Current date: 2026-02-11
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Number of records retrieved: 622
Keyword score statistics
score 8 -- 1 abstracts
score 6 -- 2 abstracts
score 5 -- 4 abstracts
score 4 -- 8 abstracts
score 3 -- 7 abstracts
score 2 -- 16 abstracts
in total -- 38 abstracts
Articles that appeared on 2026-02-11
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[abstract 1 / 38] Wow! (score: 8)
- Title: X-ray Timing and Spectral studies of bare AGN Mrk 110Authors: Deblina Lahiri, K. Sriram, Vivek Kumar Agrawal,Comments: 16 pages, 8 figures, 2 tables, PASJ (under Review), received minor commentsSubjects: astro-ph.HECreated: 2026-02-10; Updated: 2026-02-11; Datestamp: 2026-02-11
The origin of the soft X-ray excess below 2 keV in ACTIVE GALACTIC NUCLEi (AGNs) remains debated, with RELATIVISTIC reflection from the inner accretion disk and warm Comptonization in an optically thick corona being the leading explanations. We investigate the timing and spectral properties of the Seyfert galaxy Mrk 110 using six XMM-Newton observations. A frequency-dependent lag analysis in the 7-9 $\times 10^{-5}$ Hz range reveals a soft X-ray lag of 889-3000s in the combined 2019 data, detected with a significance of 80%. The cross-correlation function analysis, supported by simulations, also detects lags of similar nature. Spectral modeling performed by adopting both proposed BLACK HOLE masses in the literature for Mrk 110 confirms the presence of a warm corona in all observations, along with a weak RELATIVISTIC reflection component and the reflection fraction remains low (Rf < 1). Interpreting the measured soft lag in terms of light travel time implies an emission radius 4.5 Rg for a supermassive BLACK HOLE mass of $M = 1.4 \times 10^8$ solar mass , favoring a reflection scenario. However, if a lower mass of $M = 2 \times 10^7$ solar mass is adopted, the inferred radius increases, and both RELATIVISTIC reflection and warm Comptonization can plausibly contribute to the observed soft lag. The warm corona radius appears larger in the high accretion state and smaller in a lower accretion state, although no trend can be established. The persistently low reflection fraction suggests an outflowing inner corona in Mrk 110, consistent with the recent detection of JET activity in this source.
[abstract 2 / 38] Yes (score: 6) - Title: The Multi-Wavelength Context of Delayed Radio Emission in TDEs: Evidence for Accretion-Driven OutflowsAuthors: Kate D. Alexander, Raffaella Margutti, Sebastian Gomez, Michael Stroh, Ryan Chornock, Tanmoy Laskar, Y. Cendes, Edo Berger, Tarraneh Eftekhari, Noah Franz, Aprajita Hajela, B. D. Metzger, Giacomo Terreran, Michael Bietenholz, Collin Christy, Fabio de Colle, S. Komossa, Matt Nicholl, Enrico Ramirez-Ruiz, Richard Saxton, Genevieve Schroeder, Peter K. G. Williams, William Wu,Comments: 35 pages, 5 figures, 8 tables. Accepted to ApJ; text updated to match accepted version. All data used in this analysis will be made publicly available at https://otter.idies.jhu.edu/ upon article publicationSubjects: astro-ph.HECreated: 2026-02-09; Updated: 2026-02-11; Datestamp: 2026-02-11
Recent observations presented in Cendes et al. (2024a) show that optically selected tidal disruption events (TDEs) commonly produce delayed radio emission that can peak years post-disruption. Here, we explore the multi-wavelength properties of a sample of radio-observed optically selected TDEs to shed light on the physical process(es) responsible for the late-rising radio emission. We combine new late-time X-ray observations with archival optical, UV, X-ray, and radio data to conclude that a diversity of accretion-driven outflows may power delayed radio emission in TDEs. Our analysis suggests that some late radio outflows may be launched by a delayed phase of super-Eddington accretion onto the central supermassive BLACK HOLE (SMBH), while others may result from a state transition to a ``low-hard'' radiatively inefficient accretion flow or the deceleration of an off-axis RELATIVISTIC JET. We find that TDEs with delayed radio emission are less likely to exhibit helium emission lines at early times ($p=0.002$) and may have larger optical/UV photospheric radii ($p=0.026$) than other TDEs, possibly also indicating that the onset of SMBH accretion is delayed in these systems. Our results have implications for our understanding of state changes in SMBH accretion flows, the circularization timescale for TDE debris, and the prevalence of off-axis JETs in TDEs, and motivate systematic, long-term monitoring of these unique transients. The objects in our sample with the brightest radio emission are also detected in the VLA Sky Survey (VLASS), demonstrating that all-sky radio surveys can play an important role in discovering unexpected properties of the TDE population.
[abstract 3 / 38] Yes (score: 6) - Title: 2D or not 2D? Exploring 3D RELATIVISTIC MAGNETic RECONNECTion dynamics with highly accurate numerical simulationsAuthors: Vittoria Berta, Matteo Bugli, Andrea Mignone, Giancarlo Mattia, Luca Del Zanna, Stefano Truzzi,Comments: Accepted for publication on MNRASSubjects: astro-ph.HECreated: 2026-02-09; Updated: 2026-02-11; Datestamp: 2026-02-11
Fast RECONNECTion in MAGNETically dominated plasmas is widely invoked in models of dissipation in pulsar winds, gamma-ray flares in the Crab nebula, and to explain the radio nanoshots of pulsars. When current sheets evolve reaching a critical inverse aspect ratio, scaling as $S^{-1/3}$ with the plasma Lundquist number, the so-called \textit{ideal} tearing instability sets in, with modes growing, independently of $S$, extremely rapidly on timescales of only a few light-crossing times of the sheet length. We present the first set of fully 3D simulations of current-sheet disruption triggered by the ideal tearing instability within the resistive RELATIVISTIC MHD approximation, as appropriate in situations where the Alfvén velocity approaches the speed of light. We compare 3D setups with different initial conditions with their 2D counterparts, and we assess the impact of dimensionality and of the MAGNETic field topology on the onset, evolution, and efficiency of RECONNECTion. In force-free configurations, 3D runs develop ideal tearing, secondary instabilities, and a thick, turbulent current layer, sustaining dissipation of MAGNETic energy longer than in 2D. In pressure-balanced current sheets with a null guide field, 2D reference runs show the familiar RECONNECTion dynamics, whereas in 3D tearing dynamics is quenched after the linear phase, as pressure-driven modes growing on forming plasmoids outcompete plasmoid coalescence and suppress fast dissipation of MAGNETic energy. Taken together, these results suggest that the evolution and efficiency of RECONNECTion depend sensitively on the local plasma conditions and current-sheet configuration, and can be properly captured only in fully 3D simulations.
[abstract 4 / 38] Yes (score: 5) - Title: Polarization Signatures of Inspiraling Hotspots around Kerr Black HolesAuthors: Pablo Ruales, Delilah E. A. Gates, Alejandro Cárdenas-Avendaño,Comments: 16 pages, 9 figuresSubjects: astro-ph.HE gr-qcCreated: 2026-02-09; Updated: 2026-02-11; Datestamp: 2026-02-11
Polarimetric interferometry is a powerful tool for probing both BLACK HOLE accretion physics and the background spacetime. Current models aimed at explaining the observed multiwavelength flares in Sgr A* often assume hotspots moving on geodesic, Keplerian orbits. In many scenarios, though, a hotspot may instead follow an inspiraling trajectory, potentially transitioning into a plunge toward the BLACK HOLE. In this work, we present a general framework to simulate the polarized emission from generic equatorial inspiraling hotspots in Kerr spacetime using a parametric four-velocity profile. This parametrization defines a continuous family of flows, ranging from Cunningham's disk model (fixed radius orbits outside the innermost stable circular orbit and plunging motion within the innermost stable circular orbit) to purely radial motion, thereby extending the standard assumptions. Within this framework, we show that inspiral motion produces a distinctive observational signature: a precessing, unwinding evolution of the polarimetric Stokes Q-U looping pattern, in sharp contrast with the closed Q-U loops associated with stable orbits at a fixed radius. We then explore how the morphology of these signatures depends on BLACK HOLE spin, observer inclination, and MAGNETic-field configuration. The presented model can be applied to current and near-future interferometric observations of linear POLARIZATION, offering a new avenue to probe the physics of matter spiraling inward and the RELATIVISTIC velocities of plunging plasma.
[abstract 5 / 38] Yes (score: 5) - Title: Unraveling the mysteries of Jets in peculiar NLSy1 galaxies through multi-wavelength variabilityAuthors: Vineet Ojha, Xue-Bing Wu, Luis C. Ho, Raj Prince, Joysankar Majumdar, Hum Chand, Chi-Zhuo Wang,Comments: Submitted to the A&A Journal. 10 figures and 5 tables in the main text and 3 figures in the appendix. Comments and suggestions are most welcome. A reduced abstract is presented here due to the arXiv limitSubjects: astro-ph.GA astro-ph.HECreated: 2026-02-09; Updated: 2026-02-11; Datestamp: 2026-02-11
Radio-quiet narrow-line Seyfert 1 galaxies (RQ-NLSy1s) are generally considered to be dominated by thermal emission from the accretion disk. However, recurring 37 GHz radio flares detected from seven RQ-NLSy1s by the Metsahovi Radio Observatory suggest that non-thermal processes may also contribute to their emission. We present a systematic optical and mid-infrared (MIR) variability study combined with broadband SED modeling to investigate the origin of their flux variations and assess the relative contributions of accretion disk and possible JET-related components. High-cadence optical light curves in the g, r, and i bands were obtained from ZTF, while long-term MIR light curves in the W1 and W2 bands were taken from WISE. Optical variability was quantified using the FAGN-test, peak-to-peak variability amplitude, and fractional variability, while MIR variability was characterized using redshift-corrected intrinsic variability amplitudes. Optical variability was examined from intra-night to long-term timescales, and MIR variability on long-term timescales. All RQ-NLSy1s show statistically significant long-term optical variability, with amplitudes increasing toward shorter wavelengths. Three sources exhibit bluer-when-brighter trends and increasing variability amplitudes across the optical bands, indicating a non-thermal contribution. Intrinsic MIR variability is detected in three of the four sources. Significant optical-MIR and MIR intra-band lags are observed, while optical intra-band lags are insignificant. Optical variability amplitudes are anti-correlated with the Eddington ratio and positively correlated with BLACK HOLE mass. These results suggest that a subset of RQ-NLSy1s hosts weak or intermittent JETs contributing to their optical and MIR emission, supported by SED modeling. Coordinated multi-wavelength monitoring is required to better constrain the origin of these variations.
[abstract 6 / 38] Yes (score: 5) - Title: Transient Relativistic Iron Emission Line from an X-ray Flaring Supermassive Black HoleAuthors: Xiurui Zhao, Marco Ajello, Francesca Civano, Javier A. Garcıa, Elias Kammoun, Stefano Marchesi, Yue Shen, Daniel Stern, Qian Yang, Peter G. Boorman, Fiona Harrison, Erin Kara, Andrealuna Pizzetti, Ross Silver, Kirill V. Sokolovsky, Zachary Stone, Nuria Torres-Alba, Qiaoya Wu, Peixin Zhu,Comments: 13 pages, 3 figures, Accepted to ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-02-09; Updated: 2026-02-11; Datestamp: 2026-02-11
We report the discovery of the first transient RELATIVISTIC iron Kα line in an Active Galactic Nucleus (AGN) J1047+5907. The line was detected 21.5 days (rest-frame) after an X-ray coronal flare observed in 2008 and it exhibits significant broadening consistent with RELATIVISTIC reflection from the accretion disk in the vicinity of the central supermassive BLACK HOLE (SMBH). The line has a width of ~300 eV, corresponding to a Keplerian velocity of 14,000 km s-1, at a distance of 5-41 light-days from the SMBH, strongly implying that the observed coronal flare triggered the emergence of the line. This event provides rare direct evidence of the response of the accretion disk to impulsive coronal illumination and offers a new method to probe the SMBH and disk physics. The RELATIVISTIC modeling favors a broadened line produced by distant reflection from an accretion disk around a rapidly spinning BLACK HOLE viewed at an intermediate inclination, consistent with other observations. Systematic monitoring of type 1 AGN following strong X-ray flares may open a new observational window into the innermost regions of AGN, enabling constraints on the physics of SMBH and its accretion disk at different radii that are otherwise challenging to access.
[abstract 7 / 38] Yes (score: 5) - Title: A deep MeerKAT view of associated HI absorption in radio AGNs at intermediate redshift: Role of absorber geometry and conditions of the gasAuthors: Raffaella Morganti, Tom Oosterloo, Clive Tadhunter, Suma Murthy,Comments: 14 pages, Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.GACreated: 2026-02-10; Updated: 2026-02-11; Datestamp: 2026-02-11
We present MeerKAT observations searching for HI absorption in a sample of 17 powerful ($L_{\rm 1.4GHz}> 10^{27}$ W Hz$^{-1}$) radio sources at intermediate redshifts ($0.25
[abstract 8 / 38] Yes (score: 4) - Title: Kiloparsec-scale turbulence driven by reionization may grow intergalactic MAGNETic fieldsAuthors: Christopher Cain, Matthew McQuinn, Evan Scannapieco, Anson D'Aloisio, Hy Trac,Comments: 6 pages + 2 figures main text, 2 pages + 1 figure appendices, 9 pages + 7 figures supplementary material. Equivalent to the version published in PRDSubjects: astro-ph.CO astro-ph.GACreated: 2026-02-10; Updated: 2026-02-11; Datestamp: 2026-02-11
The intergalactic medium (IGM) underwent intense heating that resulted in pressure disequilibrium in the wake of ionization fronts during cosmic reionization. The dynamical relaxation to restore pressure balance may have driven small-scale turbulence and, hence, the amplification of intergalactic MAGNETic fields. We investigate this possibility for the first time using a suite of $\approx 100$ pc resolution radiation-hydrodynamics simulations of IGM gas dynamics. We show that as the spatial resolution improves beyond that achieved with most prior studies, much of the IGM becomes turbulent unless it was pre-heated to $\gg 100~$K before reionization. In our most turbulent simulations, we find that the gas energy spectrum follows the expected $k^{-5/3}$ Kolmogorov scaling to the simulation's resolution, and the eddy turnover time of the turbulence is $< 1$ Gyr at $k \approx 1 ~$kpc$^{-1}$. Turbulence will grow MAGNETic fields, and we show that the fields grown by reionization-driven turbulence could explain lower limits on the strength of volume-filling B-fields from observations of TeV BLAZARs. As reionization sweeps over the cosmos, this mechanism could create turbulence throughout the cosmic volume with a character that only depends on the amount of IGM preheating.
[abstract 9 / 38] Yes (score: 4) - Title: If QUASARs form from primordial BLACK HOLEsAuthors: Jeremy Mould, Adam Batten,Comments: for submission to Open Journal of AstrophysicsSubjects: astro-ph.GACreated: 2026-02-09; Updated: 2026-02-11; Datestamp: 2026-02-11
We explore the consequences of a novel but increasingly well-supported hypothesis that supermassive BLACK HOLEs may have formed from primordial BLACK HOLEs form ed prior to, and rapidly growing in, the radiation-dominated universe. We show that this hypothesis can predict the luminosity of QUASARs and their luminosity distribution. With reasonable values of the parameters introduced, these predictions are borne out by observations. The model predicts density evolution in accordance with observations. If the same galaxy interaction rate creates QUASARs and RADIO GALAXies, whose primordial BLACK HOLE nuclei seem somewhat less massive, their relative number densities reflect relative lifetimes in these states.
[abstract 10 / 38] Yes (score: 4) - Title: FPIC: a new Particle-In-Cell code for stationary and axisymmetric black-hole spacetimesAuthors: Claudio Meringolo, Luciano Rezzolla,Comments: 14 pages, 10 figuresSubjects: astro-ph.HE gr-qc physics.plasm-phCreated: 2026-02-07; Updated: 2026-02-11; Datestamp: 2026-02-11
In this paper we present a newly developed GRPIC code framework called FPIC, providing a detailed description of the Maxwell-equations solver, of the particle ``pushers'', and of the other algorithms that are needed in this approach. We describe in detail the code, which is written in Fortran and exploits parallel architectures using MPI directives both for the fields and particles. FPIC adopts spherical Kerr-Schild coordinates, which encode the overall spherical topology of the problem while remaining regular at the event horizon. The Maxwell equations are evolved using a finite-difference time-domain solver with a leapfrog scheme, while multiple particle ``pushers'' are implemented for the evolution of the particles. In addition to well-known algorithms, we introduce a novel hybrid method that dynamically switches between the most appropriate scheme based on the violation of the Hamiltonian energy. We first present results for neutral particles orbiting around BLACK HOLEs, both in the Schwarzschild and Kerr metrics, monitoring the evolution of the Hamiltonian error across different integration schemes. We apply our hybrid approach, showing that it is capable of achieving improved energy conservation at reduced computational cost. We apply FPIC to investigate the Wald solution, first in electrovacuum and subsequently in plasma-filled configurations. In the latter case, particles with negative energy at infinity are present inside the ergosphere, indicating that the Penrose process is active. Finally, we present the split-monopole solution in a plasma-filled environment and successfully reproduce the Blandford-Znajek luminosity, finding very good agreement with analytical predictions.
[abstract 11 / 38] Yes (score: 4) - Title: Probing Dust Composition in Distant Galaxies with JWST Mid-IR Spectroscopy of Quasars with Foreground 2175 A Absorbers I: MethodologyAuthors: Viacheslav V. Klimenko, Varsha P. Kulkarni, Monique C. Aller,Comments: 23 pages, 8 figuresSubjects: astro-ph.GACreated: 2026-02-09; Updated: 2026-02-11; Datestamp: 2026-02-11
Interstellar dust plays a crucial role in gas cooling and molecule formation, influencing galaxy evolution. However, the composition and structure of dust in distant galaxies are still poorly understood. We have started a JWST MIRI MRS program investigating the dust features in gas-rich and dusty galaxies at redshifts $z<$1.2, with strong 2175~Å bumps detected in absorption along the lines of sight to distant background QUASARs. Here we describe our program strategy, and present MIRI MRS observations of IR dust features at $z=0.5-1.2$ in five QUASAR spectra that form the first part of our full sample. We identify artifacts in MIRI MRS data that affect the background in IFU cubes, and propose methods to reduce their effects. We pay special attention to modeling the QUASAR mid-IR continuum, which shows significant variation depending on AGN morphology, redshift, and BLACK HOLE mass. Dust in foreground galaxies produces significant absorption from the 10~$μ$m silicate feature in all five QUASAR spectra. Compared with the average 10~$μ$m silicate feature in the diffuse ISM of the Milky Way, we find differences in the absorption peak position, width of the features, and asymmetry of the profiles. A detailed study of these silicate features is presented in our next paper (Klimenko et al. 2026b). In two QUASAR spectra, we tentatively detect weak IR features near 3.0 and 3.4~$μ$m. Their strengths are comparable to those seen in the Milky Way ISM, but follow-up observations are required to confirm these detections.
[abstract 12 / 38] Yes (score: 4) - Title: Development of a Reduced Multi-Fluid Equilibrium Model and Its Application to Proton-Boron Spherical TokamaksAuthors: Huasheng Xie, Xingyu Li, Jiaqi Dong, Zhiwei Ma, Yunfeng Liang, Yuejiang Shi, Wenjun Liu, Yueng-Kay Martin Peng, Lai Wei, Zhengxiong Wang, Hanyue Zhao,Comments: 11 pages, 7 figuresSubjects: physics.plasm-phCreated: 2026-02-09; Updated: 2026-02-11; Datestamp: 2026-02-11
Proton-Boron fusion requires extreme ion temperatures and robust confinement, making Spherical Tokamaks (ST) with high-power neutral beam injection primary candidates. In these devices, strong toroidal rotation and the large mass disparity between protons and boron ions drive complex multi-fluid effects - specifically centrifugal species separation and electrostatic POLARIZATION - that standard single-fluid MAGNETohydrodynamic (MHD) models fail to capture. While comprehensive multi-fluid models are often numerically stiff, we develop a reduced model balancing physical fidelity with computational robustness. By retaining dominant toroidal rotation and self-consistent potential while neglecting poloidal inertia and pressure anisotropy, the model couples a generalized Grad-Shafranov equation with species-specific Bernoulli relations and a quasi-neutrality constraint. The model is applied to two representative p-B ST configurations: the experimental EHL-2 and reactor-scale EHL-3B. Simulation results demonstrate that equilibrium modifications are governed by the ion Mach number ($M$). In the low-rotation regime ($M < 0.5$), multi-fluid effects are weak and solutions approach the single-fluid limit. However, at $M > 2$, strong centrifugal forces drive significant boron accumulation at the low-field side (LFS) and generate an internal electrostatic potential on the order of 10 kV. These findings confirm the necessity of multi-fluid modeling for accurate p-$^{11}$B reactor design and establish a theoretical foundation for future investigations into stability, transport, and free-boundary dynamics.
[abstract 13 / 38] Yes (score: 4) - Title: A Gravitational Wave Background from Intermediate Mass Black Holes in AGN DisksAuthors: Chiara M. F. Mingarelli,Comments: 8 pages, 1 figure. This is Paper II. Paper 1 is Mingarelli (2026a)Subjects: astro-ph.GACreated: 2026-02-09; Updated: 2026-02-11; Datestamp: 2026-02-11
Intermediate mass BLACK HOLEs (IMBHs) formed in ACTIVE GALACTIC NUCLEus (AGN) disks are expected to inspiral into their central supermassive BLACK HOLEs (SMBHs), generating a stochastic gravitational-wave (GW) background in the mHz--decihertz band. Using the population-agnostic energetic formalism, we treat the AGN-disk channel as a mass-flow pipeline connecting the stellar-mass BLACK HOLE population observed by LIGO/Virgo/KAGRA (LVK) to the SMBH mass reservoir via IMBHs. By anchoring this estimate to the LVK merger rate densities and the cosmic SMBH mass density derived from scaling relations, we derive a limit on the background amplitude. We show that the total energy density of the background is bounded by the global mass budget of SMBH growth. For fiducial parameters consistent with the fourth Gravitational-Wave Transient Catalog (GWTC-4), this yields a characteristic strain $A_{\rm IMR} \simeq (1.2_{-0.2}^{+0.2})\times 10^{-21}$ at $3\,{\rm mHz}$. While this fiducial amplitude is subdominant to the Galactic white dwarf foreground and the stellar-mass Extreme Mass Ratio Inspiral (EMRI) background, we show it can be distinguished by its non-Gaussian statistics and higher frequency cutoff. This new background may be detectable in the decihertz band where proposed detectors such as the Big Bang Observer or long-baseline lunar interferometers can measure it cleanly. A detection would provide a direct, model-independent constraint on the efficiency with which AGN disks process stellar remnants into SMBH mass growth, linking the LVK and LISA bands.
[abstract 14 / 38] Yes (score: 4) - Title: Systematic Study of the Simultaneous Events Detected by GECAMAuthors: Yang-Zhao Ren, Feng-Rong Zhu, Shao-Lin Xiong, Yan-Qiu Zhang, Chen-Wei Wang, Jia-Cong Liu, Hao-Xuan Guo, Shuo Xiao, Dong-Ya Guo, Zheng-Hua An, Ce Cai, Pei-Yi Feng, Min Gao, Ke Gong, Yue Huang, Bing Li, Xiao-Bo Li, Xin-Qiao Li, Xiao-Jing Liu, Ya-Qing Liu, Xiang Ma, Wen-Xi Peng, Rui Qiao, Li-Ming Song, Xi-Lei Sun, Wen-Jun Tan, Jin Wang, Jin-Zhou Wang, Ping Wang, Yue Wang, Xiang-Yang Wen, Sheng-Lun Xie, Wang-Chen Xue, Sheng Yang, Qi-Bin Yi, Zheng-Hang Yu, Da-Li Zhang, Fan Zhang, Hong-Mei Zhang, Jin-Peng Zhang, Peng Zhang, Shuang-Nan Zhang, Wen-Long Zhang, Zhen Zhang, Xiao-Yun Zhao, Yi Zhao, Chao Zheng, Shi-Jie Zheng,Comments: 15 pages,17 figuresSubjects: astro-ph.HECreated: 2026-02-10; Updated: 2026-02-11; Datestamp: 2026-02-11
GECAM is a constellation of all-sky monitors in hard X-ray and gamma-ray band primarily aimed at high energy transients such as GAMMA-RAY BURSTs, soft gamma-ray repeaters, solar flares and terrestrial gamma-ray flashes. As GECAM has the highest temporal resolution (0.1~$μ$s) among instruments of its kind, it can identify the so-called simultaneous events (STE) that deposit signals in multiple detectors nearly at the same time (with a 0.3~$μ$s window). However, the properties and origin of STE have not yet been explored. In this work, we implemented, for the first time, a comprehensive analysis of the STE detected by GECAM, including their morphology, energy deposition, and the dependence on the geoMAGNETic coordinates. We find that these STE probably result from direct interactions between high-energy charged COSMIC RAYs and satellite. These results demonstrate that GECAM can detect, identify, and characterize high-energy COSMIC RAYs, making it a Micro Cosmic-Ray Observatory (MICRO) in low Earth orbit.
[abstract 15 / 38] Yes (score: 4) - Title: EMU Radio Observations of Barred Spiral Galaxy NGC 5938 (Araish)Authors: H. Zakir, M. D. Filipović, L. Barnes, R. Z. E. Alsaberi, T. An, K. Dage, S. W. Duchesne, A. M. Hopkins, A. Kapinska, B. Koribalski, S. Lazarević, D. Leahy, Z. Liu, R. P. Norris, A. Rau, Z. J. Smeaton, T. Jarrett,Comments: This Paper has been accepted for publication in PASA. It contains 12 Pages, 7 figures, and 2 TablesSubjects: astro-ph.GACreated: 2026-02-10; Updated: 2026-02-11; Datestamp: 2026-02-11
We present multi-wavelength observations of the nearby spiral galaxy NGC 5938 (Araish) to investigate the origin of its radio emission, specifically the contribution from ACTIVE GALACTIC NUCLEus (AGN) activity and STAR FORMATION. Using Evolutionary Map of the Universe (EMU) data, we detect extended radio emission extending outwards to the galactic axis, with a steep non-thermal spectral index ($α= -1.2 \pm 0.2$) indicative of SYNCHROTRON radiation from an AGN JET. The JET has a physical extent of $\approx 8.2\,kpc$ (angular length of $64^{\prime\prime}$). Multi-wavelength data from The Dark Energy Camera Plane Survey 2 (DECaPS2), Wide-field Infrared Survey Explorer (WISE), and extended Roentgen Survey with an Imaging Telescope Array (eROSITA) provide further support for this interpretation. The colour-colour diagram presenting WISE infrared observations suggests the presence of dust and young stars that trace the galaxy's disk structure. Our analysis reveals a radio JET, alongside STAR FORMATION traced by infrared emission, demonstrating the complex interplay of AGN activity and STAR FORMATION in this well-resolved galaxy. Intriguingly, the spatial relationship reveals the brighter X-ray emission to be largely adjacent to and enveloping the extended radio emission. This suggests that the radio JET, while extending at a significant angle to the galactic disk, is confined by the larger X-ray gas halo, similar to other systems (i.e., ESO 295-IG022, Centaurus A) and may indicate JET collimation and channelling effects.
[abstract 16 / 38] (score: 3) - Title: Circumgalactic medium of QUASAR host galaxies at 0.4[abstract 17 / 38] (score: 3)Authors: Paryag Sharma, Raghunathan Srianand, Hum Chand, Labanya Kumar Guha,Comments: Published in MNRASSubjects: astro-ph.GACreated: 2026-02-10; Updated: 2026-02-11; Datestamp: 2026-02-11
Using a sample of 166 projected QUASAR pairs we investigate the influence of ACTIVE GALACTIC NUCLEi on the circumgalactic medium (CGM) of the QUASAR host galaxies probed using strong Mg II absorption (i.e., $W_{2796}\ge 1\dot{A}$) at impact parameters ($D$) $<$100 kpc. The foreground QUASARs are restricted to the redshift range $0.4 \leq z \leq 0.8$ and have median bolometric luminosity and stellar mass of $10^{45.1} erg~s^{-1}$and $10^{10.89} M_\odot$ respectively. We report detections of Mg II absorption in 29 cases towards the background QUASAR and in 4 cases along the line of sight to the foreground QUASARs. We do not find any difference in the distribution of $W_{2796}$ and covering fraction ($f_c$) as a function of $D$ between QUASAR host galaxies and control sample of normal galaxies. These results are different from what has been reported in the literature, possibly because: (i) our sample is restricted to a narrow redshift range, (ii) comparative analysis is carried out after matching the galaxy parameters, (iii) we focus mainly on strong Mg II absorption and (iv) our sample lacks foreground QUASARs with high bolometric luminosity (i.e., $L_{bol}>10^{45.5}$ erg s$^{-1}$). Future studies probing luminous foreground QUASARs, preferably at lower impact parameters and higher equivalent width sensitivity is needed to consolidate our findings.
arXiv:2509.15425 [pdf, ps, other]We address three two-dimensional MAGNETohydrodynamics models: reduced MAGNETohydrodynamics (RMHD), Hazeltine's model, and the Charney--Hasegawa--Mima (CHM) equation. These models are derived to capture the basic features of MAGNETohydrodynamic turbulence and plasma behaviour. They all possess non-canonical Hamiltonian formulations in terms of Lie--Poisson brackets, which imply an infinite number of conservation laws along with symplecticity of the phase flow. This geometric structure in phase space affects the statistical long-time behaviour. Therefore, to capture the qualitative features in long-time numerical simulations, it is critical to use a discretization that preserves the rich phase space geometry. Here, we use the matrix hydrodynamics approach to achieve structure-preserving discretizations for each model. We furthermore carry out long-time simulations with randomized initial data and a comparison between the models. The study shows consistent behaviour for the MAGNETic potential: both RMHD and Hazeltine's model produce MAGNETic dipoles (in CHM, the MAGNETic potential is prescribed). These results suggest an inverse cascade of MAGNETic energy and of the mean-square MAGNETic potential, which is empirically verified via spectral scaling diagrams. On the other hand, the vorticity field dynamics differs between the models: RMHD forms sharp vortex filaments with rapidly growing vorticity values, whereas Hazeltine's model and CHM show only small variation in the vorticity values. Related to this observation, both Hazeltine's model and CHM give spectral scaling diagrams indicating an inverse cascade of kinetic energy not present in RMHD.
arXiv:2510.00440 [pdf, ps, other]We present a detailed dePOLARIZATION analysis of the RADIO GALAXy \texttt{ILTJ012215.21+254334.8} using polarimetric data from the \textit{LOFAR Two-metre Sky Survey} (LoTSS) Data Release 2 (DR2) catalogue. This source, with \textit{RM} $\sim$ 47 rad m$^{-2}$ and projected linear size $\sim$ 335 kpc at $z \approx 0.05$, serves as a pilot for systematic QU-fitting of unresolved LoTSS sources, building on prior single-target studies that established the need for multi-component Faraday models in complex MAGNETo-ionic media. Fitting five dePOLARIZATION models to the LoTSS HBA (120-168 MHz) fractional POLARIZATION spectra reveals a decisively preferred three-component model (one Faraday-thin instrumental leakage, plus two external Faraday dispersions), demonstrating that LoTSS data alone can constrain moderate Faraday complexity in typical DR2 galaxies. Our results highlight turbulence and inhomogeneity in the foreground MAGNETo-ionic medium and outline a path for population studies of LoTSS FR-I sources.
arXiv:2512.17770 [pdf, ps, other]The exteriors of stellar and galactic dynamos are usually modeled as a current-free potential field. A more realistic description might be that of a force-free MAGNETic field. Here, we suggest that, in the absence of outflows, neither of those reflect the actual behavior when the MAGNETic field spreads diffusively into a more poorly conducting turbulent exterior outside dynamo. In particular, we explain why the usual ordering of the dipole MAGNETic field being the most slowly decaying one is altered, and that the quadrupole can develop a toroidal component that decays even more slowly with radial distance. This behavior is best seen for spherical dynamo volumes and becomes more complicated for oblate ones. In either case, however, those fields are confined within a MAGNETosphere beyond which the field drops exponentially. The MAGNETosphere radius expands ballistically (i.e., linearly in time $t$) during the exponential growth phase of the dynamo, but diffusively proportional to $t^{1/2}$ during the saturated phase. We demonstrate that the Faraday displacement current, which plays a role in a vacuum, can safely be neglected in all cases. The superposition of MAGNETic fields from galaxies in the outskirts of the voids between galaxy clusters can therefore not explain the void MAGNETization of the intergalactic medium, reinforcing the conventional expectation that those fields are of primordial origin. For quadrupolar configurations, the SYNCHROTRON emission from the MAGNETosphere is found to be constant along concentric rings. Dipolar or the quadrupolar configurations display large-scale radial trends that are potentially distinguishable with existing radio telescopes.
arXiv:2601.10393 [pdf, ps, other]Long Period Transients (LPTs) are a recently identified class of sources characterized by periodic radio bursts lasting seconds to minutes, with flux densities that might reach several tens of Jy. These radio bursts repeat with periodicity from minutes to hours, and they exhibit strong POLARIZATION and transient activity periods. To date, about 12 such sources have been identified, which might encompass the same or different physical scenarios. Proposed explanations include binary systems with a white dwarf and a low-mass star companion, slow-spinning MAGNETars, highly MAGNETized isolated white dwarfs, and other exotic objects. In a few cases the optical counterpart indeed points toward a white dwarf with a low-mass companion, while in other cases, transient X-ray emission was detected, very common in MAGNETars. However, despite being able to reproduce partially some of the characteristics of LPTs, all the proposed scenarios find difficulty in explaining the exact physical origin of their bright, highly polarized and periodic radio emission. We review here the state-of-the-art in the observations and interpretation of this puzzling class of radio transients.
arXiv:2602.09124 [pdf, ps, other]Supersoft X-ray sources (SSSs) host white dwarfs (WDs) accreting at rates that sustain steady nuclear burning, driving rapid mass growth, radial contraction, and MAGNETic field amplification. Angular-momentum transfer from the accretion disk naturally spins up the WD, while the amplified internal MAGNETic field induces a non-axisymmetric deformation in presence of a misaligned rotation. Such WDs emits continuous gravitational waves (CGWs). We model the coupled evolutions of stellar mass, spin, and MAGNETic structure in accreting WDs in SSSs with \texttt{MESA}, and compute the resulting quadrupolar deformation with the Einstein-Maxwell solver \texttt{XNS}. We show that WDs in SSSs, particularly near the end ofthermal timescale mass transfer and close to the Chandrasekhar mass limit, produce CGWs predominantly in the deci-Hz band accessible to planned detectors such as DECIGO, BBO, Deci-Hz, ALIA, and LGWA, and are distinguishable from other Galactic CGW sources such as AM\,CVn systems, detached double WDs, and isolated WDs. Well-studied SSSs such as CAL~83 and RX~J0019+2156 can be detectable, enabling targeted CGW measurements that directly probe WD's internal MAGNETic fields and rotation, while blind searches can reveal hundreds of obscured SSSs otherwise missed in soft X-rays and map the hidden population of accreting, rapidly rotating, MAGNETized WDs in nearby galaxies. A CGW detection from WDs in SSSs could also identify potential pre-explosion Type~Ia progenitors.
arXiv:2602.09837 [pdf, ps, other]Understanding the earliest stage of star and planet formation requires detailed observations to address the connection and interplay between the accretion, outflow, and disk evolution. We present results from observations of the low luminosity ($L_{\mathrm{bol}} \sim 0.2,L_{\odot}$) and low mass ($M_{*} \sim 0.15,M_{\odot}$) Class 0 protostar IRAS~16253$-$2429, conducted as part of the eDisk ALMA Large Program and the JWST Cycle~1 GO program IPA. Observations reveal a wide hourglass-shaped continuum cavity traced in scattered light (at $\leq 5,μ$m), with a brighter, extended northern side. We detect 15 pure rotational H$2$ transitions ($E{\mathrm{up}} = 1015$--21411~K), revealing a wide-angle molecular outflow. The outflow width traced by H$_2$~0-0~S(11) at the protostellar location measures $\leq 35$~au, slightly larger than the dust and Keplerian disk diameters ($\sim 30$~au) but wider than the 20--23~au JET width in [Fe~II]. The opening angle narrows from 40--35 degrees for the low-$J$ H$_2$ lines (up to S(5)) and the cold gas component traced by ALMA $^{12}$CO to $\sim 28$--19 degrees for the high-$J$ H$_2$ lines (S(7)--S(11)). Position--velocity diagrams of H$2$ reveal higher velocities for higher $E{\mathrm{up}}$, ranging from $\sim 12.5$~km~s$^{-1}$ for H$_2$~0-0~S(1) and S(2) to $\sim 28.5$~km~s$^{-1}$ for H$_2$~0-0~S(5) and S(7) with respect to the mean flow velocity. The nested excitation and velocity structure of the collimated JET and wide-angle wind suggests a MAGNETohydrodynamic wind as a likely launching mechanism, similar to findings in other protostars and Class~II sources. The lower-velocity millimeter CO emission may be gas from the infalling envelope accelerated outward by the wide-angle wind along the cavity walls.
arXiv:2412.16508 [pdf, ps, other]Worthington JETs ejected after the impact of a solid or liquid object on a liquid surface have extensive applications in natural, industrial, and scientific contexts. Here, we present a combined experimental and theoretical investigation of the JET generated by sphere impact with no cavity formed. Experiments identify three distinct pinch-off modes, whose regime boundaries are independent of sphere wettability and density, and are theoretically determined by the Rayleigh--Plateau instability. From momentum and energy conservation, a new scaling law is derived for the dimensionless maximum JET height and agrees remarkably well with experiments across various impact conditions, thus validating its universal character and clarifying its dependence on the Froude, Weber, and Reynolds numbers as well as the density ratio. Coupling self-similar solutions with a kinematic condition at the JET tip yields good predictions for the evolution of JET height and shape, revealing gravity-dominated JET dynamics, with a modification from surface tension that is most pronounced without pinch-off. These findings demonstrate that the upward JET is sustained by the collision of converging flow behind the sphere, a generation mechanism fundamentally distinct from the cavity collapsing forced case.
arXiv:2503.01983 [pdf, ps, other]The new era of high-resolution X-ray spectroscopy will significantly improve our understanding of the intra-cluster medium (ICM) by providing precise constraints on its underlying physical properties. However, spectral fitting requires reasonable assumptions on the thermal and chemical distributions of the gas. We use the output of TNG-Cluster, the newest addition to the IllustrisTNG suite of cosmological MAGNETohydrodynamical simulations, to provide theoretical expectations for the multi-phase nature of the ICM across hundreds of z=$ clusters (M$_{500c} = 10^{14.0-15.3}~M_\odot$) based upon a realistic model for galaxy formation and evolution. We create and analyse, in an observer-like manner, end-to-end XRISM/Resolve mock observations towards cluster centres. We then systematically compare the intrinsic temperature and Fe abundance of the simulated gas with the inferred ones from spectral fitting via a variety of commonly used spectral-emission models. Our analysis suggests that models with a distribution of temperatures, better describe the broad thermal distributions of the ICM, as predicted by TNG-Cluster, but still incur biases in the inferred temperature of 0.5-2 keV (16th-84th percentiles). However, all spectral-emission models systematically underestimate the Fe abundance of the central ICM by 0.12 Solar (22 per cent), almost an order of magnitude higher than the abundance errors reported in the literature, primarily due to projection effects. Selecting only strong cool core clusters leads to minor improvements on inference quality, removing the majority of outliers but maintaining similar overall biases and cluster-to-cluster scatter.
arXiv:2504.03840 [pdf, ps, other]Recent eROSITA measurements of the radial profiles of the hot CGM in the Milky-Way stellar mass (MW-mass) regime provide us with a new benchmark to constrain the hot gas around MW-mass central and satellite galaxies and their halo mass distributions. Modelling this rich data set with state-of-the-art hydrodynamical simulations is required to further our understanding of the shortcomings in the current paradigm of galaxy formation and evolution models. We develop forward models for the stacked X-ray radial surface brightness profile measured by eROSITA around MW-mass galaxies. Our model contains two emitting components: hot gas (around central galaxies and satellite galaxies hosted by more massive halos) and X-ray point sources (X-ray binaries and Active Galactic Nuclei). We model the hot gas profile using the TNG300-based products. We generate mock observations with our TNG300-based model (matching stellar mass and redshift with observations) with different underlying halo mass distributions. We show that for the same mean stellar mass, a factor 2x increase in the mean value of the underlying halo mass distribution results in a ~4x increase in the stacked X-ray luminosity from the hot CGM. The point sources are described by a simple point-spread-function (PSF) of eROSITA, and we fit their normalization in this work. Using empirical models to derive a permissible range of AGN and XRB luminosities in the MW-mass X-ray galaxy stack, we choose our forward model best describing the hot CGM for the eROSITA observations. We find that at < 40 kpc from the galaxy centre, the hot CGM from central galaxies and the X-ray point sources emission each account for 40-50% of the total X-ray emission budget. In summary, we show that the gas physics driving the shape of the observed hot CGM (in stellar-mass-selected samples) is tightly correlated by the underlying halo-mass distribution (abridged).
arXiv:2510.19798 [pdf, ps, other]We explore the observational prospects for detecting gravitational lensing induced by cosmological matter currents, a RELATIVISTIC correction to the standard density lensing effect arising from the motion of matter. We propose to isolate this contribution by cross-correlating the weak-lensing convergence field with a reconstructed cosmic momentum field inferred from galaxy redshift surveys. Using numerical simulations, we demonstrate that this reconstructed momentum field is uncorrelated with the density lensing signal, enabling a clean separation of the gravitoMAGNETic component. We then forecast the detectability of this signal for upcoming wide-field galaxy and weak-lensing surveys, showing that a statistically significant detection may be achievable under realistic observational conditions. Such a measurement would provide the first direct probe of the large-scale cosmic momentum field, offering a novel test of general relativity and Lorentz invariance on cosmological scales.
arXiv:2602.00312 [pdf, ps, other]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.
arXiv:2602.06794 [pdf, ps, other]We derive robust constraints on the initial abundance of evaporating primordial BLACK HOLEs (PBHs) using the reionization history of the Universe as a cosmological probe. We focus on PBHs that inject electroMAGNETic (EM) energy into the intergalactic medium (IGM) after recombination, in the mass range $3.2\times 10^{13}\,\mathrm{g} \lesssim M_{\rm PBH} \lesssim 5\times 10^{14}\,\mathrm{g}$. For each PBH mass, we compute the redshift-dependent energy injection from Hawking evaporation using \texttt{BlackHawk}, fully accounting for the time evolution of the PBH mass and the complete spectrum of emitted Standard Model particles and gravitons. The resulting photons and electrons are propagated through the primordial plasma using \texttt{DarkHistory}, which self-consistently models EM cascades and determines the fraction of injected energy deposited into ionization, excitation, and heating of the IGM. These modifications to the ionization and thermal histories are incorporated into a Gaussian Process reconstruction of the free-electron fraction based on low-$\ell$ CMB POLARIZATION data from the \textit{Planck} mission. This non-parametric approach allows for a statistically well-defined separation between exotic high-redshift energy injection and late-time astrophysical reionization, allowing PBH evaporation to be constrained through its contribution to the high-redshift optical depth. Requiring consistency with current CMB measurements, we obtain upper limits on the initial PBH abundance that are robust against reionization modeling uncertainties and systematically more conservative than existing bounds, reflecting the fully numerical and time-dependent treatment of Hawking evaporation and energy deposition. Our results demonstrate the power of reionization observables as a precision probe of PBH evaporation and other scenarios involving late-time energy injection.
arXiv:2602.09088 [pdf, ps, other]The Laser Interferometer Space Antenna (LISA) will observe massive BLACK HOLE binaries (MBHBs) with astoundingly high signal-to-noise ratio, leaving parameter estimation with these signals susceptible to seemingly small waveform errors. Of particular concern for MBHBs are errors due to neglected higher-order modes. We extend Yi et al. [arXiv:2502.12237] to examine errors due to neglected higher-order modes for MBHBs with nonzero (aligned) progenitor spins and total mass up to $10^8\,M_\odot$. For these very massive systems, there can be regions of parameter space in which the $(\ell, |m|)=(2,\,2)$ modes are no longer dominant with respect to higher-order ones. We find that the extent of systematic bias can change significantly when varying the progenitor spins of the binary. We also find that for the heaviest, and therefore shortest, MBHB signals, slight systematic errors can cause severe mis-inference of the sky localization parameters. We propose an improved likelihood optimization scheme with respect to previous work as a way to predict these effects in a computationally efficient manner.
arXiv:2602.09168 [pdf, ps, other]In this paper, the optical effects that occur near a Schwarzschild-like BLACK HOLE (BH) with a Dehnen-type $(1,4,2)$ DARK MATTER (DM) halo are explored. We first derive the photon sphere radius and obtain an analytical expression for the deflection angle in the weak-field regime by applying the Gauss-Bonnet theorem (GBT). For the strong-field regime, we perform ray-tracing calculations to examine the behavior of light trajectories and determine the corresponding number of orbits. We further compute the BH shadow and gravitational lensing in a plasma medium and provide constraints arising from the DM halo parameters. We also extend our analysis to weak gravitational lensing within plasma environments, considering both uniform and singular isothermal sphere (SIS) distributions. We find the analytical expressions for the deflection angle in the presence of plasma and examine the resulting effects on image magnification. The overall results highlight how DM halo properties and plasma characteristics jointly alter observable lensing signatures.
arXiv:2602.09404 [pdf, ps, other]A fundamental challenge in STAR FORMATION is understanding how a protostar accretes mass from its circumstellar disk while removing excess angular momentum. Protostellar JETs are widely invoked as the primary channels for angular momentum removal, yet the mechanism by which they are launched and extract angular momentum remains poorly constrained. Here we report high-resolution ALMA Band 7 (345 GHz) and Band 6 (230 GHz) observations of CO (3-2), CO (2-1), and SiO (5-4) emission from the protostar HOPS 10 (G209.55-19.68S2). The combined data trace both the entrained outflow and the collimated JET with excellent spatial and velocity resolution, revealing a uniquely monopolar protostellar JET, the clearest example reported to date. The system exhibits a distinctly unipolar high-velocity JET with velocity offsets of +44 to +66 km s-1, unlike the predominantly bipolar morphology characteristic of most protostellar JETs. While the low-velocity outflow, with velocity offsets of -20 to +30 km s-1, is detected in both directions, the high-velocity JET appears only on one side, and this monopolarity is consistent across all tracers. Given the nearly edge-on geometry and low submillimeter extinction, comparable emission would normally be expected from both lobes. The shock tracer SiO emission confirms a genuine, highly collimated JET rather than cloud contamination, and no ambient structure is capable of obscuring a counterJET. We argue that intrinsically asymmetric mass loading along the disk MAGNETic field lines provides the most plausible explanation for the observed monopolarity.
arXiv:2602.09453 [pdf, ps, other]In this paper, we investigate periodic bound orbits and gravitational wave (GW) emission in the Schwarzschild-Bertotti-Robinson (Schwarzschild-BR) spacetime-an exact electrovacuum solution describing a static BLACK HOLE (BH) immersed in a uniform MAGNETic field. We explore how the background MAGNETic field qualitatively alters the BH's gravitational dynamics, affecting timelike geodesics such as the marginally bound orbit (MBO) and the innermost stable circular orbit (ISCO). We then analyze periodic bound orbits using the frequency ratio ${ω_φ}/{ω_{r}}$, which characterizes the orbits by their azimuthal and radial motions. Based on the numerical kludge method we further compute the gravitational waveforms emitted from periodic orbits around a supermassive Schwarzschild-BR BH. We show that the background MAGNETic field significantly changes orbital frequencies, resonance conditions, zoom-whirl structures, and the resulting waveforms. Finally, we examine the frequency spectra in the mHz range and the detectability of these GW signals by computing the characteristic strain via a discrete Fourier transform on the time-domain waveforms, comparing the results with the sensitivity curves of space-based GW detectors such as LISA, Taiji, and TianQin. Our results show that intrinsically MAGNETic fields modify spacetime and leave observable imprints on extreme mass-ratio inspiral GWs, which may be tested by future observations.
arXiv:2602.09635 [pdf, ps, other]In the present work, large-eddy simulations of free supersonic JET flows are performed to investigate the influence of inflow conditions on the JET flow field and its turbulent properties. A high-order nodal discontinuous Galerkin method is employed to solve the governing equations on the generated mesh. Three different inflow profiles are evaluated to represent the nozzle-exit conditions, namely, inviscid, steady viscous, and unsteady viscous profiles. Velocity and shear stress tensor component profiles obtained from the simulations are compared with experimental data. Among the investigated profiles, the steady viscous inflow shows the most significant deviation from the inviscid case, particularly in the near-field region of the JET inlet. The steady viscous profile also leads to reduced peak velocity fluctuations, showing better agreement with experimental results. Further downstream, the influence of the inflow condition diminishes, with all three profiles converging toward the experimental reference. In addition, power spectral density analyses of streamwise velocity fluctuations reveal that the inflow conditions have little effect on spectral distributions, with numerical results showing consistent agreement with experimental data within the accessible Strouhal range. Beyond these findings, the study provides a highly detailed, high-fidelity database of supersonic JET flow simulations, encompassing six large-eddy computations with different meshes, polynomial refinements, and inflow conditions. The database includes high-frequency data in relevant regions of the JET flow field and is openly available in the Zenodo repository, ensuring accessibility and reusability for the scientific community.
arXiv:2602.09672 [pdf, ps, other]Relying on atomic scattering factors from evaluated databases, a new model for the reflectivity of x rays on solid surfaces has been developed for FLUKA v4-6.0. This model accounts for the variation of reflectivity as a function of the photon energy, its incidence angle, and linear polarisation; surface roughness effects are also taken into account. FLUKA reflectivities agree well with those obtained from state-of-the-art codes used for the characterization of optical devices, both for homogeneous solids and for multilayer mirrors. This new capability renders FLUKA a nearly one-stop shop for SYNCHROTRON radiation simulations: emission from bending MAGNETs and wigglers, photon transport and interaction, electroMAGNETic (and hadronic when applicable) shower development in complex geometries, as well as x-ray reflection at designated solid surfaces can now be all accounted for in a single FLUKA run. This streamlined FLUKA simulation workflow greatly simplifies the plethora of simulation tools that Monte Carlo practitioners previously needed to rely on. Two application scenarios of this new reflectivity model are showcased: first, the use of a multilayer mirror to deflect x rays from an optical hutch onto an experimental hall at the MINERVA beamline of the ALBA SYNCHROTRON and, second, the assessment of the photon flux near the interaction point at the CERN's Future Circular Collider (in its electron-positron stage) as a result of upstream x-ray reflections.
arXiv:2602.09759 [pdf, ps, other]In this paper, the wave-particle turbulent simulation (WPTS), a recently developed multiscale, non-equilibrium turbulence modeling approach, is coupled with a turbulence characteristic-time closure derived from Prandtl mixing-length hypothesis and applied to spatially developing round JETs. In WPTS, fluid elements in strongly turbulent regions are represented by Lagrangian particles that travel a finite distance before interacting with the background flow field represented in a wave-like (Eulerian) form. This mechanism bears conceptual similarity to the discrete fluid parcels invoked in the Prandtl mixing-length picture. WPTS differs from conventional mixing-length-based turbulence models in two key respects. First, particle evolution follows a non-equilibrium transport mechanism, rather than the equilibrium assumptions typically embedded in eddy-viscosity closures. Second, WPTS advances the wave and particle components in a coupled manner, with the particle fraction governed primarily by the modeled turbulence characteristic time, enabling laminar and turbulent regimes to be represented within a unified framework. Because spatially developing JETs provide a canonical test case with well-established similarity behavior, they are used here for evaluation. Specifically, this work (1) develops a mixing-length-based characteristic-time model tailored to JET flows and (2) incorporates it into WPTS to assess predictive performance. The resulting WPTS framework accurately reproduces the JET similarity solution and other characteristic features at Reynolds numbers of 5,000 and 20,000, demonstrating the promise of WPTS as a practical tool for turbulence modeling and simulation.
arXiv:2602.09886 [pdf, ps, other]The INTEGRAL satellite explored the gamma-ray sky since its launch on October 17, 2002, and until the end of its scientific operation on February 28, 2025. A large fraction of the available data is still largely untouched, due to the complexity of analysis. We describe the latest in-flight calibration of the Compton mode of the INTEGRAL/IBIS telescope, taking into account more than twenty years of data. The spectroscopy and POLARIZATION of the standard candle that is the Crab Nebula is analyzed in detail. We operate the IBIS telescope as a Coded mask Compton telescope, using the Crab Nebula to refine the calibration, as is usually done for high-energy instruments. We have determined the spectroscopic and polarimetric properties of the IBIS Compton mode and their evolution along the entire duration of the mission. In addition, the long-term evolution of the Crab Nebula's POLARIZATION has been successfully measured and compared with other high-energy experiments. We could estimate the energy dependence of the Crab Nebula POLARIZATION in four bands between 200 keV and 1 MeV. In particular, the detection of polarized emissions strictly above 400 keV makes it the highest energy measurement ever performed for the Crab Nebula. A Python library was also made publicly available to analyze processed data.
arXiv:2602.09931 [pdf, ps, other]Motivated by the need to better understand flow unsteadiness in hydraulic turbines, we perform a local linear stability and adjoint-based sensitivity analysis of the turbulent swirling JET at the outlet of a Francis turbine. We use measured mean flow and turbulence profiles at several operating conditions (below, at, and above the best efficiency point (BEP) flow rate) and perform a stability analysis. Incorporating eddy viscosity $ν_t$ into the analysis strongly damps inviscid growth rates and restricts instability to low azimuthal modes $m\in [-1,2]$, in better agreement with experiments. Three turbulent viscosity closures (constant, mixing-length and measured $k-\varepsilon$ based) yield similar spectra, with close agreement between mixing length and measured models, all identify partial load (0.92 BEP) as the most unstable regime. Sensitivity results show that axial velocity modifications primarily control growth rates, whereas azimuthal velocity changes mainly shift frequencies. We also derive the sensitivity kernel of the spectrum to turbulent viscosity modifications and find that spatial variations of eddy viscosity are essential for predicting the unstable mode range. The predictions accurately estimate stability changes for small variations in operating point. We further analyze the flow using classical inviscid swirling JET instability criteria (the generalized Rayleigh discriminant) and WKB analysis to predict the stability to broader operating points and reconcile these results to the stability and sensitivity analyses. The approach used in this study is fast and simple to model, but it neglects draft tube geometry (non-parallel effects), motivating future global stability and sensitivity analyses.
arXiv:2602.09993 [pdf, ps, other]Title: The SUPERNOVA remnant J0450.4-7050 possesses a JETs-shaped point-symmetric morphologyAuthors: Noam Soker,Comments: It will be submitted in two days to allow for comments (including missing references)Subjects: astro-ph.HECreated: 2026-02-10; Updated: 2026-02-11; Datestamp: 2026-02-11By examining recently published images in different wavelengths, I identify a point-symmetric morphology in the Large Magellanic Cloud core-collapse SUPERNOVA (CCSN) remnant (CCSNR) J0450.4-7050 (SNR 0450-70.9; nicknamed Veliki), which I attribute to at least three pairs of energetic JETs that participated in the explosion of the progenitor in the framework of the jittering JETs explosion mechanism (JJEM). Two pairs of ears, a pair of blowouts in the north and south along the long axis of this SNR, and a pair of dents compose the point symmetric morphology. The fact that the symmetry axes of two pairs include pairs of opposite structural features in the inner ejecta implies that the shaping is by JETs and not due to an interaction with an ambient material. While the JJEM predicts such morphologies, the competing neutrino-driven mechanism cannot account for point-symmetric morphologies. This study provides strong support for the claim that the JJEM is the primary CCSN explosion mechanism.
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