Adaptive optics: observations and prospects for AGN studies
Ric Davies

I will begin these 2 lectures with a look at the technique of adaptive optics,
since it is only by understanding how adaptive optics works that one can make
the best use of it. We will discuss atmospheric turbulence and the effect it
has on a propagating plane wavefront, how one might measure the shape of this
wavefront, and what can be done to correct it.  By considering the limitations
of adaptive optics systems, and the techniques available to overcome these, we
make a realistic estimate of the expected performance.

Armed with this knowledge, we can explore where adaptive optics can make the
biggest impact in studies of AGN. We begin with QSOs at high and low redshift,
where the aim has been to detect and measure the properties of their host
galaxies. The biggest issue here is how to correct for the bright nucleus in
order to study the faint extended emission. We discuss the implications of this
work in the context of where the most powerful QSOs reside, and of the possible
evolutionary scenario linking them to ultraluminous galaxies.

At the other extreme (in terms of luminosity and distance) we turn to the
Galactic Centre where there is a 4 million solar mass black hole that is
radiating at only 10^-5 of its Eddington luminosity. We look at why the
accretion rate is so low; and how, by tracking the orbits and measuring the
spectral types of individual stars, adaptive optics has led to rapid
developments in our understanding of the environment around the black hole in
the centre of our Galaxy.

Perhaps the most obvious application of adaptive optics is in studies of nearby
AGN. In these galaxies, one is able to begin studying the various components
that comprise an AGN.  I show how one can make progress in measuring black hole
masses, and what this might tell us about the broad line region; that it is
possible to directly observe the obscuring torus, and how these data fit into
the context of interferometric observations; and how one can derive the star
formation history close around the AGN, and what this implies for the
starburst-AGN connection.

I will finish the 2 lectures with a short outlook on what might be possible in
5 years time with the 2nd generation VLT adaptive optics instruments.