Keck Spectroscopy of Giant Arcs in Abell 2390

Abstract

We present new Keck observations of giant arcs in the cluster Abell 2390. High resolution two-dimensional spectra of two arcs show metal lines at z=4.040 +/- 0.005 with Lyman-alpha emission spatially separated from the stellar continuum. In addition, spectroscopy along the notorious `straight' arc reveals two unrelated galaxies, at z=0.913 and z=1.033, with absorption lines of MgII and FeII at z=0.913 seen against the more distant object, indicating the presence of a large gaseous halo.

3 pages, 3 figures. To appear in "The Young Universe", (Rome Observatory, Oct. 1997), eds. S. D'Ordorico, A. Fontana, and E. Giallongo