Cosmic Star Formation History Required from Infrared Galaxy Number Count : Future Prospect for Infrared Imaging Surveyor (iris)

We constructed a model of infrared and sub-mm (hereafter IR) galaxy number count and estimated history of the IR luminosity density. We treat the evolutionary change of galaxy luminosities as a stepwise nonparametric form, in order to explore the most suitable evolutionary history which reproduces the present observational results. We found the evolutionary patterns which satisfy both constraints required from Cosmic Infrared Background (CIRB) and IR galaxy number counts. One order of magnitude increase of luminosity at redshift z = 0.75 − 1.0 was found in IR 60 μm luminosity density evolution. We also found that a large number of galaxies ( ∼ 10 in the whole sky) will be detected in all-sky survey at far-infrared by Infrared Imaging Surveyor (IRIS); Japanese infrared satellite project Astro-F.