3C 223.1: A source with unusual spectral properties

Abstract

Analysis of Giant Metrewave Radio Telescope low frequency data for an X-shaped source, 3C 223.1 has revealed an unusual result. The radio morphologies of it at 240 and 610 MHz show well defined X-shape with a pair of active jets along the north-south axis and a pair of wings along the east-west axis, that pass symmetrically through the undetected radio core. The wings (or low surface brightness jets) have flatter spectral indices with respect to the high surface brightness jets, which confirms the earlier marginal result obtained at high frequency by Dennett-Thorpe et al. (2002). Although unusual, it is a valuable result which puts stringent constraints on the formation models and nature of these sources. This result clearly shows the value of mapping the sample of X-shaped sources at low frequencies.