Environmental dependence of 8 μm luminosity functions of galaxies at z ~ 0.8: Comparison between RXJ1716.4+6708 and the AKARI NEP-deep field

Creators: Goto, T.; Koyama, Y.; Wada, T.; Pearson, C.; Matsuhara, H.; Tagaki, T.; Shim, H.; Im, M.; Lee, M. G.; Inami, H.; Malkan, M.; Okamura, S.; Takeuchi, T. T.; Serjeant, S.; Kodama, T.; Nakagawa, T.; Oyabu, S.; Ohyama, Y.; Lee, H. M.; Hwang, N.; Hanami, H.; Imai, K.; Ishigaki, T.

Abstract

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 L^∗ 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.

Additional Information

© ESO 2010. Received 14 October 2009. Accepted 22 December 2009. Published online 03 May 2010. We thank the anonymous referee for many insightful comments, which significantly improved the paper. We are grateful to Masayuki Tanaka for useful discussions. We thank L. Bai for providing data for comparison. T.G., Y.K., and H.I. acknowledge financial support from the Japan Society for the Promotion of Science (JSPS) through JSPS Research Fellowships for Young Scientists. M.I. was supported by the Korea Science and Engineering Foundation (KOSEF) grant No. 2009-0063616, funded by the Korea government (MEST). H.M.L. acknowledges the support from KASI through its cooperative fund in 2008. This research is based on the observations with AKARI, a JAXA project with the participation of ESA. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this sacred mountain.

Attached Files

Published - Goto2010p10127Astron_Astrophys.pdf

Files

Goto2010p10127Astron_Astrophys.pdf

Files (159.0 kB)

Name	Size	Download all
Goto2010p10127Astron_Astrophys.pdf md5:08d7b33adabbbfa1565671e612284477	159.0 kB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes