Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-02-13
Astronomy and Astrophysics
Astrophysics
ApJL, accepted version; 4 pages, 2 figures
Scientific paper
10.1086/519277
Resent observations of a number of galaxy clusters using the Sunyaev-Zel'dovich effect indicate that about 1/3 of baryonic mass is missing from the hot intracluster medium (ICM), which is significantly larger than the fraction of stars and cool gas, which account for only about 10%. Here we address the question whether the remaining $22\pm10%$ can be accounted for by thermal evaporation of gas from clusters. We have found that evaporation can occur only from the cluster ``surface'', $r\sim r_{\rm vir}$, and not from it's interior. We evaluated particle diffusion through the magnetized ICM for several scenarios of ISM turbulence and found that diffusivity is suppressed by at least a factor of 100 or more, compared to the Spitzer value. Thus, only particles from radii $r\ga0.9r_{\rm vir}$ can evaporate. Diffusion of particles from inside the cluster, $r\la0.9r_{\rm vir}$, takes longer than the Hubble time. This lowers the cluster-averaged fraction of the evaporated hot gas to few percent or less. However, if the missing hot component {\it is indeed} due to evaporation, this strongly constrains the magnetic field structure in the cluster envelope, namely either (i) the gas is completely unmagnetized ($B\le10^{-21}$ gauss) in the cluster halo or (ii) the magnetic fields in the ICM are rather homogeneous and non-turbulent.
No associations
LandOfFree
Can Cluster Evaporation Explain the Missing Thermal Energy in Galaxy Clusters? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Can Cluster Evaporation Explain the Missing Thermal Energy in Galaxy Clusters?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Can Cluster Evaporation Explain the Missing Thermal Energy in Galaxy Clusters? will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-208962