ABSTRACT

I review recent work on galaxy formation and relate it to questions concerning the formation and fuelling of active galactic nuclei. The theory of galaxy formation has developed dramatically in recent years as a result of new analytic methods coupled with substantial programs of direct numerical simulation. Many aspects of how galaxies might form in a universe where structure grows by hierarchical clustering are understood quite well. Others, particularly those that are closely linked to the star formation process, remain highly uncertain. Nevertheless, it is now possible to calculate formation and interaction rates for galaxies with some confidence in a wide variety of cosmogonies. It seems likely that nuclear activity, either starburst or AGN, is an inevitable consequence of the violent, asymmetric, and time-dependent processes which occur during the assembly of galaxies.

INTRODUCTION

The idea that quasars might be related to galaxy formation followed quickly after the first measurements of QSO redshifts but was somewhat neglected after the near-universal acceptance of the argument that QSO luminosities are more easily explained by accretion onto a supermassive black hole than by starlight. In such a model black hole formation and fuelling are major issues which must be addressed before QSO's and galaxy formation can be linked. There has always been some dissent from this model, most notably in recent years from R. Terlevich and his collaborators (e.g. Terlevich and Boyle 1993), but recent discussions of quasar formation have tended to emphasize how late the onset of quasar activity may be in comparison with the initial collapse of a protogalaxy (see, for example, Turner 1991).