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The dominant origin of diffuse Lyα halos around LAEs explored by SED 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. (2018) The dominant origin of diffuse Lyα halos around LAEs explored by SED fitting and clustering analysis. . (Submitted)

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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⋆), SFR, 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 by Momose et al. (2016), which we find agree 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 streams (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 scattered 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 HI gas masses implied from lower Mh at fixed M⋆, or from another Lyα source in the central part.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper
Ouchi, Masami0000-0002-1049-6658
Harikane, Yuichi0000-0002-6047-430X
Silverman, John D. 0000-0002-0000-6977
Additional Information: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 Kenichi Tadaki for kindly providing their data plotted in figures 4, and 6–8 and figure 4, respectively. 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 (The Astropy Collaboration et al. 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: high-redshift — galaxies: star formation — galaxies: halos—intergalactic medium
Record Number:CaltechAUTHORS:20180904-155810395
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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:04 Sep 2018 23:06

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