Extended emission around GPS radio sources

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 (∼10 8 yr).

Radio continuum spectra of gigahertz-peaked spectrum galaxies

“…This has been argued earlier by, among other, Snellen et al (1999) and Stanghellini et al (2001). Recent results by Stanghellini et al (2005) and Orienti et al (2006) support this view. Stanghellini et al (2005) studied extended emission around GPS sources and conclude that, if a GPS quasar exhibits a core-jet or a complex VLBI morphology, it is likely that it represents an intermediately beamed full-size radio source related to common flat-spectrum radio sources.…”

“…Recent results by Stanghellini et al (2005) and Orienti et al (2006) support this view. Stanghellini et al (2005) studied extended emission around GPS sources and conclude that, if a GPS quasar exhibits a core-jet or a complex VLBI morphology, it is likely that it represents an intermediately beamed full-size radio source related to common flat-spectrum radio sources. Thus, it would not be related to truly compact and young/recurrent/frustrated GPS galaxies at all.…”

Radio properties of CSSs and GPSs

“…Extended, mostly low brightness, emission on arcsec (tens of kpc) scales is seen in a considerable fraction of HFPs [(31 ±10)%, Tinti et al (2005)] and GPSs [(18±8)%, Stanghellini et al (2005)] but in less than 5% of cases in the 3CR CSSs studied by van Breugel et al (1992). Since such extended emissions cannot form in less than a few thousand years (the estimated lifetime of CSOs, Sect.…”

Compact sources in the Bologna Complete Sample: high-resolution VLA observations and optical data

“…We want also emphasize how rare it is to see extended emission in a CSO. Up to now the only known sources with these properties are 0108+388 (Stanghellini et al 2005) and 0402+379 (Zhang et al 2003). We have no optical spectroscopic information on this sources, so its classification is not possible.…”