Possible Relic Lobes in Giant Radio Sources

We present low-frequency observations with the GMRT of three giant radio sources (J0139+3957, J0200+4049 and J0807+7400) with relaxed diffuse lobes which show no hotspots and no evidence of jets. The largest of these three, J0200+4049, exhibits a depression in the centre of the western lobe, while J0139+3957 and J0807+7400 have been suggested earlier by Klein et al. and Lara et al. respectively to be relic radio sources. We estimate the spectral ages of the lobes. All three sources have compact radio cores. Although the radio cores suggest that the sources are currently active, we suggest that the lobes in these sources could be due to an earlier cycle of activity.