The Fastest Relativistic Jets: VLBA Observations of Blazars with Apparent Speeds Exceeding 25c

We have measured peak apparent speeds of 25.6c+/-7.0c, 25.6c+/-4.4c, and 28.2c+/-6.6c in the jets of 0235+164, 0827+243, and 1406-076, respectively, based on six epochs of high-sensitivity VLBA observations at 22 and 43 GHz during 2002 and 2003 (H0=71 km s-1 Mpc-1, Ωm=0.27, and ΩΛ=0.73). These blazars had been identified as potentially having apparent speeds exceeding 40c in an earlier VLBA survey of EGRET blazars by Jorstad and coworkers. We therefore confirm (with high confidence in 0827+243, and lower confidence in 0235+164 and 1406-076) the presence of highly relativistic pattern speeds in these three jets, although not at the \u3e40c levels reported by Jorstad and coworkers. The lower limit to the bulk Lorentz factor implied by the observed apparent speeds is Γ\u3e~25-30 in these three sources, if the pattern speeds are equal to or slower than the bulk flow speed

Confirmation of Apparent Speeds Exceeding 25c in the Jets of Three EGRET Blazars

We present multi-epoch Very Long Baseline Array (VLBA) observations at 22 and 43 GHz of the three EGRET blazars 0235+164, 0827+243, and 1406-076. These three blazars had been identified as potentially having apparent speeds exceeding 40c in the snapshot VLBA survey of EGRET blazars by Jorstad et al. (2001). Based on six epochs of full-track VLBA observations of each source during 2002 and 2003, we have measured apparent speeds of 31±6c, 26±4c, and 30±9c in the jets of 0235+164, 0827+243, and 1406-076, respectively (H0=71 km s-1 Mpc-1, Ωm=0.27, and ΩΛ=0.73). We therefore confirm the presence of ultra-relativistic pattern speeds in these three sources, with the implied lower limit to the bulk Lorentz factor from the observed apparent speeds being Γ\u3e∼25-30, if the pattern speeds do not exceed the bulk apparent speed