2006/12/31 by Marc S. Seigar, Alister W. Graham, Helmut Jerjen · 1 citation
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Adaptive optics and wavefront sensing #Advanced Fluorescence Microscopy Techniques #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2007.11899.x
published as Mon.Not.Roy.Astron.Soc.378:1575-1588,2007 · 15 pages, 8 figures and 4 tables, now accepted for publication in MNRAS. Full resolution paper available at http://webfiles.uci.edu/mseigar/papers/Seigar_cDs.pdf
arxiv created 2007/04/23 · openalex publication_date 2007/06/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We have analysed deep R-band images, down to a limiting surface brightness of 26.5 R-mag arcsec-2 (equivalent to ~28 B-mag arcsec-2), of 5 cD galaxies to determine the shape of the surface brightness profiles of their extended stellar envelopes. Both de Vaucouleurs R1/4 model and Sersic's R1/n model, on their own, provide a poor description of the surface brightness profiles of cD galaxies. This is due to the presence of outer stellar envelopes, thought to have accumulated over the merger history of the central cluster galaxy and also from the tidal stripping of galaxies at larger cluster radii. We therefore simultaneously fit two Sersic functions to measure the shape of the inner and outer components of the cD galaxies. We show that, for 3 out of our 5 galaxies, the surface brightness profiles are best fit by an inner Sersic model, with indices n~1-6, and an outer exponential component. For these systems, the galaxy-to-envelope size ratio is 0.1 - 0.4 and the contribution of the stellar envelope to the total R-band light (i.e. galaxy + envelope) is around 60 to 80 per cent (based on extrapolation to a 300 kpc radius). The exceptions are NGC 6173, for which our surface brightness profile modelling is consistent with just a single component (i.e. no envelope) and NGC 4874 which appears to have an envelope with a de Vaucouleurs, rather than exponential, profile.