Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2009-08-21
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
MNRAS, accepted
Scientific paper
We use high signal-to-noise spectroscopy for a sample of 232 quiescent galaxies in the Shapley Supercluster, to investigate how their stellar populations depend on velocity dispersion, luminosity and stellar mass. The sample spans a large range in velocity dispersion (sigma from 30-300 km/s) and in luminosity (M_R from -18.7 to -23.2). Estimates of age, total metallicity (Z/H) and alpha-element abundance ratio (a/Fe) were derived from absorption-line analysis, using single-burst models. Age, Z/H and a/Fe are all correlated positively with velocity dispersion, but we also find significant residual trends with luminosity: at given sigma, the brighter galaxies are younger, less alpha-enriched, and have higher Z/H. At face value, these results might suggest that the stellar populations depend on stellar mass as well as on velocity dispersion. However, we show that the observed trends can be reproduced by models in which the stellar populations depend systematically only on sigma, and are independent of stellar mass Mstel. For age, the observed luminosity correlation arises because young galaxies are brighter, at fixed Mstel. For metallicity, the observed luminosity dependence arises because metal-rich galaxies, at fixed mass, tend also to be younger, and hence brighter. We find a good match to the observed luminosity correlations with Age ~ sigma^0.40, Z/H ~ sigma^0.35, a/Fe ~ sigma^0.20, where the slopes are close to those found when fitting traditional scaling relations. We conclude that the star formation and enrichment histories of galaxies are determined primarily by the depth of their gravitational potential wells. The observed residual correlations with luminosity do not imply a corresponding dependence on stellar mass.
Hudson Michael J.
Lucey John R.
Smith Jeffrey R.
No associations
LandOfFree
Ages and metallicities for quiescent galaxies in the Shapley Supercluster: Driving parameters of the stellar populations 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 Ages and metallicities for quiescent galaxies in the Shapley Supercluster: Driving parameters of the stellar populations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ages and metallicities for quiescent galaxies in the Shapley Supercluster: Driving parameters of the stellar populations will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-665780