The radio galaxy PictorA { a study with the VLA

摘要: Detailed multi-frequency VLA observations of the prominentsouthernradiogalaxyPictorAaredescribed.Thera- diostructureisfoundtocompriseverydim,nearlycircularlobes with an extraordinarily bright and compact hot spot located at thewesternextremityofthewesternlobe.Afaintjetisobserved to connect this radio nucleus. No counter-jet is seen. The eastern lobe contains two spots much lesser brightness compactness. lobes have signicantly differentspectralindices,withtheeastern(un-jetted)lobebeing 'steeper'. Enhanced spectral steepening found in central regions surrounding nucleus, around periph- eriesofbothradiolobes.Theeasternlobedepolarizesatahigher frequencythanthewesternlobe,andalsodisplaysamuchhigher rms scatter derived rotation measure, although mean measure very similar both lobes. Steepening high frequency index (6cm to2cm) seen near western spot. From similarity structure { including extended lament between optical wavelengthrangesitisconcludedthatalloftheextendedoptical emission due synchrotron process. implications these ndings are discussed.