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Cool start to hydrogen ionization

Simulations of the cosmos cast doubt on assumptions about the temperature of primordial hydrogen gas when it was ionized by the first stars and galaxies, complicating the interpretation of ongoing observations. See Letter p.197

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Figure 1: A topographic analogy.



  1. Fialkov, A., Barkana, R. & Visbal, E. Nature 506, 197–199 (2014).

    ADS  CAS  Article  Google Scholar 

  2. Fragos, T. et al. Astrophys. J. 764, 41 (2013).

    ADS  Article  Google Scholar 

  3. Fragos, T., Lehmer, B. D., Naoz, S., Zezas, A. & Basu-Zych, A. Astrophys. J. 776, L31 (2013).

    ADS  Article  Google Scholar 

  4. Van Haarlem, M. P. et al. Astron. Astrophys. 556, A2 (2013).

    Article  Google Scholar 

  5. Parsons, A. R. et al. Preprint at (2013).

  6. Tingay, S. J. et al. P. Astron. Soc. Aust. 30, e007 (2013).

    ADS  Article  Google Scholar 

  7. Furlanetto, S. R., Oh, S. P. & Briggs, F. H. Phys. Rep. 433, 181–301 (2006).

    ADS  CAS  Article  Google Scholar 

  8. Lidz, A., Zahn, O., McQuinn, M., Zaldarriaga, M. & Hernquist, L. Astrophys. J. 680, 962–974 (2008).

    ADS  Article  Google Scholar 



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Correspondence to Judd D. Bowman.

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Bowman, J. Cool start to hydrogen ionization. Nature 506, 163–164 (2014).

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