SILVERRUSH. XII. Intensity Mapping for Ly α Emission Extending over 100-1000 Comoving Kpc around z ∼2-7 LAEs with Subaru HSC-SSP and CHORUS Data

Shotaro Kikuchihara*, Yuichi Harikane, Masami Ouchi, Yoshiaki Ono, Takatoshi Shibuya, Ryohei Itoh, Ryota Kakuma, Akio K. Inoue, Haruka Kusakabe, Kazuhiro Shimasaku, Rieko Momose, Yuma Sugahara, Satoshi Kikuta, Shun Saito, Nobunari Kashikawa, Haibin Zhang, Chien Hsiu Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We conduct intensity mapping to probe for extended diffuse Lyα emission around Lyα emitters (LAEs) at z ∼2-7, exploiting very deep (∼26 mag at 5σ) and large-area (∼4.5 deg2) Subaru/Hyper Suprime-Cam narrowband (NB) images and large LAE catalogs consisting of a total of 1540 LAEs at z = 2.2, 3.3, 5.7, and 6.6 obtained by the HSC-SSP and CHORUS projects. We calculate the spatial correlations of these LAEs with ∼1-2 billion pixel flux values of the NB images, deriving the average Lyα surface brightness (SBLyα ) radial profiles around the LAEs. By carefully estimating systematics such as fluctuations of sky background and point-spread functions, we detect Lyα emission at 100-1000 comoving kpc around z = 3.3 and 5.7 LAEs at the 3.2σ and 3.7σ levels, respectively, and tentatively (=2.0σ) at z = 6.6. The emission is as diffuse as ∼10-20-10-19 erg s-1 cm-2 arcsec-2 and extended beyond the virial radius of a dark matter halo with a mass of 1011 M. While the observed SBLyα profiles have similar amplitudes at z = 2.2-6.6 within the uncertainties, the intrinsic SBLyα profiles (corrected for the cosmological dimming effect) increase toward high redshifts. This trend may be explained by increasing hydrogen gas density due to the evolution of the cosmic volume. Comparisons with theoretical models suggest that extended Lyα emission around an LAE is powered by resonantly scattered Lyα photons in the CGM and IGM that originate from the inner part of the LAE and/or neighboring galaxies around the LAE.

Original languageEnglish
Article number97
JournalAstrophysical Journal
Volume931
Issue number2
DOIs
Publication statusPublished - 2022 Jun 1

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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