A weak lensing study of the Coma cluster

Raphael Gavazzi (1) , Christophe Adami (2) , Florence Durret (1) , Jean-Charles Cuillandre (3) , Olivier Ilbert (2) , Alain Mazure (2) , Roser Pello (4) , Melville P. Ulmer (5)

1 IAP - Institut d'Astrophysique de Paris
2 LAM - Laboratoire d'Astrophysique de Marseille
3 CFHT - Canada-France-Hawaii Telescope Corporation
4 LATT - Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées
5 Physics & Astronomy Department, Northwestern University

Due to observational constraints, dark matter determinations in nearby clusters based on weak lensing are still extremely rare, in spite of their importance for the determination of cluster properties independent of other methods. We present a weak lensing study of the Coma cluster (redshift 0.024) based on deep images obtained at the CFHT. After obtaining photometric redshifts for the galaxies in our field based on deep images in the u (1x1 deg2), and in the B, V, R and I bands (42'x52'), allowing us to eliminate foreground galaxies, we apply weak lensing calculations on shape measurements performed in the u image. We derive a map of the mass distribution in Coma, as well as the radial shear profile, and the mass and concentration parameter at various radii. We obtain M_200c = 5.1+4.3-2.1 x10^14 Msun and c_200c=5.0+3.2-2.5, in good agreement with previous measurements. With deep wide field images it is now possible to analyze nearby clusters with weak lensing techniques, thus opening a broad new field of investigation.

Mots clés: Gravitational lensing; clusters of galaxies; Coma

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Cosmologie et astrophysique extra-galactique [astro-ph.CO]

Raphael Gavazzi, Christophe Adami, Florence Durret, Jean-Charles Cuillandre, Olivier Ilbert, et al.. A weak lensing study of the Coma cluster. 2009. ⟨hal-00372581⟩