTIC speeds as they propagate to the radio region. IBLs are regarded as transitional objects between FSRQs+LBLs and HBLs.

[abstract 2 / 23] Wow! (score: 7)
arXiv:2609.02681 [pdf, ps, other]

Title: Multiwavelength View of Black Hole X-ray Binary SWIFT J151857.0-572147

Authors: Manoj Mandal, Sachindra Naik, Souvik Manik, Sabyasachi Pal,

Comments: Accepted for publication in ApJ

Subjects: astro-ph.HE

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

We investigate multiwavelength timing and spectral properties of the newly discovered BLACK HOLE X-ray binary SWIFT J151857.0-572147 during its 2024 outburst using observations from AstroSat, NUSTAR, NICER, SWIFT, and MeerKAT. The AstroSat/LAXPC20 power density spectrum reveals a $\sim$8 Hz low-frequency QPO with a quality factor of $\sim2.8$. The broadband X-ray spectrum of the source exhibits prominent reflection features, which are modeled to constrain the geometry and physical properties of the accretion disk. The spectral analysis indicates that the source was in the soft/intermediate spectral state, characterized by a steep power law with a photon index of $Γ\approx 2.6$ and a relatively high disk temperature of $\sim0.9$ keV. The reflection modeling suggests a disk inclination of $23-31^{\circ}$ and a highly ionized accretion disk with $\logξ\sim 3.3$-4.0. The MeerKAT monitoring revealed a strong radio variability that closely tracked the hard X-ray evolution, including a bright radio flare during the hard-to-soft state transition, supporting close coupling between the accretion flow and JET activity. Using the quasi-simultaneous AstroSat, SWIFT/XRT and MeerKAT observations, we investigated the radio/X-ray correlation and found that SWIFT J151857.0-572147 follows the established $L_{\rm X}$-$L_{\rm R}$ relation for Galactic BLACK HOLE X-ray binaries. Its location in the $L_{\rm X}$-$L_{\rm R}$ plane is consistent with that of Galactic BLACK HOLE X-ray binaries, further supporting its BLACK HOLE nature.

[abstract 3 / 23] Yes (score: 6)
arXiv:2605.31554 [pdf, ps, other]

Title: Expanding the Population of Short Gamma-Ray Transients with a Coherent FERMI/GBM Search. A 13-year catalog of short GRBs

Authors: Ariel Perera, Barak Zackay, Tejaswi Venumadhav,

Comments:

Subjects: astro-ph.HE

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

In this paper, we present an archival search for short GAMMA-RAY BURSTs (sGRBs) over 13 years (2013-2025) of FERMI/GBM data using a Poisson matched-filter pipeline that performs a fully coherent analysis across all detectors and energy channels, significantly improving sensitivity relative to the onboard triggering algorithms. A central component of the analysis is the empirical estimation of trigger significance using 'timeslided' data, allowing each candidate to be assigned a probability of astrophysical origin. We also developed a new parameter-estimation framework based on the Poisson matched filter, which uses the global structure of the detected event across spectral, temporal, and spatial parameter spaces. This enables us to systematically classify bursts and distinguish between GRBs, soft gamma repeaters, terrestrial gamma-ray flashes, and solar flares. We identify 568 new GRB candidates with $p_{\text{astro}}\geq0.9$ and thousands of MAGNETar bursts, significantly expanding the known short-transient population in GBM data. To further strengthen the significance of the GRB candidates, we performed a targeted follow-up search in SWIFT/BAT rate data. Applying the followup to all of our triggers - including triggers below the detection threshold yielded 1736 temporally coincident events with association probability above $90\%$. The resulting probabilistically ranked catalog substantially expands the population of short GRBs and MAGNETar flares detected in GBM data and provides a statistically robust framework for multimessenger searches.

[abstract 4 / 23] Yes (score: 6)
arXiv:2609.03140 [pdf, ps, other]

Title: Thermal and non-thermal emission from supermassive BLACK HOLE circumbinary disks: Disks, Coronae, Streams, and Cavities

Authors: Chris Nagele, Julian H. Krolik, Brooks E. Kinch, Jeremy D. Schnittman, Scott Noble,

Comments: Submitted to ApJ Comments welcome!

Subjects: astro-ph.HE

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

The search for electroMAGNETic signals from supermassive BLACK HOLE (SMBH) binary systems is one of the cornerstones of multi-messenger astrophysics, complementing gravitational wave observations of such systems by pulsar timing arrays and LISA. Although extensive simulations have been run to understand the time variability of the bolometric luminosity from accreting binary SMBH systems, comparatively few spectral predictions have been made, and none that go beyond simple emission models. In this paper, we post-process a \texttt{HARM3D} simulation snapshot of a binary at $20 M$ separation accreting at 0.01 Eddington. For BLACK HOLE masses $10^6$, $10^7$, and $10^8\, M_\odot$, we self-consistently solve for the radiated spectrum on the basis of time-steady radiation transfer, thermal balance, and ionization equilibrium, including all relevant RELATIVISTIC effects as well as emission and absorption processes. Although most of the bolometric luminosity is radiated thermally by the disk, the low density regions evacuated by the binary's quadrupole moment produce copious X-rays, with $\sim40\%$ of the observed luminosity in a soft X-ray power law ($Γ= 2.3$). We identify two modes of observed azimuthal variation. The X-ray continuum varies by $\sim10\%$ due to an underlying asymmetry in the gas temperature of spiral shocks in the disk. The Fe~K$α$ equivalent width dips by $\sim25\%$ when the line of sight to the inner disk is partially obscured by the lump. These two effects share the same period and are $\sim π/2$ out of phase; the period is order days to weeks for typical AGN masses and a 20$M$ separation.

[abstract 5 / 23] Yes (score: 5)
arXiv:2408.04401 [pdf, ps, other]

Title: The propagation-induced circular POLARIZATION of fast radio bursts in RELATIVISTIC plasma

Authors: Z. Y. Zhao, F. Y. Wang,

Comments: 12 pages, 11 figures, 2 tables, accepted for publication in A&A

Subjects: astro-ph.HE

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

Although the physical origin of fast radio bursts (FRBs) remains unknown, MAGNETars are the most likely candidates. The POLARIZATION properties of FRBs offer crucial insights into their origins and radiation mechanisms. Significant circular POLARIZATION (CP) has been observed in some FRBs. CP may result from intrinsic radiation or propagation effects, both within and outside the MAGNETosphere. Recent observations indicate that POLARIZATION properties of FRB 20201124A can change over short timescales (about tens of milliseconds), challenging models that attribute CP to out-of-MAGNETosphere emission and propagation. Additionally, some MAGNETospheric radiation models predict that bursts with high CP produced by off-axis emission will be systematically fainter, which contradicts the observations. We propose that CP arises from MAGNETospheric propagation effects caused by RELATIVISTIC plasma. We identify the conditions under which high CP occurs, finding it to be rare. Moreover, our model accounts for the more commonly observed low CP and the varying handedness of CP.

[abstract 6 / 23] Yes (score: 5)
arXiv:2609.03019 [pdf, ps, other]

Title: Multi-epoch Detection of an Ultra-fast Inflow in ESP 39607: Evidence for an Accretion Cascade

Authors: Alessandro Peca, Michael J. Koss, Roberto Serafinelli, C. Megan Urry, Claudio Ricci, Keigo Fukumura, Massimo Gaspari, Elias Kammoun, Alessia Tortosa, Giulia Cerini, Peter G. Boorman, Richard Mushotzky, Quirino D'Amato,

Comments: Resubmitted to ApJ after addressing a positive referee report

Subjects: astro-ph.HE astro-ph.GA

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

We present simultaneous XRISM, XMM-Newton, and NUSTAR observations of ESP 39607, a Seyfert 2 galaxy at $z = 0.201$. XRISM/Resolve reveals two absorption features near 4.7 and 4.9 keV in the observed frame, consistent with redshifted Fe XXV He-$α$/Fe XXVI Ly-$α$ absorption from gas inflowing at $v_{\rm in} \simeq 0.16c$. The high velocity identifies the absorber as an ultra-fast inflow (UFI), which is detected at $\sim 3$-$3.7σ$ across different methods and continuum models. Photoionization modeling yields $\log ξ/{\rm erg\,s^{-1}\,cm} \simeq 3.7$-$3.8$ and a column density $\log N_{\rm H,abs}/{\rm cm^{-2}} \simeq 23.2$-$23.8$, the latter depending on the assumed metallicity. The inflow velocity and line properties are consistent with those reported from two earlier NUSTAR epochs, indicating that similar inflowing material was present over a baseline of at least 2.2 yr in the source rest frame. Across all three epochs, the combined detection significance of the UFI is $5.3σ$. Given the dynamical timescale of a few days at the inferred radius, $R \simeq 49$-$77\,R_{\rm g}$, the multi-year evidence favors a scenario in which the inflow is continuously replenished, forming an accretion "cascade", rather than a single long-lived cloud. With an estimated mass inflow rate of $\dot{M}_{\rm in} \simeq 0.3$-$1.4\,M_\odot$ yr$^{-1}$, depending on metallicity, and a ratio $\dot{M}_{\rm in}/\dot{M}_{\rm acc} \simeq 0.2$-$1.0$, the inflow could supply a substantial fraction of the accretion needed to power the central ACTIVE GALACTIC NUCLEus.

[abstract 7 / 23] Yes (score: 5)
arXiv:2609.03250 [pdf, ps, other]

Title: Radiative Efficiency Enhancement by ElectroMAGNETic Energy Dissipation in Strongly Magnetized Supercritical Accretion Flows around Kerr Black Holes

Authors: Hiroyuki R. Takahashi, Ken Ohsuga, Ryohei Kobayashi, Akihiro Inoue, Yuta Asahina, Akira Nukada, Taisuke Boku,

Comments: 18 pages, 10 figures, 1 table. Accepted for publication in ApJ

Subjects: astro-ph.HE

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

We investigate how BLACK HOLE spin and the amount of MAGNETic flux affect electroMAGNETic energy dissipation and radiation transport in supercritical accretion flows. For this purpose, we perform general RELATIVISTIC radiation MAGNETohydrodynamic simulations of MAD and SANE accretion flows with different BLACK HOLE spins. In the high-spin MAD model, we find that a fraction of the electroMAGNETic energy extracted by the Blandford--Znajek mechanism is dissipated near the disk surface in the vicinity of the BLACK HOLE. This dissipation significantly contributes to the generation of radiative energy and enhances the luminosity. The time-averaged radiative efficiency reaches $η_{\rm rad}=0.60$, which is much larger than $0.088$ for the non-spinning BLACK HOLE case and $0.21$ for the weak-MAGNETic-flux case, corresponding to the SANE state. As a result, the effective trapping radius, defined as the radius at which the outward radiative luminosity becomes equal to the inward radiative luminosity, is $r_{\rm trap}=2.5r_{\rm g}$, comparable to the ISCO radius. This value is significantly smaller than $12r_{\rm g}$ for the non-spinning case and $8.5r_{\rm g}$ for the SANE state. These results suggest that the amount of MAGNETic flux accumulated on the BLACK HOLE can affect the radiative properties of supercritical accretion flows and should therefore be considered, in addition to BLACK HOLE mass, spin, and mass accretion rate, when interpreting observed luminosities and spectra.

[abstract 8 / 23] Yes (score: 4)
arXiv:2609.03011 [pdf, ps, other]

Title: Unlocking the QPE Mystery: Star-Disk Collisions in Realistic AGN Disks

Authors: Zhaohuan Zhu, Xiaoshan Huang, Yan-Fei Jiang, Shunquan Huang,

Comments: 11 pages, 6 figures. Revised after the first referee report

Subjects: astro-ph.HE

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

Quasi-periodic eruptions (QPEs) are luminous, recurring soft X-ray outbursts observed in the nuclei of low-mass galaxies. They display two remarkable trends: outburst durations are $\sim$10-20% of the recurrence timescale, and longer bursts are more luminous. A promising theory that naturally explains the quasi-periodicity invokes collisions between a star on an extreme mass-ratio inspiral (EMRI) orbit and the accretion disk around the supermassive BLACK HOLE. However, it remains unclear how this model reproduces the observed trends. We therefore carry out two-dimensional, multi-frequency radiation hydrodynamic (RH) simulations of star--disk collisions. Crucially, we adopt a more realistic circumnuclear disk structure from previous Radiation MHD simulations of sub-Eddington accretion disks. We find that the thick, puffed-up disk atmosphere, extending to $z/r\sim1$, causes different portions of the bow shock to break out at different times, producing prolonged thermal emission as the shock emerges through the breakout surface at $z/r\sim0.7$. The X-ray flare duration is set by the shock propagation time through the optically thick disk--a $\sim$10% of the orbital timescale, reproducing the observed duty cycle. A more oblique star-disk interaction yields a longer, more luminous flare. The realistic AGN disk models also exhibit a surface density $Σ\propto r^2$, giving a collisional energy $E\propto P^{2/3}$ that may explain the luminosity--period trend, especially for the weaker QPEs. Overall, we suggest that a more realistic circumnuclear disk structure can explain several observed QPE trends-and QPEs may, in turn, constrain the disk structure.

[abstract 9 / 23] Yes (score: 4)
arXiv:2609.03232 [pdf, ps, other]

Title: CLAS+: A large catalog of Changing-Look AGN candidates selected through S-PLUS narrow-band photometry

Authors: L. Nakazono, L. L. Oliveira, R. R. Valença, P. Sánchez-Sáez, G. Oliveira-Schwarz, N. M. Cardoso, A. L. O'Mill, S. Panda, E. Telles, R. Demarco, W. Schoenell, T. Ribeiro, A. Kanaan, C. Mendes de Oliveira,

Comments: Accepted in ApJ. Crossmatch of CLAS+ with LSST is available in https://marixko.github.io/CLAS_lsst_fup/

Subjects: astro-ph.GA

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

Changing-look ACTIVE GALACTIC NUCLEi (CLAGN) exhibit rapid spectral transitions on timescales of months to years, challenging standard AGN unification models and providing unique insight into accretion-disk variability and obscuration processes. Despite their scientific importance, systematic searches for CLAGN remain limited by the scarcity of multi-epoch spectroscopy and the difficulty of constructing large samples efficiently. We introduce CLAS+, a catalog constructed by comparing synthetic photometry derived from DESI DR1 and SDSS DR17 spectra with contemporaneous narrow-band imaging from the S-PLUS survey. Applying our pipeline to a parent sample of 98,139 QUASARs, we select high-confidence CLAGN candidates above a threshold of reduced chi-squared $χ_r^2 > 15$. We identify 3,554 strong CLAGN candidates, corresponding to 3.6\% of the parent sample. This selected fraction is conditional on the adopted criterion and should not be interpreted as an intrinsic CLAGN occurrence rate. Cross-matching with existing CLAGN compilations shows that CLAS+ identifies a large population of previously unreported high-priority candidates (3,481). Among the spectroscopic--photometric comparisons with reliable temporal classification, 40\% are classified as photometric turn-on, 41\% as intermediate, and 19\% as turn-off. We also find an apparent redshift dependence in the relative fractions, with photometric turn-on candidates becoming more common at higher redshifts within the CLAS+ selected sample. Therefore, narrow-band photometry provides a powerful and efficient alternative to purely spectroscopic searches for identifying CLAGN candidates at scale. CLAS+ substantially expands the known CLAGN candidate population and provides a valuable target list for future spectroscopic follow-up and time-domain studies with facilities such as Rubin/LSST.

[abstract 10 / 23] (score: 3)
arXiv:2609.03007 [pdf, ps, other]

Title: Tidally-enhanced resonances in extreme-mass-ratio inspirals: A tertiary path to chaos

Authors: Kyriakos Destounis, Takuya Katagiri, Sajal Mukherjee, Kostas D. Kokkotas,

Comments: 22 pages, 11 figures

Subjects: gr-qc astro-ph.HE hep-ph hep-th nlin.CD

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

Extreme-mass-ratio inspirals (EMRIs) provide a unique laboratory for probing strong-field gravity and complex RELATIVISTIC dynamics. We study a tidally deformed EMRI composed of a stellar-mass secondary orbiting a supermassive (non-)rotating BLACK HOLE embedded in an external, adiabatically varying tidal environment. These systems provide a restricted, yet astrophysically motivated, realization of the RELATIVISTIC three-body problem, expected to appear in ACTIVE GALACTIC NUCLEi, with a clear hierarchy of masses and radiation-reaction timescales. The external tidal deformation breaks the axisymmetry of the Kerr spacetime, rendering the geodesic dynamics non-integrable and giving rise to chaotic motion. The resulting signature of non-integrability is characterized through Poincaré maps and rotation curves constructed from the ratios of the fundamental frequencies of bound radial, polar, and azimuthal motion. We identify two prominent plateaus whose widths increase with the tidal field amplitude, signaling a transition from weak to strong chaos. We then demonstrate the sensitivity of the chaotic dynamics to the orientation of the orbit relative to the tidal field. We further analyze the proper-time evolution of the action-angle variables, showing that the angle combinations associated with the dominant commensurabilities are phase locked, thereby allowing the associated tidal contributions to induce secular changes in the constants of motion, whereas off-plateau angle combinations circulate. These results clarify the dynamical significance of the prominent plateaus and provide a novel phase-space characterization of tidal resonances in EMRIs. Finally, we discuss the potential role of radiation-reaction effects in driving EMRIs through tidal island crossings and the implications for gravitational-wave inference with future detectors.

[abstract 11 / 23] (score: 3)
arXiv:2609.03088 [pdf, ps, other]

Title: Direct Four-Spacecraft Measurement of Reconnection Exhaust Thickness in the Solar Wind

Authors: Mani K Chettri, Rupak Mukherjee, Hemam D. Singh,

Comments: 9 pages, 3 figures, 1 table

Subjects: physics.space-ph astro-ph.SR

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

The thickness of a RECONNECTing solar wind current sheet is normally inferred from a single spacecraft as the product of the boundary-normal speed and the crossing duration. Multipoint measurements have tested this method for generic solar wind current sheets and constrained the geometry of RECONNECTion exhausts, but a direct comparison with single-spacecraft thickness estimates for the same RECONNECTion-associated crossings is still lacking. We analyze four current-sheet crossings observed by Magnetospheric Multiscale in the pristine solar wind on 2017 November 10 the two boundaries of a confirmed RECONNECTion exhaust and two nearby current sheets. The tetrahedron separation was $\approx 16$ km. Cross-correlation of the MAGNETic-field ramps gives millisecond-level lag uncertainties, boundary normals to $4^\circ-8^\circ$ and speeds to $5\%-8\%$, while single-threshold timing at these separations is noise dominated. The exhaust edges are 29-31 ion inertial lengths ($d_i$) thick. The two edge normals differ by $22^\circ$ (68% interval [$19^\circ,26^\circ$]), resolving a nonparallel exhaust geometry. At the exhaust edges, the measured boundary speeds agree with three standard single-spacecraft estimates to 4%-15% and remain within about one Alfvén speed of the plasma motion. Estimating the normal from one spacecraft is the larger source of error, though the thickness is still recovered to within tens of percent when a degenerate minimum-variance solution is rejected. At the actively RECONNECTing sheet, the boundary speed exceeds the local plasma speed along the normal by $29\% \pm 10\%$.

[abstract 12 / 23] (score: 3)
arXiv:2609.03159 [pdf, ps, other]

Title: The Accretion Explorer Interferometer (AEI) Phase I NASA Innovative Advanced Concepts Final Report

Authors: Kimberly A. Weaver, Jenna M. Cann, Kenneth Carpenter, Maurice Leutenegger, Takashi Okajima, Scott Rohrbach, Liz Matson, Craig Stevens, George Bussey, Jean-Etienne Dongmo, David Kim, Jess Lewis, Khashayar Parsay, Sharon Peabody, Alison Rao, Sara Riall, Marta Shelton, Kan Yang, Isabella Carlton, Webster Cash, Kaylee DeGennaro, Emma Kleiner, John Krizmanic, Erini Lambrides, Miranda McCarthy, Jeffrey McKaig, Atul Mohan, Teresa Monsue, Ryan Pfeifle, Mainak Singha, Melville Ulmer, Laura D. Vega, Kelly E. Whalen,

Comments: 39 pages plus appendices

Subjects: astro-ph.IM

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

We must create superb X-ray images to understand the detailed physical processes behind some of the most powerful astronomical objects. The need to achieve this capability has been known for decades. But as time proceeds, X-ray astronomy falls further behind other wavebands that are steadily increasing their imaging capacity. Radio astronomy in particular has reached an angular resolution on the order of micro arcseconds via aperture synthesis interferometry, using the interference of electroMAGNETic waves from many small telescopes together to simulate having a much larger telescope. Developing an equivalent high-resolution capability in the X-ray band would be a game changer for high-energy astrophysics. We will understand how supermassive BLACK HOLEs grow and evolve. We will learn what powers astrophysical JETs. We will learn how young, active stars affect the habitability of their planets. Technologically, our NIAC study has shown that the Accretion Explorer Interferometer (AEI) concept, unlike the original MAXIM concept, is more feasible in operation, being only 2 km long, versus approximately 450 km. Our study has also shown that satellite station keeping is possible, leveraging from LISA pathfinder technology, and using large mirror flats plus an X-ray beamsplitter for enabling technology is feasible.

[abstract 13 / 23] (score: 3)
arXiv:2609.03183 [pdf, ps, other]

Title: Hall-MHD in driven turbulence FLASH simulations

Authors: A. Mohapatra, E. C. Hansen, A. Reyes, A. F. A. Bott, E. G. Blackman, P. Tzeferacos,

Comments: 28 pages, 14 figures, 2 tables

Subjects: physics.plasm-ph

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

The origin of MAGNETic fields in turbulent astrophysical systems has long been a central problem in plasma astrophysics. Fluctuation dynamos are a class of field amplification mechanisms that occur in turbulent MAGNETohydrodynamics whereby stochastically forced motions of plasma at sufficiently high MAGNETic Reynolds numbers exponentially amplify MAGNETic energy. For steady forcing, such dynamos saturate with MAGNETic energies at a sizable fraction of the turbulent kinetic energy. Although fluctuation dynamo is widely studied within the framework of resistive MAGNETohydrodynamics (MHD) and driven-turbulence numerical simulations, this work explores the difference when the Hall term is included in the MAGNETo-fluid's generalized Ohm's law. The inclusion is motivated in part by recent high energy-density plasma experiments studying fluctuation dynamo that are governed by an extended MAGNETohydrodynamics (xMHD) ansatz, which includes the Hall term. We first discuss the details of the Hall-MHD implementation in the FLASH code, the tool we use to model xMHD fluctuation dynamo. We then investigate the influence of the Hall term on the fluctuation dynamo in a three-dimensional periodic box, driven with stochastic forcing at the box scale. We compare cases with a Hall term of varying magnitude to no-Hall cases with respect to the MAGNETic field growth rate, saturation level, and MAGNETic field structure. The Hall-MHD fluctuation dynamo is found to saturate at lower MAGNETic energies and with fewer small-scale MAGNETic structures than the no-Hall cases. Both findings are consistent with the interpretation that the Hall term acts as an additional, non-linear transport term, akin to an enhanced turbulent diffusivity.

[abstract 14 / 23] (score: 3)
arXiv:2609.03408 [pdf, ps, other]

Title: Search for intranight optical variability in a large sample of intermediate-mass BLACK HOLEs

Authors: Himanshu Sharma, Gopal-Krishna, Vibhore Negi, Hum Chand, Krishan Chand, Anshul Kumar Sharma,

Comments: 14 pages, 9 figures, 2 tables. Submitted to MNRAS

Subjects: astro-ph.GA

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

Using the extensive archival database of the Zwicky Transient Facility (ZTF) survey, we have investigated intranight optical variability (INOV) in a large sample of low-mass ACTIVE GALACTIC NUCLEi (LMAGN) powered by intermediate-mass BLACK HOLEs (IMBHs). After applying a sequence of well-motivated selection filters, we constructed an unbiased, representative sample of 62 IMBHs for which $r$-band intranight photometric sequences are available in the ZTF database, yielding 167 sessions with a minimum duration of 2 h. By performing aperture photometry on the sequence of exposures in each session, we derived differential light curves (DLCs) of the target LMAGN relative to two carefully selected non-varying comparison stars monitored simultaneously with the LMAGN in the same exposure sequence. Application of the widely used test based on $F$-statistics to all these DLCs revealed no case of statistically significant INOV. We discuss this result for the present large sample of LMAGN in the context of an earlier report of INOV detections in another, albeit much smaller and differently selected, sample of LMAGN that had been monitored in targeted observations.

[abstract 15 / 23] (score: 2)
arXiv:2511.07578 [pdf, ps, other]

Title: From Feedback-Free Star Clusters to Little Red Dots via Compaction

Authors: Avishai Dekel, Dhruba Dutta Chowdhury, Sharon Lapiner, Zhiyuan Yao, Shmuel Gilbaum, Daniel Ceverino, Joel Primack, Rachel Somerville, Romain Teyssier,

Comments: 24 pages, 8 figures, accepted for publication in ApJ

Subjects: astro-ph.GA

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

We address the origin of the Little Red Dots (LRDs) seen by JWST at cosmic morning ($z \!=\! 4 \!-\! 8$) as compact stellar systems with over-massive BLACK HOLEs (BHs). We propose that LRDs form naturally after feedback-free starbursts (FFB) in thousands of star clusters and following wet compaction. Analytically, we show how the clusters enable efficient dry migration of stars and BHs to the galaxy center by two-body segregation and dynamical friction against the disk. The clusters merge to form compact central stellar systems as observed. Mutual tidal stripping does not qualitatively affect the analysis. The young, rotating clusters are natural sites for the formation of BH seeds via rapid core collapse. The migrating clusters carry the BH seeds, which merge into central super-massive BHs (SMBHs). Compactions are required to deepen the potential wells such that the SMBHs are retained after post-merger gravitational-wave recoils, locked to the galaxy centers. Using cosmological simulations at different epochs, with different codes and physical recipes, we evaluate the additional growth of LRD-matching compact central stellar systems by global compaction events. Adding to the dry growth by cluster mergers, the compactions can increase the escape velocities to retain the SMBHs. The LRDs appear at $z \!\sim\! 8$, after the formation of FFB clusters, and disappear after $z \!\sim\! 4$ when the stellar mass is above $10^9 M_\odot$ by growing post-compaction blue disks around the nuclear LRDs. The LRD abundance is expected to be $\sim\! 10^{-5} \!-\! 10^{-4}\,{\rm Mpc}^{-3}$, increasing from $z \!\sim\! 4$ to $z\!\sim\! 8$.

[abstract 16 / 23] (score: 2)
arXiv:2512.07140 [pdf, ps, other]

Title: A unified model of active repeating fast radio bursts associated with persistent radio sources

Authors: F. Y. Wang, H. T. Lan, Z. Y. Zhao, Q. Wu, Y. Feng, S. X. Yi, Z. G. Dai, K. S. Cheng,

Comments: title changed, 16 pages, 6 figures, 1 table, accepted for publication in ApJ

Subjects: astro-ph.HE

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

Fast radio bursts (FRBs) are intense pulses with unknown origins. A subclass of repeating FRBs show some common features, such as associated compact persistent radio sources (PRSs), high burst rates, and large host-galaxy dispersion measures (DMs). Meanwhile, they show diverse DM and rotation measure (RM) variations, which cannot be explained by current models. A unified model urgently needs to be established. Here we show the first evidence for a SUPERNOVA remnant surrounding the FRB 20190520B source. We then demonstrate that the five active repeating FRB sources associated with PRSs can be understood within a single model in which central objects are young MAGNETars in massive binary systems embedded in SUPERNOVA remnants. This model naturally predicts distinct variations of DM and RM for repeating FRBs. Crucially, young MAGNETar wind nebulae can generate bright PRSs. As a MAGNETar becomes older, the luminosity of a PRS will fade, which can naturally explain less-luminous PRSs for some active FRBs. Our results support a unified population of active FRBs in dynamic MAGNETized environments.

[abstract 17 / 23] (score: 2)
arXiv:2606.31926 [pdf, ps, other]

Title: A Suppressed Volumetric Rate of High-Luminosity Mid-Infrared Selected Tidal Disruption Events

Authors: Prajna Nair, Christos Panagiotou, Megan Masterson, Kishalay De, Erin Kara, Eleanor Winkler, M. Subhi Abo Rdan,

Comments: 11 pages, 4 figures (+ 4 pages, 4 figures in appendix); Accepted for publication in ApJ

Subjects: astro-ph.HE

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

Tidal Disruption Events (TDEs) serve as direct probes of the population of supermassive BLACK HOLEs in the center of galaxies and are nowadays regularly detected in optical wide-field time-domain sky surveys. Recent studies have demonstrated that a large fraction of TDEs can be uniquely identified in the infrared (IR) waveband, but these studies have to date been limited to relatively nearby events. In this work, we searched for highly luminous IR-bright TDEs that are rare and thus missed by searches in the local universe. We performed a systematic search of the NEOWISE archive and developed a new selection criterion based on the evolution of the W1-W2 color to select TDE candidates. We identified 10 IR bright TDEs with peak luminosities above $L_{\rm peak\, W2} \simeq 3 \times 10^{43}$ erg s$^{-1}$ and estimated an event rate of $1.2^{+0.5}_{-0.4}\times10^{-10}$ Mpc$^{-3}$year$^{-1}$ for the luminosity range of our sample. Compared to the existing local luminosity function of lower luminosity events, we detect a suppressed rate for these highly luminous events. This turn-over in the luminosity function can be naturally explained by the suppressed amount of TDEs taking place in systems with larger BLACK HOLE masses, thereby confirming the TDE nature of our sources.

[abstract 18 / 23] (score: 2)
arXiv:2609.02868 [pdf, ps, other]

Title: Inelastic Dark Photon Dark Matter for the LUX-ZEPLIN High-Recoil Event and the Galactic Halo Gamma-Ray Excess

Authors: Kimiko Yamashita,

Comments: 4 pages, 1 figure, 2 tables

Subjects: hep-ph astro-ph.HE

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

We show that a dark-photon DARK MATTER framework can simultaneously account for two recently reported anomalies: the halo-like Galactic gamma-ray excess identified by Totani in 15 years of FERMI-LAT data, and the $E_{\rm nr}=248\pm23\,({\rm stat})\pm23\,({\rm sys})$ keV nuclear-recoil event of interest reported by the LUX-ZEPLIN Collaboration. The DARK MATTER is a $U(1)_X$ dark photon $X$ with mass $m_X=420$ GeV, stabilized by a dark parity that forbids kinetic mixing with the Standard Model photon. A light scalar mediator $ϕ$, required to explain the Totani excess via Sommerfeld enhancement, is joined by a second light scalar $ϕ'$ that couples a nearly degenerate heavier vector partner $V$ to $X$. The resulting inelastic transition $X+N\to V+N$, with mass splitting $δ\simeq316$ keV close to the kinematic endpoint for $m_X=420$ GeV, naturally reproduces the localized LZ event once the detector energy resolution is included, while leaving the relic abundance and the halo phenomenology of the original Totani-motivated benchmark essentially unchanged.

[abstract 19 / 23] (score: 2)
arXiv:2609.02994 [pdf, ps, other]

Title: Sub-TeV Singlino Dark Matter in light from Sagittarius A$^\ast$ and LUX-ZEPLIN Nuclear-Recoil Event

Authors: Utpal Chattopadhyay, Debottam Das, Rahul Puri, Joydeep Roy,

Comments: 24 pages, 9 figures, 3 tables

Subjects: hep-ph astro-ph.HE

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

We investigate the impact of a DARK MATTER density spike surrounding the Milky Way's supermassive BLACK HOLE (SMBH) on the detectability of Singlino-dominated neutralino DARK MATTER within the Next-to-Minimal Supersymmetric Standard Model (NMSSM). Similar density enhancements, or mini-spikes, around stellar-mass BLACK HOLEs (sBHs), have also been considered. Such a DARK MATTER (DM) candidate typically produces weak indirect detection signals in conventional DARK MATTER halos. Additionally, a Singlino-like lightest supersymmetric particle (LSP) is very difficult to probe at the LHC or through the direct DM search experiments. On top of that, recent observation of the LUX-ZEPLIN 248 keV Nuclear-Recoil Event may hint towards a DM that can be accommodated by a Singlino with mass more than 200 GeV. Keeping these in consideration, we examine the prospects for detecting these sub-TeV DARK MATTER scenarios through gamma-ray observations of the regions surrounding the SMBH Sgr A$^\ast$ and the sBH in the low-mass X-ray binary XTE J1118+480.

[abstract 20 / 23] (score: 2)
arXiv:2609.03016 [pdf, ps, other]

Title: Strong Constraints for Line Signals from Dark Matter Annihilation in Sub-halo

Authors: Asier Salces Pérez, Thong T. Q. Nguyen, Pedro De la Torre Luque, Tim Linden,

Comments: 10 pages, 9 figures

Subjects: hep-ph astro-ph.HE

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

We present a dedicated search for monochromatic gamma-ray emission from a recently proposed nearby DARK MATTER subhalo candidate. Using nearly 15 years of FERMI-LAT Pass 8 data, we perform a sliding-window search for gamma-ray lines between 10 and 300 GeV. We do not find any statistically significant evidence for a line signal. The largest excess occurs at $E_γ\simeq 28 \, {\rm GeV}$ with a local significance of $2.5σ$. We therefore derive 95% confidence level upper limits on the annihilation cross section for $χχ\rightarrow γγ$. Under the assumed NFW subhalo model, the resulting constraints are stronger than existing Galactic Center line limits over much of the explored mass range. We further translate these line constraints into bounds on well-motivated WIMP models, such as Higgs-portal and Wino DARK MATTER scenarios, restricting previously open parameter regions consistent with thermal freeze-out as well as models associated with DARK MATTER interpretations of the Galactic Center Excess.

[abstract 21 / 23] (score: 2)
arXiv:2609.03072 [pdf, ps, other]

Title: Energy-Energy Correlators in $Z$-Tagged Jets in $pp$ Collisions

Authors: João Barata, Zhong-Bo Kang, Xoán Mayo López, Jani Penttala, Yiyu Zhou,

Comments: 10 pages, 5 figures

Subjects: hep-ph hep-ex

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

We present predictions for the collinear energy-energy correlator (EEC) measured inside $Z$-tagged JETs in proton-proton collisions across the confinement transition. Our framework combines transverse-momentum-dependent factorization for back-to-back $Z+$JET production with an exclusive differential EEC JET function incorporating perturbative evolution and flavor-dependent non-perturbative fragmentation. The EEC JET function is evaluated at $\mathrm{NLL}^{\prime}$ accuracy, with separate QUARK and gluon non-perturbative scales constrained by existing $e^+e^-$ and inclusive-JET data. We provide predictions for forward $Z+$JET production at $\sqrt{s}=8~\mathrm{TeV}$ and $13~\mathrm{TeV}$ in the JET transverse-momentum intervals $(20, 30)$, $(30, 50)$ and $(50, 100) \, \mathrm{GeV}$. The EEC distributions as functions of $z_χ$ exhibit finite plateaus at small $z_χ$, while the corresponding angular distributions display the characteristic turnover associated with the confinement transition. A flavor decomposition shows that this transition becomes increasingly dominated by QUARK-initiated JETs as the JET transverse momentum increases. Forward $Z$-tagged JETs therefore provide a clean probe of non-perturbative QUARK fragmentation and offer a direct test of whether the characteristic confinement scale extracted from $e^+e^-$ collisions remains universal in a hadronic environment.

[abstract 22 / 23] (score: 2)
arXiv:2609.03089 [pdf, ps, other]

Title: TDCOSMO XXIX: JWST/NIRSpec IFU Spatially Resolved Kinematics of Three Time-delay Lenses

Authors: Shawn Knabel, Pritom Mozumdar, Anowar J. Shajib, Tommaso Treu, Devon M. Williams, Michele Cappellari, David Law, Simon Birrer, Takahiro Morishita, William Sheu, Massimo Stiavelli,

Comments: 23 pages, 18 figures, 6 tables; submitted to Physical Review D

Subjects: astro-ph.CO astro-ph.GA

Created: 2026-09-02; Updated: 2026-09-04; Datestamp: 2026-09-04

Spatially resolved stellar kinematics are critical to the high precision achieved by cosmological probes utilizing time delays of strongly lensed QUASARs. Combined with high-resolution imaging and lens modeling, dynamical models of the 2D resolved kinematics of the deflector galaxy tightly constrain the mass profile and break the mass-sheet degeneracy, in turn providing tight constraints on the Hubble constant when the time delays are included. We extract stellar kinematics of the deflector galaxies in the quadruply lensed QUASAR systems HE0435-1223, PG1115+080, and WFI2033-4723 from James Webb Space Telescope Near-Infrared Spectrograph (JWST-NIRSpec) integral field spectroscopy. The kinematic maps reach average per-bin total (statistical and systematic) uncertainties of 6-11%, with average bin-to-bin correlated errors of only $\sim 1.2\%$. The aperture-integrated velocity dispersions are statistically consistent with the values used in the previous TDCOSMO analysis (all within $0.9σ$), with their average uncertainty reduced from 3.7% to 2.4% owing to improvements in the data reduction and kinematic-extraction methodology. We classify PG1115+080 as a fast rotator, HE0435-1223 and WFI2033-4723 as slow rotators within the probed radii, and we refine the source redshifts from the kinematics of the lensed host galaxies. Kinematic maps will be combined with time delays, lens models, and line-of-sight convergence estimates to measure cosmological parameters in the upcoming TDCOSMO 2026 milestone publication.

[abstract 23 / 23] (score: 2)
arXiv:2609.03298 [pdf, ps, other]

Title: Bifurcations in the Heliosphere: Global-scale Coronal Pseudostreamer Evolution and the Creation of Secondary Heliospheric Current Sheets

Authors: Lizet S. Casillas, Benjamin J. Lynch, Victor Réville, Olga A. Panasenco, Marco Velli,

Comments: 16 pages 8 figures Accepted for publication in ApJ

Subjects: astro-ph.SR physics.space-ph

Created: 2026-09-03; Updated: 2026-09-04; Datestamp: 2026-09-04

The heliospheric current sheet (HCS) is the boundary between open MAGNETic fields of opposite polarity in the solar wind that connect back to their respective open flux regions in the corona. The HCS is often described as a disc-like sheet warped by the combined effects of the inclination of the MAGNETic equator on the Sun, solar rotation, and solar wind expansion. The HCS is an extension of the helmet streamer belt-the closed-flux region resulting from the global dipole component of the observed photospheric MAGNETic field. In the absence of a strong dipole, a dominant quadrupole can result in two separate HCSs. Here we report on a set of idealized, axisymmetric solar wind simulations designed to study the transition of the single-HCS corona and inner heliosphere into a multiple-HCS configuration, run with the WindPredict-AW PLUTO MHD code. We systematically vary the relative strengths of the dipole/quadrupole contributions to the global field and show this results in the formation of a large-scale, closed-flux pseudostreamer that interacts with the ambient solar wind. We find that when the dipole and quadrupole magnitudes are approximately equal, our model corona can oscillate between a one- and two-HCS configuration on the timescale of days-to-weeks. We characterize the plasma dynamics of the transition of a global-scale pseudostreamer into a localized, secondary helmet-streamer belt with its own HCS surrounding a newly-opened, opposite-polarity coronal hole. We discuss the implications of our results for solar cycle evolution and the dynamic coupling of the highly structured corona and inner heliosphere.