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arXiv · 1704.00516

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

Pratik Dabhade·Madhuri Gaikwad·Joydeep Bagchi·M. Pandey-Pommier·Shishir Sankhyayan·Somak Raychaudhury
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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.

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Pratik Dabhade, Madhuri Gaikwad, Joydeep Bagchi, M. Pandey-Pommier, Shishir Sankhyayan, Somak Raychaudhury. 2017-04-03. Discovery of Giant Radio Galaxies from NVSS: Radio & Infrared Properties. https://doi.org/10.1093/mnras/stx860

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