Dynamical evolution of compact groups of galaxies
Final Report Abstract
We studied the nature of compact groups of galaxies, investigating their formation and dynamical evolution in an unprecedented manner. We examined the optical intragroup light that permeates most of those systems, the galaxies themselves and investigated correlated properties. The intragroup light, formed by stripped stellar material dispersed in the gravitational potential, is revealed in wide-field images with high accuracy by a new technique that we had developed based on wavelet transforms. Using deep wide-field B- and R-band images observed with the LAICA camera at the 3.5-m telescope at the Calar Alto observatory (CAHA) we analyzed six groups: HCG 15, 35, 51, 79, 88, 95. The mean surface brightness can be as low as 28.4 B-mag/arcsec^-2. The total light in the IGL component has varying fractions between 10% and 50% and its colours are compatible with old stellar populations. The distribution comes also in a variety from compact to irregular shapes. The fraction of intragroup light correlates, in a qualitative way, with other indicators of dynamical evolution, such as the fraction of early-type galaxies in the group and the crossing times. Thus, we have a new tool to study the evolutionary stage of compact groups that can reveal the assembly history of these structures.
Publications
- (2008). Intragroup diffuse light in compact groups of galaxies–II. HCG 15, 35 and 51. Monthly Notices of the Royal Astronomical Society, 388(3), 1433-1443
Da Rocha, C., Ziegler, B. L. & Mendes de Oliveira, C.
(See online at https://doi.org/10.1111/j.1365-2966.2008.13500.x)
