J/MNRAS/452/217 HI cosmological mass density at z=5 (Crighton+, 2015)
The neutral hydrogen cosmological mass density at z = 5.
Crighton N.H.M., Murphy M.T., Prochaska J.X., Worseck G., Rafelski M.,
Becker G.D., Ellison S.L., Fumagalli M., Lopez S., Meiksin A., O'meara J.M.
<Mon. Not. R. Astron. Soc., 452, 217-234 (2015)>
=2015MNRAS.452..217C 2015MNRAS.452..217C (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts
Keywords: quasars: absorption lines - cosmological parameters
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, OmegaHI. 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 OmegaHI. We
find OmegaHI=0.98+0.20-0.18x10-3 at =4.9, assuming a 20
percent contribution from lower column density systems below the DLA
threshold. By comparing to literature measurements at lower redshifts,
we show that OmegaHI can be described by the functional form
OmegaHI(z)∝(1+z)0.4. This gradual decrease from z=5 to 0
is consistent with the bulk of HI 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.
Description:
Our main data sample consists of Gemini Multi-Object Spectrograph
(GMOS) spectra for the 163 QSOs which comprise the Giant Gemini GMOS
(GGG) survey (Worseck et al., 2014, Cat. J/MNRAS/445/1745).
We also use a smaller sample of 59 QSOs with higher resolution
spectra, listed in Table 1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 43 59 Higher resolution spectra used in our analysis
table3.dat 44 163 Redshift limits used to calculate the redshift
search path for DLAs for each QSO
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See also:
J/MNRAS/445/1745 : Giant Gemini GMOS survey. I. (Worseck+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS QSO SDSS name (JHHMMSS.ss+DDMMSS.s)
26- 29 F4.2 --- zem QSO emission redshift
31- 34 A4 --- Inst Instrument used to take the spectrum
36- 39 F4.1 --- S/N Median S/N per pixel over rest-frame
wavelengths 1240-1280Å
41- 43 A3 --- GGG? [Yes/No ] Whether the QSO is in the GGG sample
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
5- 23 A19 --- SDSS QSO SDSS name (JHHMMSS.ss+DDMMSS.s)
26- 30 F5.3 --- zmin Start redshift for the DLA search
33- 37 F5.3 --- zmax End redshift for the DLA search
40- 44 F5.3 --- zem QSO emission redshift
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 13-Jan-2016