Unique broad-line profile variations in the radio galaxy 3C 390.3

Abstract

The results of a variability study of the flux and profile of H-beta in 3C 390.3 are presented. Spectra of this object were obtained at 39 epochs during the years 1974-1988. It is shown that the fluctuations of the H-beta flux closely mimic the variations of the optical continuum during that period. The time scale for the emission-line variations is shorter than a year, and perhaps as short as a month. The blue side of the H-beta profile ('blue bump') also followed closely the continuum variations, but the red side ('red bump') did not. The ratio of the fluxes of the blue and red bumps behaved in a very regular, nearly sinusoidal fashion. It reached a maximum in mid-1975 and at the end of 1985, a time interval of 10.4 yr. The velocity of the peak of the blueshifted bump drifted by +900 km/s during the 14-yr interval covered by the observations. 103 refs.