The neutral hydrogen cosmological mass density at z = 5
Abstract
We present the largest homogeneous survey of z > 4.4 damped Lyα systems (DLAs) using the spectra of 163 QSOs 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, Ω_(Hi). At such high redshift, important systematic uncertainties in the identification of DLAs are produced by strong intergalactic medium absorption and QSO continuum placement. These can cause spurious DLA detections, result in real DLAs being missed or bias the inferred DLA column density distribution. We correct for these effects using a combination of mock and higher resolution spectra, and show that for the GGG DLA sample the uncertainties introduced are smaller than the statistical errors on Ω_(Hi). We find Ω_(HI)=0.98^(+0.20)_(−0.18) × 10^(−3) at 〈z〉 = 4.9, assuming a 20 per cent contribution from lower column density systems below the DLA threshold. By comparing to literature measurements at lower redshifts, we show that Ω_(Hi) can be described by the functional form Ω_(HI)(z)∝(1+z)^(0.)4. This gradual decrease from z = 5 to 0 is consistent with the bulk of H I gas being a transitory phase fuelling star formation, which is continually replenished by more highly ionized gas from the intergalactic medium and from recycled galactic winds.
Additional Information
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 May 21. Received 2015 May 21. In original form 2015 February 3. First published online July 2, 2015. We thank Marcel Neeleman for comments on an earlier version of this paper, Regina Jorgenson for providing a MagE spectrum of one of the GGG DLAs and the referee for their suggestions. Simeon Bird, Claudia Lagos, Romeel Davé and Edoardo Tescari kindly provided tables of their model predictions. We also thank the late Arthur M. Wolfe for providing unpublished ESI spectra and for early contributions to this work. Our analysis made use of ASTROPY (Astropy Collaboration 2013), XIDL6 and MATPLOTLIB (Hunter 2007). NC and MM thank the Australian Research Council for Discovery Project grant DP130100568 which supported this work. MF acknowledges support by the Science and Technology Facilities Council (grant number ST/L0075X/1). SL has been supported by FONDECYT grant number 1140838 and received partial support from Center of Excellence in Astrophysics and Associated Technologies (PFB 06). Based on observations obtained at the Gemini and W. M. Keck Observatories. We wish to acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.Attached Files
Published - MNRAS-2015-Crighton-217-34.pdf
Submitted - 1506.02037v1.pdf
Supplemental Material - tab5.txt
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Additional details
- Eprint ID
- 60706
- Resolver ID
- CaltechAUTHORS:20151002-120202736
- DP130100568
- Australian Research Council
- ST/L0075X/1
- Science and Technology Facilities Council (STFC)
- 1140838
- Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)
- PFB 06
- Center of Excellence in Astrophysics and Associated Technologies
- Created
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2015-10-02Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)