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

Revealing the cosmic star formation history hidden by dust

¹ Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI, 96822, USA e-mail: tomo@ifa.hawaii.edu
² National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan
³ Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 229-8510, Japan
⁴ Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
⁵ Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK
⁶ Department of Physics, University of Lethbridge, 4401 University Drive,Lethbridge, Alberta T1J 1B1, Canada
⁷ Astrophysics Group, Department of Physics, The Open University, Milton Keynes, MK7 6AA, UK
⁸ Laboratoire d'Astrophysique de Marseille, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12, France
⁹ CEA-Saclay, Service d'Astrophysique, France
¹⁰ Academia Sinica, Institute of Astronomy and Astrophysics, Taiwan
¹¹ Department of Physics and Astronomy, UCLA, Los Angeles, CA, 90095-1547, USA
¹² Department of Physics & Astronomy, FPRD, Seoul National University, Shillim-Dong, Kwanak-Gu, Seoul 151-742, Korea
¹³ Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125, USA
¹⁴ Department of Astronomical Science, The Graduate University for Advanced Studies, Hayama, Miura, Kanagawa, 240-0193, Japan
¹⁵ Physics Section, Faculty of Humanities and Social Sciences, Iwate University, Morioka, 020-8550, Japan
¹⁶ TOME R&D Inc. Kawasaki, Kanagawa 213 0012, Japan
¹⁷ Asahikawa National College of Technology, 2-1-6 2-jo Shunkohdai, Asahikawa-shi, Hokkaido 071-8142, Japan

Received: 26 August 2009
Accepted: 23 December 2009

Abstract

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 (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). 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.