Vertices, sources and Green correspondents of the simple modules for the large Mathieu groups

AbstractWe investigate the simple modules for the sporadic simple Mathieu groups M22, M23 and M24 as well as those of the automorphism group, the covering groups and the bicyclic extensions of M22 in characteristics 2 and 3. We determine the vertices and sources as well as the Green correspondents of these simple modules. We also find two 3-blocks with elementary abelian defect groups of order 9 in these groups which are Morita equivalent to their Brauer correspondents