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6th of December 2021
Giant Radio Sources in RACS
by Andernach et al.
Andernach et al. report the results of a visual inspection of images of the Rapid ASKAP Continuum Survey (RACS) in search of extended radio galaxies (ERG) that exceed linear sizes on the order of one Megaparsec (over three million light-years). They searched an area of 1059 square degrees, which is covered by deep multi-band optical images of the Dark Energy Survey (DES), and in which previously only three ERGs larger than 1 Mpc had been reported. For over 1800 radio galaxy candidates inspected, the search in optical and infrared images resulted in hosts for 1440 ERG. For these, spectroscopic and photometric redshifts were used to convert their largest angular size (LAS) to projected linear size (LLS). This resulted in 178 newly discovered giant radio sources (GRS) with LLS>1 Mpc, of which 18 exceed 2 Mpc and the largest one is 3.4 Mpc. Their redshifts range from 0.02 to ∼2.0, but only 10 of the 178 new GRS have spectroscopic redshifts. Merging the six most recent large compilations of GRS results in 458 GRS larger than 1 Mpc, so they were able to increase this number by ∼39% to 636. The figure above shows an all-sky Aitoff projection of the distribution of the newly discovered giant radio sources in red, together with those from six major published GRS lists. The thick blue line shows the area within 2 degrees of the Galactic plane.

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