THE ENERGY SPECTRUM OF PRIMARY COSMIC-RAY ELECTRONS IN CLUSTERS OF GALAXIES AND INVERSE COMPTON EMISSION

摘要: Models for the evolution of integrated energy spectrum primary cosmic-ray electrons in clusters galaxies have been calculated, including effects losses due to inverse Compton (IC), synchrotron and bremsstrahlung emission, Coulomb intracluster medium (ICM). The combined timescale these reaches a maximum ~3 ? 109 yr with Lorentz factor ~ 300. A variety models time particle injection are considered, which all produced at single epoch past, continuous acceleration, combinations these. Analytical solutions given number limiting cases. Numerical more general Only cluster there has substantial relativistic since z 1 will any significant population present. For were injected is high-energy cutoff ?max present electron distribution. At low energies, dominate, distribution function N(?) tends constant value, independent ?. On other hand, if being accelerated present, high energies approaches steady state. If power-law distribution, state one power steeper flatter energies. In large initial populations particles, but also rates current injection, distributions simple combination behavior models. There steep drop ?max, higher rate determined by injection. Increasing ICM thermal gas density decreases low-energy (? 100). magnetic field greater than generally expected, (B 3 ?G), reduce electrons. 300, associated peak loss time, generic feature models, as long 1. IC emission from was calculated. exponent p, spectra relax into form. law -0.15, while -1.15. These two laws meet knee 1016 Hz. no ?max) results rapid frequencies. provides small fraction total energy, show an extended hump frequencies 1017 Hz), fall off above However, they hard tail frequencies, spectral index EUV soft X-ray nearly ubiquitous. This longest times. predicted rapidly going band. extends down UV, optical, IR bands, fairly flat (-0.6 +0.3). 20 keV, should become observable against background emission. Such (HXR) 104). same produce diffuse radio (cluster halos) via Because short times HXR expected only that (or very recent) acceleration. Assuming shocks, would expect HXR/radio currently undergoing mergers. luminosity primarily acceleration clusters. most or approximately -1.1. not fit law. Instead, falloff extending