Intermittent jet activity in the radio galaxy 4C29.30?

Abstract

We present radio observations at frequencies ranging from 240 to 8460 MHz of the radio galaxy 4C29.30 (J0840+2949) using the Giant Metrewave Radio Telescope (GMRT), the Very Large Array (VLA) and the Effelsberg telescope. We report the existence of weak extended emission with an angular size of $\sim$520 arcsec (639 kpc) within which a compact edge-brightened double-lobed source with a size of 29 arcsec (36 kpc) is embedded. We determine the spectrum of the inner double from 240 to 8460 MHz and show that it has a single power-law spectrum with a spectral index of $\sim$0.8. Its spectral age is estimated to be $\lapp$33 Myr. The extended diffuse emission has a steep spectrum with a spectral index of $\sim$1.3 and a break frequency $\lapp$240 MHz. The spectral age is $\gapp$200 Myr, suggesting that the extended diffuse emission is due to an earlier cycle of activity. We reanalyse archival x-ray data from Chandra and suggest that the x-ray emission from the hotspots consists of a mixture of nonthermal and thermal components, the latter being possibly due to gas which is shock heated by the jets from the host galaxy.