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Blazar spectra are one of the most important windows into the physical processes occurring along jets. The spectrum, composed from the different emitting regions along the jet, allows us to constrain the physical conditions in the jet. I…

High Energy Astrophysical Phenomena · Physics 2015-06-17 William J. Potter , Garret Cotter

We review the acceleration of energetic particles in relativistic astrophysical jets characterized by a significant velocity shear. The possible formation of power-law momentum spectra is discussed and typical acceleration timescales are…

Astrophysics · Physics 2009-11-11 Frank M. Rieger , Peter Duffy

lasma instabilities excited in collisionless shocks are responsible for particle acceleration. We have investigated the particle acceleration and shock structure associated with an unmagnetized relativistic electron-positron jet propagating…

High Energy Astrophysical Phenomena · Physics 2015-06-03 K. -I. Nishikawa , E. J. Choi , K. Min , P. Hardee , Y. Mizuno , B. Zhang , J. Niemiec , M. Medvedev , A. Nordlund , J. Fredriksen , M. Pohl , H. Sol , D. H. Hartmann , G. J. Fishman

We have investigated particle acceleration and emission from shocks and shear flows associated with an unmagnetized relativistic jet plasma propagating into an unmagnetized ambient plasma. Strong electro-magnetic fields are generated in the…

High Energy Astrophysical Phenomena · Physics 2014-12-23 K. -I. Nishikawa , P. Hardee , I. Dutan , B. Zhang , A. Meli , E. J. Choi , K. Min , J. Niemiec , Y. Mizuno , M. Medvedev , A. Nordlund , J. T. Frederiksen , H. Sol , M. Pohl , D. Hartmann

The self-organization of magnetospheric plasma is brought about by inward diffusion of magnetized particles. Not only creating a density gradient toward the center of a dipole magnetic field, the inward diffusion also accelerates particles…

This paper describes the acceleration of high energies protons captured by electrostatic waves in the frame of jet arising in the area of instability of relativistic jet, where spiral structures are excited. The wave has a spatially…

High Energy Astrophysical Phenomena · Physics 2023-02-09 Ya. N. Istomin , A. A. Gunya

In this chapter, we review some features of particle acceleration in astrophysical jets. We begin by describing four observational results relating to the topic, with particular emphasis on jets in active galactic nuclei and parallels…

High Energy Astrophysical Phenomena · Physics 2020-11-11 James Matthews , Anthony Bell , Katherine Blundell

As powerful gamma-ray engines, blazars -- relativistic plasma jets launched toward Earth from active galactic nuclei -- are manifestly high-energy particle accelerators. Yet, exactly how these jets accelerate particles as well as what they…

High Energy Astrophysical Phenomena · Physics 2025-04-03 John Mehlhaff , Muni Zhou , Vladimir Zhdankin

We compute the dynamics and emission of dissipative shells that are subject to a strong Compton drag, under simplifying assumptions about the dissipation mechanism. We show that under conditions prevailing in blazars, substantial…

High Energy Astrophysical Phenomena · Physics 2015-08-19 Omri Golan , Amir Levinson

We discuss processes accelerating cosmic ray electrons at boundaries of relativistic jets. The resulting spectrum is expected to posses two characteristic components: a power-law distribution at lower energies and a harder high energy…

Astrophysics · Physics 2007-05-23 M. Ostrowski , L. Stawarz

The central engine causing the production of jets in radio sources may work intermittently, accelerating shells of plasma with different mass, energy and velocity. Faster but later shells can then catch up slower earlier ones. In the…

Astrophysics · Physics 2009-11-06 Maddalena Spada , Gabriele Ghisellini , Davide Lazzati , Annalisa Celotti

Relativistic plasma jets are observed in many accreting black holes. According to theory, coiled magnetic fields close to the black hole accelerate and collimate the plasma, leading to a jet being launched. Isolating emission from this…

We describe the time-dependent radiation transfer in blazar jets, within the internal shock model. We assume that the central engine, which consists of a black hole and an accretion disk, spews out relativistic shells of plasma with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Manasvita Joshi , Markus Boettcher

There are still some important unanswered questions about the detailed particle acceleration and escape occurring during the quiescent epoches. As a result, the particle distribution that is adopted in the blazar quiescent spectral model…

High Energy Astrophysical Phenomena · Physics 2019-03-06 Y. G. Zheng , S. J. Kang , C. Y. Yang , J. M. Bai

We have not identified for sure what is the mechanism launching, accelerating and collimating relativistic jets. The two most likely possibilities are the gravitational energy of the accreting matter or the rotational energy of a spinning…

High Energy Astrophysical Phenomena · Physics 2018-09-21 Gabriele Ghisellini

With their jet pointing towards us, blazars are ideal tools to study the physics and structure of extragalactic jets. Their powerful jets are cosmic particle accelerators and are alleged to be one of the production sites of the high-energy…

High Energy Astrophysical Phenomena · Physics 2025-11-25 Claudia M. Raiteri

Fermi-LAT observations provide continuous and regularly-sampled measurements of gamma-ray photon flux for hundreds of blazars. Many of these light curves, spanning almost 15 years, have been thoroughly examined for periodicity in multiple…

High Energy Astrophysical Phenomena · Physics 2023-09-26 Polina Novikova , Ekaterina Shishkina , Dmitry Blinov

X-ray observations of kilo-parsec scale jets indicate that a synchrotron origin of the sustained non-thermal emission is likely. This requires distributed acceleration of electrons up to near PeV energies along the jet. The underlying…

High Energy Astrophysical Phenomena · Physics 2021-05-26 Jie-Shuang Wang , Brian Reville , Ruo-Yu Liu , Frank M. Rieger , Felix A. Aharonian

We study the acceleration, transport, and emission of particles in relativistic jets. Localized stochastic particle acceleration, spatial diffusion, and synchrotron as well as synchrotron self-Compton emission are considered in a leptonic…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Xuhui Chen , Martin Pohl , Markus Boettcher

In several jetted AGNs, structured jets have been observed. In particular spine-sheath configurations where the jet is radially divided into two or more zones of different flow velocities. We present a model based on the particle and…

High Energy Astrophysical Phenomena · Physics 2023-08-22 Margot Boughelilba , Anita Reimer , Lukas Merten , Jon-Paul Lundquist