The Fortieth Anniversary of Extragalactic Radio Astronomy: Radiophysics in Exile

Extract

In 1931 Karl Jansky established that radio noise was associated with our own galaxy–the Milky Way. For a decade and a half there was little follow-up; those of us who were associated with low frequency radar during the war regarded it as a nuisance which could limit the detection range of enemy aircraft. Grote Reber was the first to make a detailed but fairly low resolution map of the radiation from the galaxy showing, for the first time, some detailed structure. The event which we celebrate today occurred when Gordon Stanley, Bruce Slee and I showed that three of the discrete sources that we had discovered could be identified with visual objects. One was with the Crab Nebula, a supernova remnant within our own galaxy and the other two with galaxies, far beyond our own system, in the constellations of Virgo and Centaurus. Thus began extragalactic radio astronomy. In 1982 at the Noosa meeting of the ASA, I gave an account of those early years, later to be published in the ASA Proceedings. As I don’t wish to repeat myself, I propose to speak on my involvement in a later development which was to extend the observable scale of the universe to look-back times as great as the age of the oldest stars in our own system. The first important step was Graham Smith’s identification of Cygnus A with a galaxy that was much fainter than our two. The spectrum by Minkowski revealed an instrinsically highly-luminous galaxy with strong emission lines and opened up the possibility of discovering similar objects at significantly greater distance. This was achieved nine years later with the building of the Owens Valley Observatory and my title of ‘Radiophysics in Exile’ comes from the fact the observatory owed its existence and early successes very largely to past and future staff members of Radiophysics. They were, in order of appearance, J. G. Bolton, G. J. Stanley, K. C. Westfold, J. A. Roberts, V. Radhakrishnan, D. Morris and K. I. Kellermann. Some still bear . the scars–Westfold left the tip of one index finger in the Owens Valley!