Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2010-10-19
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
29 pages and 24 figures, MNRAS accepted
Scientific paper
In this paper we study the stellar populations of 356 bright, $M_{r}$ $\leq$ -19, Coma cluster members located in a 2 degree field centred on the cluster core using SDSS DR7 spectroscopy. For the quiescent galaxies we find strong correlations between absorption line index strength and velocity dispersion ($\sigma$) for CN2, C4668, Mgb and H$\beta$. We find significant cluster-centric radial gradients in H$\beta$, Mgb and C4668 for the passive galaxies. We use state-of-the-art stellar population models \citep{schiavon07} and the measured absorption line indices to infer the single-stellar-population-equivalent (SSP-equivalent) age and [Fe/H] for each galaxy, as well as their abundance patterns in terms of [Mg/Fe], [C/Fe], [N/Fe] and [Ca/Fe]. For the passive galaxy subsample we find strong evidence for "archaeological downsizing", with age $\propto \sigma^{0.90 \pm 0.06}$. We recover significant cluster-centric radial stellar population gradients for the passive sample in SSP-equivalent age, [Mg/Fe], [C/Fe] and [N/Fe]. These trends are in the sense that, at fixed velocity dispersion, passive galaxies on the outskirts of the cluster are 24% $\pm$ 9% younger with lower [Mg/Fe] and [N/Fe] but higher [C/Fe] than those in the cluster core. We find no significant increase in cluster-centric radial stellar population gradients when fitting to a passive galaxy subset selected to cover the cluster core and South-West region, which contains the NGC 4839 subgroup. Thus we conclude that the NGC 4839 in-fall region is not unique, at least in terms of the stellar populations of bright galaxies. We speculate that the more pronounced cluster-centric radial gradients seen by other recent studies may be attributed to the luminosity range spanned by their samples, rather than to limited azimuthal coverage of the cluster.(abridged)
Huxor Avon
Lucey John R.
Phillipps Steve
Price James
Smith Jeffrey R.
No associations
LandOfFree
The Stellar Populations of Bright Coma Cluster Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Stellar Populations of Bright Coma Cluster Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Stellar Populations of Bright Coma Cluster Galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-268730