  We present results from a study of X-shaped sources based on observations
using the Giant Metrewave Radio Telescope (GMRT). These observations were
motivated by our low frequency study of 3C 223.1 (Lal & Rao 2005), an X-shaped
radio source, which showed that the wings (or low-surface-brightness jets) have
flatter spectral indices than the active lobes (or high-surface-brightness
jets), a result not easily explained by most models. We have now obtained GMRT
data at 240 and 610 MHz for almost all the known X-shaped radio sources and
have studied the distribution of the spectral index across the sources. While
the radio morphologies of all the sources at 240 and 610 MHz show the
characteristic X-shape, the spectral characteristics of the X-shaped radio
sources, seem to fall into three categories, namely, sources in which (A) the
wings have flatter spectral indices than the active lobes, (B) the wings and
the active lobes have comparable spectral indices, and (C) the wings have
steeper spectral indices than the active lobes. We discuss the implications of
the new observational results on the various formation models that have been
proposed for X-shaped sources.
