Nonthermal Radiation Mechanisms |
| |
Authors: | Vahé Petrosian Andrei Bykov Yoel Rephaeli |
| |
Institution: | (1) Department of Applied Physics, Stanford University, Stanford, CA 94305, USA;(2) Kavli Institute of Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305, USA;(3) A.F. Ioffe Institute for Physics and Technology, 194021 St. Petersburg, Russia;(4) School of Physics and Astronomy, Tel Aviv University, Tel Aviv, 69978, Israel |
| |
Abstract: | In this paper we review the possible radiation mechanisms for the observed non-thermal emission in clusters of galaxies, with
a primary focus on the radio and hard X-ray emission. We show that the difficulty with the non-thermal, non-relativistic Bremsstrahlung
model for the hard X-ray emission, first pointed out by Petrosian (Astrophys. J. 557, 560, 2001) using a cold target approximation, is somewhat alleviated when one treats the problem more exactly by including the fact
that the background plasma particle energies are on average a factor of 10 below the energy of the non-thermal particles.
This increases the lifetime of the non-thermal particles, and as a result decreases the extreme energy requirement, but at
most by a factor of three. We then review the synchrotron and so-called inverse Compton emission by relativistic electrons,
which when compared with observations can constrain the value of the magnetic field and energy of relativistic electrons.
This model requires a low value of the magnetic field which is far from the equipartition value. We briefly review the possibilities
of gamma-ray emission and prospects for GLAST observations. We also present a toy model of the non-thermal electron spectra that are produced by the acceleration mechanisms
discussed in an accompanying paper Petrosian and Bykov (Space Sci. Rev., 2008, this issue, Chap. 11). |
| |
Keywords: | Radiation mechanisms: non-thermal Magnetic fields Galaxies: clusters: general X-rays: galaxies: clusters |
本文献已被 SpringerLink 等数据库收录! |
|