@article{a823219bc3dd4d6fa941fcac5d891838,
title = "The fraction of ionizing radiation from massive stars that escapes to the intergalactic medium",
abstract = " Whether stars could have driven the reionization of the intergalactic medium depends critically on the proportion of ionizing radiation that escapes the galaxies in which it is produced. Spectroscopy of gamma-ray burst (GRB) afterglows can be used to estimate the opacity to extreme ultraviolet (EUV) radiation along the lines-of-sight to the bursts. Assuming that long-duration GRBs trace the locations of the massive stars dominating EUV production, the average escape fraction of ionizing radiation can be calculated independently of galaxy size or luminosity. Here we present a compilation of H i column density (N HI ) measures for 140 GRBs in the range 1.6 < z < 6.7. Although the sample is heterogeneous, in terms of spectral resolution and signal-to-noise ratio, fits to the Ly α absorption line provide robust constraints on N HI , even for spectra of insufficient quality for other purposes. Thus we establish an escape fraction at the Lyman limit of (f esc ) ≈ 0.005, with a 98 per cent confidence upper limit of (f esc ) ≈ 0.015. This analysis suggests that stars provide a small contribution to the ionizing radiation budget at z < 5. At higher redshifts firm conclusions are limited by the small size of the GRB sample (7/140), but any decline in average H i column density seems to be modest. We also find no significant correlation of N HI with galaxy UV luminosity or host stellar mass. We discuss in some detail potential biases and argue that, while not negligible, systematic errors in f esc are unlikely to be more than a factor ~2 in either direction, and so would not affect the primary conclusions. Given that many GRB hosts are low-metallicity dwarf galaxies with high specific star-formation rates, these results present a particular problem for the hypothesis that such galaxies dominated the reionization of the Universe. ",
keywords = "dark ages, reionization, first stars, galaxies: ISM, gamma-ray burst: general, intergalactic medium",
author = "Tanvir, {N. R.} and Fynbo, {J. P.U.} and {De Ugarte Postigo}, A. and J. Japelj and K. Wiersema and D. Malesani and Perley, {D. A.} and Levan, {A. J.} and J. Selsing and Cenko, {S. B.} and Kann, {D. A.} and B. Milvang-Jensen and E. Berger and Z. Cano and R. Chornock and S. Covino and A. Cucchiara and V. D'Elia and A. Gargiulo and P. Goldoni and A. Gomboc and Heintz, {K. E.} and J. Hjorth and L. Izzo and P. Jakobsson and L. Kaper and T. Kr{\"u}hler and T. Laskar and M. Myers and S. Piranomonte and G. Pugliese and A. Rossi and R. S{\'a}nchez-Ram{\'i}rez and S. Schulze and M. Sparre and Stanway, {E. R.} and G. Tagliaferri and Th{\"o}ne, {C. C.} and S. Vergani and Vreeswijk, {P. M.} and Wijers, {R. A.M.J.} and D. Watson and D. Xu",
note = "Funding Information: JJ acknowledges support from Nederlandse Onderzoekschool Voor Astronomie(NOVA) and The Netherlands Organisation for Scientific Research (NWO) - The S{\~a}o Paulo Research Foundation (FAPESP) grant for advanced instrumentation in astronomy. Funding Information: KEH acknowledges support by a Project Grant (162948–051) from The Icelandic Research Fund. Funding Information: Partly based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnolog{\'i}a e Innovaci{\'o}n Productiva (Argentina), and Minist{\'e}rio da Ci{\^e}ncia, Tecnologia e Inovac¸{\~a}o (Brazil). Funding Information: The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen{\textquoteright}s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. Funding Information: DAK acknowledges support from the Spanish research project AYA 2014-58381-P and Juan de la Cierva Incorporaci{\'o}n IJCI-2015-26153. Funding Information: AC acknowledges National Aeronautics and Space Administration (NASA) grant NNX15AP95A. Funding Information: NRT and KW acknowledge Science and Technology Facilities Council (STFC) consolidated grant ST/N000757/1. Funding Information: RC acknowledges partial support from National Aeronautics and Space Administration (NASA) Swift grant NNX16AB04G. Funding Information: AJL and ERS acknowledge Science and Technology Facilities Council (STFC) consolidated grant ST/L000733/1. Funding Information: This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Funding Information: This project has received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (grant agreement No. 725246). Funding Information: AdUP acknowledges support from a Ram{\'o}n y Cajal fellowship (RyC-2012-09975), a 2016 Banco Bilbao Vizcaya Argentaria (BBVA) Foundation Grant for Researchers and Cultural Creators, and from the Spanish research project AYA 2014-58381-P. Funding Information: Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The Sloan Digital Sky Survey-III (SDSS-III) web site is http://www.sdss3.org/. Publisher Copyright: {\textcopyright} 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.",
year = "2019",
month = mar,
day = "11",
doi = "10.1093/mnras/sty3460",
language = "English (US)",
volume = "483",
pages = "5380--5408",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "4",
}