Authors: Bililign T. Dullo, Alister W. Graham, Johan H. Knapen
We report the discovery of an extremely large (Rb ~ 2.77 arcsec ~ 4.2 kpc) core in the brightest cluster galaxy, IC 1101, of the rich galaxy cluster Abell 2029. Luminous core-Sérsic galaxies contain depleted cores — with sizes (Rb) typically 20-500 pc — that are thought to be formed by coalescing black hole binaries. We fit a core-Sérsic model to the Hubble Space Telescope surface brightness profile of IC 1101, finding the largest core size measured in any galaxy to date. [Abridged]