Search for the Sunyaev-Zel'dovich Effect in a Giant Radio Galaxy B1358+305

Abstract

We present results of an imaging observation of the central region of a giant radio galaxy B1358+305. The classical, standard scenario of Fanaroff-Riley II radio galaxies suggests that shock produced hot electrons contained in a radio galaxy are a good reservoir of the jet-supplied energy from active nuclei. The aim of our observation is to search for the Sunyaev-Zel'dovich effect induced by these hot electrons. The observation was performed at 21 GHz with the Nobeyama 45-m telescope. Deep imaging observation of a wide region of size 6.7'x6.7' with the beam size theta_HPBW=81.2" enables the most detailed examination of the possible thermal energy of electrons contained in a radio galaxy. The resultant intensity fluctuation is 0.56 mJy/beam (in terms of the Compton y-parameter, y=1.04x 10^{-4}) at a 95 percent confidence level. The intensity fluctuation obtained with imaging analysis sets the most stringent upper limit on the fluctuations in the central region of a giant radio galaxy obtained so far, and our results will be a toehold for future plans of SZE observation in a radio galaxy.