The role of galaxies and AGN in reionizing the IGM – III. IGM–galaxy cross-correlations at z ∼ 6 from eight quasar fields with DEIMOS and MUSE. Issue 2 (18th March 2020)

• Record Type: Journal Article
• Authors: Meyer, Romain A; Kakiichi, Koki; Bosman, Sarah E I; Ellis, Richard S; Laporte, Nicolas; Robertson, Brant E; Ryan-Weber, Emma V; Mawatari, Ken; Zitrin, Adi
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 494:Issue 2(2020)
• Page Start: 1560
• Page End: 1578
• Publication Date: 2020-03-18
• Subjects: galaxies: evolution -- galaxies: high-redshift -- intergalactic medium -- quasars: absorption lines -- dark ages, reionization, first stars; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa746
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present improved results of the measurement of the correlation between galaxies and the intergalactic medium transmission at the end of reionization. We have gathered a sample of 13 spectroscopically confirmed Lyman-break galaxies (LBGs) and 21 Lyman- α emitters (LAEs) at angular separations 20 arcsec ≲ θ ≲ 10 arcmin (∼0.1–4 pMpc at z ∼ 6) from the sightlines to eight background z ≳ 6 quasars. We report for the first time the detection of an excess of Lyman- α transmission spikes at ∼10–60 cMpc from LAEs (3.2 σ ) and LBGs (1.9 σ ). We interpret the data with an improved model of the galaxy–Lyman- α transmission and two-point cross-correlations, which includes the enhanced photoionization due to clustered faint sources, enhanced gas densities around the central bright objects and spatial variations of the mean free path. The observed LAE(LBG)–Lyman- α transmission spike two-point cross-correlation function (2PCCF) constrains the luminosity-averaged escape fraction of all galaxies contributing to reionization to $\langle f_{\rm esc} \rangle _{M_{\rm UV}\lt -12} = 0.14_{-0.05}^{+0.28}\, (0.23_{-0.12}^{+0.46})$ . We investigate if the 2PCCF measurement can determine whether bright or faint galaxies are the dominant contributors to reionization. Our results show that a contribution from faint galaxies ($M_{\rm UV} \gt -20 \, (2\sigma)$ ) is necessary to reproduce the observed 2PCCF and that reionization might be driven by different sub-populations around LBGs and LAEs at z ∼ 6.