Discovery of Giant Radio Sources from TGSS Alternative Data Release 1: Radio, Optical, and Infrared Properties

Abstract

Giant radio sources (GRSs) are the single largest astrophysical objects known in the Universe that have grown to megaparsec scales (≥0.7 Mpc). GRSs are much rarer compared with normal-sized radio galaxies. Still, the reason for the formation of their gigantic sizes is under debate. We systematically search for GRSs from the TIFR Giant Metrewave Radio Telescope Sky Survey Alternative Data Release 1 at 150 MHz. We have newly identified 34 GRSs from this study. We have also studied the multiwavelength properties (radio, optical, and infrared) of these GRSs. We have used the likelihood ratio method to identify highly reliable multiwavelength counterparts of GRSs from Pan-STARRS (optical) and Wide-field Infrared Survey Explorer (mid-IR) data. We have classified GRSs based on their accretion mode of the central black holes using optical and mid-IR data. For all sources, we also discuss the principal characteristic parameters (redshift distribution, angular and projected linear size, total integrated radio flux density, spectral index, and radio power). We show the radio evolution track and the location of the GRSs in the P–D diagram. Using a radio–optical luminosity diagram, we identify GRSs in the Fanaroff–Riley classification. Only two GRGs in our sample reside close to the centers of galaxy clusters.