TWO-PHASE PAIR CORONA MODEL FOR AGN: 
   PHYSICAL MODELLING AND DIAGNOSTICS 

   by 

   Juri Poutanen, Roland Svensson, and Boris Stern 

   The predictions of the two-phase  accretion  disc-corona models for
   active galactic nuclei are compared with  observations.  We discuss
   the possibility to use X-ray spectral slopes,  equivalent widths of
   the iron line, and the observed  flux-spectral index correlation as
   diagnostics of the X-$\gamma$-ray  source  compactness and geometry
   as well as of the  cold  disc  temperature.  As an  example  of the
   application  of the  modelling  tools,  we use  XSPEC  to  fit  the
   broad-band  data of Seyfert 1 galaxy,  IC4329A,  with a theoretical
   spectrum from a hemisphere-corona.