Discovery of giant radio sources from TGSS ADR 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 ($\ge$ 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 GMRT Sky Survey Alternative Data Release 1 (TGSS ADR 1) at 150 MHz. We have newly identified 34 GRSs from this study. We have also studied the multi-wavelength properties (radio, optical, and infrared) of these GRSs. We have used the likelihood ratio method to identify highly reliable multi-wavelength counterparts of GRSs from Pan-STARRS (optical) and WISE (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 centres of galaxy clusters.