What powers Hyperluminous Infrared galaxies at z~1-2?
  We investigate what powers hyperluminous infrared galaxies (HyLIRGs;
LIR(8-1000um)>10^13 Lsun) at z~1-2, by examining the behaviour of the infrared
AGN luminosity function in relation to the infrared galaxy luminosity function.
The former corresponds to emission from AGN-heated dust only, whereas the
latter includes emission from dust heated by stars and AGN. Our results show
that the two luminosity functions are substantially different below 10^13 Lsun
but converge in the HyLIRG regime. We find that the fraction of AGN dominated
sources increases with total infrared luminosity and at LIR >10^13.5 Lsun AGN
can account for the entire infrared emission. We conclude that the bright end
of the 1<z<2 infrared galaxy luminosity function is shaped by AGN rather than
star-forming galaxies.
