Unveiling the structure of Giant Radio Galaxies J0133-1302 and J2256-3617

Abstract

The follow-up data from the Giant Metrewave Radio Telescope (GMRT) at two different frequencies, i.e. 325 MHz and 610 MHz were reduced and imaged separately, and the radio sources in an area of the sky in RA:01h33m10s and DEC: -13◦01′59”, and RA:22h56m15s and DEC: -36◦17′59” were detected. The research study focus on previously KAT-7 discovered giant radio galaxy (GRG) J0133-1303, and GRG J2256-3617 which was never studied before, presenting a detailed analysis of their morphology, a spectral index map between 325 MHz and 610 MHz for both GRGs and a spectral index map between 325 MHz and 1400 MHz for the GRG J2256-3617 and multi-frequency associated with their optical counterparts. These two GRGs have the FR II radio morphology, but no radio jets are detected. The GRGJ0133-1303 has an overall projected size of∼3.59 Mpc. The radio core has flat spectral index, and inverted spectrum, which indicate the restarting nuclear activity. At the photo-metric redshiftz ≈0.3, the GRG J0133-1303 has a radio power of P1.4GHz≈0.16 x 1024WHz−1, which is compatible with the typical radio powers of the GRGs. The GRG J2256-3617 appears to have an inverted spectrum but this is not conclusive, hence, more data at low frequency are required to conclude this. This radio source has overall projected size of∼1.57 Mpc. The GRG J2256-3617 has a radio power of P1.4GHz≈0.19 x 1024W Hz−1 at the photometric redshift of z≈0.09