Evolution of Infrared Luminosity functions of Galaxies in the AKARI NEP-Deep field. Revealing the cosmic star formation history hidden by dust
Publication date: 05 February 2010
Authors: Goto, T. et al.
Journal: Astronomy & Astrophysics
Aims. Dust-obscured star-formation increases with increasing intensity and increasing redshift. We aim to reveal the cosmic starformation history obscured by dust using deep infrared observation with AKARI.
Methods. We constructed restframe 8 micron, 12 micron, 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 micron) by the AKARI satellite allowed us to estimate restframe 8 micron and 12 micron 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 micron (0.38 < z < 2.2), 12 micron (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 micron LFs is useful since previous work often had to use a large extrapolation from the Spitzer 24 micron to 8 micron, where SED modeling is more difficult because of the PAH emissions. In terms of cosmic infrared luminosity density (OmegaIR), which was obtained by integrating analytic fits to the LFs, we find good agreement with previous work at z < 1.2. We find the OmegaIR evolves as proportinal to (1 + z)4.4±1.0. When we separate contributions to OmegaIR 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.