Diffuse Lyα Halos around High-redshift Star-forming Galaxies I
Rieko Momose1,2*, Masami Ouchi2,3, Kimihiko Nakajima3,4, Yoshiaki Ono2, Takatoshi Shibuya2,5, Kazuhiro Shimasaku4,6, Suraphong Yuma2, Masao Mori5, Masayuki Umemura5
1Institute of Astronomy, National Tsing Hua University, Hsinchu, Taiwan
2Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Japan
3Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Kashiwa, Japan
4Department of Astronomy, Graduate School of Science, University of Tokyo, Tokyo, Japan
5Center for Computational Sciences, University of Tsukuba, Tsukuba, Japan
6Research Center for the Early Universe, Graduate School of Science, University of Tokyo, Tokyo, Japan
* presenting author:Rieko Momose, email:momo@phys.nthu.edu.tw
Theoretical studies have suggested that Lyα emission of high-z star-forming galaxies extends than their UV continuum emission which reflects star-forming regions in galaxies (e.g., Laursen & Sommer-Larsen 2007, Zheng et al. 2011, Dijkstra & Kramer 2012, Verhamme et al. 2012). This extended Lyα emission feature around galaxies is so called Lyα halos (LAHs). Because LAHs are too diffuse to detect from a single galaxy, the stacking analysis is often used to find the evidence of LAHs from observational data (e.g., Steidel et al. 2011, Matsuda et al. 2012). However, there is a argument that artifacts by the analysis are possible to produce artificial LAHs. Thus, the existence of LAHs is still under debate. In order to investigate the presence of LAHs, we use large star-forming galaxy samples at z = 2-7 found by Subaru telescope, and also carefully examine potential artifacts mimicking LAHs. In this talk, we show our analysis and results of LAHs. We also discuss their size evolution as a function of a redshift, and reionization traced by LAHs.

Keywords: high-z galaxies, reionization, galaxy evolution