Effect of Helium Sedimentation in X-ray Clusters
Abstract
Helium nuclei in the intracluster plasma can sediment in the gravitational potential well of hot X-ray luminous, dynamically relaxed galaxy clusters. In this work, we present theoretical calculations of the helium sedimentation in X-ray clusters obtained by solving the set of flow equations for a multicomponent fluid. The effect of a cooling core on helium sedimentation is examined, and it is shown that the helium excess in the core is suppressed by a factor of several compared to the previous estimate based on the assumption of isothermal core. It is also noted that the process of helium sedimentation can introduce apparent evolution in X-ray measurements of cluster gas mass fractions. We briefly discuss implications on cosmological constraints derived from X-ray observations of galaxy clusters. This work is supported by Sherman Fairchild Postdoctoral Fellowship at Caltech.
- Publication:
-
AAS/High Energy Astrophysics Division #10
- Pub Date:
- March 2008
- Bibcode:
- 2008HEAD...10.0907P