How many active galaxies and QSOs will future space missions detect?

Averaged spectral energy distributions (SEDs) of active and starburst galaxies, from the 12 mum sample in the local universe, and QSOs, from an optically selected sample at a mean redshift <z>=0.7, are built from optical, near-IR, and far-IR (FIR; IRAS and Infrared Space Observatory) photometric observations. These SEDs are then used to predict at various redshifts the number of Seyfert type 1 and type 2, starburst, and normal galaxies and QSOs that will be detected by future space missions dedicated to FIR and submillimeter astronomy, such as SIRTF and Herschel. These predictions are then compared with the expected capabilities and detection limits of future deep FIR surveys. Possible ways to identify active galactic nucleus candidates on FIR color-color plots for follow-up observations are then explored.