Galaxies Properties in the Sloan Digital Sky Survey
Mariangela Bernardi (Carnegie Mellon University)
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Galaxies Properties in the Sloan Digital Sky Survey |
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| The most massive galaxies in the universe populate the densest regions, have elliptical morphologies and old stellar populations. I discuss how to draw a sample of such galaxies from the SDSS database. The unprecendented size of the sample allows one to show that 1) many observable properties of massive galaxies depend weakly, but significantly, on environment. Objects in regions of lower density tend to have slightly lower luminosities, velocity dispersions, bluer colors, and to be less homogeneous than objects in denser cluster-like regions; 2) the observed evolution of the chemical abundances constrain how strongly the luminosity weighted age depends on environment -- this constraint does not depend on the detailed properties of stellar population synthesis models. These results, combined with other findings from the SDSS, allow for a sharp test of galaxy formation theory. As a by-product of my research, I have also obtained a sample of rare galaxies with large velocity dispersions (> 350 km/s). If the large velocity dispersions really do reflect virial equilibrium motions, then these galaxies potentially harbor the most massive black holes in the Universe, and their existence places strong constraints on galaxy formation models. I will present SDSS and HST imaging of this interesting set of extreme objects. | |
