Intra-Group Light in Hickson Compact Groups - A Wavelet Approach

Abstract

A diffuse component of intra-group light can be observed in compact groups of galaxies. This component is presumably due to stellar material tidally stripped from the member galaxies of the group, which gets trapped in the group potential. It represents an efficient tool for the determination of the stage of dynamical evolution of such structures and for mapping the gravitational potential of the group. Detecting this kind of low surface brightness structure (about 1% above the sky level) is a difficult task, which is subject to many problems like the modeling of stars and galaxy and sky subtraction. To overcome these problems, we apply a new method, the wavelet technique OV\_WAV, with which these low surface brightness structures can be revealed and analyzed by separating different components according to their spatial characteristic sizes (allowing the study of the point sources, galaxies and diffuse envelope separately). We have analyzed 3 of the of the Hickson Compact Groups Catalogue (HCG 79, HCG 88 and HCG 95) and were able to detect this diffuse component in two of the studied groups: HCG 79, where the diffuse light corresponds to $46\pm11%$ of the total B band luminosity and HCG 95, where the fraction is $11\pm26%$. HCG 88 had no component detected, as expected by its estimated early evolutionary stage.