Cosmic reionization after Planck

May 20, 2015
5 pages
Published in:
  • Mon.Not.Roy.Astron.Soc. 454 (2015) 1, L76-L80
  • Published: Nov 21, 2015
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Abstract: (Oxford University Press)
Cosmic reionization holds the key to understand structure formation in the Universe, and can inform us about the properties of the first sources, as their star formation efficiency and escape fraction of ionizing photons. By combining the recent release of Planck electron scattering optical depth data with observations of high-redshift quasar absorption spectra, we obtain strong constraints on viable reionization histories. We show that inclusion of Planck data favors a reionization scenario with a single stellar population. The mean xH i drops from ∼0.8 at z = 10.6 to ∼10^−4 at z = 5.8 and reionization is completed around 5.8 ≲ z ≲ 8.5 (2σ), thus indicating a significant reduction in contributions to reionization from high-redshift sources. We can put independent constraints on the escape fraction fesc of ionizing photons by incorporating the high-redshift galaxy luminosity function data into our analysis. We find a non-evolving fesc of ∼10 per cent in the redshift range z = 6−9.
Note:
  • Accepted in MNRAS Letters. Revised to match the accepted version
  • intergalactic medium
  • cosmology: theory
  • dark ages, reionization, first stars
  • large-scale structure of Universe