Detection of diffuse LY alpha emission from cD galaxy in Abell 1795.

Abstract

The authors report the discovery of diffuse Ly_α emission from the cD galaxy in Abell 1795 which has a high X-ray derived mass accretion rate. The Ly_α emission coincides with the main optical filamentary structures and the Ly_α/H_β ratio is close to the recombination value indicating a very low H I column density. The widely accepted assumption that the accreted mass ends up as stars is severely constrainted by the authors' UV observations. If star formation occurs at all, the IMF must be quite different from our Galaxy i.e. the formation of high mass stars (>3 M_sun;) must be less and the star formation process must be extremely efficient.