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The Neutral Hydrogen Cosmological Mass Density at z = 5
Published online by Cambridge University Press: 21 March 2017
Abstract
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 〈z〉 = 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.
- Type
- Contributed Papers
- Information
- Proceedings of the International Astronomical Union , Volume 11 , Symposium S321: Formation and Evolution of Galaxy Outskirts , March 2016 , pp. 309 - 314
- Copyright
- Copyright © International Astronomical Union 2017
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