Silverrush. IX. Lyα intensity mapping with star-forming galaxies at z = 5.7 and 6.6: Lyα emission extended at > 150 comoving kpc beyond the virial-radius scale of galaxy dark matter halos

Ryota Kakuma, Masmi Ouchi, Yuichi Harikane, Akio K. Inoue, Yutaka Komiyama, Haruka Kusakabe, Chien Hsiu Liu, Yuichi Matsuda, Yoshiki Matsuoka, Ken Mawatari, Rieko Momose, Yoshiaki Ono, Takatoshi Shibuya, Yoshiaki Taniguchi

Research output: Contribution to journalArticlepeer-review

Abstract

We present results of the cross-correlation Lyα intensity mapping with Subaru/Hyper Suprime-Cam (HSC) ultra-deep narrowband images and Lyα emitters (LAEs) at z = 5.7 and 6.6 in a total area of 4 deg2. Although overwhelming amount of data quality controls have been performed for the narrowband images and the LAE samples, we further conduct extensive analysis evaluating systematics of large-scale point spread function wings, sky subtractions, and unknown errors on the basis of physically uncorrelated signals and sources found in real HSC images and object catalogs, respectively. Removing the systematics, we carefully calculate cross-correlations between Lyα intensity of the narrowband images and the LAEs. We identify very diffuse Lyα emission with the 3σ (2σ) significance at > 150 comoving kpc (ckpc) far from the LAEs at z = 5.7 (6.6), beyond a virial radius of star-forming galaxies with Mh ∼ 1011M☉. The diffuse Lyα emission possibly extends up to 1, 000 ckpc with the surface brightness of 1020 − 1019 erg s1 cm2 arcsec2. We confirm that the small-scale (< 150 ckpc) Lyα radial profiles of LAEs in our Lyα intensity maps are consistent with those obtained by recent MUSE observations (Leclercq et al. 2017). Comparisons with numerical simulations suggest that the large-scale (∼ 150 − 1, 000 ckpc) Lyα emission are not explained by unresolved faint sources of neighboring galaxies including satellites, but by a combination of Lyα photons emitted from the central LAE and other unknown sources, such as a cold-gas stream and galactic outflow. We find no evolution in the Lyα radial profiles of our LAEs from z = 5.7 to 6.6, where theoretical models predict a flattening of the profile slope made by cosmic reionization, albeit with our moderately large observational errors.

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - 2019 Jun 1

Keywords

  • Cosmology: early universe
  • Cosmology: observations
  • Galaxies: formation

ASJC Scopus subject areas

  • General

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