Evolution of infrared luminosity functions of galaxies in the AKARI NEP-deep field

Aims. 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. Methods. We constructed restframe 8 μm, 12 μm, 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 24 μm) by the AKARI satellite allowed us to estimate restframe 8 μm and 12 μm luminosities without using a large extrapolation based on an SED fit, which was the largest uncertainty in previous work. Results. We find that all 8 μm (0.38 < z < 2.2), 12 μm (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 8 μm LFs is useful since previous work often had to use a large extrapolation from the Spitzer 24 μm to 8 μm, where SED modeling is more difficult because of the PAH emissions. In terms of cosmic infrared luminosity density (ΩIR), which was obtained by integrating analytic fits to the LFs, we find good agreement with previous work at z