EDP Sciences
Free access
Volume 498, Number 3, May II 2009
Page(s) 667 - 670
Section Astrophysical processes
DOI http://dx.doi.org/10.1051/0004-6361/200810996
Published online 19 March 2009
A&A 498, 667-670 (2009)
DOI: 10.1051/0004-6361/200810996

Research Note

Synchrotron fluence of nonlinearly cooled relativistic electrons with instantaneous flat power law injection

M. Zacharias and R. Schlickeiser

Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
    e-mail: rsch@tp4.rub.de

Received 19 September 2008 / Accepted 5 February 2009

Context. In powerful cosmic nonthermal radiation sources with a dominant magnetic field self generation, partition between the energy densities in magnetic fields and relativistic electrons is expected. As the electrons cool by synchrotron emission, the magnetic field strength becomes time-dependent and adjusts itself to the actual kinetic energy density of the radiating electrons.
Aims. For the case of instantaneous injection of power law distributed electrons with a flat power law spectral index, the nonlinear synchrotron fluence is calculated.
Results. For flat (spectral index 1<s<2) injected power laws the nonlinear synchrotron fluence at small frequencies approaches a power law ${\propto}\nu ^{-0.6}$, independent of the value of s, which is identical to the synchrotron fluence behaviour for steep injected power laws.

Key words: radiation mechanisms: non-thermal -- galaxies: active -- ISM: cosmic rays

© ESO 2009