Radio observations of a few giant sources

Abstract

We present multifrequency observations with the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array (VLA) of a sample of 17 largely giant radio sources (GRSs). These observations have either helped clarify the radio structures or provided new information at a different frequency. The broad line radio galaxy, J0313+413, has an asymmetric, curved radio jet and a variable radio core, consistent with a moderate angle of inclination to the line of sight. We attempt to identify steep spectrum radio cores (SSCs), which may be a sign of recurrent activity, and find four candidates. If confirmed, this would indicate a trend for SSCs to occur preferentially in GRSs. From the structure and integrated spectra of the sources, we suggest that the lobes of emission in J0139+399 and J0200+408 may be owing to an earlier cycle of nuclear activity. We find that inverse-Compton losses with the cosmic microwave background radiation dominate over synchrotron radiative losses in the lobes of all the sources, consistent with earlier studies. We also show that the prominence of the bridge emission decreases with increasing redshift, possibly owing to inverse-Compton losses. This could affect the appearance and identification of GRSs at large redshifts.