Coma cluster object populations down to MR ~ -9.5 *
LAM, Traverse du Siphon, 13012 Marseille, France e-mail: firstname.lastname@example.org
2 Observatoire Midi-Pyrénées, 14 Av. Edouard Belin, 31400 Toulouse, France
3 Institut d'Astrophysique de Paris, CNRS, Université Pierre et Marie Curie, 98bis Bd. Arago, 75014 Paris, France
4 Observatoire de Paris, LERMA, 61 Av. de l'Observatoire, 75014 Paris, France
5 Department of Physics and Astronomy, University of Hawaii, 200 West Kawili Street, LS2, Hilo HI 96720-4091, USA
6 Gemini Observatory, Casilla 603, La Serena, Chile
Accepted: 5 July 2007
Context.This study follows a recent analysis of the galaxy luminosity functions and colour-magnitude red sequences in the Coma cluster.
Aims.We analyze here the distribution of very faint galaxies and globular clusters in an east-west strip of ~ 42 7 arcmin2 crossing the Coma cluster center (hereafter the CS strip) down to the unprecedented faint absolute magnitude of MR ~ -9.5.
Methods.This work is based on deep images obtained at the CFHT with the CFH12K camera in the B, R, and I bands.
Results.The analysis shows that the observed properties strongly depend on the environment, and thus on the cluster history. When the CS is divided into four regions, the westernmost region appears poorly populated, while the regions around the brightest galaxies NGC 4874 and NGC 4889 (NGC 4874 and NGC 4889 being masked) are dominated by faint blue galaxies. They show a faint luminosity function slope of -2, very significantly different from the field estimates.
Conclusions.Results are discussed in the framework of galaxy destruction (which can explain part of the very faint galaxy population) and of structures infalling on to Coma.
Key words: galaxies: clusters: individual: Coma / galaxies: luminosity function, mass function
© ESO, 2007