Kinematics of the Parsec-scale relativistic jet in quasar 3C 279: 1991-1997

We present results of long-term high-frequency VLBI monitoring of the relat ivistic jet in 3C 279, consisting of 18 epochs at 22 GHz from 1991 to 1997 and 10 epochs at 43 GHz from 1995 to 1997. Three major results of this stud y are apparent speeds measured for six superluminal components range from 4 .8c to 7.5c (H-0 = 70 km s(-1) Mpc(-1), q(0) = 0.1), variations in the tota l radio flux are due primarily to changes in the VLBI core flux, and the un iform-sphere brightness temperature of the VLBI core is similar to1 x 10(13 ) K at 22 GHz after 1995, one of the highest direct estimates of a brightne ss temperature. If the variability brightness temperature measured for 3C 2 79 by & Valtaoja is an actual Lahteenmaki value and not a lower limit, then the rest-frame brightness temperature of 3C 279 is quite high and limited by inverse Compton effects rather than equipartition. The parsec-scale morp hology of 3C 279 consists of a bright, compact VLBI core, a jet component ( C4) that moved from similar to2 to similar to3.5 mas from the core during t he course of our monitoring, and an inner jet that extends from the core to a stationary component, C5, at similar to1 mas from the core. Component C4 followed a curved path, and we reconstruct its three-dimensional trajector y using polynomial fits to its position versus time. Component C5 faded wit h time, possibly due to a previous interaction with C4 similar to interacti ons seen in simulations by et al. Components in the inner jet are relativel y short lived and fade by the time they reach similar to1 Gomez mas from th e core. The components have different speeds and position angles from each other, but these differences do not match the differences predicted by the precession model of Abraham & Carrara. Although VLBI components were born a bout six months prior to each of the two observed gamma -ray high states, t he sparseness of the gamma -ray data prevents a statistical analysis of pos sible correlations.