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arXiv · astro-ph/0611322

When do early-type galaxies form?

Roberto G. Abraham·Patrick J. McCarthy·Erin Mentuch·Karl Glazebrook·Preethi Nair·Jean-Rene Gauthier·Sandra Savaglio·David Crampton·Stephanie Juneau·Richard Murowinski·Damien Le Borgne·R. G. Carlberg·Inger Jorgensen·Kathy Roth·Hsiao-Wen Chen·Ronald O. Marzke
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Abstract

We have used the Hubble Space Telescope's Advanced Camera for Surveys to measure the mass density function of morphologically selected early-type galaxies in the Gemini Deep Deep Survey fields, over the redshift range 0.9 < z < 1.6. Our imaging data set covers four well-separated sight-lines, and is roughly intermediate (in terms of both depth and area) between the GOODS/GEMS imaging data, and the images obtained in the Hubble Deep Field campaigns. Our images contain 144 galaxies with ultra-deep spectroscopy, and they have been analyzed using a new purpose-written morphological analysis code which improves the reliability of morphological classifications by adopting a 'quasi-petrosian' image thresholding technique. We find that at z = 1 approximately 70% of the stars in massive galaxies reside in early-type systems. This fraction is remarkably similar to that seen in the local Universe. However, we detect very rapid evolution in this fraction over the range 1.0 < z < 1.6, suggesting that in this epoch the strong color-morphology relationship seen in the nearby Universe is beginning to fall into place.

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Roberto G. Abraham, Patrick J. McCarthy, Erin Mentuch, Karl Glazebrook, Preethi Nair, Jean-Rene Gauthier, Sandra Savaglio, David Crampton, Stephanie Juneau, Richard Murowinski, Damien Le Borgne, R. G. Carlberg, Inger Jorgensen, Kathy Roth, Hsiao-Wen Chen, Ronald O. Marzke. 2006-11-10. When do early-type galaxies form?. https://doi.org/10.1017/s174392130601012x

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