The GRACE project: Giant RAdio galaxies and their duty CyclE

In Webseminar by admin

Cross-correlating the INTEGRAL/IBIS and Swift/BAT AGN population with radio catalogs (NVSS, FIRST, SUMSS), we found that 25% of extended radio sources are Giant Radio Galaxes (GRG), i.e. the largest individual objects in the Universe. This fraction is four time more abundant than what found in previous studies. We observed a pilot sample of these soft-gamma ray selected GRG at low radio frequencies with the GMRT, with the aim of studying the morphological and spectral properties of these objects. Thanks to these data, we discovered the second known X-shaped GRG, while another object, observed both at kpc and pc scales, showed an extreme jet re-orientation of about 90 degrees. Given these intriguing premises, we embarked on a radio/X-ray follow-up to probe the lifecycle of these soft gamma-ray selected GRG. We found that more than half of these GRG have a nucleus with typical properties of young radio sources, while the remaining ones show a restarting radio morphology from low-frequency radio surveys or literature data. Among these, two could host up to three distinct radio phases. Recently, we got access to LOFAR survey data (LoTSS) that allowed us to reconstruct the detailed morphology of 9 sources from the sample, revealing in some cases remnant radio emission not detected before. 

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