2010A&A...514A...6G

Dust-obscured star-formation increases with increasing intensity and increasing redshift. We aim to reveal the cosmic star-formation history obscured by dust using deep infrared observation with AKARI. We constructed restframe 8µm, 12µm, and total infrared (TIR) luminosity functions (LFs) at 0.15<z<2.2 using 4128 infrared sources in the AKARI NEP-deep field. A continuous filter coverage in the mid-IR wavelength (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and 24µm) by the AKARI satellite allowed us to estimate restframe 8µm and 12µm luminosities without using a large extrapolation based on an SED fit, which was the largest uncertainty in previous work. We find that all 8µm (0.38<z<2.2), 12µm (0.15<z<1.16), and TIR LFs (0.2<z<1.6) show continuous and strong evolution toward higher redshift. Our direct estimate of 8µm LFs is useful since previous work often had to use a large extrapolation from the Spitzer 24µm to 8µm, where SED modeling is more difficult because of the PAH emissions. In terms of cosmic infrared luminosity density (Ω_IR), which was obtained by integrating analytic fits to the LFs, we find good agreement with previous work at z<1.2. We find the Ω_IR evolves as ∝(1+z)^4.4±1.0. When we separate contributions to Ω_IR by LIRGs and ULIRGs, we found more IR luminous sources are increasingly more important at higher redshift. We find that the ULIRG (LIRG) contribution increases by a factor of 10 (1.8) from z=0.35 to z=1.4.