Spectra of High Redshift Galaxies using a Cluster as a Gravitational Telescope

Abstract

Using the Focal Reducer Spectrograph (FORS) at the Very Large Telescope (VLT) during the FORS commissioning time in December 1998 we took long slit spectra of the gravitational arc visible on images of the galaxy cluster 1E 0657 (z = 0.296). This cluster is one of the hottest (massive) cluster known so far and hence perfectly acts as a gravitational telescope magnifying the flux of background sources up to a factor of 17. Here we present the spectra of the gravitational arc (z = 3.23) and 4 additional high redshift objects (z=2.35 to 3.09), that also fall on the slit by chance coincidence. We briefly discuss the stellar contents of these galaxies and show first models of the observed spectra. Furthermore we point out the effectivity of using FORS in combination with available gravitational telescopes.