Häußler, Boris; Bell, Eric F.; Barden, Marco;McIntosh, Daniel H.; Rix, Hans-Walter; Borch, Andrea;Beckwith, Steven V. W.; Caldwell, John A. R.;Heymans, Catherine; Jahnke, Knud; Jogee, Shardha;Koposov, Sergey E.; Meisenheimer, Klaus;Peng, Chien Y.; Sánchez, Sebastian F.;Somerville, Rachel S.; Wisotzki, Lutz;Wolf, Christian. GEMS: The destiny of Blue Spheroidal Galaxies. Galaxy Evolution Across the Hubble Time, Edited by F. Combes and J. Palous, Proceedings of the International Astronomical Union 2, IAU Symposium #235, held 14-17 August, 2006 in Prague, Czech Republic. Cambridge: Cambridge University Press, 2007., pp.102-102. 2007, Vol. , p. -2007.
One of the key predictions of hierarchical galaxy formation models is that a significant fraction of elliptical galaxies form in late merging events. One of the most important observations of such an assembly is the existence of blue spheroidal galaxies, which have spheroid-dominated morphologies and blue colors indicating recent star formation, as an intermediate step in the evolution of elliptical galaxies. We present results from the GEMS survey showing the properties of these galaxies derived from 2-D galaxy fitting of the ˜8000 galaxies with photometric redshifts in the 28'x28' HST mosaic. For the first time we were able to divide the observed population of blue elliptical galaxies into sub-populations of different stellar masses. We found that massive blue ellipticals are likely to be the progenitors of red elliptical galaxies while low-mass blue ellipticals have half-light radii considerably in excess of those measured for low-mass present day elliptical galaxies and instead have larger sizes similar to present-day disk-dominated systems with substantial bulges (see Figure)
One of the key predictions of hierarchical galaxy formation models is that a significant fraction of elliptical galaxies form in late merging events. One of the most important observations of such an assembly is the existence of blue spheroidal galaxies, which have spheroid-dominated morphologies and blue colors indicating recent star formation, as an intermediate step in the evolution of elliptical galaxies. We present results from the GEMS survey showing the properties of these galaxies derived from 2-D galaxy fitting of the ˜8000 galaxies with photometric redshifts in the 28'x28' HST mosaic. For the first time we were able to divide the observed population of blue elliptical galaxies into sub-populations of different stellar masses. We found that massive blue ellipticals are likely to be the progenitors of red elliptical galaxies while low-mass blue ellipticals have half-light radii considerably in excess of those measured for low-mass present day elliptical galaxies and instead have larger sizes similar to present-day disk-dominated systems with substantial bulges (see Figure)