Unveiling the Origin of Fossil Groups with Gemini-XMM-HST
PI:
Renato Dupke
Co-I(s):
Rodrigo Carrasco, Yolanda Jimenez-Teja, Anton Koekemoer, Jimmy Irwin, Yuanyuan Su, Lucas Johnson, Eric Miller, Rebeca Bataha de Melo, Nicolas Oliveira
Abstract
Fossil groups of galaxies (FG) continue to continue to perplex theories of structure formation. Their lack of bright central galaxies and the high measured concentration parameters indicate early formation epochs, in contradiction with the observed lack of anticipated large cool cores seen in X-rays. The recent application of a new method using the intracluster light (ICL) to gauge the relative age of two FGs indicates that they seem to be indeed very old, which deepens the mystery surrounding the presence of hot cores at their centers. To test the ubiquity of these initial results we propose here a short observational program of the only two other FGs that have all the ancillary data available for this analysis (including HST & X-rays). For accurate ICL measurements one needs to remove fore/background galaxies, especially for systems with low density of galaxies such as FGs. For that we propose here to measure spec-zs for these systems.