A Spectroscopic Study of Fossil Group Systems: Are Fossil Groups Truly Fossilized?
American Astronomical Society, AAS Meeting #220, #435.02
Published in May 2012
The majority of nearby galaxies reside in galaxy groups, where the internal velocities of the member galaxies are comparable to the velocity dispersion of the group, conditions that are conducive to galaxy merging. Simulations (Dariush et al. 2007, 2010) suggest that merging within galaxy groups will lead to a giant, relatively isolated elliptical galaxy, termed a fossil group. While fossil groups are unique objects that have the potential to answer many questions about galaxy evolution, we know little about the dynamics of the fossil group environment. Here we present the results from a spectroscopic study of eight fossil group systems and their environments using the Hydra multifiber instrument on the WIYN 3.5m telescope. For each configuration, we obtain spectra for approximately 70 galaxies. For each fossil group system, we use the velocity distribution of the galaxies to determine the dynamical mass of the fossil group and explore the possible infall of new members and the extent to which fossil groups are truly dynamically relaxed.
(c) 2012: American Astronomical Society