INTEGRAL spectroscopy of three powerful radio galaxies: jet--cloud interactions seen in three dimensions

Abstract

Integral-field spectroscopic observations are presented for three powerful radio galaxies, namely 3C 277.3 (Coma A; z = 0.0857), 3C 171 (z = 0.2384) and 3C 265 (z = 0.811), which are known to be undergoing jet—cloud interactions.The morphology, kinematics and ionization of the gas in the emission-line structure of these sources are mapped and analysed.One-dimensional spectra are also extracted and integrated over the different emission-line regions in each galaxy. In two of the galaxies (3C 277.3 and 3C 171) the radio sizes are of similar extent to the emission-line structure.For these, enhanced emission-line regions are found associated with the radio structures, in addition to complex kinematics and low ionization states close to the radio hotspots, indicating that jet-induced shocks disturb and ionize the gas.Interestingly, the bright — presumably shock-ionized — emission-line region coincident with the radio jet knot in 3C 277.3 shows quiescent kinematics and high ionization state.Possible explanations for this puzzling result are proposed. The images of 3C 171 and 3C 265 indicate that the lateral expansion of the cocoon has a significant effect on the kinematics and ionization of the gas, showing for the first time that the effects of the radio source are felt far from the jet axis. In addition, the presence of a stellar-photoionized H ii region is detected in the extended emission-line nebula of the radio galaxy 3C 277.3.