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The dominant origin of diffuse Lyα halos around Lyα emitters explored by spectral energy distribution fitting and clustering analysis

Kusakabe, Haruka and Shimasaku, Kazuhiro and Momose, Rieko and Ouchi, Masami and Nakajima, Kimihiko and Hashimoto, Takuya and Harikane, Yuichi and Silverman, John D. and Capak, Peter L. (2019) The dominant origin of diffuse Lyα halos around Lyα emitters explored by spectral energy distribution fitting and clustering analysis. Publications of the Astronomical Society of Japan, 71 (3). Art. No. 55. ISSN 0004-6264. doi:10.1093/pasj/psz029.

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The physical origin of diffuse Lyα halos (LAHs) around star-forming galaxies is still a matter of debate. We present the dependence of LAH luminosity [L(Lyα)_H] on the stellar mass (M⋆), star formation rate, color excess [E(B − V)⋆], and dark matter halo mass (M_h) of the parent galaxy for ∼900 Lyα emitters (LAEs) at z ∼ 2 divided into ten subsamples. We calculate L(Lyα)_H using the stacked observational relation between L(Lyα)H and central Lyα luminosity of Momose et al. (2016, MNRAS, 457, 2318), which we find agrees with the average trend of VLT/MUSE-detected individual LAEs. We find that our LAEs have relatively high L(Lyα)_H despite low M⋆ and M_h, and that L(Lyα)_H remains almost unchanged with M⋆ and perhaps with M_h. These results are incompatible with the cold stream (cooling radiation) scenario and the satellite-galaxy star-formation scenario, because the former predicts fainter L(Lyα)_H and both predict steeper L(Lyα)_H vs. M⋆ slopes. We argue that LAHs are mainly caused by Lyα photons escaping from the main body and then scattering in the circum-galactic medium. This argument is supported by LAH observations of Hα emitters (HAEs). When LAHs are taken into account, the Lyα escape fractions of our LAEs are about ten times higher than those of HAEs with similar M⋆ or E(B − V)⋆, which may partly arise from lower H I gas masses implied from lower M_h at fixed M⋆, or from another Lyα source in the central part.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ouchi, Masami0000-0002-1049-6658
Harikane, Yuichi0000-0002-6047-430X
Silverman, John D.0000-0002-0000-6977
Capak, Peter L.0000-0003-3578-6843
Alternate Title:The dominant origin of diffuse Lyα halos around LAEs explored by SED fitting and clustering analysis
Additional Information:© The Author(s) 2019. Published by Oxford University Press on behalf of the Astronomical Society of Japan. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Received: 28 March 2018; Accepted: 21 February 2019; Published: 16 May 2019. We thank the anonymous referee for constructive comments and suggestions. We are grateful to Kazuyuki Ogura and Masahiro Nagashima for kindly providing ν2GC data and giving helpful comments. We are grateful to Yoshiaki Ono for giving insightful comments and suggestions on SED fitting. We would like to express our gratitude to Jorryt Matthee and Ken-ichi Tadaki for kindly providing their data, plotted in figure 4, and figures 6–8 and 6, respectively. We thank David Sobral for giving insightful comments and suggestions. We acknowledge Ryosuke Goto, Akira Konno, Ryota Kawamata, Taku Okamura, Kazushi Irikura, Ryota Kakuma, and Makoto Ando for constructive discussions at meetings. This work is based on observations taken by the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. Based on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. This research made use of IRAF, which is distributed by NOAO, which is operated by AURA under a cooperative agreement with the National Science Foundation, and of Python packages for astronomy: Astropy (Astropy Collaboration 2013), Colossus, CosmoloPy, and PyRAF, which is produced by the Space Telescope Science Institute, which is operated by AURA for NASA. H.K. acknowledges support from the JSPS through the JSPS Research Fellowship for Young Scientists. This work is supported in part by KAKENHI (16K05286) Grant-in-Aid for Scientific Research (C) through the JSPS.
Group:COSMOS, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)16K05286
Subject Keywords:galaxies: halos galaxies: star formation (galaxies:) intergalactic medium galaxies: high-redshift
Issue or Number:3
Record Number:CaltechAUTHORS:20180904-155810395
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Official Citation:Haruka Kusakabe, Kazuhiro Shimasaku, Rieko Momose, Masami Ouchi, Kimihiko Nakajima, Takuya Hashimoto, Yuichi Harikane, John D Silverman, Peter L Capak, The dominant origin of diffuse Lyα halos around Lyα emitters explored by spectral energy distribution fitting and clustering analysis, Publications of the Astronomical Society of Japan, Volume 71, Issue 3, June 2019, 55,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89369
Deposited By: Tony Diaz
Deposited On:04 Sep 2018 23:06
Last Modified:16 Nov 2021 00:34

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