A local clue to the reionization of the universe
A light leak to transform the universe
After the universe had cooled into an expanse of neutral gas after the Big Bang, how did the first starlight emerge from the dark? Borthakur et al. found a local starburst galaxy that leaks continuum radiation, which may provide some clues. Wind-generated gaps in the neutral gas enable large fractions of ionizing radiation to escape, possibly mimicking processes in the early universe.
Science, this issue p. 216
Abstract
Identifying the population of galaxies that was responsible for the reionization of the universe is a long-standing quest in astronomy. We present a possible local analog that has an escape fraction of ionizing flux of 21%. Our detection confirms the existence of gaps in the neutral gas enveloping the starburst region. The candidate contains a massive yet highly compact star-forming region. The gaps are most likely created by the unusually strong winds and intense ionizing radiation produced by this extreme object. Our study also validates the indirect technique of using the residual flux in saturated low-ionization interstellar absorption lines for identifying such leaky galaxies. Because direct detection of ionizing flux is impossible at the epoch of reionization, this represents a highly valuable technique for future studies.
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Information & Authors
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Published In
Science
Volume 346 | Issue 6206
10 October 2014
10 October 2014
Copyright
Copyright © 2014, American Association for the Advancement of Science.
Submission history
Received: 1 April 2014
Accepted: 20 August 2014
Published in print: 10 October 2014
Acknowledgments
We thank A. Aloisi for assistance during the observations of this project, and the reviewers for their comments. S.B. is supported by a grant under program 12886 provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy Inc. under NASA contract NAS5-26555. Data used for this paper are publicly available in the Mikulski Archive for Space Telescopes (MAST) under programs 12886 and 11727.
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- Gravitational lensing reveals ionizing ultraviolet photons escaping from a distant galaxy, Science, 366, 6466, (738-741), (2019)./doi/10.1126/science.aaw0978
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