A weak lensing study of the Coma cluster

TL;DR

This study uses deep wide-field imaging and photometric redshifts to perform a weak lensing analysis of the Coma cluster, providing mass distribution and concentration parameters consistent with previous results.

Contribution

It demonstrates the feasibility of applying weak lensing techniques to nearby clusters using deep wide-field images and photometric redshifts, expanding the scope of such analyses.

Findings

Mass estimate M_200c = 5.1+4.3-2.1 x10^14 Msun

Concentration parameter c_200c = 5.0+3.2-2.5

Agreement with previous measurements

Abstract

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.