On the Nature of Red Galaxies in the Early Universe

Increasing numbers of extremely red galaxies are being found in the high redshift universe. We present accurate near-IR photometry and NICMOS imaging for one of these galaxies, and demonstrate that it is a merging pair of early type galaxies. The merger is triggering only very moderate rates of star formation: even after many such mergers, the dominant stellar population will be old. This suggests that hierarchical formation models for elliptical galaxies can work