Mon. Not. R. Astron. Soc., 343, 719-724 (2003/August-2)
Relic radio `bubbles' and cluster cooling flows.
DE YOUNG D.S.
Abstract (from CDS):
Recent suggestions that buoyant radio emitting cavities in the intracluster medium (ICM) can cause significant reheating of cooling flows are re-examined when the effects of the intracluster magnetic field are included. Expansion of the cavity creates a tangential field in the ICM surrounding the cavity, and this field can suppress instabilities that mix the ICM and the radio source. Onset of instability can be delayed for ∼108 yr, and calculation of the subsequent turbulent cascade shows that actual reheating of the ICM may be delayed for up to ∼5x108 yr. These results may explain why the relic radio cavities remain as intact entities at times ≥108 yr, and the delay in injection of energy from the radio source into the ICM may mean that the role of radio sources in reheating cooling flows should be re-examined. In addition, the existence of relic radio cavities may also imply that the particle content of radio source lobes is primarily electrons and protons rather than electrons and positrons.
galaxies: active - galaxies: clusters: general - cooling flows