Current date: 2025-03-19
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Datestamp limit: 2025-03-19 (0 days ago)
Created/updated limit: 2025-03-12 (7 days ago)
Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics
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OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2025-03-19&until=2025-03-19&set=physics&metadataPrefix=arXiv
Number of records retrieved: 601
Keyword score statistics
score 4 -- 3 abstracts
score 3 -- 4 abstracts
score 2 -- 8 abstracts
score 1 -- 17 abstracts
in total -- 32 abstracts
Articles that appeared on 2025-03-19
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[abstract 1 / 32] Yes (score: 4)
- Title: Exploring POLARIZATION and geometry in the X-ray pulsar 4U 1538-52Authors: Vladislav Loktev, Sofia V. Forsblom, Sergey S. Tsygankov, Juri Poutanen, Alexander A. Mushtukov, Alessandro Di Marco, Jeremy Heyl, Ruth M. E. Kelly, Fabio La Monaca, Mason Ng, Swati Ravi, Alexander Salganik, Andrea Santangelo, Valery F. Suleimanov, Silvia Zane,Comments: 9 pages, 8 figuresSubjects: astro-ph.HECreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
The Imaging X-ray Polarimetry Explorer (IXPE) observations of accreting X-ray pulsars (XRPs) continue to provide novel insights into the physics and geometry of these sources. We present the first X-ray polarimetric study of the persistent wind-fed XRP 4U 1538-52, based on five IXPE observations totaling 360 ks, conducted in March and October 2024. We detect marginally significant POLARIZATION in the combined data set in the full 2--8 keV energy band, with a POLARIZATION degree (PD) of 3.0+-1.1% and POLARIZATION angle (PA) of -18 degrees. The energy-resolved analysis shows a clear energy dependence of the POLARIZATION properties, with a remarkable ~70 degrees switch in PA between low and high energies. Similarly, the pulse phase-resolved spectro-polarimetric analysis reveals different signatures at low and high energies. At low (2--3 keV) energies, the PD ranges between ~2% and ~18%, with the PA varying between -16 and 70 degrees. At higher (4--8 keV) energies, the PD varies between ~3% and ~12%, with a drastically different PA behavior. Fitting the rotating vector model to the pulse phase dependence of the PA at the lower energies, we constrain the geometric configuration of the pulsar. The analysis favors a high spin-axis inclination of >50 which agrees with both previous pulse-phase-dependent spectral fitting of the cyclotron line region and the known high orbital inclination of the binary system. The MAGNETic obliquity is estimated to be 30 degrees and the spin position angle to be 19 degrees. A sharp switch in PA around 3 keV presents a particular theoretical challenge, as it is not consistent with the right-angle switch that was only seen in one other pulsar Vela X-1.
[abstract 2 / 32] Yes (score: 4) - Title: Deep Chandra observations of PLCKG287.0+32.9: a clear detection of a shock front in a heated former cool coreAuthors: M. Gitti, A. Bonafede, F. Brighenti, F. Ubertosi, M. Balboni, F. Gastaldello, A. Botteon, W. Forman, R. J. van Weeren, M. Brüggen, K. Rajpurohit, C. Jones,Comments: Accepted for publication in Astronomy & AstrophysicsSubjects: astro-ph.CO astro-ph.HECreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
The massive, hot galaxy cluster PSZ2 G286.98+32.90 (hereafter PLCKG287, z=0.383) hosts a giant radio halo and two prominent radio relics which are signs of a disturbed dynamical state. However, despite optical and radio observations indicate a clear multiple merger, the X-ray emission of the cluster, derived from XMM-Newton observations, shows only moderate disturbance. We present new 200 ks Chandra observations of PLCKG287. We detect a shock front to the NW direction at a distance of ~390 kpc from the X-ray peak, characterized by a Mach number M~1.3, as well as a cold front at a distance of ~300 kpc from the X-ray peak, nested in the same direction of the shock in a typical configuration expected by a merger. We also find evidence for X-ray depressions to the E and W, that could be the signature of feedback from the ACTIVE GALACTIC NUCLEus (AGN). The radial profile of the thermodynamic quantities show a temperature and abundance peak in the cluster center, where also the pressure and entropy have a rapid increase. Based on these properties, we argue that PLCKG287 is what remains of a cool core after a heating event. We estimate that both the shock energy and the AGN feedback energy, implied by the analysis of the X-ray cavities, are sufficient to heat the core to the observed temperature of ~17 keV in the central ~160 kpc. We discuss the possible origin of the detected shock by investigating alternative scenarios of merger and AGN outburst, finding that they are both energetically viable. However, no single model seems able to explain all the X-ray features detected in this system. This suggests that the combined action of merger and central AGN feedback is likely necessary to explain the reheated cool core, the large-scale shock and the cold front. The synergy of these two processes may act in shaping the distribution of cool core and non cool core clusters. [Abridged]
[abstract 3 / 32] Yes (score: 4) - Title: Constraints on LIGO/Virgo Compact Object Mergers from Late-time Radio ObservationsAuthors: Ashna Gulati, Tara Murphy, Dougal Dobie, Adam Deller, David L. Kaplan, Emil Lenc, Ilya Mandel, Stefan Duchesne, Vanessa Moss,Comments: The paper has already been accepted for publication in MNRAS. It consists 17 pages, 8 figures, 6 tables and supplementary materialSubjects: astro-ph.HECreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
We present results from a search for radio afterglows of compact object mergers conducted with the Australian SKA Pathfinder. We used data from four epochs of the Rapid ASKAP Continuum Survey to search compact binary merger localization regions observed during the LIGO/Virgo O2, and O3 observing runs. Our investigation focused on eleven events (published in the GWTC-1, GWTC-2, and GWTC-3 catalogues of gravitational-wave events) with 90\% posterior localisations smaller than $150\,\deg^2$ and $\ge$99\% probabilities of being of astrophysical origin, to identify potential radio afterglow-like transients up to $\lesssim$1500 days post-merger. We identified candidate afterglow-type variable sources in the 90\% localisation for events -- GW190503, GW200202 and GW200208, which were ruled out as unlikely to be related to the corresponding GW event on further analysis. Since we find no likely candidate counterparts, we constrain the inclination angle and the circum-merger density at isotropic equivalent energies ranging from $2\times10^{51} -1\times10^{54}\rm \:erg$. These constraints are based on the assumption that the electron energy distribution in the associated JETs follows a power-law index of $ p = 2.2$, with 1% of the shock energy in the MAGNETic field ($ \epsilon_B = 0.01$) and 10% in the electrons ($\epsilon_e = 0.1$). We discuss the detectability of late-time afterglows as a function of merger distance and inclination angles with millijansky surveys.
[abstract 4 / 32] Yes (score: 3) - Title: The emission geometry of pulsars with interpulsesAuthors: S. N. Sun, N. Wang, W. M. Yan, S. Q. Wang,Comments: 11 figures, 4 tables, Accepted for publication in The Astrophysical JournalSubjects: astro-ph.HECreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
We present POLARIZATION profiles of 23 pulsars exhibiting interpulse (IP) emissions using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). By applying the rotating vector model (RVM), we measured the inclination and impact angles for 16 pulsars, allowing us to investigate their beam geometries. Our analysis indicates that for 5 pulsars, the IP emissions likely originate from the same MAGNETic pole as the main pulse (MP), whereas for the remaining 11 pulsars, the IP and MP emissions originate from opposite MAGNETic poles. For the 7 pulsars that do not conform to the RVM, we are unable to determine whether the IP emissions originate from the same or opposite MAGNETic pole as the MPs. By analyzing the beam configurations of pulsars, we found that the emission within the beam is not fully active across both longitude and latitude. Filling factors ranging from 0.27 to 0.99 were obtained for pulsars with opposite pole IP emissions, suggesting an underestimation of emission height when applying the geometrical method. The emissions for MPs and IPs occur at different heights in the pulsar MAGNETosphere, with the difference in emission height ranging from tens to thousands of kilometers. We also found that some pulsars have wide emission beams, indicating that radio emissions may occur in regions of high altitude within the pulsar MAGNETosphere.
[abstract 5 / 32] Yes (score: 3) - Title: Galaxy scale consequences of tidal disruption events: extended emission line regions, extreme coronal lines and infrared-to-optical light echoesAuthors: Andrew Mummery, Muryel Guolo, James Matthews, Megan Newsome, Chris Lintott, William Keel,Comments: 35 pages, 23 figures. To be submitted to MNRAS, comments welcomeSubjects: astro-ph.HECreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
Stars in galactic centers are occasionally scattered so close to the central supermassive BLACK HOLE that they are completely disrupted by tidal forces, initiating a transient accretion event. The aftermath of such a tidal disruption event (TDE) produces a bright-and-blue accretion flow which is known to persist for at least a decade (observationally) and can in principle produce ionizing radiation for hundreds of years. Tidal disruption events are known (observationally) to be overrepresented in galaxies which show extended emission line regions (EELRs), with no pre-TDE classical AGN activity, and to produce transient ``coronal lines'', such as [FeX] and [FeXIV]. Using coupled CLOUDY-TDE disk simulations we show that tidal disruption event disks produce a sufficient ionizing radiation flux over their lifetimes to power both EELR of radial extents of $r \sim 10^4$ light years, and coronal lines. EELRs are produced when the ionizing radiation interacts with low density $n_H \sim 10^1 - 10^3 \, {\rm cm}^{-3}$ clouds on galactic scales, while coronal lines are produced by high density $n_H \sim 10^6 - 10^8 \, {\rm cm}^{-3}$ clouds near the galactic center. High density gas in galactic centers will also result in the rapid switching on of narrow line features in post-TDE galaxies, and also various high-ionization lines which may be observed throughout the infrared with JWST. Galaxies with a higher intrinsic rate of tidal disruption events will be more likely to show macroscopic EELRs, which can be traced to originate from the previous tidal disruption event in that galaxy, which naturally explains why TDEs are more likely to be discovered in galaxies with EELRs. We further argue that a non-negligible fraction of so-called optically selected ``AGN'' are tidal disruption events.
[abstract 6 / 32] Yes (score: 3) - Title: The EXOD search for faint transients in XMM-Newton observations. Part IIAuthors: Norman Khan, Erwan Quintin, Natalie A. Webb, Robbie Webbe, Maitrayee Gupta, Inés Pastor-Marazuela, Florent Castellani, Axel D. Schwope, Iris Traulsen, Ada Nebot,Comments: 23 Pages 17 FiguresSubjects: astro-ph.HECreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
The XMM-Newton observatory has accumulated a vast archive of over 17,000 X-ray observations over the last 25 years. However, the standard data processing pipelines may fail to detect certain types of transient X-ray sources due to their short-lived or dim nature. Identifying these transient sources is important for understanding the full range of temporal X-ray behaviour, as well as understanding the types of sources that could be routinely detected by future missions such as Athena. This work aims to reprocess XMM-Newton archival observations using newly developed dedicated software in order to identify neglected and missed transient X-ray sources that were not detected by the existing pipeline. We use a new approach that builds upon previous methodologies, by transforming event lists into data cubes, which are then searched for transient variability in short time windows. Our method enhances the detection capabilities in the Poisson regime by accounting for the statistical properties of sparse count rates, and allowing for transient search in previously discarded periods of high background activity. Our reprocessing efforts identified 32,247 variable sources at the 3-sigma level and 4,083 sources at the 5-sigma level in 12,926 XMM archival observations. We highlight four noteworthy sources: A candidate quasi-periodic eruption (QPE), a new MAGNETar candidate, a previously undetected Galactic hard X-ray burst and a possible X-ray counterpart to a Galactic radio pulsar. Our method demonstrates a new, fast, and effective way to process event list data from XMM-Newton, which is efficient in finding rapid outburst-like or eclipsing behaviour. This technique can be adapted for use with future telescopes, such as Athena, and can be generalised to other photon counting instruments operating in the low-count Poisson regime.
[abstract 7 / 32] Yes (score: 3) - Title: ElectroMAGNETic field solver for QED POLARIZATION in super-strong MAGNETic fields of MAGNETar and LASER plasmasAuthors: Mahmoud Alawashra, Jan Benáček, Martin Pohl, Mikhail Medvedev,Comments: Submitted to JCAPSubjects: physics.plasm-ph astro-ph.HECreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
Super-strongly MAGNETized plasmas play a crucial role in extreme environments of MAGNETar and laboratory LASER experiments, demanding comprehensive understanding of how quantum electrodynamic (QED) effects influence plasma behaviour. Earlier analytical and semi-analytical calculations have shown that QED effects can significantly modify the plasma POLARIZATION mode behaviour around MAGNETars using analytical and semi-analytical calculations. In this work, we present the first electroMAGNETic field solver that is valid beyond the Schwinger limit. QED vacuum POLARIZATION in super-strong MAGNETic fields are modeled with nonlinear Maxwell equations. We show that electroMAGNETic waves in simulations follow the analytical solutions well and reproduce the birefringence effects of electroMAGNETic wave modes between the $O$ and $X$ POLARIZATIONs of perpendicular electroMAGNETic waves and those between $L$ and $R$ POLARIZATIONs of parallel waves. This new framework can be applied to kinetic as well as in other types of computer simulations. The solver's key advantage lies in its versatility, allowing it to be used in gyro-motion, gyro-center, and gyro-kinetic simulations, which do not resolve the cyclotron motion, or in plasma studies with ground-level Landau quantization.
[abstract 8 / 32] (score: 2) - Title: Distinguishing Between Dark Matter-Black Hole Systems and Naked Singularities via Quasi-Periodic OscillationsAuthors: Zheng Ma, Meirong Tang, Zhaoyi Xu,Comments:Subjects: gr-qc astro-ph.HECreated: 2025-03-15; Updated: ; Datestamp: 2025-03-19
Quasi-Periodic Oscillations (QPOs) are an important phenomenon commonly observed in the X-ray radiation of BLACK HOLEs and neutron stars, closely related to the dynamics of accretion disks around compact objects and general RELATIVISTIC effects. The objective of this study is to use the QPO phenomenon to distinguish between DARK MATTER-BLACK HOLE systems and naked singularities, as well as to investigate the effects of different DARK MATTER models (Cold Dark Matter, CDM, and Scalar Field Dark Matter, SFDM) on the accretion disk dynamics. By introducing a DARK MATTER correction model within the framework of general relativity, we systematically investigate the differences in dragging effects, characteristic frequency distribution, and the innermost stable circular orbit (ISCO) radius between DARK MATTER-BLACK HOLE systems and naked singularities, while analyzing the potential coupling between QPO frequencies and DARK MATTER distribution. The main results of this study are as follows: $\nu_r$ and $\nu_\theta$ in DARK MATTER-BLACK HOLE systems can be identified as HFQPOs, while for lower spins ($a < 0.5$), $\nu_\text{nod}$ can be identified as LFQPOs, and for higher spins ($1 > a \geq 0.5$), $\nu_\text{nod}$ falls within the HFQPO observation range. Cold Dark Matter (CDM) and Scalar Field Dark Matter (SFDM) modulate the accretion disk dynamics at the order of $10^{-6}$.
[abstract 9 / 32] (score: 2) - Title: Development of the Timing System for the X-Ray Imaging and Spectroscopy MissionAuthors: Yukikatsu Terada, Megumi Shidatsu, Makoto Sawada, Takashi Kominato, So Kato, Ryohei Sato, Minami Sakama, Takumi Shioiri, Yuki Niida, Chikara Natsukari, Makoto S Tashiro, Kenichi Toda, Hironori Maejima, Katsuhiro Hayashi, Tessei Yoshida, Shoji Ogawa, Yoshiaki Kanemaru, Akio Hoshino, Kotaro Fukushima, Hiromitsu Takahashi, Masayoshi Nobukawa, Tsunefumi Mizuno, Kazuhiro Nakazawa, Shin'ichiro Uno, Ken Ebisawa, Satoshi Eguchi, Satoru Katsuda, Aya Kubota, Naomi Ota, Atsushi Tanimoto, Yuichi Terashima, Yohko Tsuboi, Yuusuke Uchida, Hideki Uchiyama, Shigeo Yamauchi, Tomokage Yoneyama, Satoshi Yamada, Nagomi Uchida, Shin Watanabe, Ryo Iizuka, Rie Sato, Chris Baluta, Matt Holland, Michael Loewenstein, Eric D Miller, Tahir Yaqoob, Robert S. Hill, Morgan D. Waddy, Mark Mekosh, Joseph B. Fox, Emily Aldoretta, Isabella Brewer, Koji Mukai, Kenji Hamaguchi, Francois Mernier, Anna Ogorzalek, Katja Pottschmidt, Mihoko Yukita, Toshihiro Takagi, Yugo Motogami, Teruaki Enoto, Takaaki Tanaka, Taichi Nakamoto, Chulsoo Kang, Tsuyoshi Miyazaki,Comments: 18 pages, 8 figures, 6 tables. Accepted for publication SPIE JATIS XRISM special issue 2025Subjects: astro-ph.IMCreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
This paper describes the development, design, ground verification, and in-orbit verification, performance measurement, and calibration of the timing system for the X-Ray Imaging and Spectroscopy Mission (XRISM). The scientific goals of the mission require an absolute timing accuracy of 1.0~ms. All components of the timing system were designed and verified to be within the timing error budgets, which were assigned by component to meet the requirements. After the launch of XRISM, the timing capability of the ground-tuned timing system was verified using the millisecond pulsar PSR~B1937+21 during the commissioning period, and the timing jitter of the bus and the ground component were found to be below $15~\mu$s compared to the NICER (Neutron star Interior Composition ExploreR) profile. During the performance verification and calibration period, simultaneous observations of the Crab pulsar by XRISM, NUSTAR (Nuclear Spectroscopic Telescope Array), and NICER were made to measure the absolute timing offset of the system, showing that the arrival time of the main pulse with XRISM was aligned with that of NICER and NUSTAR to within $200~\mu$s. In conclusion, the absolute timing accuracy of the bus and the ground component of the XRISM timing system meets the timing error budget of $500~\mu$s.
[abstract 10 / 32] (score: 2) - Title: Shock with Confidence: Formal Proofs of Correctness for Hyperbolic Partial Differential Equation SolversAuthors: Jonathan Gorard, Ammar Hakim,Comments: 13 pages, prepared for submission to ACMSubjects: cs.LO cs.NA math.NA physics.comp-phCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
First-order systems of hyperbolic partial differential equations (PDEs) occur ubiquitously throughout computational physics, commonly used in simulations of fluid turbulence, shock waves, electroMAGNETic interactions, and even general RELATIVISTIC phenomena. Such equations are often challenging to solve numerically in the non-linear case, due to their tendency to form discontinuities even for smooth initial data, which can cause numerical algorithms to become unstable, violate conservation laws, or converge to physically incorrect solutions. In this paper, we introduce a new formal verification pipeline for such algorithms in Racket, which allows a user to construct a bespoke hyperbolic PDE solver for a specified equation system, generate low-level C code which verifiably implements that solver, and then produce formal proofs of various mathematical and physical correctness properties of the resulting implementation, including L^2 stability, flux conservation, and physical validity. We outline how these correctness proofs are generated, using a custom-built theorem-proving and automatic differentiation framework that fully respects the algebraic structure of floating-point arithmetic, and show how the resulting C code may either be used to run standalone simulations, or integrated into a larger computational multiphysics framework such as Gkeyll.
[abstract 11 / 32] (score: 2) - Title: Propagation Times and Energy Losses of Cosmic Protons and Antiprotons in Interplanetary SpaceAuthors: Nicola Tomassetti, Bruna Bertucci, Emanuele Fiandrini, Behrouz Khiali,Comments: 16 pages, 11 figuresSubjects: astro-ph.HE astro-ph.SR hep-ph physics.space-phCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
In this paper, we investigate the heliospheric modulation of COSMIC RAYs in interplanetary space, focusing on their propagation times and energy losses over the solar cycle. To perform the calculations, we employed a data-driven model based on the stochastic method. Our model was calibrated using time-resolved and energy-resolved data from several missions including AMS-02, PAMELA, EPHIN/SOHO, BESS, and data from Voyager-1. This approach allows us to calculate probability density functions for the propagation time and energy losses of cosmic protons and antiprotons in the heliosphere. Furthermore, we explore the temporal evolution of these probabilities spanning from 1993 to 2018, covering a full 22-year cycle of MAGNETic polarity, which includes two solar minima and two MAGNETic reversals. Our calculations were carried out for cosmic protons and antiprotons, enabling us to investigate the role of charge-sign dependent effects in COSMIC RAY transport. These findings provide valuable insights into the physical processes of cosmic-ray propagation in the heliosphere and contribute to a deeper understanding of the solar modulation phenomenon.
[abstract 12 / 32] (score: 2) - Title: gammapy_SyLC: A Package for Simulating and Fitting Variability in High-Energy Light CurvesAuthors: Claudio Galelli,Comments: 8 pages, 15 figuresSubjects: astro-ph.HE astro-ph.IMCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
Characterizing the temporal variability of astrophysical sources is key to understanding the underlying physical processes driving their emissions. This work introduces a gammapy_SyLC, a Python package that offers tools to simulate and fit time-domain data, with a focus on Active Galactic Nuclei (AGN) variability. The package was developed taking into account possible interactions with gammapy but does not directly depend on it. gammapy_SyLC incorporates optimized implementations of the Timmer & Koenig and Emmanoulopoulos algorithms for light curve simulation, capable of generating synthetic lightcurves from specified PSDs and amplitude distribution models. It also provides functionalities for PSD fitting, histogram-based PDF interpolation, and Monte Carlo-based parameter estimation, making it a full-stack tool for investigating variable phenomena and specifically the long-term behavior of AGNs. To showcase its capabilities, the package was applied to gamma-ray light curves from the FERMI Large Area Telescope repository, reconstructing PSDs and PDFs and constraining variability models for observed sources.
[abstract 13 / 32] (score: 2) - Title: Integral modelling and Reinforcement Learning control of 3D liquid metal coating on a moving substrateAuthors: Fabio Pino, Edoardo Fracchia, Benoit Scheid, Miguel A. Mendez,Comments:Subjects: physics.flu-dyn math-ph math.MPCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
Metallic coatings are used to improve the durability of metal surfaces, protecting them from corrosion. These protective layers are typically deposited in a fluid state via a liquid film. Controlling instabilities in the liquid film is crucial for achieving uniform and high-quality coatings. This study explores the possibility of controlling liquid films on a moving substrate using a combination of gas JETs and electroMAGNETic actuators. To model the 3D liquid film, we extend existing integral models to incorporate the effects of electroMAGNETic actuators. The control strategy was developed within a reinforcement learning framework, where the Proximal Policy Optimization (PPO) algorithm interacts with the liquid film via pneumatic and electroMAGNETic actuators to optimize a reward function, accounting for the amplitude of the instability waves through a trial and error process. The PPO found an optimal control law, which successfully reduced interface instabilities through a novel control mechanism, where gas JETs push crests and electroMAGNETs raise troughs using the Lorentz force.
[abstract 14 / 32] (score: 2) - Title: Association of 220 PeV Neutrino KM3-230213A with Gamma-Ray BurstsAuthors: Ruiqi Wang, Bo-Qiang Ma,Comments: 4 latex pages, 1 table, no figureSubjects: astro-ph.HE gr-qc hep-phCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
Recently, the KM3NeT Collaboration released the detection of a 220 PeV neutrino from the celestial coordinates RA=94.3\degree~ and Dec.=-7.8\degree~ on 13 February 2023 at 01:16:47 UTC \cite{KM3NeT:2025npi}. The source for this extra-ordinary cosmic neutrino, designated KM3-230213A, is not identified yet but there has been a speculation that it might be associated with a gamma-ray burst GRB~090401B \cite{Amelino-Camelia:2025lqn}. The purpose of this report is to search the association of this 220 PeV neutrino with potential GRB sources from a more general consideration of Lorentz invariance violation (LV) without fixed LV scale. We try to associate this extra-ordinary neutrino with potential GRBs within angular separation of 1\degree, 3\degree~ and 5\degree~ respectively and the results are listed in Table 1. We find the constraints $E_{\rm{LV}}\leq 5.3\times 10^{18}$~GeV for subluminal LV violation and $E_{\rm{LV}}\leq 5.6\times 10^{19}$~GeV for superluminal LV violation if KM3-230213A is a GRB neutrino.
[abstract 15 / 32] (score: 2) - Title: Velocity Structure Correlations between the Nebular, Molecular, and Atmospheric Gases in the Cores of Four Cool Core ClustersAuthors: Muzi Li, B. R. McNamara, Alison L. Coil, Marie-Joelle Gingras, Fabrizio Brighenti, H. R. Russell, Prathamesh D. Tamhaneh, S. Peng Oh, Serena Perrotta,Comments: 25 pages; 12 figures; Accepted by ApJ in March 2025, DOI: 10.3847/1538-4357/adc102Subjects: astro-ph.GACreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
We investigate the velocity structure of nebular gas in the central galaxies of four clusters: Abell 1835, PKS 0745-191, Abell 262, and RXJ0820.9+0752, using data from the Keck Cosmic Web Imager (KCWI). Velocity structure functions (VSFs) of the [OII] emission line are compared to VSFs of molecular clouds observed with the Atacama Large Millimeter/submillimeter Array (ALMA). Apart from Abell 262 where the gas is located in a circumnuclear disk, the nebular gas in the remaining galaxies lies in off-nuclear filamentary structures with VSFs steeper than the Kolmogorov slope. This steepening may be plausibly attributed to gravity although other factors, such as MAGNETic stresses and bulk motion,} may be significant. The VSFs of CO and [OII] emission are similar in RXJ0820 and Abell 262, indicating close coupling of the nebular and molecular gases. In contrast, the nebular and molecular gases are differentiated on most scales in PKS 0745 and Abell 1835. This discrepancy is likely due to the radio-AGN churning the gas. We compare the scale-dependent velocity amplitudes of the hot atmospheres constrained by X-ray surface brightness fluctuation analysis using Chandra observations to the nebular VSFs. The large-scale consistency in Abell 1835 and RXJ0820 is consistent with condensation from the hot atmospheres. {We explore substantial systematic biases, including projection effects, windowing, and smoothing effects when comparing VSFs using different telescopes and instruments.
[abstract 16 / 32] (score: 1) - Title: The nebular spectra of SN 2023ixf: A lower mass, partially stripped progenitor may be the result of binary interactionAuthors: Philip D. Michel, Paolo A. Mazzali, Daniel A. Perley, K-Ryan Hinds, Jacob L. Wise,Comments: 16 Pages, 12 Figures, 5 TablesSubjects: astro-ph.HE astro-ph.GA astro-ph.SRCreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
SN 2023ixf is one of the brightest Core Collapse Supernovae of the 21st century and offers a rare opportunity to investigate the late stage of a Supernova through nebular phase spectroscopy. We present four nebular phase spectra from day +291 to +413 after explosion. This is supplemented with high cadence early phase spectroscopic observations and photometry covering the first 500 days to investigate explosion parameters. The narrow and blue-shifted nebular Oxygen emission lines are used to infer an ejected Oxygen mass of $<0.65M_\odot$, consistent with models of a relatively low mass ($M_{ZAMS}<15M_\odot$) progenitor. An energy of 0.3 to $1.4 \times10^{51}$ erg and a light curve powered by an initial $^{56}$Ni mass of $0.049 \pm 0.005 M_\odot$ appear consistent with a relatively standard Type II explosion, while an incomplete $\gamma$-ray trapping (with timescale of $240\pm4$ days) suggests a lower ejecta mass. Assuming a typical explosion, the broad Hydrogen and Calcium profiles suggest a common origin within a lower mass, partially stripped envelope. Hydrogen emission broadens with time, indicating contribution from an additional power source at an extended distance; while the emergence of high velocity ($\sim$6,000 km s$^{-1}$) Hydrogen emission features (beginning around day +200) may be explained by Shock Interaction with a dense Hydrogen-rich region located at $\sim1.5 \times 10^{16}$cm. Such envelope mass loss for a low mass progenitor may be explained through theoretical models of Binary interaction.
[abstract 17 / 32] (score: 1) - Title: Supernova Gamma-Ray Constraints from Heavy Sterile Neutrino DecaysAuthors: Garv Chauhan, R. Andrew Gustafson, Ian M. Shoemaker,Comments: 10 pages + 6 page appendixSubjects: hep-ph astro-ph.HECreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
Heavy sterile neutrinos can be produced in core-collapse SUPERNOVAe (CCSNe), which are superb particle generators because of their high densities and temperatures. If the sterile neutrinos are long-lived, these may be produced inside the SUPERNOVA core and escape the stellar envelope, later decaying into SM particles like photons and neutrinos. In this work, we first improve the calculation of the $\gamma$-ray fluxes. We then revisit the bounds on the sterile neutrino parameter space from the non-observation of $\gamma$-rays from SN1987A by the Solar Maximum Mission (SMM) and constraints from the diffuse $\gamma$-ray background arising from sterile neutrino decays. We find that the constraints arising from both the SMM data and the diffuse $\gamma$-ray background are weaker than those that have previously appeared in the literature. Finally, we study the sensitivity of several present and near-future $\gamma$-ray telescopes such as e-ASTROGAM and FERMI-LAT, assuming a nearby future galactic CCSN. We show that future observations can probe mixing angles as low as $|U_{\tau/\mu4}|^2\sim 5\times10^{-17}$.
[abstract 18 / 32] (score: 1) - Title: Searching for rotation in X-COP galaxy clustersAuthors: Tommaso Bartalesi, Stefano Ettori, Carlo Nipoti,Comments: 25 pages, 16 figuresSubjects: astro-ph.COCreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
We search for evidence of rotational support by analyzing the thermodynamic profiles of the intracluster medium (ICM) in a sample of nearby, massive galaxy clusters. For each object of the XMM-Newton Cluster Outskirts Project (X-COP) sample, we present axisymmetric models of rotating ICM with composite polytropic distributions, in equilibrium in spherically symmetric dark halos, exploring cases both with and without turbulent support in the ICM. The profile of rotation velocity and the distribution of turbulent velocity dispersion are described with flexible functional forms, consistent with the properties of synthetic clusters formed in cosmological simulations. The models are tuned via a Markov Chain Monte Carlo algorithm to reproduce the radial profiles of the thermodynamic variables as resolved in the XMM-Newton and Planck maps, and to be consistent with the mass distributions estimated either from weak lensing observations (when available) or under the assumption of a "universal" value of the baryon fraction. Our models indicate that there is room for non-negligible rotation in the ICM of massive clusters, with typical peak rotation speed 300 km/s and peak rotation-velocity-to-velocity-dispersion ratio of 0.3. According to our models, the ICM in Abell 2255 can have a rotation speed as high as 500 km/s, corresponding to a rotation-velocity-to-velocity-dispersion ratio of 0.3, at a distance of 100 kpc from the center, where the X-ray emissivity is still high. This makes Abell 2255 a very promising candidate for the presence of rotation in the ICM that could be detected with the currently operating XRISM observatory, as we demonstrate computing and analyzing a mock X-ray spectrum.
[abstract 19 / 32] (score: 1) - Title: Computational Framework for White Hole Detection in Gravitational Waves and CMB DataAuthors: Antonios Valamontes, Ioannis Adamopoulos,Comments:Subjects: gr-qcCreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
This study presents a computational framework for evaluating the detectability of white hole-induced gravitational wave signals and their imprints on the cosmic microwave background (CMB). The approach integrates stochastic gravitational wave background (SGWB) POLARIZATION data from LISA with CMB-S4 B-mode anisotropies, utilizing Monte Carlo simulations, Bayesian inference, and signal-to-noise ratio (SNR) estimations to determine detection feasibility.
[abstract 20 / 32] (score: 1) - Title: Consistencies and inconsistencies in redshift-independent distancesAuthors: José Antonio Nájera, Harry Desmond,Comments: 17 pages, 5 figuresSubjects: astro-ph.CO astro-ph.GACreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
Redshift-independent distances underpin much of astrophysics, and there exists a plethora of methods to estimate them. However, the extent to which the distances they imply are consistent, while crucial for the integrity of the distance ladder, has been little explored. We construct a statistical framework to assess both internal (between measurements with the same method) and external (between-method) consistency by comparing differences between distances to their quoted statistical uncertainties in the NASA/IPAC Extragalactic Database of Distances (NED-D). 66 of the 76 indicators in NED-D are amenable to a consistency test by having at least two measurements to the same galaxy or at least one measurement to a galaxy also measured by another method. We find that only 12 of these methods produce self-consistent distances across literature determinations, of which 7 are also consistent with distances to the same galaxies measured by all other methods. The most consistent 6 methods (M-stars luminosity, Novae, Masers, Globular Cluster Fundamental Plane, O- and B-type Supergiants and BL Lac Luminosity) also give similar average distances to the mean of all indicators, while the 7th (Proper Motion) underestimates distances relative to the mean by 17.1%. We also investigate consistency of Cepheid distances in the SH0ES 2022 catalogue, finding no evidence for unaccounted-for systematics. Our NED-D results imply that considerable work remains to obtain reliable distances by a multitude of methods, a crucial endeavour for constructing a multiply cross checked and fully robust distance ladder.
[abstract 21 / 32] (score: 1) - Title: Innermost stable circular orbits around a Reissner-Nordstr\"om-global monopole spacetime in a homogeneous MAGNETic fieldAuthors: Hamza M. Haddad, M. Haluk Seçuk, Özgür Delice,Comments: 14 pages, 6 Figures, RevTex4-2Subjects: gr-qc astro-ph.SR hep-thCreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
We investigate the dynamics of charged particles in the spacetime of a global monopole swallowed by a Reissner-Nordstr\"om (RN) BLACK HOLE in the presence of a external weak asymptotically homogeneous MAGNETic field. We carefully analyze and deduce the conditions to have such a MAGNETic field around this BLACK HOLE and show that this is indeed possible in the small but nontrivial charge and monopole term limit. We obtain general equations of motion and analyze them for special cases of circular orbits, focusing on the inner-most stable circular orbit (ISCO) of this configuration. The richness of the parameters and complicated forms of the resulting equations of motion necessitate a numerical approach. Hence, we have presented our results with numerous graphs, which help to understand the evolution of ISCO as a function of the external test MAGNETic field and the monopole term depending on the parameters of the BLACK HOLE, such as its electrical charge as well as the properties of the test particle such as its specific charge, angular momentum, and energy. We have also analyzed the effective potential that these fields generate and deduced results for the aforementioned values of external and internal parameters of spacetime.
[abstract 22 / 32] (score: 1) - Title: Grid instability growth rates for explicit, electrostatic momentum- and energy-conserving particle-in-cell algorithmsAuthors: Luke C Adams, Gregory R Werner, John R Cary,Comments: 13 pages, 6 figuresSubjects: physics.plasm-ph physics.comp-phCreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
When the Debye length is not resolved in a particle-in-cell (PIC) simulation, the plasma will unphysically heat until the Debye length becomes resolved via a phenomenon known as grid heating. The article presents detailed numerical measurements of grid heating for several explicit PIC algorithms including the first systematic (covering the Debye length resolution and drift-velocity parameter space) study of grid-heating growth rates for the standard electrostatic momentum-conserving PIC algorithm. Additionally, we derive and test a cubic-spline-based PIC algorithm that ensures that the interpolated electric field has a continuous first derivative. Also considered are energy-conserving PIC algorithms with linear and quadratic interpolation functions. In all cases, we find that grid heating can occur for for some combinations of Debye under-resolution and plasma drift. We demonstrate analytically and numerically that grid heating cannot be eliminated by using a higher-order field solve, and give an analytical expression for the cold-beam stability limits of some energy-conserving algorithms.
[abstract 23 / 32] (score: 1) - Title: Universal structure of propagation-invariant optical pulsesAuthors: Rafael Russo Almeida, Dillon Ramsey, Ayman F. Abouraddy, John P. Palastro, Jorge Vieira,Comments: 12 pages, 4 figures, to be submitted to Optics LettersSubjects: physics.optics physics.plasm-phCreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
Space-time structuring of light - where spatial and temporal degrees of freedom are deliberately coupled and controlled - is an emerging area of optics that enables novel configurations of electroMAGNETic fields. Of particular importance for applications are optical pulses whose peak intensity travels at an arbitrary, tunable velocity while maintaining its spatiotemporal profile. Space-time wave packets and the ideal flying focus are two prominent realizations of these pulses. Here, we show that these realizations share an identical spatiotemporal field structure, and that this structure represents a universal solution for constant-velocity, propagation-invariant pulses.
[abstract 24 / 32] (score: 1) - Title: Minifilament Eruptions as the Last Straw to Break the Equilibrium of a Giant Solar FilamentAuthors: Hechao Chen, Hui Tian, Quanhao Zhang, Chuan Li, Chun Xia, Xianyong Bai, Zhenyong Hou, Kaifan Ji, Yuanyong Deng, Xiao Yang, Ziyao Hu,Comments: 17 pages, 8 figures. Accepted to be published in ApJSubjects: astro-ph.SRCreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
Filament eruptions are MAGNETically driven violent explosions commonly observed on the Sun and late-type stars, sometimes leading to monster coronal mass ejections that directly affect the nearby planets' environments. More than a century of research on solar filaments suggests that the slow evolution of photospheric MAGNETic fields plays a decisive role in initiating filament eruptions, but the underlying mechanism remains unclear. Using high-resolution observations from the \textit{Chinese H$\alpha$ Solar Explorer}, the \textit{Solar Upper Transition Region Imager}, and the \textit{Solar Dynamics Observatory}, we present direct evidence that a giant solar filament eruption is triggered by a series of minifilament eruptions occurring beneath it. These minifilaments, which are homologous to the giant filament but on a smaller tempo-spatial scale, sequently form and erupt due to extremely weak mutual flux disappearance of opposite-polarity photospheric MAGNETic fields. Through multi-fold MAGNETic interactions, these erupting minifilaments act as the last straw to break the force balance of the overlying giant filament and initiate its ultimate eruption. The results unveil a possible novel pathway for small-scale MAGNETic activities near the stellar surface to initiate spectacular filament eruptions, and provide new insight into the MAGNETic coupling of filament eruptions across different tempo-spatial scales.
[abstract 25 / 32] (score: 1) - Title: Anisotropic Turbulent Flows Observed in Above the Loop-top Regions During Solar FlaresAuthors: Xiaoyan Xie, Chengcai Shen, Katharine Reeves, Bin Chen, Xiaocan Li, Fan Guo, Sijie Yu, Yuqian Wei, Chuanfei Dong,Comments:Subjects: astro-ph.SRCreated: 2025-03-17; Updated: ; Datestamp: 2025-03-19
Solar flare above-the-loop-top (ALT) regions are vital for understanding solar eruptions and fundamental processes in plasma physics. Recent advances in 3D MHD simulations have revealed unprecedented details on turbulent flows and MHD instabilities in flare ALT regions. Here, for the first time, we examine the observable anisotropic properties of turbulent flows in ALT by applying a flow-tracking algorithm on narrow-band Extreme Ultraviolet (EUV) images that are observed from the face-on viewing perspective. First, the results quantitatively confirm the previous observation that vertical motions dominate and that the anisotropic flows are widely distributed in the entire ALT region with the contribution from both upflows and downflows. Second, the anisotropy shows height-dependent features, with the most substantial anisotropy appearing at a certain middle height in ALT, which agrees well with the MHD modeling results where turbulent flows are caused by Rayleigh-Taylor-type instabilities in the ALT region. Finally, our finding suggests that supra-arcade downflows (SADs), the most prominently visible dynamical structures in ALT regions, are only one aspect of turbulent flows. Among these turbulent flows, we also report the anti-sunward-moving underdense flows that might develop due to MHD instabilities, as suggested by previous three-dimensional flare models. Our results indicate that the entire flare fan displays group behavior of turbulent flows where the observational bright spikes and relatively dark SADs exhibit similar anisotropic characteristics.
[abstract 26 / 32] (score: 1) - Title: On Using Gradient Dynamic Spectra (GraDS) to Study Type-II Solar Radio BurstsAuthors: Puja Majee, Devojyoti Kansbanik, Divya Oberoi,Comments: 6 pages, 3 figures; acceptedSubjects: astro-ph.SRCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
Solar type-II radio bursts are coherent plasma emissions arising from MAGNETohydrodynamic shocks produced by either coronal mass ejections (CMEs) or flares. Type-II bursts sometimes show split-band emissions in the dynamic spectrum. When these split-band emissions come from regions just upstream and downstream of the shock, type-II band-splitting can be used as an important tool for estimating MAGNETic fields at the shock front. Earlier studies have shown that only $\sim$20\% of the type-IIs show morphologically similar split-bands. Imaging studies can unambiguously identify such instances, though they remain very rare. Here we suggest a useful approach to augment dynamic spectra-based studies by also examining the Gradient Dynamic Spectra (GraDS) of type-II emission. We also verified the conclusions of this approach against those from an imaging study.
[abstract 27 / 32] (score: 1) - Title: Variations in the Radiation Intensity of Pulsar B0950+08: Nine Years of Monitoring at 110 MHzAuthors: T. V. Smirnova, M. O. Toropov, S. A. Tyul'bashev,Comments: 8 pages, 6 figures, published in Astronomy Reports, translated by Yandex translator with correction of scientific lexisSubjects: astro-ph.HECreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
The analysis of variations in the emission intensity of the pulsar B0950+08 from 2014 to 2022 with scales from minutes to years was carried out. The observations were obtained in a round-the-clock daily survey conducted on the Large Phased Array (LPA) radio telescope. The high variability of emission is shown not only from pulse to pulse, but also at scales greater than 3 min. The average value of the estimated amplitude of these variations in 3.2 minutes is 25~Jy, the modulation index is 1. The average relative amplitude of the interpulse (IP) is $2.00 \pm 0.28\%$ of the main pulse. In individual pulses, the amplitude of the interpulse may exceed the amplitude of the main pulse (MP), but this is a rare event. Emission is observed in almost the entire period of the pulsar. For the first time, the relative amplitude of emission between the main pulse and the interpulse (emission bridge) was measured. When averaging about 10 hours, it varies from $0.8\%$ to $1.31\%$ with an average value of $1.04 \pm 0.28\%$. A high correlation was found between MP and IP amplitude variations both when averaging profiles over 3.2 minutes and when averaging over years. This correlation is due to refractive interstellar scintillation. The frequency scale of IP diffraction interstellar scintillation was measured for the first time and it was shown that the spectral forms for IP and MP are well correlated and have the same frequency scale. There are strong variations in the frequency scale of scintillation $f_{dif}$ from session to session (time interval from one day) on scales of 200-800 kHz. The refractive scale of scintillation for 1-2 days has been determined. A modulation of emission with a characteristic scale of about 130 days was detected, which, apparently, is also associated with refractive scintillation.
[abstract 28 / 32] (score: 1) - Title: The CatSouth Quasar Candidate Catalog for the Southern Sky and a Unified All-Sky Catalog Based on Gaia DR3Authors: Yuming Fu, Xue-Bing Wu, R. J. Bouwens, Karina I. Caputi, Yuxuan Pang, Rui Zhu, Da-Ming Yang, Jin Qin, Huimei Wang, Christian Wolf, Yifan Li, Ravi Joshi, Yanxia Zhang, Zhi-Ying Huo, Y. L. Ai,Comments: 20 pages, 7 figures, to be submitted to ApJS. The catalogs (CatSouth, and CatGlobe) can be downloaded in https://nadc.china-vo.org/res/r101575/Subjects: astro-ph.GA astro-ph.IMCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
The Gaia DR3 has provided a large sample of more than 6.6 million QUASAR candidates with high completeness but low purity. Previous work on the CatNorth QUASAR candidate catalog has shown that including external multiband data and applying machine-learning methods can efficiently purify the original Gaia DR3 QUASAR candidate catalog and improve the redshift estimates. In this paper, we extend the Gaia DR3 QUASAR candidate selection to the southern hemisphere using data from SkyMappper, CatWISE, and VISTA surveys. We train an XGBoost classifier on a unified set of high-confidence stars and spectroscopically confirmed QUASARs and galaxies. For sources with available Gaia BP/RP spectra, spectroscopic redshifts are derived using a pre-trained convolutional neural network (RegNet). We also train an ensemble photometric redshift estimation model based on XGBoost, TabNet, and FT-Transformer, achieving an RMSE of 0.2256 and a normalized median absolute deviation of 0.0187 on the validation set. By merging CatSouth with the previously published CatNorth catalog, we construct the unified all-sky CatGlobe catalog with nearly 1.9 million sources at $G<21$, providing a comprehensive and high-purity QUASAR candidate sample for future spectroscopic and cosmological investigations.
[abstract 29 / 32] (score: 1) - Title: Comparison Between Cycle-to-Cycle Variations in the Coefficient of Joy's Law and Covariance of Rotation Residuals and Meridional Motions of Sunspot GroupsAuthors: J. Javaraiah,Comments: 8 pages, 6 figurees, accepted by MNRASSubjects: astro-ph.SRCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
The tilts of bipolar MAGNETic regions are believed to be caused by the action of Coriolis force on rising MAGNETic flux tubes. Here we analysed the combined Greenwich and Debrecen observatories sunspot-group data during the period 1874-2017 and the tilt angles of sunspot groups measured at Mt. Wilson Observatory during the period 1917-1986 and Debrecen Observatory during the period 1994-2013. We find that there exists about 8-solar cycle (Gleissberg cycle) trend in the long-term variation of the slope of Joy's law (increase of tilt angle with latitude). There exists a reasonably significant correlation between the slope/coefficient of Joy's law and the slope (namely, residual covariance) of the linear relationship between the rotation residuals and meridional motions of sunspot groups in the northern hemisphere and also in the southern hemisphere during Solar Cycles 16-21. We also find that there exists a good correlation between north--south difference (asymmetry) in the coefficient of Joy's law and that in the residual covariance. We consider the residual covariance represents tentatively the coefficient of angular momentum transport. These results suggest that there exists a relationship between the surface/subsurface poleward/equatorward angular momentum transport and the Joy's law. There is a suggestion of the strength of the Joy's law depends on the strength of the poleward angular momentum transport.
[abstract 30 / 32] (score: 1) - Title: XL-Calibur measurements of polarised hard X-ray emission from the CrabAuthors: Hisamitsu Awaki, Matthew G. Baring, Richard Bose, Dana Braun, Jacob Casey, Sohee Chun, Pavel Galchenko, Ephraim Gau, Kazuho Goya, Tomohiro Hakamata, Takayuki Hayashi, Scott Heatwole, Kun Hu, Ryo Imazawa, Daiki Ishi, Manabu Ishida, Fabian Kislat, Mózsi Kiss, Kassi Klepper, Henric Krawczynski, Haruki Kuramoto, R. James Lanzi, Lindsey Lisalda, Yoshitomo Maeda, Filip af Malmborg, Hironori Matsumoto, Shravan Vengalil Menon, Aiko Miyamoto, Asca Miyamoto, Takuya Miyazawa, Kaito Murakami, Azuki Nagao, Takashi Okajima, Mark Pearce, Brian F. Rauch, Nicole Rodriguez Cavero, Kohei Shima, Kentaro Shirahama, Carlton M. Snow, Sean Spooner, Hiromitsu Takahashi, Sayana Takatsuka, Keisuke Tamura, Kojiro Tanaka, Yuusuke Uchida, Andrew Thomas West, Eric A. Wulf, Masato Yokota, Marina Yoshimoto,Comments: 8 pages, 4 figures. Accepted for publication in Monthly Notices of the Royal Astronomical SocietySubjects: astro-ph.HE astro-ph.IMCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
We report measurements of the linear polarisation degree (PD) and angle (PA) for hard X-ray emission from the Crab pulsar and wind nebula. Measurements were made with the XL-Calibur ($\sim$15-80 keV) balloon-borne Compton-scattering polarimeter in July 2024. The polarisation parameters are determined using a Bayesian analysis of Stokes parameters obtained from X-ray scattering angles. Well-constrained ($\sim$8.5$\sigma$) results are obtained for the polarisation of the $\sim$19-64 keV signal integrated over all pulsar phases: PD=(25.1$\pm$2.9)% and PA=(129.8$\pm$3.2)$^\circ$. In the off-pulse (nebula-dominated) phase range, the PD is constrained at $\sim$4.5$\sigma$ and is compatible with the phase-integrated result. The PA of the nebular hard X-ray emission aligns with that measured by IXPE in the 2-8 keV band for the toroidal inner region of the pulsar wind nebula, where the hard X-rays predominantly originate. For the main pulsar peak, PD=(32.8$^{+18.2}_{-28.5}$)% and PA=(156.0 $\pm$ 21.7)$^\circ$, while for the second peak (inter-pulse), PD=(0.0$^{+33.6}_{-0.0}$)% and PA=(154.5 $\pm$ 34.5)$^\circ$. A low level of polarisation in the pulsar peaks likely does not favour emission originating from the inner regions of the pulsar MAGNETosphere. Discriminating between Crab pulsar emission models will require deeper observations, e.g. with a satellite-borne hard X-ray polarimeter.
[abstract 31 / 32] (score: 1) - Title: Neutron portal to ultra-high-energy neutrinosAuthors: Gustavo F. S. Alves, Matheus Hostert, Maxim Pospelov,Comments: 11 pages, 6 figuresSubjects: hep-ph astro-ph.HE hep-exCreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
Current data on ultra-high-energy (UHE) COSMIC RAYs suggest they are predominantly made of heavy nuclei. This indicates that the flux of neutrinos produced from proton collisions on the cosmic microwave background is small and hard to observe. Motivated by the recent extremely-high-energy muon event reported by KM3NeT, we explore the possibility of enhancing the energy-flux of cosmogenic neutrinos through nuclear photodisintegration in the presence of new physics. Specifically, we speculate that UHE neutrons may oscillate into a new state, dark (or mirror) neutron $n'$ that in turn decays injecting large amount of energy to neutrinos, $n\to n'\to \nu_\text{UHE}$. While this mechanism does not explain the tension between the KM3NeT event and null results from IceCube, it reconciles the experimental preference for a heavier COSMIC RAY composition with a large diffuse cosmogenic flux of UHE neutrinos.
[abstract 32 / 32] (score: 1) - Title: Origin of holes and rings in the Green Monster of Cassiopeia A: Insights from 3D MAGNETohydrodynamic simulationsAuthors: S. Orlando, H. -T. Janka, A. Wongwathanarat, F. Bocchino, I. De Looze, D. Milisavljevic, M. Miceli, T. Temim, J. Rho, S. Nagataki, M. Ono, V. Sapienza, E. Greco,Comments: The manuscript consists of 17 pages, 11 figures, 2 Appendices, 2 online movies, and 3 interactive graphicsSubjects: astro-ph.HECreated: 2025-03-18; Updated: ; Datestamp: 2025-03-19
[Abridged] Cassiopeia A (Cas A) provides a unique opportunity to study SUPERNOVA (SN) dynamics and interactions with the circumstellar medium (CSM). Recent JWST observations revealed the "Green Monster" (GM), a structure with a likely CSM origin. We investigate its pockmarked morphology, characterized by circular holes and rings, by examining the role of small-scale ejecta structures interacting with a dense circumstellar shell. We adopted a neutrino-driven SN model to trace the evolution of its explosion from core collapse to the age of the Cas A remnant using high-resolution 3D MAGNETohydrodynamic simulations. Besides other processes, the simulations include self-consistent calculations of radiative losses, accounting for deviations from electron-proton temperature equilibration and ionization equilibrium, as well as the ejecta composition derived from the SN. The GM's morphology is reproduced by dense ejecta clumps and fingers interacting with an asymmetric, forward-shocked circumstellar shell. The clumps and fingers form by hydrodynamic instabilities growing at the interface between SN ejecta and shocked CSM. Radiative cooling accounting for effects of non-equilibrium of ionization enhances the ejecta fragmentation, forming dense knots and thin filamentary structures that penetrate the shell, producing a network of holes and rings with properties similar to those observed. The origin of the holes and rings in the GM can be attributed to the interaction of ejecta with a shocked circumstellar shell. By constraining the timing of this interaction and analyzing the properties of these structures, we provide a distinction of this scenario from an alternative hypothesis, which attributes these features to fast-moving ejecta knots penetrating the shell ahead of the forward shock.
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