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The polarization signatures of the blazar emissions are known to be highly variable. In addition to small fluctuations of the polarization angle around a mean value, sometimes large (> 180^o) polarization angle swings are observed. We…

High Energy Astrophysical Phenomena · Physics 2015-06-24 Haocheng Zhang , Xuhui Chen , Markus Boettcher , Fan Guo , Hui Li

Blazars are relativistic magnetized plasma outflows from supermassive black holes that point very close to our line of sight. Their emission is nonthermal dominated and highly variable across the entire electromagnetic spectrum.…

High Energy Astrophysical Phenomena · Physics 2020-10-14 Haocheng Zhang , Xiaocan Li , Dimitrios Giannios , Fan Guo , Yi-Hsin Liu , Lingyi Dong

We show that magnetic reconnection in a magnetically-dominated fast-cooling plasma can naturally produce bright flares accompanied by rotations in the synchrotron polarization vector. With particle-in-cell simulations of reconnection, we…

High Energy Astrophysical Phenomena · Physics 2020-07-30 David N. Hosking , Lorenzo Sironi

Relativistic magnetic reconnection events can widely exist in magnetized plasmas in astrophysical systems. During this process, oppositely directed magnetic field lines reconnect and release magnetic energy, efficiently accelerating…

High Energy Astrophysical Phenomena · Physics 2018-08-08 Haocheng Zhang , Xiaocan Li , Fan Guo , Dimitrios Giannios

This work presents a new detailed study on the energy-dependent variation in the X-ray polarisation of the Crab Pulsar Wind Nebula (PWN), obtained using data from the Imaging X-ray Polarimetry Explorer (IXPE). For the entire PWN, we…

High Energy Astrophysical Phenomena · Physics 2025-04-15 Wenhao Wei , Fei Xie , Fabio La Monaca , Wei Deng , Mingyu Ge , Kuan Liu , Chao Zuo , Wei Chen

Time-variable polarization is an extremely valuable observational tool to probe the dynamical physical conditions of blazar jets. Since 2008, we have been monitoring the flux and linear polarization of a sample of gamma-ray bright blazars…

High Energy Astrophysical Phenomena · Physics 2021-05-04 Alan P. Marscher , Svetlana G. Jorstad

We present a model of blazar variability that can both reproduce smooth large polarization angle swings, and at the same time allow for the seemingly random behaviour of synchrotron fluxes, polarization fraction and, occasionally, $\pi$/2…

High Energy Astrophysical Phenomena · Physics 2017-03-22 Maxim Lyutikov , Evgeniya Kravchenko

We investigate the temporal variability of polarization of synchrotron radiation from blazar jets. Multiwavelength observations revealed high-amplitude rotations of the electric vector position angle (EVPA), both in the optical and in the…

High Energy Astrophysical Phenomena · Physics 2026-01-13 Filippo Bolis , Emanuele Sobacchi , Fabrizio Tavecchio

Powerful flares from blazars with short ($\sim$ min) variability timescales are challenging for current models of blazar emission. Here, we present a physically motivated ab initio model for blazar flares based on the results of recent…

High Energy Astrophysical Phenomena · Physics 2016-09-07 Maria Petropoulou , Dimitrios Giannios , Lorenzo Sironi

Fast $\gamma$-ray variability in blazars remains a central puzzle in high-energy astrophysics, challenging standard shock acceleration models. Blazars, a subclass of active galactic nuclei (AGN) with jets pointed close to our line of sight,…

High Energy Astrophysical Phenomena · Physics 2025-11-26 Chandan Kumar Das , Bhargav Vaidya , Amit Shukla , Giancarlo Mattia , Karl Mannheim

We present a detailed polarimetric analysis of Cen X-3 using \ixpe observations during its high state, revealing complex energy-dependent polarization behavior. While phase-averaged polarization shows marginal energy dependence,…

The jet composition and energy dissipation mechanism of Gamma-ray bursts (GRBs) and Blazars are fundamental questions which remain not fully understood. One plausible model is to interpret the $\gamma$-ray emission of GRBs and optical…

High Energy Astrophysical Phenomena · Physics 2016-04-27 Wei Deng , Haocheng Zhang , Bing Zhang , Hui Li

Solar flares are explosive releases of magnetic energy stored in the solar corona, driven by magnetic reconnection. These events accelerate electrons, generating hard X-ray emissions and often display Quasi Periodic Pulsations (QPPs) across…

Solar and Stellar Astrophysics · Physics 2025-11-25 Luiz A. C. A. Schiavo , Natasha L. S. Jeffrey , Gert J. J. Botha , James A. McLaughlin

Rapid and luminous flares of non-thermal radiation observed in blazars require an efficient mechanism of energy dissipation and particle acceleration in relativistic active galactic nuclei (AGN) jets. Particle acceleration in relativistic…

High Energy Astrophysical Phenomena · Physics 2016-09-08 Krzysztof Nalewajko

The origin of extremely fast variability is one of the long-standing questions in the gamma-ray astronomy of blazars. While many models explain the slower, lower energy variability, they cannot easily account for such fast flares reaching…

High Energy Astrophysical Phenomena · Physics 2023-10-18 J. Jormanainen , T. Hovatta , I. M. Christie , E. Lindfors , M. Petropoulou , I. Liodakis

The author presents a model for variability of the flux and polarization of blazars in which turbulent plasma flowing at a relativistic speed down a jet crosses a standing conical shock. The shock compresses the plasma and accelerates…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Alan P. Marscher

Blazars are highly variable active galactic nuclei which emit radiation at all wavelengths from radio to gamma-rays. Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energies and it also varies…

The dissipation of energy flux in blazar jets plays a key role in the acceleration of relativistic particles. Two possibilities are commonly considered for the dissipation processes, magnetic reconnection -- possibly triggered by…

High Energy Astrophysical Phenomena · Physics 2018-06-13 F. Tavecchio , M. Landoni , L. Sironi , P. Coppi

We report on the variation in the optical polarization of the blazar PKS 1749+096 observed in 2008--2015. The degree of polarization (PD) tends to increase in short flares having a time-scale of a few days. The object favors a polarization…

High Energy Astrophysical Phenomena · Physics 2017-12-20 Makoto Uemura , Ryosuke Itoh , Ioannis Liodakis , Dmitry Blinov , Masanori Nakayama , Longyin Xu , Naoko Sawada , Hsiang-Yun Wu , Issei Fujishiro

It is commonly believed that blazar jets are relativistic magnetized plasma outflows from supermassive black holes. One key question is how the jets dissipate magnetic energy to accelerate particles and drive powerful multi-wavelength…

High Energy Astrophysical Phenomena · Physics 2022-01-26 Haocheng Zhang , Xiaocan Li , Dimitrios Giannios , Fan Guo , Hannes Thiersen , Markus Böttcher , Tiffany Lewis , Tonia Venters
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