| Type |
Journal Article |
| Names |
G. Brunetti, A. Lazarian |
| Publication |
Monthly Notices of the Royal Astronomical Society |
| Volume |
410 |
| Issue |
1 |
| Pages |
127-142 |
| Date |
January 1, 2011 |
| Short Title |
Acceleration of primary and secondary particles in galaxy clusters by compressible MHD turbulence |
| URL |
http://adsabs.harvard.edu/abs/2011MNRAS.410..127B |
| Library Catalog |
NASA ADS |
| Abstract |
Radio observations discovered large-scale non-thermal sources in the
central Mpc regions of dynamically disturbed galaxy clusters (radio
haloes). The morphological and spectral properties of these sources
suggest that the emitting electrons are accelerated by spatially
distributed and gentle mechanisms, providing some indirect evidence for
turbulent acceleration in the intergalactic medium (IGM).
Only deep upper limits to the energy associated with relativistic
protons in the IGM have been recently obtained through gamma and radio
observations. Yet these protons should be (theoretically) the main
non-thermal particle component in the IGM implying the unavoidable
production, at some level, of secondary particles that may have a deep
impact on the gamma-ray and radio properties of galaxy clusters.
Following Brunetti & Lazarian, in this paper we consider the
advances in the theory of magnetohydrodynamics (MHD) turbulence to
develop a comprehensive picture of turbulence in the IGM and extend our
previous calculations of particle acceleration by compressible MHD
turbulence by considering self-consistently the re-acceleration of both
primary and secondary particles. Under these conditions we expect that
radio to gamma-ray emission is generated from galaxy clusters with a
complex spectrum that depends on the dynamics of the thermal gas and
dark matter. The non-thermal emission results in very good agreement
with radio observations and with present constraints from hard X-ray and
gamma-ray observations. In our model giant radio haloes are generated in
merging (turbulent) clusters only. However, in case secondaries dominate
the electron component in the IGM, we expect that the level of the
Mpc-scale synchrotron emission in more relaxed clusters is already close
to that of the radio upper limits derived by present observations of
clusters without radio haloes. Important constraints on cluster physics
from future observations with present and future telescopes are also
discussed. |
| Tags |
Acceleration of Particles, GALAXIES: CLUSTERS: GENERAL, X-rays: general, radiation mechanisms: non-thermal, radio continuum: general, turbulence |