Extended emission around GPS radio sources

¹ Istituto di Radioastronomia - INAF, Via Gobetti 101, 40129 Bologna, Italy e-mail: cstan@ira.cnr.it
² Department of Physics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623, USA
³ Dipartimento di Astronomia, Università degli Studi, via Ranzani 1, 40127 Bologna, Italy
⁴ Istituto di Radioastronomia - INAF, CP 141, 96017 Noto SR, Italy
⁵ Center for Imaging Science, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623, USA
⁶ Dipartimento di Fisica, Università degli Studi, via Irnerio 46, 40126 Bologna, Italy

Received: 21 October 2004
Accepted: 22 June 2005

Abstract

Extended radio emission detected around a sample of GHz Peaked Spectrum (GPS) radio sources is discussed. Evidence for extended emission which is related to the GPS source is found in 6 objects out of 33. Three objects are associated with quasars with core-jet pc-scale morphology, and three are identified with galaxies with symmetric (CSO) radio morphology. We conclude that the core-jet GPS quasars are likely to be beamed objects with a continuous supply of energy from the core to the kpc scale. It is also possible that low surface brightness extended radio emission is present in other GPS quasars but the emission is below our detection limit due to the high redshifts of the objects. On the other hand, the CSO/galaxies with extended large scale emission may be rejuvenated sources where the extended emission is the relic of previous activity. In general, the presence of large scale emission associated with GPS  galaxies is uncommon, suggesting that in the context of the recurrent activity model, the time scale between subsequent bursts is in general longer than the radiative lifetime of the radio emission from the earlier activity (~10⁸ yr).