A Test for the Gravitational Lens Hypothesis in the Most Luminous Quasar: S5 0014+81

Abstract

The most luminous quasar known, S5 0014+81 (z = 3.41), was extensively studied with direct CCD imaging, and with radio interferometric techniques using the VLA as well as MK II and MK III VLBI systems. Optical spectroscopic observations revealed a high column density metal absorption system at z = 1.11, and VLA maps displayed a weak second radio component. We thus had evidence for the possible existence of a gravitational lens, which may have boosted the observed flux of the quasar towards an energy output of about 5*10⁴⁸ erg/s. However, results from subsequent VLA and VLBI observations are not compatible with such interpretation, instead the weak radio component is probably associated with a jet-like phenomenon and does not provide evidence for or against a gravitational lens.