Edinburgh Research Explorer

The Neutral Hydrogen Cosmological Mass Density at z = 5

Research output: Contribution to conferencePaper

  • Neil H. M. Crighton
  • Michael T. Murphy
  • J. Xavier Prochaska
  • Gábor Worseck
  • Marc Rafelski
  • George D. Becker
  • Sara L. Ellison
  • Michele Fumagalli
  • Sebastian Lopez
  • Avery Meiksin
  • John M. O'Meara

Related Edinburgh Organisations

Original languageEnglish
Publication statusPublished - 1 Mar 2017


We present the largest homogeneous survey of redshift > 4.4 damped Lyα systems (DLAs) using the spectra of 163 quasars that comprise the Giant Gemini GMOS (GGG) survey. With this survey we make the most precise high-redshift measurement of the cosmological mass density of neutral hydrogen, ΩHI. After correcting for systematic effects using a combination of mock and higher-resolution spectra, we find ΩHI= 0.98+0.20 -0.18 × 10-3 at = 4.9, assuming a 20% contribution from lower column density systems below the DLA threshold. By comparing to literature measurements at lower redshifts, we show that ΩHI can be described by the functional form ΩHI(z) ~ (1 + z)0.4. This gradual decrease from z = 5 to 0 suggests that in the galaxies which dominate the cosmic star formation rate, Hi is a transitory gas phase fuelling star formation which must be continually replenished by more highly-ionized gas from the intergalactic medium, and from recycled galactic winds.

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