Optical-infrared studies of arcs in Abell 370

Abstract

We demonstrate the potential of optical-infrared photometry in deciphering the nature of high redshift galaxies responsible for the arcs seen in foreground rich clusters. Using the arcs in Abell 370 as an example, we find that photometry of various portions of the giant arc is consistent with a common spectral energy distribution equivalent to that of a background spiral galaxy as determined spectroscopically by Soucail et al. However, the faint arc A5 is not detected in a deep 2μm exposure, suggesting that the lensed z>1 galaxy is at least as blue as the most extreme star-forming galaxies observed today.

Additional details