Current date: 2026-02-04

Setting default datestamp limit: 0

Datestamp limit: 2026-02-04 (0 days ago)

Created/updated limit: 2026-01-28 (7 days ago)

Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics

Setting default set: physics

OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-02-04&until=2026-02-04&set=physics&metadataPrefix=arXiv

Scoring abstracts

Number of records retrieved: 715

Keyword score statistics

score 9 -- 2 abstracts

score 6 -- 2 abstracts

score 5 -- 2 abstracts

score 4 -- 4 abstracts

score 3 -- 8 abstracts

score 2 -- 15 abstracts

in total -- 33 abstracts

Articles that appeared on 2026-02-04

[abstract 1 / 33] Wow! (score: 9)
arXiv:2511.07643 [pdf, ps, other]

Title: Blazar PKS 0446+11 -- Neutrino connection study using a lepto-hadronic model

Authors: Rukaiya Khatoon, Markus Boettcher, Joshua Robinson,

Comments: Accepted for publication in the Astrophysical Journal: 11 pages, 2 figures, 1 table

Subjects: astro-ph.HE

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We present a multi-wavelength study of a BLAZAR PKS 0446+11, motivated by its spatial association with the neutrino event IC240105A detected by the IceCube Neutrino Observatory on 2024 January 5. The source is located 0.4 degrees from the best-fit neutrino direction and satisfies selection criteria for VLBI-selected, radio-bright AGN that have been identified as highly probable neutrino associations. PKS 0446+11 exhibited a major gamma-ray flare in November 2023, reaching approximately 18x its 4FGL-DR4 catalog average. Around the neutrino epoch, PKS 0446+11 remained in an elevated state, with the gamma-ray flux more than six times above its catalog level, the X-ray flux an order of magnitude above the archival measurements, and the optical-UV emission also enhanced. We used FERMI-LAT, SWIFT-XRT/UVOT, and archival multi-wavelength data to construct multi-wavelength light curves and spectral energy distributions (SEDs). SED modeling shows that the emission is best described by a leptonic scenario, with SYNCHROTRON emission at low energies and external Compton scattering of broad-line region and dusty torus photons dominating the X-ray - gamma-ray output. A lepto-hadronic model fails to adequately reproduce the observed SED, although hadronic cascades can broadly account for the X-ray and gamma-ray spectral coverage at lower flux levels. We compute the expected neutrino flux for the hadronic scenario and compare it to the IceCube 90% upper limit. Our results highlight the importance of continued multi-wavelength and neutrino monitoring to better understand the physical conditions under which this BLAZAR may serve as neutrino source.

[abstract 2 / 33] Wow! (score: 9)
arXiv:2512.19259 [pdf, ps, other]

Title: Projected sensitivity of CTAO to axion-like particles from BLAZARs with a machine learning approach

Authors: Francesco Schiavone, Leonardo Di Venere, Francesco Giordano,

Comments:

Subjects: astro-ph.HE

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

Blazars are a class of ACTIVE GALACTIC NUCLEi, supermassive BLACK HOLEs located at the centres of distant galaxies characterised by strong emission across the entire electroMAGNETic spectrum, from radio waves to gamma rays. Their RELATIVISTIC JETs, closely aligned to the line of sight from Earth, are a rich and complex environment, characterised by the presence of strong MAGNETic fields over parsec-scale lengths. Owing to their cosmological distance from Earth, these sources serve as ideal targets to probe non-standard gamma-ray propagation. In particular, axion-like particles (ALPs) could be detected through their coupling to photons, which enables ALP-photon conversions in external MAGNETic fields, leading to distinct signatures in the BLAZARs' gamma-ray spectra. In this work, we estimate the potential of the Cherenkov Telescope Array Observatory (CTAO) to constrain the ALP parameter space by simulating observations of two bright BLAZARs, Mrk 501 and PKS 2155$-$304. We obtain projected $2σ$ exclusion regions, demonstrating that CTAO will be able to consistently improve present limits thanks to its greater energy resolution and point-source sensitivity with respect to present ground-based gamma-ray telescopes. In addition to the standard statistical technique based on the likelihood ratio test, we further demonstrate the application of a new method based on machine learning classifiers, which may help in reducing the effect of systematic model-dependent uncertainties in future ALP searches.

[abstract 3 / 33] Yes (score: 6)
arXiv:2601.03530 [pdf, ps, other]

Title: Jet-torus interaction revealed by sub-parsec SO absorption in NGC 1052

Authors: Satoko Sawada-Satoh, Seiji Kameno, Nozomu Kawakatsu, Do-Young Byun, Se-Jin Oh, Sang-Sung Lee, Duk-Gyoo Roh, Chungsik Oh, Jae-Hwan Yeom, Dong-Kyu Jung, Hyo- Ryoung Kim, Young-Sik Kim, Sanghyun Kim,

Comments: 8 pages, 5 figures, accepted for publication in PASJ

Subjects: astro-ph.GA

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We report the first λ2-mm very long baseline interferometry (VLBI) observations of the RADIO GALAXy NGC 1052, conducted with the Korean VLBI Network (KVN) using a wide-band recording mode. Leveraging the wide bandwidth covering a velocity range at 2300 km/s, we successfully detect broad (> 700 km/s) multi-component SO J_N = 3_3 - 2_2 absorption against the sub-parsec-scale continuum structure. The absorption profile consists of both redshifted and blueshifted components, including a newly identified blueshifted feature at -412 km/s relative to the systemic velocity. Significant SO absorption is confined to the central components, with no substantial detection toward the outer JET components. This constrains the location of SO gas to a compact region smaller than 0.45 pc in the sub-parsec vicinity of the supermassive BLACK HOLE (SMBH). Our results support the scenario in which SO molecules are evaporated through shock heating caused by JET-torus interaction. The SO gas clumps are likely driven outward by the JET, with some returning toward the SMBH as inflowing material. Comparison with 321 GHz H2O masers reveals partial similarities in spatial distribution and radial velocity, suggesting that the JET-torus interaction may also trigger the excitation of H2O masers.

[abstract 4 / 33] Yes (score: 6)
arXiv:2602.02923 [pdf, ps, other]

Title: Investigating particle acceleration in the Wolf-Rayet bubble NGC 2359

Authors: Anindya Saha, Anandmayee Tej, Santiago del Palacio, Michaël De Becker, Paula Benaglia, Ramananda Santra, Ishwara Chandra CH,

Comments: 15 pages, 7 figures, and 5 tables. Accepted for publication in A&A

Subjects: astro-ph.HE

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

Massive stars have been proposed as candidates to be major factories of Galactic COSMIC RAYs (GCRs).However, this claim lacks enough empirical evidence, especially for isolated stars.The powerful stellar winds from massive stars impact the ambient medium producing strong shocks suitable for accelerating RELATIVISTIC particles.The detection of non-thermal emission-particularly SYNCHROTRON emission in low radio frequencies-serves as a key proof of particle acceleration sites.We aim to assess the potential of isolated massive stars as sources of GCRs.We observed the Wolf-Rayet bubble, NGC 2359, using the upgraded Giant Metrewave Radio Telescope at Band 3 (250-500 MHz) and Band 4 (550-950 MHz).Additionally, we used complementary archival radio datasets at different frequencies to derive the broad spectral energy distribution (SED) for several regions within the bubble.To further characterize the interaction between the stellar wind and the ambient medium, we introduced a composite SED model including SYNCHROTRON and free-free emission, and two low-frequency turnover processes, the Razin-Tsytovich (RT) effect and free-free absorption (FFA).We used a Bayesian inference approach to fit the SEDs and constrain the electron number density and MAGNETic field strength.The SEDs of several regions reveal spectral indices steeper than -0.5, indicative of SYNCHROTRON emission. and show a turnover below ~1 GHz.Our SED modelling suggests that the observed turnover is primarily caused by the RT effect, with a minor contribution from internal FFA.Our analysis confirms the presence of SYNCHROTRON radiation within NGC 2359.This is the second detection of non-thermal emission in a stellar bubble surrounding a WR star, reinforcing the idea that such environments are sites of RELATIVISTIC particle acceleration and supporting the hypothesis that isolated massive stars are sources of GCRs of at least GeV energies.

[abstract 5 / 33] Yes (score: 5)
arXiv:2508.00981 [pdf, ps, other]

Title: Cosmological Zoom-In Simulation of Odd Radio Circles as Merger-Driven Shocks in Galaxy Groups

Authors: Anna Ivleva, Ludwig M. Böss, Klaus Dolag, Bärbel S. Koribalski, Ildar Khabibullin,

Comments: 14 pages, 12 figures, published in A&A

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

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

Odd Radio Circles (ORCs) are a new class of distinct radio objects that has recently been discovered. The origin of these features is yet unclear because their peculiar properties are a challenge for our current understanding of astrophysical sources for diffuse radio emission. In this work we test the feasibility of major mergers in galaxy groups as a possible formation channel for ORCs. By modeling the assembly of a massive galaxy group with a final virial mass of $M_{200}\sim 10^{13}\, \rm M_\odot$ in a MAGNETohydrodynamic zoom-in simulation with on-the-fly COSMIC RAY treatment, we are able to derive the X-ray and radio properties of the system self-consistently and compare them to observations. We show that the X-ray properties for the simulated system are agreeing with characteristics of observed galaxy groups in the regarded mass range, legitimating the comparison between the radio properties of the simulated halo and those of observed ORCs. A major merger between two galaxies in the simulation is triggering a series of strong shocks in the circumgalactic medium, which in unison are forming a ring if the line of sight is perpendicular to the merger axis. The shock is rapidly expanding in radial direction and quickly reaches the virial radius of the halo. This formation channel can hence readily explain the morphology and large extent of ORCs. However, the inferred radio luminosity of these features is lower than for observed counterparts, while the degree of POLARIZATION seems to be systematically overpredicted by the simulation. Fossil COSMIC RAY populations from AGN and stellar feedback might be necessary to explain the full extent of the radio properties of ORCs, since diffusive shock acceleration was the only source term for non-thermal electrons considered in this work.

[abstract 6 / 33] Yes (score: 5)
arXiv:2602.03499 [pdf, ps, other]

Title: Similarities and differences between solar and stellar flare pulsation processes

Authors: Fabio Reale,

Comments: 16 pages, 8 figures, in press on Phil Trans A

Subjects: astro-ph.SR

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

Quasi-periodic pulsations (QPPs) are oscillatory signatures commonly detected in the light curves of solar and stellar flares, offering valuable diagnostics of the underlying MAGNETic and plasma processes. This review compares the observational characteristics, detection methods, and physical interpretations of QPPs in both solar and stellar contexts. Solar flare QPPs, extensively studied in X-rays and EUV bands using instruments such as GOES, STIX, and FERMI, display typical periods of tens of seconds and show correlations with flare duration and MAGNETic loop length. Stellar QPPs, observed in X-rays and white light by missions such as Kepler, TESS, and XMM-Newton, exhibit much longer periods - ranging from minutes to hours - consistent with larger-scale MAGNETic structures in more active stars. Despite differences in scale and observing band, statistical and comparative studies reveal common scaling relations and damping behaviors, suggesting that both solar and stellar QPPs are manifestations of the same fundamental mechanisms, likely MAGNETohydrodynamic oscillations or oscillatory RECONNECTion within flare loops. The comparison underscores a continuity between solar and stellar MAGNETic activity, linking the solar detailed physical processes to stellar-scale phenomena and providing constraints for future models and surveys.

[abstract 7 / 33] Yes (score: 4)
arXiv:2510.09742 [pdf, ps, other]

Title: The Gravitational Wave Memory from Binary Neutron Star Mergers

Authors: Jamie Bamber, Antonios Tsokaros, Milton Ruiz, Stuart L. Shapiro, Marc Favata, Matthew Karlson, Fabrizio Venturi Piñas,

Comments: 8 pages, 5 figures. Movies and additional visualizations available at https://tinyurl.com/shapiromovies

Subjects: gr-qc astro-ph.HE

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

The gravitational wave signal produced by the merger of two compact objects includes both an oscillatory transient and a non-oscillatory part, the so-called memory effect. This produces a permanent displacement of test masses and has not yet been measured. We use general RELATIVISTIC MAGNETohydrodynamic simulations, including neutrinos, with several representative viable equations of state, to quantify--for the first time--the effects of the neutron star MAGNETic field, neutrino emission, and the ejected mass on the linear and nonlinear displacement memory in binary neutron star mergers. We find that the additional contributions due to the emission of electroMAGNETic radiation, neutrinos and baryonic ejecta can be ~15% of the total memory for moderate MAGNETic fields and up to ~50% for extreme MAGNETic fields. The memory is most affected by changes in the equation of state, the binary mass, and the MAGNETic field. In particular, for moderate premerger field strengths, the dominant impact of the electroMAGNETic field is the change in the gravitational wave luminosity, and the associated gravitational wave null memory, due to the unstable growth of the MAGNETic field and the resulting redistribution of angular momentum it induces in the remnant. While the direct electroMAGNETic contribution to the null memory is additive, the change in the gravitational wave null memory can--in some cases--result in the total memory being smaller than that from the corresponding nonMAGNETized binary. Furthermore, in contrast to binary BLACK HOLE mergers, the growth of the memory in binary neutron star mergers is extended due to the long emission timescale of electroMAGNETic fields, neutrinos, and ejecta. These results necessitate the consideration of the MAGNETic field, as well as the equation of state, for accurate parameter estimation in future analyses of gravitational wave memory data.

[abstract 8 / 33] Yes (score: 4)
arXiv:2512.02292 [pdf, ps, other]

Title: Solitary Alfvén Waves

Authors: Zesen Huang, Marco Velli, Chen Shi, Yuliang Ding,

Comments:

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

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We present the solitary Alfvén wave, an exact nonlinear solution of the ideal MAGNETohydrodynamic (MHD) equations, and construct a three-dimensional numerical model -- an \emph{Alfvénon}. The model is characterized by an unperturbed far field, quasi-constant $|\boldsymbol{B}|$, and open field-line topology. Direct MHD simulations of the Alfvénon demonstrate remarkable stability, confirming that it behaves as a nonlinear solitary Alfvénic solution under ideal MHD evolution.

[abstract 9 / 33] Yes (score: 4)
arXiv:2602.02953 [pdf, ps, other]

Title: FORGE'd in the Early Universe: The Effect of Protostellar Outflows on Pop III Accretion

Authors: Yasmine J. Meziani, Philip F. Hopkins, Michael Y. Grudić, Shivan Khullar, Claude-André Faucher-Giguère, Pratik J. Gandhi,

Comments: 11 pages, 8 figures, submitted to Physical Review D

Subjects: astro-ph.SR astro-ph.GA

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We present a cosmological zoom-in radiation MAGNETo-hydrodynamic (RMHD) simulation, using FORGE'd in FIRE, that follows the formation, growth, and evolution of a single metal-free Pop. III (proto)star at redshift $z \sim 14$. The simulation captures a rotationally supported circumstellar disk and protostellar JETs, both resolved down to $<100$ au scales. We find the star grows to $\sim 27$ M$_{\odot}$ over $31,000$ years, with its final mass regulated by accretion and protostellar JETs. Protostellar JETs form because the MAGNETic mass-to-flux ratio lies within the regime that allows JET launching, and they are further enabled by a rotating circumstellar disk with sufficient gas-MAGNETic-field coupling, both present in this simulation. These JETs regulate accretion onto the (proto)star and drive outflows that collide with infalling gas, slowing inflow at large radii due to the substantial momentum they carry. A circumstellar disk forms, extending out to $\sim 0.01$ pc, which remains gravitationally stable (Q $\gg 1$). The stability of the disk is maintained through both thermal support and turbulence. In this paper we focus on how JETs play a critical role not only in shaping the final masses of Pop. III stars but also in directly influencing their surroundings by regulating accretion. These results will provide important insights into the initial mass function and feedback processes in the earliest star-forming regions of the Universe.

[abstract 10 / 33] Yes (score: 4)
arXiv:2602.03836 [pdf, ps, other]

Title: JWST Discovery of High-Velocity Mid-Infrared Ionized Outflows in Ultraluminous Infrared Galaxies F11119+3257 and F05189-2524

Authors: Jerome Seebeck, Kylie Yui Dan, Sylvain Veilleux, David Rupke, Eduardo Gonzalez-Alfonso, Ismael Garcia-Bernete, Weizhe Liu, Dieter Lutz, Marcio Melendez, Miguel Pereira-Santaella, Eckhard Sturm, Francesco Tombesi,

Comments: 24 pages, 13 figures

Subjects: astro-ph.GA

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

Ultra-fast outflows (UFOs) are thought to be a driving mechanism of large-scale winds driven by ACTIVE GALACTIC NUCLEi, which cause significant galactic feedback through quenching STAR FORMATION and regulating supermassive BLACK HOLE growth. We present James Webb Space Telescope (JWST) Mid-Infrared Instrument Medium-Resolution Spectrometer observations of two nearby ultraluminous infrared galaxies (ULIRGs), F11119+3257 and F05189-2524, with nuclear X-ray detected UFOs and kiloparsec-scale outflow. These galaxies show remarkably similar mid-infrared continuum and emission line features, notably including a high-velocity $v_{90}$ $\sim$ 4000 km s$^{-1}$ outflow detected in highly ionized neon emission lines, e.g., \nevi. In F05189-2524, we see a slightly slower biconical outflow extending up to $\sim2$ kpc in the same neon emission lines. Both sources show evidence of AGN-driven radiative feedback through a deficit of rotational molecular hydrogen lines in the nuclear region, $<$1 kpc from the central QUASAR, but no clear evidence of any molecular gas entrained in the QUASAR-driven outflow. Energetic analysis shows that the warm ionized gas in both of these sources contributes minimally ($\sim0.1-5\%$) to the momentum outflow rate of these sources and leaves the conclusions of previous literature unchanged: the energetics of these sources are broadly consistent with a momentum-conserving outflow.

[abstract 11 / 33] (score: 3)
arXiv:2510.03141 [pdf, ps, other]

Title: Nonmodal growth and optimal perturbations in MAGNETohydrodynamic shear flows

Authors: Adrian E. Fraser, Alexis K. Kaminski, Jeffrey S. Oishi,

Comments: 8 pages, 2 figures, version accepted for publication in Physical Review E

Subjects: physics.flu-dyn astro-ph.SR physics.plasm-ph physics.space-ph

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

In astrophysical shear flows, the Kelvin-Helmholtz (KH) instability is generally suppressed by MAGNETic tension provided a sufficiently strong streamwise MAGNETic field. This is often used to infer upper (or lower) bounds on field strengths in systems where shear-driven fluctuations are (or are not) observed, on the basis that perturbations cannot grow in the absence of linear instability. On the contrary, by calculating the maximum growth that small-amplitude perturbations can achieve in finite time for such a system, we show that perturbations can grow in energy by orders of magnitude even when the flow is sub-Alfvénic, raising the possibility that shear-driven turbulence may be found even in the presence of strong MAGNETic fields, and challenging inferences from the observed presence or absence of shear-driven fluctuations. We further show that MAGNETic fields introduce additional nonmodal growth mechanisms relative to the hydrodynamic case, and that 2D simulations miss key aspects of these growth mechanisms.

[abstract 12 / 33] (score: 3)
arXiv:2512.11694 [pdf, ps, other]

Title: A Spatially Resolved Evolutionary Sequence of Multi-wavelength AGN Host Galaxies

Authors: Gaoxiang Jin, Guinevere Kauffmann, Y. Sophia Dai, Martin J. Hardcastle, Bohan Yue,

Comments: 18 pages, 14 figures, accepted by MNRAS

Subjects: astro-ph.GA

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

We study the spatially resolved STAR FORMATION, gas ionisation, and outflow properties of 1813 ACTIVE GALACTIC NUCLEi (AGNs) from the MaNGA survey, which we classify into infrared (IR), broad-line (BL), narrow-line (NL), and radio (RD) AGNs based on their mid-infrared colours, optical spectra, and/or radio photometry. We also provide estimations of AGN power at different wavelengths. AGN incidence is found to increase with stellar mass following a power-law, with the high-mass end dominated by RDAGNs and the low-mass end dominated by NLAGNs. Compared to their mass-matched non-AGN counterparts, we find that IRAGNs, BLAGNs, and NLAGNs on average show enhanced specific STAR FORMATION rates, younger stellar populations, and harder ionisation towards the centre. RDAGNs, in contrast, show radial profiles similar to quiescent galaxies. [OIII] outflows are more common and stronger in BL/IRAGNs, while RDAGNs on average show no outflow features. The outflow incidence increases with [OIII] luminosity, and the features in BL/IRAGNs on average extend to ~2 kpc from the nuclei. We further discuss a possible evolutionary sequence of AGNs and their host galaxies, where AGNs with strong emission lines or dust tori are present in star-forming galaxies. Later, young compact radio JETs emerge, the host galaxies gradually quench, and the AGN hosts eventually evolve into globally quiescent systems with larger radio JETs that prevent further gas cooling.

[abstract 13 / 33] (score: 3)
arXiv:2512.12728 [pdf, ps, other]

Title: DAO: A New and Public Non-Relativistic Reflection Model

Authors: Yimin Huang, Honghui Liu, Cosimo Bambi, Adam Ingram, Jiachen Jiang, Andrew Young, Zuobin Zhang,

Comments: 25 pages, 19 figures. Code available at https://github.com/ABHModels/DAO

Subjects: astro-ph.HE

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We present a new non-RELATIVISTIC reflection model, DAO, designed to calculate reflection spectra in the rest frame of accretion disks in X-ray binaries and ACTIVE GALACTIC NUCLEi. The model couples the XSTAR code, which treats atomic processes, with the Feautrier method for solving the radiative transfer equation. A key feature of DAO is the incorporation of a high-temperature corrected cross section and an exact redistribution function to accurately treat Compton scattering. Furthermore, the model accommodates arbitrary illuminating spectra, enabling applications across diverse physical conditions. We investigate the spectral dependence on key physical parameters and benchmark the results against the widely used reflionx and xillver codes.

[abstract 14 / 33] (score: 3)
arXiv:2512.19800 [pdf, ps, other]

Title: New and updated timing models for seven young energetic X-ray pulsars, including the Big Glitcher PSR J0537-6910

Authors: Wynn C. G. Ho, Lucien Kuiper, Cristobal M. Espinoza, Timothy Leon, Bennett Waybright, Sebastien Guillot, Zaven Arzoumanian, Slavko Bogdanov, Alice K. Harding,

Comments: 16 pages, 17 figures; published in MNRAS; minor changes to better match published version

Subjects: astro-ph.HE astro-ph.SR

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We present new timing models and update our previous ones for the rotational evolution of seven young energetic pulsars, including four of the top five in spin-down luminosity Edot among all known pulsars. For each of the six pulsars that were monitored on a regular basis by NICER, their rotation phase-connected timing model covers the entire period of NICER observations, in many cases from 2017-2025. For PSR J0058-7218, which was only identified in 2021, we extend the baseline of its timing model by 3 years and report detections of its first three glitches. The timing model for PSR J0537-6910 over the entire 8 years of NICER monitoring is presented, including a total of 23 glitches; we also report its spin frequency and pulsed spectrum from a 2016 NUSTAR observation. For PSR B0540-69, its complete timing model from 2015-2025 is provided, including a braking index evolution from near 0 to 1.6 during this period. The 8-year timing model for PSR J1412+7922 (also known as Calvera) is reported, which includes a position that is consistent with that measured from imaging. For PSR J1811-1925, we present its 3.5-year timing model. For PSR J1813-1749, its incoherent timing model is extended through early 2025 using new Chandra observations. For PSR J1849-0001, its 7-year timing model is provided, including a position that is consistent with and more accurate than its imaging position and its first glitch that is one of the largest ever measured. Our timing models of these seven X-ray pulsars enable their study at other energies and in gravitational wave data.

[abstract 15 / 33] (score: 3)
arXiv:2602.03032 [pdf, ps, other]

Title: How Distance Affects GRB Prompt Emission Measurements

Authors: Michael J. Moss, Amy Y. Lien, S. Bradley Cenko, Sylvain Guiriec, Craig B. Markwardt,

Comments: 19 pages, 14 figures

Subjects: astro-ph.HE

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We investigated how Gamma-Ray Burst (GRB) prompt emission measurements are affected by increasing distance to the source. We selected a sample of 26 bright GRBs with measured redshifts $z<1$ observed by the Burst Alert Telescope (BAT) on board the Neil Gehrels SWIFT Observatory (SWIFT) and simulated what BAT would have observed if the GRBs were at larger redshifts. We measured the durations of the simulated gamma-ray signals using a Bayesian block approach and calculated the enclosed fluences and peak fluxes. As expected, we found that almost all durations (fluences) measured for simulated high-$z$ GRBs were shorter (less) than their true durations (energies) due to low signal-to-noise ratio emission becoming completely dominated by background, i.e., the ``tip-of-the-iceberg'' effect. This effect strongly depends on the profile and intensity of the source light curve. Due to the uniqueness of GRB light curves, there is no common behavior in the evolution of measured durations with redshift. We compared our synthetic high-$z$ (i.e., $z>3$) GRBs to a sample of 72 observed high-$z$ bursts and found that the two samples were not inconsistent with being drawn from the same underlying population. We conclude that: (i) prompt emission durations (fluences) of high-$z$ GRBs observed by SWIFT/BAT are most likely underestimations, sometimes by factors of $\sim$several tens ($\sim2$), and (ii) changes in the average GRB prompt emission duration and fluence with increasing redshift are consistent with the tip-of-the-iceberg effect.

[abstract 16 / 33] (score: 3)
arXiv:2602.03161 [pdf, ps, other]

Title: Magnetic field effects on spherical orbit in Kerr-Bertotti-Robinson spacetime: constraints from JET precession of M87*

Authors: Chao-Hui Wang, Xiang-Cheng Meng, Shao-Wen Wei,

Comments: 21 pages, 9 figures

Subjects: gr-qc hep-th

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

The recently reported precession period of about $11.24$ years of the M87* JET provides a sensitive probe of strong field gravity and the electroMAGNETic environment in the immediate vicinity of supermassive BLACK HOLEs. In this work, we study the precession of the spherical orbit in the Kerr-Bertotti-Robinson geometry describing a rotating BLACK HOLE immersed in a uniform electroMAGNETic field. Although the timelike geodesics is non-separable, we develop a Hamiltonian approach to investigate the spherical orbits. For sufficiently strong MAGNETic fields, the study shows that the spherical orbits can only exist within a finite radial range for given orbital inclination. Requiring the existence of the spherical orbits, we obtain an upper bound of the MAGNETic field, i.e., $B<0.33 M^{-1}$ for prograde and $B<0.0165 M^{-1}$ for retrograde motion. Furthermore, imposing the observed JET precession period, we obtain a significantly tighter constraint, $B\lesssim 0.0145 M^{-1}$, providing a new constrain on the MAGNETic field of M87* independent of the shadow. Our results provide unified constraints on the parameters of the KBR BLACK HOLE and demonstrate that the JET precession offers a robust and complementary probe of MAGNETized BLACK HOLEs in the strong gravity regime.

[abstract 17 / 33] (score: 3)
arXiv:2602.03637 [pdf, ps, other]

Title: Jet-associated Balance Functions of Charged and Identified Hadrons in pp Collisions at $\sqrt{s}=13.6$ TeV using PYTHIA8

Authors: Subash Chandra Behera, Arvind Khuntia,

Comments: 10 pages, 6 figures

Subjects: hep-ex hep-ph nucl-ex

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We present a study of charge balance functions inside JETs in proton-proton collisions at $\sqrt{s}=13.6$ TeV using the PYTHIA8 event generator. The balance function is a differential observable of opposite-charge correlations, which is calculated in the JET frame for inclusive charged hadrons and the identified $π$, $K$, and $p$. The results show a clear narrowing of the balancing width with increasing JET charged multiplicity, indicating that particle production becomes more localized in momentum space in high-multiplicity JETs.This trend resembles features attributed to collective expansion in heavy-ion collisions. The species dependence highlights sensitivity to the redistribution of strangeness and baryon number during string fragmentation and color RECONNECTion. The new CR tune yields a little broader proton balance-function width in $Δϕ^{*}$ than CP5, hinting at enhanced baryon-production dynamics, whereas meson widths differ only mildly. These comparisons suggest that multiparton interactions and color RECONNECTion contribute to the observed trends, potentially generating collective like features inside JETs, especially in high multiplicity JETs, via nontrivial color dynamics alongside standard fragmentation. Taken together, the results establish identified hadron balance functions in high multiplicity JETs as a sensitive probe of hadronization and provide new constraints for models of small system collectivity.

[abstract 18 / 33] (score: 3)
arXiv:2602.03672 [pdf, ps, other]

Title: JWST imaging of the Pleiades: anisotropy of turbulence in the cold neutral medium

Authors: G. Vigoureux, N. Flagey, F. Boulanger, A. Noriega-Crespo, V. Guillet, A. J. Alvarez-Castro, N. deJesus-Rivera, E. Allys, J. M. Delouis, E. Falgarone, B. Godard, P. Guillard, F. Levrier, P. Lesaffre, A. Marcowith, M. A. Miville-Deschênes, G. Pineau des Forêts,

Comments:

Subjects: astro-ph.GA

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

Interstellar medium studies rely on MAGNETohydrodynamic (MHD) turbulence as a framework for interpretation. In this context, the statistical characterization of interstellar observations is of prime importance. We open a new perspective on diffuse interstellar matter by analyzing James Webb Space Telescope (JWST) observations of the Pleiades nebula with NIRCam. These observations are remarkable in that they provide a microscope view at the cold neutral medium (CNM) with a spatial resolution of 0.2 mpc (40 au). A two-dimensional Fourier analysis is used to characterize the structure of PAH emission in regions near and far from the Pleiades star Merope. To produce maps of the interstellar emission, stars and galaxies are filtered out. The final step in the data cleaning involves subtracting a component, in Fourier space, which we infer to be a residual of the near-infrared cosmic background. The PAH emission power spectra are highly anisotropic. They are well fitted with a break-free power-law, suggesting that we do not observe a specific scale for energy dissipation. Power-law indices are -3.5 near Merope and -3 in the more distant field. The MAGNETic field orientation, as derived from the Planck dust POLARIZATION data, aligns with the PAH anisotropy. The power anisotropy is constant across scales. These findings are discussed in relation to interstellar turbulence that may be driven by the Pleiades stars. The JWST observations of the Pleiades offer a new viewpoint for comparing observations and theoretical models, as they examine physical scales at which turbulence in the CNM is subsonic and decoupled from the thermal instability. The observations may indicate that the turbulent energy cascade in the CNM is anisotropic.

[abstract 19 / 33] (score: 2)
arXiv:2510.13066 [pdf, ps, other]

Title: Gravitational-Wave Signatures of Highly Eccentric Stellar-Mass Binary Black Holes in Galactic Nuclei

Authors: Evgeni Grishin, Isobel M. Romero-Shaw, Alessandro A. Trani,

Comments: MNRAS accepted version

Subjects: astro-ph.HE gr-qc

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

A significant fraction of compact-object mergers in galactic nuclei are expected to be eccentric in the Laser Interferometer Space Antenna (LISA) frequency sensitivity range, $10^{-4} - 10^{-1}\ \rm Hz$. Several compact binaries detected by the LIGO-Virgo-KAGRA Collaboration may retain hints of residual eccentricity at $\sim 10$ Hz, suggesting dynamical or triple origins for a significant fraction of the gravitational-wave-observable population. In triple systems, von-Zeipel-Lidov-Kozai oscillations perturb both the eccentricity and the argument of pericentre, $ω$, of the inner BLACK HOLE binary. The latter could be fully \textit{circulating}, where $ω$ cycles through $2π$, or may \textit{librate}, with $ω$ ranges about a fixed value with small or large variation. We use \texttt{TSUNAMI}, a regularised N-body code with up to 3.5 post-Newtonian (PN) term corrections, to identify four different families of orbits: (i) circulating, (ii) small and (iii) large amplitude librating, and (iv) merging orbits. We develop and demonstrate a new method to construct gravitational waveforms using the quadrupole formula utilising the instantaneous {\it total} acceleration of each binary component in \texttt{TSUNAMI}. We show that the four orbital families have distinct waveform phenomenologies, enabling them to be distinguished if observed in LISA. The orbits are also distinguishable from an isolated binary or from a binary perturbed by a different tertiary orbit, even if the secular timescale is the same. Future burst timing models will be able to distinguish the different orbital configurations. For efficient binary formation, about $\sim 1000$ binaries can have highly eccentric, librating orbits in the Galactic Centre.

[abstract 20 / 33] (score: 2)
arXiv:2510.19443 [pdf, ps, other]

Title: The impact of superradiance on the spin evolution of variably accreting massive BLACK HOLEs

Authors: Adithya Nandakumar, Ricarda S. Beckmann, Vid Irsic,

Comments: 13 pages, accepted in MNRAS

Subjects: astro-ph.HE

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

This paper explores how time-varying increases in mass accretion onto rapidly spinning BLACK HOLEs influence their long-term spin evolution when affected by superradiance - a process where energy is extracted from the BLACK HOLE by a surrounding axion field. Using simulations the study tracks how sudden accretion boosts affect a critical spin-down phase (the superradiance drop) during which the BLACK HOLE's spin rapidly decreases while its mass remains nearly constant. The BLACK HOLE spin evolution is controlled by the competition between two processes: how fast angular momentum is added through accretion, and how fast it is removed by the axion cloud. One major conclusion is that boosts to the accretion rate before the superradiance drop have the strongest effect, as they can delay or reshape the drop and significantly shrink the region of the mass-spin plane depopulated due to the superradiance. In particular, a super-Eddington accretion rate of 5 times Eddington accretion, lasting for 4 Myr and occurring 30 Myr before the superradiance drop can reduce the superradiance exclusion region in the mass-spin plane by 40 percent. In contrast, boosts to the accretion rate after the superradiance drop only cause temporary changes in the BLACK HOLE spin. The study also shows that BLACK HOLEs with lighter axion clouds are more sensitive to these early boosts and can show observable spin changes lasting tens to hundreds of millions of years. Heavier axion clouds, however, require much stronger or longer-lasting boosts to produce similar effects, making them more stable under variable accretion.

[abstract 21 / 33] (score: 2)
arXiv:2510.20898 [pdf, ps, other]

Title: Illuminating gravitational wave sources with Sgr A* flares

Authors: Pau Amaro Seoane,

Comments: Submitted. Added section on Airy analysis to justify the choice of the relativistic electron population

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

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

Sagittarius A* exhibits daily energetic flares characterized by non-thermal emission in the infrared and X-ray bands. While the underlying accretion flow is a Radiatively Inefficient Accretion Flow (RIAF) peaking at radio frequencies, the mechanism powering these non-thermal transients remains debated. Stellar dynamics predict a population of faint brown dwarfs orbiting Sgr A*. We investigate whether the tidal stripping of brown dwarfs provides a viable fueling mechanism for the observed flares. These objects are progenitors of Extremely Large Mass Ratio Inspirals (XMRIs), crucial sources of low-frequency gravitational waves for the future LISA mission. We present high-resolution hydrodynamic simulations of grazing tidal interactions coupled with a parameterized non-thermal radiation model. We numerically model the stripping of the brown dwarf envelope and the subsequent accretion of this material. We demonstrate that the dynamics of the tidal fallback and subsequent viscous evolution naturally reproduce the fundamental temporal characteristics of observed flares: the peak luminosity and the characteristic 1-hour duration. We show that this fueling mechanism is dynamically viable and energetically consistent, placing strong constraints on the required efficiency of the non-thermal emission process, suggesting extreme radiative inefficiency. These findings provide compelling evidence for a hidden population of brown dwarfs in the Galactic Center. Crucially, the observed high flare frequency implies tight orbits characteristic of advanced inspirals. This establishes a direct link between electroMAGNETic transients and active gravitational wave sources, alerting the LISA consortium years in advance to the presence of specific XMRI systems promising exceptionally high signal-to-noise ratios for precision tests of general relativity.

[abstract 22 / 33] (score: 2)
arXiv:2511.10427 [pdf, ps, other]

Title: Extending the Frontier of Spatially-Resolved Supermassive Black Hole Mass Measurements to at $1\lesssim z\lesssim2$: Simulations with ELT/MICADO High-Resolution Mass Models and HARMONI Integral-Field Stellar Kinematics

Authors: Dieu D. Nguyen, Michele Cappellari, Tinh Q. T. Le, Hai N. Ngo, Elena Gallo, Niranjan Thatte, Fan Zou, Tien H. T. Ho, Tuan N. Le, Huy G. Tong, Miguel Pereira-Santaella,

Comments: 18 pages, 14 figures, 5 tables; Accepted to MNRAS

Subjects: astro-ph.GA

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

Current spatially resolved kinematic measurements of supermassive BLACK HOLE (SMBH) masses are largely confined to the local Universe (distances $\lesssim100$ Mpc). We investigate the potential of the Extremely Large Telescope's (ELT) first-light instruments, MICADO and HARMONI, to extend these dynamical measurements to galaxies at redshift $1\lesssim z\lesssim2$. We select a sample of five bright, massive, quiescent galaxies at these redshifts, adopting their Sérsic profiles from HST photometry as their intrinsic surface brightness distributions. Based on these intrinsic models, we generate mock MICADO images using SimCADO and mock HARMONI integral-field spectroscopic data cubes using HSIM. The HARMONI simulations utilize input stellar kinematics derived from Jeans Anisotropic Models (JAM). We then process these mock observations: the simulated MICADO images are fitted with Multi-Gaussian Expansion to derive stellar mass models, and stellar kinematics are extracted from mock HARMONI cubes with pPXF. Finally, these derived stellar mass models and kinematics are used to constrain JAM dynamical models within a Bayesian framework. Our analysis demonstrates that SMBH masses can be recovered with an accuracy of $\sim$10%. We find that MICADO can provide detailed stellar mass models with $\sim$1 hour of on-source exposure. HARMONI requires longer minimum integrations for reliable stellar kinematic measurements of SMBHs. The required on-source time scales with apparent brightness, ranging from 5-7.5 hours for galaxies at $z\approx1$ (F814W, 20-20.5 mag) to 5 hours for galaxies at $1SMBH mass measurements to $z\approx2$, enabling crucial tests of SMBH-galaxy co-evolution at the top end of the galaxy mass function.

[abstract 23 / 33] (score: 2)
arXiv:2601.14113 [pdf, ps, other]

Title: Accretion flow around Kerr metric in the infra-red limit of asymptotically safe gravity

Authors: Orhan Donmez, Sushant G. Ghosh, M. Yousaf, G. Mustafa, Farruh Atamurotov,

Comments: 17 pages, 8 figures, 1 Table, Updated to match the published version

Subjects: astro-ph.HE gr-qc

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We investigate accretion disk dynamics and the formation of quasi-periodic oscillations (QPOs) in the infrared limit around Kerr-like BLACK HOLEs in asymptotically safe gravity. Relativistic hydrodynamic solutions of Bondi-Hoyle-Lyttleton (BHL) accretion reveal that quantum corrections significantly modify the structure of the shock cone formed around the BLACK HOLE. The BLACK HOLE spin controls the azimuthal asymmetry of the shock cone through frame-dragging effects, whereas the quantum correction parameter effectively reduces the strength of gravitational focusing by modifying the metric coefficients in the strong-field region, resulting in a wider shock opening angle, weaker post-shock compression, and reduced density concentration within the cone. Time-dependent mass accretion rates reveal oscillation modes trapped within the shock cone. The power spectral density (PSD) investigations suggest that these modes naturally generate low-frequency QPOs, whose amplitudes, coherence, and harmonic structure depend on both the spin and the quantum correction parameter. The PSD analyses performed at different radial locations reveal that identical QPO frequencies are obtained in all cases. The numerically detected frequencies result from the excitation of global oscillation modes trapped within the post-shock region. The resulting global modes are found to consist of fundamental frequencies, their associated harmonic overtones, and near-commensurate frequency ratios such as 2:1 and 3:2. Coherent oscillations are enhanced and near-commensurate frequency ratios are produced when moderate rotation and moderate quantum corrections are coupled. Large quantum correction parameters, on the other hand, wash out unique spectral peaks and suppress oscillation amplitudes.

[abstract 24 / 33] (score: 2)
arXiv:2601.23012 [pdf, ps, other]

Title: Scalar-tensor-vector gravity theory is tested by BLACK HOLE photon rings

Authors: Qiao Yue, Zhaoyi Xu, Meirong Tang,

Comments: 18pages,15figures

Subjects: gr-qc

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

This paper investigates the photon ring and shadow structure of the Reissner-Nordström BLACK HOLE in the scalar-tensor-vector gravitational framework. The BLACK HOLE is characterized by the ( MOG) parameter (α) and the charge (Q). The study finds that as (α) increases, the event horizon radius (r_h), photon sphere radius (r_{ph}), and critical impact parameter (b_{ph}) all increase, while these decrease as (Q) increases. The innermost stable circular orbit radius (r_{isco}) exhibits similar monotonic behavior. Ray-tracing shows that as (Q) increases, the impact parameter (b) interval between the lensing ring and photon ring widens; (b_{\text{ph}}) is non-degenerate, and the photon ring radius is uniquely determined by (α) and (Q). Using $EHT$ constraints on (SgrA^*) and (M87^*), the bounds on (α) and (Q) are derived. For (Q = 0), (0.5), and (1), the allowed ranges are (α\in [0, 0.06]), ([0, 0.11]), and ([0.19, 0.36]), respectively. Radiative simulations show that for fixed (Q), larger (α) leads to a larger, non-degenerate photon ring. The Schwarzschild case is approached only when both (α) and (Q) are small. This provides a computational basis for testing modified BLACK HOLEs and offers a non-degenerate observational criterion for distinguishing quantum gravity models, consistent with current $EHT$ data. Future observations with $ngEHT$ and multi-band POLARIZATION can further test this. The results suggest that studying the photon ring structure of a Reissner-Nordström BLACK HOLE in scalar-tensor-vector gravity provides a unique optical diagnostic for potential quantum-gravity tests and BLACK HOLE properties.

[abstract 25 / 33] (score: 2)
arXiv:2602.00312 [pdf, ps, other]

Title: Self ordering to imposed ordering of dust -- a continuous spatial phase transition experiment in MDPX

Authors: Siddharth Bachoti, Saikat Chakraborty Thakur, Rahul Banka, Cameron Royer, Edward Thomas,

Comments:

Subjects: physics.plasm-ph

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

Previous experiments conducted in the Magnetized Dusty Plasma eXperiment (MDPX) revealed an intriguing phenomenon first referred to as imposed ordering. This occurs when micron-sized dust particles become aligned with the geometry of a conducting mesh placed above the dust (at a distance much larger than the plasma Debye length or the ion-neutral or electron-neutral mean free paths) in the presence of a strong MAGNETic field perpendicular to the mesh. In this work, results of a transition experiment are presented wherein starting from a classical two-dimensional Coulomb crystal with hexagonal symmetry in an unMAGNETized plasma $(B = 0\,T)$, dust transitions to a state in which it flows along the geometry of a conducting mesh placed above it, mapping out the 4-fold symmetry of the boundary condition. It is hypothesized that beyond a certain MAGNETization, elongated electric potential structures emanating from the mesh drive the dust motion to reflect the mesh morphology, transitioning from a 6-fold self ordering to 4-fold imposed ordering. The various dust phases are quantified and a critical value of MAGNETic field is identified in the transition experiment indicating the onset of imposed ordering.

[abstract 26 / 33] (score: 2)
arXiv:2602.02656 [pdf, ps, other]

Title: Radiation-hydrodynamics of star-disc collisions for quasi-periodic eruptions

Authors: Taj Jankovič, Clément Bonnerot, Sergey Karpov, Aleksej Jurca,

Comments: Submitted to A&A, comments are welcome!

Subjects: astro-ph.HE

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

Quasi-periodic eruptions (QPEs) are recently discovered transients of unknown nature occurring near supermassive BLACK HOLEs, which feature bright X-ray bursts separated by hours to days. A promising model for QPEs is the star-disc collisions model, where a star repeatedly interacts with an accretion disc around a BLACK HOLE, creating shocks that expel dense outflows of gas from which radiation emerges. We investigate the dynamics of the star-disc collisions, the properties of the outflows, and the resulting radiation signatures. Our study focuses on the generic case where the star remains unperturbed by the collision and the stellar crossing time through the disc is sufficiently long for shocked gas to flow around the star. We performed a three-dimensional (3D) radiation-hydrodynamics simulation of the star-disc collision. The star was modeled as a solid, spherical body, and the interaction was simulated for a small, local section of the accretion disc. We found that star-disc collisions generate a nearly paraboloidal bow shock. The heating of gas is not confined to the column of gas directly ahead of the star but also extends laterally as the shock front expands sideways while traveling with the star. As the star crosses the disc, it injects momentum preferentially along its direction of motion, leading to an asymmetric redistribution of energy and momentum. As a result, two outflows emerge on opposite sides of the disc with different properties: the forward outflow expands faster, contains more mass, carries more energy, and is about twice as luminous as the backward outflow. Our findings suggest that the asymmetry in outflow properties and luminosity arises naturally from the collision dynamics, offering a possible explanation for the alternating strong-weak flare patterns observed in several QPE sources.

[abstract 27 / 33] (score: 2)
arXiv:2602.02733 [pdf, ps, other]

Title: Cyclotron lines in subcritical X-ray pulsars: Monte Carlo simulations reveal the origin of the observed variability

Authors: Prodromos Fotiadis, Nick Loudas, Nikolaos D. Kylafis, Joachim Trümper,

Comments: 14 pages, 11 figures, 2 tables. Submitted for publication to A&A

Subjects: astro-ph.HE

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

Observed cyclotron resonant scattering features (CRSFs) in X-ray pulsars (XRPs) exhibit strong variability. In the subcritical luminosity regime, the centroid energy ($E_{CRSF}$) and line width ($σ_{CRSF}$) often show positive correlations with the X-ray luminosity. We investigate the physical origin of the observed variability quantitatively, focusing on the effects of resonant scattering and Doppler shift induced by the plasma flow in the accretion funnel. We developed a RELATIVISTIC Monte Carlo code to perform detailed radiative transfer calculations in the accretion funnel above the hotspot and derive angle-dependent spectra. Analytical plasma density and velocity profiles were adopted to account for the effects of radiation pressure on the flow. Approximate resonant scattering cross-sections were employed. We varied the accretion luminosity to explore the resulting variability of the CRSF properties. The emergent spectra exhibit a prominent, asymmetric CRSF accompanied by a broad blue wing. The CRSF is systematically redshifted relative to the classical cyclotron energy, with the magnitude of the redshift decreasing at higher luminosities and for larger viewing angles $θ$. Both $E_{CRSF}$ and $σ_{CRSF}$ correlate positively with luminosity for all viewing angles. Their absolute values, however, depend strongly on the viewing angle, indicating substantial variability over the pulse cycle and sensitivity to the system geometry. At fixed luminosity, $E_{CRSF}$ ($σ_{CRSF}$) decreases (increases) with increasing $\cosθ$. Consequently, phase-resolved observations are expected to reveal an anticorrelation between the CRSF centroid energy and width. When applied to the XRP GX 304$-$1, the model reproduces the observed CRSF variability over nearly an order of magnitude in luminosity for geometries in which the accretion funnel is predominantly viewed edge-on.

[abstract 28 / 33] (score: 2)
arXiv:2602.02778 [pdf, ps, other]

Title: Probing The Dark Matter Halo of High-redshift Quasar from Wide-Field Clustering Analysis

Authors: Hao Meng, Huanian Zhang, Guangping Ye,

Comments: 5 figures and 3 tables, submitted

Subjects: astro-ph.GA

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

High-redshift QUASARs have been an excellent tracer to study the astrophysics and cosmology at early Universe. Using 216,949 high-redshift QUASAR candidates ($5.0 \leq z < 6.3$) selected via machine learning from the Legacy Survey Data Release 9 and the Wide-field Infrared Survey Explorer, we perform wide-field clustering analysis to investigate the large-scale environment of those high-redshift QUASARs. We construct the projected auto correlation function of those high-redshift QUASARs that is weighted by its predicted probability of being a true high-redshift QUASAR, from which we derive the bias parameter and the typical DARK MATTER halo mass of those QUASARs. The DARK MATTER halo mass of QUASARs estimated from the projected auto correlation function is $\log(M_h/M_{\odot})=12.2 ^{+0.2}_{-0.7}$ ($11.9^{+0.3}_{-0.7}$), with the bias parameter $b$ of $12.34 ^{+4.26}_{-4.37}$ ($11.52^{+4.02}_{-4.14}$) for the redshift interval of $5.0 \leq z <5.7$ ($5.7 \leq z <6.3$). Our results, combined with other measurements of DARK MATTER halo masses for QUASARs or ACTIVE GALACTIC NUCLEus which obtain a lower DARK MATTER halo mass of $\sim 10^{11.5}$ M$_\odot$ at similar redshift, suggest a more complex, and possibly non-monotonic evolution of QUASAR hosting DARK MATTER halo. Moreover, we estimate the duty cycle of those QUASARs, which is $0.008^{+0.135}_{-0.007}$ ($0.003+^{+0.047}_{-0.003}$) for the redshift interval of $5.0 \leq z <5.7$ ($5.7 \leq z <6.3$).

[abstract 29 / 33] (score: 2)
arXiv:2602.03078 [pdf, ps, other]

Title: Long-term timing evolution of four Anomalous X-Ray Pulsars

Authors: Han-Long Peng, Shan-Shan Weng, Ming-Yu Ge, Shi-Qi Zhou, Erbil Gügercinoğlu, Wen-Tao Ye, You-Li Tuo, Liang Zhang, Juan Zhang, Shi-Jie Zheng, Yu-Jia Zheng, Xian-Ao Wang,

Comments: 21 pages, 10 figures, 10 tables, accepted for publication in ApJ

Subjects: astro-ph.HE

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are believed to be manifestations of MAGNETars. Typically, AXPs exhibit higher X-ray luminosities, whereas SGRs are generally fainter and display significantly high signal-to-noise ratios only during their outburst phases. In this work, we report the long-term timing evolution of four AXPs: 1E 2259+586, 4U 0142+61, 1RXS J170849.0-400910 and 1E 1841-045, which were regularly monitored with NICER from 2017 to 2024. Over this period, we identify a total of 10 timing events. In addition to one glitch and one anti-glitch in 1E 2259+586 reported in literature, we detect another 8 new timing events: 5 glitches, 2 anti-glitches, and 1 unusual state transition event. Notably, both anti-glitches were observed in 4U 0142+61, making it the most frequent source of such events, and there is a hint of regular evolution in its pulse profile. In the case of 1RXS J170849.0-400910, it continues to exhibit pronounced high-frequency timing anomalies and undergoes a state transition event. Finally, we study the evolution of the pulse profiles and find that the profiles of 1E 2259+586 and 4U 0142+61 both evolve. This is consistent with the earlier finding that pulse profile evolution is a generic feature of MAGNETars.

[abstract 30 / 33] (score: 2)
arXiv:2602.03375 [pdf, ps, other]

Title: Effect of static MAGNETic island on ITG of ADITYA-U tokamak

Authors: Vibhor Kumar Singh, Amal R Biju, Jaya Kumar Alageshan, Kaushalender Singh, Deepti Sharma, Joydeep Ghosh, Nishant Sirse, Abhijit Sen, Sarveshwar Sharma, Manjunatha Valmiki, Sandeep Agrawal, Sanjay Wandhekar, Animesh Kuley,

Comments: 19 pages, 11 figures

Subjects: physics.plasm-ph

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

Magnetic islands play a crucial role in regulating plasma confinement in tokamaks by interacting with micro-instabilities, such as the ion temperature gradient (ITG) mode. This work presents a detailed investigation of the effects of static MAGNETic islands on ITG instability, relevant to the ADITYA-U tokamak, using the Global Gyrokinetic Code in Cylindrical Coordinates (G2C3), a particle-in-cell (PIC) framework that employs a neural-network-assisted projection scheme. A two-phase simulation strategy is adopted. In the first phase, static MAGNETic islands with mode numbers (m, n) = (2, 1) and (3, 1) are introduced by perturbing the equilibrium MAGNETic flux functions. Particle dynamics within these modified topologies result in the flattening of plasma density profiles in the island regions, confirming island formation and its impact on the equilibrium profiles. In the second phase, the flattened profiles serve as new equilibria for linear electrostatic gyrokinetic simulations with adiabatic electrons, enabling the study of the modified ITG behavior. Magnetic islands significantly restructure the ITG mode, producing a spatial redistribution of potential fluctuations within and around the island region. Moreover, as the island width increases, the growth rates of different toroidal ITG modes converge, suggesting a universal stabilization trend. A comparison between the (2,1) and (3,1) islands indicates that higher-q islands lead to a more spatially extended ITG mode structure, reflecting the longer MAGNETic connection lengths and weaker curvature drive at outer flux surfaces. These results demonstrate the pivotal role of island-induced equilibrium modifications in determining ITG stability and mode structure in tokamak plasmas.

[abstract 31 / 33] (score: 2)
arXiv:2602.03502 [pdf, ps, other]

Title: Shells and bubbles around compact clusters of massive stars: 3D MHD simulations

Authors: D. V. Badmaev, A. M. Bykov, M. E. Kalyashova,

Comments: 13 pages, 7 figures, author's translation, to be published in Astronomy Letters, 51, No.6 (2025)

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

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

We present the results of three-dimensional MAGNETohydrodynamic (3D MHD) simulations of the plasma flow structure in the vicinity of a compact cluster of young massive stars. The cluster is considered at the evolutionary stage dominated by Wolf-Rayet stars. This stage occurs in clusters with ages of several million years, close to the onset of SUPERNOVA explosions; the well-known objects Westerlund 1 and 2 are the prototypes. The collisions of powerful winds from massive stars in the cluster core, calculated as interactions of individual outflows, are accompanied by their partial thermalization and produce a collective cluster wind. The MHD dynamics of the cluster wind bubble expansion into the interstellar medium is considered, depending on the density of the surrounding medium with a uniform MAGNETic field. We show that when expanding into a cold neutral medium, the cluster wind is able to reshape its surrounding environment over the Wolf-Rayet star lifetime, sweeping up more than $10^4$ $M_{\odot}$ of gas in $\sim 2 \times 10^5$ yr and producing extended, thin and dense shells with an amplified MAGNETic field. In a cold neutral medium with a density of $\sim 20$ cm$^{-3}$ and a MAGNETic field of $\sim 3.5$ $μ$G, a thin shell forms around the cluster wind bubble, characterized by a cellular structure in its density and MAGNETic field distributions. The cellular MAGNETic field structure appears in parts of the shell expanding transversely to the orientation of the external MAGNETic field. Magnetic fields in the shell are amplified to strengths $\gtrsim 50$ $μ$G. The formation of the cellular structure is associated with the development of instabilities. The expansion of the bubble into a warm neutral interstellar medium also leads to the formation of a shell with an amplified MAGNETic field.

[abstract 32 / 33] (score: 2)
arXiv:2602.03629 [pdf, ps, other]

Title: A case for Case A: detailed look at binary BLACK HOLE formation through stable mass transfer

Authors: Max M. Briel, Anastasios Fragkos, Monica Gallegos-Garcia, Anarya Ray, Michael Zevin, Abhishek Chattaraj, Jeff J. Andrews, Vicky Kalogera, Seth Gossage, Philipp M. Srivastava, Elizabeth Teng,

Comments: Submitted to A&A

Subjects: astro-ph.HE

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

In isolated binary evolution, binary BLACK HOLE (BBH) mergers are generally formed through stable mass transfer (SMT) or common envelope evolution. In recent years, the SMT channel has received significant attention due to detailed binary models showing increased mass transfer stability compared to previous studies. In this work, we perform a full zero-age-main-sequence to compact object merger analysis using detailed binary models at eight metallicities between $10^{-4}Z_\odot$ and $2Z_\odot$ to self-consistently model the population properties of BBH mergers in the SMT channel, determined their progenitor initial conditional, and investigate the binary physics governing their formation and metallicity dependence. We use the population synthesis code POSYDON to determine the population of BBH mergers from SMT. Using its extended grids of MESA binary models, we determine the essential physics in the formation of BBH mergers. SMT produces BBH mergers predominantly from systems with $P_{ZAMS}\leq10$ days. In these systems, both the initial mass transfer between two stars and the subsequent interaction between the remaining star and the first-born BH take place while the respective donor star is on the main-sequence (Case A). We find a limited contribution from wider Case B/C systems. Without a natal kick, the SMT channel does not produce BBH mergers above $Z>0.2Z_\odot$ due to orbital widening from stellar wind mass loss. The primary BH mass distribution shows a strong dependence on metallicity, while the mass ratio prefers unity independent of metallicity due to mass ratio reversal. Additionally, the $χ_{eff}$ distributions contain peaks at $χ_{eff}=0$ and ~0.15 of which the former disappears at high metallicities. A mass-scaled natal kick leave this sub-population unchanged but introduce a low-mass, unequal mass ratio sub-population that merges due to their high eccentricity.

[abstract 33 / 33] (score: 2)
arXiv:2602.03759 [pdf, ps, other]

Title: A High-order piecewise field-aligned triangular finite element method for electroMAGNETic gyrokinetic particle simulations of tokamak plasmas with open field lines

Authors: Zhixin Lu, Guo Meng, Eric Sonnendruecker, Roman Hatzky, Giorgio Daneri, Gengxian Li, Peiyou Jiang, Klaus Reuter, Matthias Hoelzl,

Comments: 16 pages, 8 figures

Subjects: physics.plasm-ph

Created: 2026-02-03; Updated: 2026-02-04; Datestamp: 2026-02-04

A high-order piecewise field-aligned triangular finite element method is developed and implemented for global electroMAGNETic gyrokinetic particle-in-cell simulations of tokamak plasmas with open field lines. The approach combines locally field-aligned finite element basis functions with unstructured $C^{1}$ triangular meshes in cylindrical coordinates, enabling whole-volume simulations with substantially reduced computational effort, while avoiding the grid distortion associated with globally field-aligned coordinates and the associated singularity at the separatrix of diverted plasmas. The formulation is compatible with both $δf$ and full-$f$ models and employs mixed-variable representations, along with a generalized pullback scheme, to control numerical cancellation in electroMAGNETic simulations. The method is implemented in the TRIMEG-C1 code and demonstrated using linear and nonlinear electroMAGNETic simulations of the TCV-X21 configuration. The results indicate that the approach accurately captures the key features of electroMAGNETic ion-temperature-gradient and kinetic ballooning mode physics, including the separatrix regions in the simulation, thereby providing a robust framework for whole-volume electroMAGNETic gyrokinetic simulations in realistic tokamak geometries.