Coma cluster object populations down to MR ~ -9.5

C. Adami (1) , J.-P. Picat (2) , Florence Durret (3, 4) , A. Mazure (1) , R. Pello (2) , M. West (5)

1 LAM - Laboratoire d'Astrophysique de Marseille
2 LATT - Laboratoire Astrophysique de Toulouse-Tarbes
3 IAP - Institut d'Astrophysique de Paris
4 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
5 Department of Physics and Astronomy, University of Hawaii

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 M_R ~ -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.

Domaines: Astrophysique [astro-ph]

C. Adami, J.-P. Picat, Florence Durret, A. Mazure, R. Pello, et al.. Coma cluster object populations down to MR ~ -9.5. Astronomy and Astrophysics - A&A, 2007, 472, pp.749-755. ⟨10.1051/0004-6361:20077446⟩. ⟨hal-03742540⟩