Lyman-alpha companions to high-z quasars

Abstract

We report the results of a narrow-band filter search for Lyα companions to z > 2.8 quasars. Three out of 10 radio-loud quasars are found to have candidate Lyα companions, while no candidates are seen in seven optically selected quasars. Follow-up spectros copy has confirmed two of the candidates, with one yet to be observed. All the companions lie close to the quasar (≲6″) and are consistent with being ionized by it. In addition to these survey data, we present imaging data in a line-free continuum band on the previously known companion to PKS 1614 + 051. Spectral energy distributions for this Lyα companion, and for a second object lying between it and the quasar, are given, and discussed with comparison to flat-spectrum sources known in the literature. Both PKS 1614 + 051 and the three new systems show a striking similarity in sizes, luminosities, and morphologies with nebulosity seen around low-z quasars. We argue that the apparent lack of evolution in the quasar nebulosity strongly favors a tidal interaction model.