Intragroup diffuse light in compact groups of galaxies II. HCG 15, 35 and 51

TL;DR

This study uses deep imaging and wavelet analysis to measure intragroup diffuse light in compact galaxy groups HCG 15, 35, and 51, providing new insights into their formation and evolution.

Contribution

It introduces a wavelet-based method with stable flatfielding to accurately detect and analyze intragroup diffuse light in multiple compact galaxy groups.

Findings

Diffuse light constitutes 15-26% of total group light.

Diffuse light colors indicate old stellar populations.

Surface brightness of diffuse light can be as low as 28.4 B mag arcsec^{-2}.

Abstract

This continuing study of intragroup light in compact groups of galaxies aims to establish new constraints to models of formation and evolution of galaxy groups, specially of compact groups, which are a key part in the evolution of larger structures, such as clusters. In this paper we present three additional groups (HCG 15, 35 and 51) using deep wide field $B$ and $R$ band images observed with the LAICA camera at the 3.5m telescope at the Calar Alto observatory (CAHA). This instrument provides us with very stable flatfielding, a mandatory condition for reliably measuring intragroup diffuse light. The images were analyzed with the OV\_WAV package, a wavelet technique that allows us to uncover the intragroup component in an unprecedented way. We have detected that 19, 15 and 26% of the total light of HCG 15, 35 and 51, respectively, is in the diffuse component, with colours that are compatible with old stellar populations and with mean surface brightness that can be as low as $28.4 {\rm B mag arcsec^{-2}}$. Dynamical masses, crossing times and mass to light ratios were recalculated using the new group parameters. Also tidal features were analyzed using the wavelet technique.