Intragroup diffuse light in compact groups of galaxies: HCG 79, 88 and 95

Deep B and R images of three Hickson Compact Groups, HCG 79, 88 and 95, have been analysed using a new wavelet technique to measure possible intragroup diffuse light present in these systems. The method used, OV WAV ,i sa wavelet technique particularly suitable for detecting low surface brightness extended structures, down to a signal-to-noise ratio (S/N ) = 0.1 per pixel, which corresponds to a 5σ detection level in wavelet space. The three groups studied are in different evolutionary stages, as can be judged by their very different fractions of the total light contained in their intragroup haloes: 46 ± 11 per cent for HCG 79 and 11 ± 26 per cent for HCG 95, in the B band, and HCG 88 had no component detected down to a limiting surface brightness of 29.1 B mag arcsec −2 .F or HCG 95, the intragroup light (IGL) is red, similar to the mean colours of the group galaxies themselves, suggesting that it is formed by an old population with no significant ongoing star formation. For HCG 79, however, the intragroup material has a significantly bluer colour than the mean colour of the group galaxies, suggesting that the diffuse light may, at least in part, come from stripping of dwarf galaxies which dissolved into the group potential well. Ke yw ords: galaxies: clusters: general ‐ galaxies: evolution ‐ galaxies: interactions ‐ intergalactic medium ‐ dark matter.