Comparison between RXJ1716.4+6708 and the AKARI NEP-deep field
Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA e-mail: email@example.com
2 National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
3 Department of Astronomy, School of Science, The University of Tokyo, Tokyo 113-0033, Japan
4 Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 229-8510, 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 Department of Physics & Astronomy, FPRD, Seoul National University, Shillim-Dong, Kwanak-Gu, Seoul 151-742, Korea
9 Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125, USA
10 Department of Astronomical Science, The Graduate University for Advanced Studies
11 Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547, USA
12 Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
13 Academia Sinica, Institute of Astronomy and Astrophysics, Taiwan
14 Physics Section, Faculty of Humanities and Social Sciences, Iwate University, Morioka 020-8550, Japan
15 TOME R&D Inc. Kawasaki, Kanagawa 213 0012, Japan
16 Asahikawa National College of Technology, 2-1-6 2-jo Shunkohdai, Asahikawa-shi, Hokkaido 071-8142, Japan
Accepted: 22 December 2009
Aims. We aim to reveal environmental dependence of infrared luminosity functions (IR LFs) of galaxies at z ~ 0.8 using the AKARI satellite. AKARI's wide field of view and unique mid-IR filters help us to construct restframe 8 μm LFs directly without relying on SED models.
Methods. We construct restframe 8 μm IR LFs in the cluster region RXJ1716.4+6708 at z = 0.81, and compare them with a blank field using the AKARI north ecliptic pole deep field data at the same redshift. AKARI's wide field of view (10' × 10') is suitable to investigate wide range of galaxy environments. AKARI's 15 μm filter is advantageous here since it directly probes restframe 8 μm at z ~ 0.8, without relying on a large extrapolation based on a SED fit, which was the largest uncertainty in previous work.
Results. We have found that cluster IR LFs at restframe 8 μm have a factor of 2.4 smaller and a steeper faint-end slope than that of the field. Confirming this trend, we also found that faint-end slopes of the cluster LFs becomes flatter and flatter with decreasing local galaxy density. These changes in LFs cannot be explained by a simple infall of field galaxy population into a cluster. Physics that can preferentially suppress IR luminous galaxies in high density regions is required to explain the observed results.
Key words: galaxies: evolution / galaxies: interactions / galaxies: starburst / galaxies: peculiar / galaxies: formation / infrared: galaxies
© ESO, 2010