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Durham University

Department of Physics

Staff profile

Publication details for Professor Ian Smail

Ellis, Richard, Allington-Smith, Jeremy & Smail, Ian (1991). Spectroscopy of arcs in the rich cluster Abell 963. Monthly Notices of the Royal Astronomical Society 249(1): 184-190.

Author(s) from Durham

Abstract

Spectra are presented for portions of the two arcs observed close to the dominant cD galaxy in the rich cluster Abell 963 (z = 0.206). The spectrum of the northern arc displays a strong emission line at 6600 Å which is seen along the entire arc. The feature cannot be understood unless the redshift is greater than that of the cluster, the most likely interpretation being [O II] 3727 Å at z = 0.771. The southern arc is considerably fainter and its spectrum shows no obvious features. However, new CCD photometry is consistent with a near-constant blue color ( B – R ~ 0.3) along both arcs, supporting the suggestion that they arise from the gravitationally lensed light of a background object. The optical and infrared color is consistent with a spiral galaxy undergoing strong star formation at this redshift. We discuss briefly the implication of this result, and the possible role lensing surveys may play in the study of high-redshift galaxies.