EMERGENCE OF DOUBLE-PEAKED EMISSION-LINES IN THE BROAD-LINE RADIO GALAXY PICTOR-A

A new optical spectrum of the nearby broad-line radio galaxy (BLRG) Pi ctor A reveals a prominent double-peaked component of the Balmer lines which does not appear in any historical spectra of this object. Carri ed out with the hope of obtaining exactly such a result, this observat ion is a key to the interpretation of double-peaked emitters. It bolst ers our previous conclusion that there is a set of additional properti es which are associated with the rare class of double-peaked emitters, namely F-R II radio morphology, strong low-ionization forbidden lines , weak UV continuum, and flat far-infrared spectrum. Furthermore, the low-velocity, ''ordinary'' broad Balmer lines in Pictor A remained rel atively unchanged as the new twin peaks appeared, which justifies the practice of applying models that fit only the double peaks and not the low-velocity components that are often present in spectra of this typ e. We discuss the relative merits of accretion-disk models and other m odels for double-peaked emission lines in the light of this new observ ation.