OX-169 - EVIDENCE FOR A RECENT MERGER

We present new imaging and spectroscopy of the faint jetlike structure extending to the southeast from the luminous QSO OX 169 as well as new observations of the unusual double-peaked broad Balmer lines in the spectrum of the QSO itself. The luminosity of the "jet" is clearly of stellar origin, and the feature is apparently a planar distribution of stars seen edge-on. However, because of its strong asymmetry, it cannot be a normal galactic disk and, by analogy with other objects seen roughly face-on, is quite plausibly a tidal tail. Previous discussions of the double-peaked Balmer lines in OX 169 have suggested Balmer self-absorption in an intervening broad-line cloud or a superposition of broad- and narrow-line profiles at different redshifts. More recently, double-peaked broad lines in other objects have been interpreted in terms of Keplerian disk models. We see significant differences in the H-beta profile between spectra of OX 169 obtained in 1983 and 1989: while a relativistic disk model is an excellent fit to the 1989 profile, no such profile can fit the 1983 profile unless azimuthal asymmetries are introduced. These differential variations in two spectra obtained 6 yr apart allow us to perform a rough deconvolution of the profile and to show that the broad-line radiation likely arises in two essentially independent regions. A bipolar geometry remains a possibility, but a supermassive binary, each component with its own broad-line region, is attractive because such a model can encompass additional phenomena often observed in active nuclei. If this latter explanation is, in fact, correct, then the two observationally disparate phenomena we discuss in this paper could have a common physical origin.