ar X iv : a st ro - p h / 02 02 25 5 v 1 1 3 Fe b 20 02 3 C 129 at 90 cm : Evidence for a Radio Relic ?

We present a new wide-field map of the radio galaxy 3C 129 and its companion galaxy 3C 129.1 at λ = 90 cm. We see a distinct steep-spectrum feature near the head of 3C 129, extending in a direction perpendicular to the radio tails. We propose that this Crosspiece might consist of fossil radio plasma, which has been re-energized by the compression of the bow shock of the supersonically moving galaxy 3C 129. One possible origin of the fossil radio plasma could be the tail of a nearby head-tail radio galaxy. We discuss the implications of, and give testable predictions for, this scenario. 1. Background The radio galaxy 3C 129 and its companion 3C 129.1 are part of an X-ray galaxy cluster at z=0.021 (4U 0446+44). The cluster lies in the galactic plane (b= 0.5 o , l= 160 o) and is only known to include one other member galaxy (WEIN 048) which lies to the south of 3C 129 (Nilsson et al. 2000). Because of their latitude, the cluster and the radio sources have been excluded from many optical studies. Both radio sources have jets extending beyond their elliptical host galaxies and into the intra-cluster medium (ICM). 3C 129 shows prototypi-cal narrow-angle-tail (NAT) morphology, with a plume-like double-tail extending nearly 30' at λ ∼ 90 cm. It has a total flux density of ∼ 5.3 Jy at 1400 MHz (White & Becker 1992). 3C 129.1, although considerably smaller, is a wide-angle-tail (WAT) source, with a total flux density of ∼ 1.9 Jy at 1400 MHz (Condon et al. 1998). ROSAT X-ray data place the cluster center just to the southwest of 3C 129.1. The X-ray contours 1