@article{d70331f6427644e6b093ceee82c57bed,
title = "The role of galaxies and agn in reionizing the IGM-I. Keck spectroscopy of 5 < z < 7 galaxies in the QSO field J1148+5251",
abstract = "We introduce a new method for determining the influence of galaxies and active galactic nuclei (AGN) on the intergalactic medium (IGM) at high redshift and illustrate its potential via a first application to the field of the z = 6.42 QSO J1148+5251. Correlating spatial positions Lyman break galaxies (LBGs) with the Lyman alpha forest seen in the spectrum of a background QSO, we provide a statistical measure of the typical escape fraction of Lyman continuum photons. Using Keck DEIMOS spectroscopy to locate seven colour-selected LBGs in the range 5.3≲z≲6.4 we examine the spatial correlation between this sample and Lyα/Lyβ transmission fluctuations in a Keck ESI spectrum of the QSO. Interpreting the statistical HI proximity effect as arising from faint galaxies clustered around the LBGs, we translate the observed mean Lya transmitted flux into a constraint on the mean escape fraction (fesc) ≥ 0.08 at z ≃ 6. We also report individual transverse HI proximity effect for a z = 6.177 luminous LBG via a Lyβ transmission spike and two broad Lyα transmission spikes around the z = 5.701 AGN. We discuss the origin of such associations which suggest that while faint galaxies are primarily driving reionization, luminous galaxies and AGN may provide important contributions to the UV background or thermal fluctuations of the IGM at z≃6. Although a limited sample, our results demonstrate the potential of making progress using this method in resolving one of the most challenging aspects of the contribution of galaxies and AGN to cosmic reionization.",
keywords = "Cosmology: observations, Dark ages, reionization, first stars, Galaxies: formation, Galaxies: high, Intergalactic medium, Quasars: absorption lines, Redshift",
author = "Koki Kakiichi and Ellis, {Richard S.} and Nicolas Laporte and Adi Zitrin and Eilers, {Anna Christina} and Emma Ryan-Weber and Meyer, {Romain A.} and Brant Robertson and Stark, {Daniel P.} and Bosman, {Sarah E.I.}",
note = "Funding Information: We acknowledge financial support from European Research Council Advanced Grant FP7/669253 (KK, NL, RSE, RAM, SEIB). DPS acknowledges support from the National Science Foundation through grant AST-1410155. ERW acknowledges support from the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. It is a pleasure to thank the following for useful discussion: Will Hartley, Andreu Font-Ribera, Harley Katz, Tom Fletcher, Jamie Bolton, Masami Ouchi, and Akio Inoue. We acknowledge useful email correspondence with Fred Davies and Ali Rahmati regarding their simulations. We thank the referee for useful comments and, in particular, on suggestions for improving the analysis with larger data sets. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this beautiful mountain. This work was undertaken using the UCL Grace High Performance Computing Facility (Grace@UCL) and we thank the associated support services. BR acknowledges partial support through NASA contract NNG16PJ25C, and grants 17-ATP17-0034 and HST-GO-14747. Funding Information: We acknowledge financial support from European Research Council Advanced Grant FP7/669253 (KK, NL, RSE, RAM, SEIB). DPS acknowledges support from the National Science Foundation through grant AST-1410155. ERWacknowledges support from the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. It is a pleasure to thank the following for useful discussion: Will Hartley, Andreu Font-Ribera, Harley Katz, Tom Fletcher, Jamie Bolton, Masami Ouchi, and Akio Inoue. We acknowledge useful email correspondence with Fred Davies and Ali Rahmati regarding their simulations.We thank the referee for useful comments and, in particular, on suggestions for improving the analysis with larger data sets. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna kea has always had within the indigenous Hawaiian community.We are most fortunate to have the opportunity to conduct observations from this beautiful mountain. This work was undertaken using the UCL Grace High Performance Computing Facility (Grace@UCL) and we thank the associated support services. BR acknowledges partial support through NASA contract NNG16PJ25C, and grants 17-ATP17-0034 and HST-GO- 14747. Publisher Copyright: {\textcopyright} 2018 The Author(s). Published by Oxford University Press on behalf of The Royal Astronomical Society.",
year = "2018",
month = sep,
day = "1",
doi = "10.1093/mnras/sty1318",
language = "English",
volume = "479",
pages = "43--63",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",
}