The z=0.8 precursors of today's bulges
arXiv:0710.0494 · doi:10.1017/S1743921308018310
Abstract
We study the color structure of disk galaxies in the Groth strip at redshifts 0.1<z<1.2. Our aim is to test formation models in which bulges form before/after the disk. We find smooth color distributions with gentle outward blueing across the galaxy image: bulges are not distinctly redder than their disks; and bulge colors strongly correlate with global colors. The results suggest a roughly coeval evolution of bulges and disks. About 50% of the nuclei of galaxies with central light excesses above the outer exponential profile hold passively evolving red populations. The remainder 50% are galaxies with central blue colors similar to their disks. They may be bulges in formation, or the central parts of disks with non-exponential surface brightness profiles.
arXiv comment4 pages, 2 figures, contributed paper to IAU Symposium 245 "Formation and Evolution of Galaxy Bulges", Oxford, 16-20 July 2007
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