Self-generated electromagnetic fields: Instabilities and energetic charged particle beams
Zusammenfassung der Projektergebnisse
TeV air Cherenkov telescopes, such as the H.E.S.S. collaboration, have established many relativistic outflow sources (active galactic nuclei, microquasars, pulsar wind nebulas, shell-type Supernovae remnants) as powerful sources of high-energy photon radiation. Moreover, there is increasing observational evidence from the AMANDA/IceCube neutrino experiment that extragalactic TeV 7-ray sources also emit high-energy neutrino radiation, providing the first evidence for the hadronic acceleration of cosmic rays in blazar-type active galactic nuclei. Such defines a subclass with prominent relativistic jets whose interactions with the surrounding interstellar and intergalactic medium (according to current understanding) give rise to the generation of nonthermal TeV 7-radiation. These observations provide strong evidence that the dissipation of the free kinetic energy of powerful particle beams in the interstellar and/or intergalactic medium is the basic energization process for nonthermal relativistic particles that generate the observed radiation. Our project was concerned with the microphysical plasma processes of this dissipation mechanism. Especially in active galactic nuclei the enormous energy conversion is attributed ultimately to the accretion of matter onto a central supermassive black hole, forming an accretion disk with perpendicular relativistic jets containing relativistic charged particles such as electrons, positrons and hadrons. These processes provide enormous amounts of kinetic energy in the form of directed particle beams whose dissipation in the surounding collision-free plasmas by twostream-instabilities and magnetized shock waves leads to intense plasma heating and particle acceleration. Both, the accelerated jet hadrons and the electron-positron pairs are responsible for generating nonthermal photon and neutrino radiation from these sources. Three main research topics were investigated in this project: 1) the detailed development of the relativistic pick-up model concerning the relaxation of relativistic charged particle beams by kinetically self-excited plasma wave fields in compact luminous sources of nonthermal radiation, 2) the investigation of plasma instabilities in the interstellar precursor region by counterstreaming distribution functions and implications for the formation of magnetized relativistic shock waves, and 3) the transport of energetic charged particles in the self-generated plasma turbulence. The achieved results have advanced our knowledge on the microphysical plasma processes involved in converting directed kinematic outflow energies into relativistic charged particles.
Projektbezogene Publikationen (Auswahl)
- Cosmic-Ray Diffusion Approximation with Weak Adiabatic Focusing. 2008, ApJ 686, 292
Schlickeiser, R., Shalchi, A.
- Linear Theory of Weakly Amplified, Parallel Propagating, Transverse Temperature-anisotropy Instabilities in Magnetized Thermal Plasmas. 2010, ApJ 716, 1596
Schlickeiser, R., Skoda, T.
- On the Magnetization of Cosmic Outflows: Plasma Modes and Instabilities of Unmagnetized Plasma Beams. 2010, ApJ 714, 868
Michno, M. J., Schlickeiser, R.
- Scaling Theory for Cross-Field Transport of Cosmic Rays in Turbulent Fields. 2010, ApJ 711, 997
Hauff, T., Jenko, F., Shalchi, A., Schlickeiser, R.
- Jump Conditions for Relativistic Magnetohydrodynamic Shocks in a Gyrotropic Plasma. 2011, ApJ 733, 32
Gerbig, D., Schlickeiser, R.
- Spontaneously growing, weakly propagating, transverse fluctuations in anisotropic magnetized thermal plasmas. 2011, Phys. Plasmas 18, 012103
Schlickeiser, R., Lazar, M., Skoda, T.
