A quasar with ultrastrong, ultraviolet Fe II emission

Abstract

We report the discovery of an unusual quasar, 2226-3905, found during a survey of quasar candidates. The ultraviolet spectrum (intrinsic frame) of the object is dominated by extremely strong Fe II emission. The emission lines are narrow (typical FWHM ∼ 2150 km s-1) and show little trace of their usually broad wings. C III] λ 1909 appears to be blended with an Fe III multiplet and we identify Fe II lines originating from high-energy levels (∼ 10 eV). We consider two possible explanations: either the quasar is a low-ionization broad absorption line (BAL) quasar in which the sight-line does not intersect any BAL clouds or Lyα fluorescence is the main physical process involved in the formation of Fe II. Our observations do not favour the BAL interpretation, but rather support the latter process. Higher resolution observations would give definite support to the Lyα fluorescence.