# Discovery of Giant Radio Galaxies from NVSS: Radio & Infrared Properties

## TL;DR

This study systematically discovers 25 giant radio galaxies from NVSS data, analyzes their radio and infrared properties, and classifies their host galaxies, providing new insights into their size, rarity, and physical characteristics.

## Contribution

It presents the first IR-based classification of GRG hosts and reports the discovery of several extremely large and rare GRGs, expanding the known sample.

## Key findings

- 25 new GRGs discovered with sizes up to 4 Mpc
- Eight GRGs exceed 2 Mpc in size, a rarity
- Four hosts identified as radio loud quasars

## Abstract

Giant radio galaxies (GRGs) are one of the largest astrophysical sources in the Universe with an overall projected linear size of ~0.7 Mpc or more. Last six decades of radio astronomy research has led to the detection of thousands of radio galaxies. But only ~ 300 of them can be classified as GRGs. The reasons behind their large size and rarity are unknown. We carried out a systematic search for these radio giants and found a large sample of GRGs. In this paper, we report the discovery of 25 GRGs from NVSS, in the redshift range (z) ~ 0.07 to 0.67. Their physical sizes range from ~0.8 Mpc to ~4 Mpc. Eight of these GRGs have sizes greater than 2Mpc which is a rarity. In this paper, for the first time, we investigate the mid-IR properties of the optical hosts of the GRGs and classify them securely into various AGN types using the WISE mid-IR colours. Using radio and IR data, four of the hosts of GRGs were observed to be radio loud quasars that extend up to 2 Mpc in radio size. These GRGs missed detection in earlier searches possibly because of their highly diffuse nature, low surface brightness and lack of optical data. The new GRGs are a significant addition to the existing sample that will contribute to better understanding of the physical properties of radio giants.