Probing of Interactions between the Hot Plasmas and Galaxies in Clusters over a Cosmological Timescale
Abstract
After reionization the Universe can no longer be considered as neutral fluids, but must be treated as ionized media which are ubiquitously threaded by magnetic fields. It remains still unexplored how the magneto-plasma nature of matter affects the formation and evolution of galaxies and galaxy clusters, and how the galaxies and cluster plasmas interact each other. We consider a unique scenario, "galaxies moving through the cluster will interact strongly with the ICM, transfer their free energies to the ICM, and will gradually fall to the cluster center". To verify this scenario, the key is to compare the spatial extents of galaxy and ICM at different redshifts. In Gu et al. 2013, ApJ 767 157, we studied the expected galaxy infall using a sample of 34 massive clusters with redshift range of 0.1 to 0.9. We have detected, for the first time, a significant evolution spanning 6 Gyr; while the galaxy component was as spatially extended as the ICM at z∼0.9, towards the lower redshifts, it has indeed become more centrally-concentrated relative to ICM/DM. Recently we confirm this discovery by a new complete sample of 316 clusters. This reveals the presence of strong ICM drag on galaxies over cosmological timescale.
- Publication:
-
The X-ray Universe 2014
- Pub Date:
- July 2014
- Bibcode:
- 2014xru..confE..87G