Search for X/Z-shaped radio sources from TGSS ADR 1

Abstract

ABSTRACT A small subclass of radio galaxies, exhibiting a pair of secondary low-surface-brightness radio lobes oriented at an angle to the primary high-surface-brightness lobes, is the group known as X-shaped radio galaxies (XRGs). In some cases, it is seen that less luminous secondary lobes emerge from the edges of the primary high-brightness lobes, giving a Z-symmetric morphology. These objects are known as Z-shaped radio galaxies (ZRGs). From the Tata Institute of Fundamental Research (TIFR) Giant Metrewave Radio Telescope (GMRT) Sky Survey at 150 MHz, we present systematic search results for XRGs and ZRGs. We identified a total of 58 radio sources, out of which 40 are XRGs and 18 are ZRGs. Taking advantage of the large sample size of XRGs and ZRGs reported in the current work, different properties of XRGs and ZRGs are studied. Out of 58 XRGs and ZRGs presented here, 19 (32 per cent) are FR I and 33 (57 per cent) are FR II radio galaxies. For four XRGs and three ZRGs, the morphology is so complex that they could not be classified. We have estimated the radio luminosity and spectral index of newly discovered winged radio galaxies and made a comparative study with previously detected XRGs and ZRGs. Most of the XRGs show a steep spectral index between 150 and 1400 MHz and only 14 per cent of the sources show a flat spectrum, but for ZRGs a good proportion of the sources (36 per cent) show a flat spectrum.