The ESO UVES advanced data products quasar sample:  II. Cosmological evolution of the neutral gas mass density

T. Zafar; C. Péroux; A. Popping; B. Milliard; J. -M. Deharveng; S. Frank

doi:10.1051/0004-6361/201321154

The ESO UVES advanced data products quasar sample: II. Cosmological evolution of the neutral gas mass density

T. Zafar, C. Péroux, A. Popping, B. Milliard, J. -M. Deharveng, S. Frank

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141 Citations (Scopus)

Abstract

Damped absorbers, seen in the spectra of background quasars, are unique probes to select H I-rich galaxies. These galaxies allow one to estimate the neutral gas mass over cosmological scales. The neutral gas mass is a possible indicator of gas consumption as star formation proceeds. The damped Lyα absorbers (DLAs; N_{H I} ≥ 2 × 10²⁰ cm^-2) and sub-DLAs (10¹⁹ ≤ N_{H I} ≤ 2 × 10²⁰ cm^-2) are believed to contain a large fraction of neutral gas mass in the Universe. In Paper I of the series, we presented the results of a search for DLAs and sub-DLAs in the European Southern Observatory (ESO) Ultraviolet Visual Echelle Spectrograph (UVES) advanced data products dataset of 250 quasars. Here we use an unbiased subsample of sub-DLAs from this dataset to derive their statistical properties. We built a subset of 122 quasars ranging from 1.5 < z_em < 5.0, suitable for statistical analysis. The statistical sample was analyzed in conjunction with other sub-DLA samples from the literature. This resulted in a combined sample of 89 sub-DLAs over a redshift path of Δz = 193. We derived the redshift evolution of the number density and the line density for sub-DLAs and compared them with the Lyman-limit systems (LLSs) and DLA measurements from the literature. The results indicate that these three classes of absorbers are evolving in the redshift interval 1.0 < z < 5.0. Thanks to the ESO UVES advanced data products data, we were able to determine the column density distribution, f_{H I}(N,z), down to the sub-DLA limit. The flattening of f_{H I}(N,z) in the sub-DLA regime is present in the observations. The redshift evolution of f_{H I}(N,z) down to log N_{H I}= 19.0 cm^-2 is also presented, indicating that there are more sub-DLAs at high redshift than at low redshift. f_{H I}(N,z) was also used to determine the neutral gas mass density, Ωg, at 1.5 < z < 5.0. The complete sample shows that sub-DLAs contribute 8–20% to the total Ωg from 1.5 < z < 5.0. In agreement with previous studies, no evolution of Ω_g was observed from low to high redshift (i.e., 1.5 < z < 5.0), suggesting that star formation alone cannot explain this non-evolution and replenishment of gas and that recombination of ionized gas is needed.

Original language	English
Article number	A141
Pages (from-to)	1-20
Number of pages	20
Journal	Astronomy and Astrophysics
Volume	556
DOIs	https://doi.org/10.1051/0004-6361/201321154
Publication status	Published - Aug 2013
Externally published	Yes

Keywords

galaxies: abundances
galaxies: evolution
galaxies: high-redshift
quasars: absorption lines
quasars: general

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@article{5f2ae2e8e7eb4d82bb5c4312cf1c4dab,

title = "The ESO UVES advanced data products quasar sample: II. Cosmological evolution of the neutral gas mass density",

abstract = "Damped absorbers, seen in the spectra of background quasars, are unique probes to select H I-rich galaxies. These galaxies allow one to estimate the neutral gas mass over cosmological scales. The neutral gas mass is a possible indicator of gas consumption as star formation proceeds. The damped Lyα absorbers (DLAs; NH I ≥ 2 × 1020 cm-2) and sub-DLAs (1019 ≤ NH I ≤ 2 × 1020 cm-2) are believed to contain a large fraction of neutral gas mass in the Universe. In Paper I of the series, we presented the results of a search for DLAs and sub-DLAs in the European Southern Observatory (ESO) Ultraviolet Visual Echelle Spectrograph (UVES) advanced data products dataset of 250 quasars. Here we use an unbiased subsample of sub-DLAs from this dataset to derive their statistical properties. We built a subset of 122 quasars ranging from 1.5 < zem < 5.0, suitable for statistical analysis. The statistical sample was analyzed in conjunction with other sub-DLA samples from the literature. This resulted in a combined sample of 89 sub-DLAs over a redshift path of Δz = 193. We derived the redshift evolution of the number density and the line density for sub-DLAs and compared them with the Lyman-limit systems (LLSs) and DLA measurements from the literature. The results indicate that these three classes of absorbers are evolving in the redshift interval 1.0 < z < 5.0. Thanks to the ESO UVES advanced data products data, we were able to determine the column density distribution, fH I(N,z), down to the sub-DLA limit. The flattening of fH I(N,z) in the sub-DLA regime is present in the observations. The redshift evolution of fH I(N,z) down to log NH I = 19.0 cm-2 is also presented, indicating that there are more sub-DLAs at high redshift than at low redshift. fH I(N,z) was also used to determine the neutral gas mass density, Ωg, at 1.5 < z < 5.0. The complete sample shows that sub-DLAs contribute 8–20% to the total Ωg from 1.5 < z < 5.0. In agreement with previous studies, no evolution of Ωg was observed from low to high redshift (i.e., 1.5 < z < 5.0), suggesting that star formation alone cannot explain this non-evolution and replenishment of gas and that recombination of ionized gas is needed.",

keywords = "galaxies: abundances, galaxies: evolution, galaxies: high-redshift, quasars: absorption lines, quasars: general",

author = "T. Zafar and C. P{\'e}roux and A. Popping and B. Milliard and Deharveng, {J. -M.} and S. Frank",

year = "2013",

month = aug,

doi = "10.1051/0004-6361/201321154",

language = "English",

volume = "556",

pages = "1--20",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - The ESO UVES advanced data products quasar sample

T2 - II. Cosmological evolution of the neutral gas mass density

AU - Zafar, T.

AU - Péroux, C.

AU - Popping, A.

AU - Milliard, B.

AU - Deharveng, J. -M.

AU - Frank, S.

PY - 2013/8

Y1 - 2013/8

N2 - Damped absorbers, seen in the spectra of background quasars, are unique probes to select H I-rich galaxies. These galaxies allow one to estimate the neutral gas mass over cosmological scales. The neutral gas mass is a possible indicator of gas consumption as star formation proceeds. The damped Lyα absorbers (DLAs; NH I ≥ 2 × 1020 cm-2) and sub-DLAs (1019 ≤ NH I ≤ 2 × 1020 cm-2) are believed to contain a large fraction of neutral gas mass in the Universe. In Paper I of the series, we presented the results of a search for DLAs and sub-DLAs in the European Southern Observatory (ESO) Ultraviolet Visual Echelle Spectrograph (UVES) advanced data products dataset of 250 quasars. Here we use an unbiased subsample of sub-DLAs from this dataset to derive their statistical properties. We built a subset of 122 quasars ranging from 1.5 < zem < 5.0, suitable for statistical analysis. The statistical sample was analyzed in conjunction with other sub-DLA samples from the literature. This resulted in a combined sample of 89 sub-DLAs over a redshift path of Δz = 193. We derived the redshift evolution of the number density and the line density for sub-DLAs and compared them with the Lyman-limit systems (LLSs) and DLA measurements from the literature. The results indicate that these three classes of absorbers are evolving in the redshift interval 1.0 < z < 5.0. Thanks to the ESO UVES advanced data products data, we were able to determine the column density distribution, fH I(N,z), down to the sub-DLA limit. The flattening of fH I(N,z) in the sub-DLA regime is present in the observations. The redshift evolution of fH I(N,z) down to log NH I = 19.0 cm-2 is also presented, indicating that there are more sub-DLAs at high redshift than at low redshift. fH I(N,z) was also used to determine the neutral gas mass density, Ωg, at 1.5 < z < 5.0. The complete sample shows that sub-DLAs contribute 8–20% to the total Ωg from 1.5 < z < 5.0. In agreement with previous studies, no evolution of Ωg was observed from low to high redshift (i.e., 1.5 < z < 5.0), suggesting that star formation alone cannot explain this non-evolution and replenishment of gas and that recombination of ionized gas is needed.

AB - Damped absorbers, seen in the spectra of background quasars, are unique probes to select H I-rich galaxies. These galaxies allow one to estimate the neutral gas mass over cosmological scales. The neutral gas mass is a possible indicator of gas consumption as star formation proceeds. The damped Lyα absorbers (DLAs; NH I ≥ 2 × 1020 cm-2) and sub-DLAs (1019 ≤ NH I ≤ 2 × 1020 cm-2) are believed to contain a large fraction of neutral gas mass in the Universe. In Paper I of the series, we presented the results of a search for DLAs and sub-DLAs in the European Southern Observatory (ESO) Ultraviolet Visual Echelle Spectrograph (UVES) advanced data products dataset of 250 quasars. Here we use an unbiased subsample of sub-DLAs from this dataset to derive their statistical properties. We built a subset of 122 quasars ranging from 1.5 < zem < 5.0, suitable for statistical analysis. The statistical sample was analyzed in conjunction with other sub-DLA samples from the literature. This resulted in a combined sample of 89 sub-DLAs over a redshift path of Δz = 193. We derived the redshift evolution of the number density and the line density for sub-DLAs and compared them with the Lyman-limit systems (LLSs) and DLA measurements from the literature. The results indicate that these three classes of absorbers are evolving in the redshift interval 1.0 < z < 5.0. Thanks to the ESO UVES advanced data products data, we were able to determine the column density distribution, fH I(N,z), down to the sub-DLA limit. The flattening of fH I(N,z) in the sub-DLA regime is present in the observations. The redshift evolution of fH I(N,z) down to log NH I = 19.0 cm-2 is also presented, indicating that there are more sub-DLAs at high redshift than at low redshift. fH I(N,z) was also used to determine the neutral gas mass density, Ωg, at 1.5 < z < 5.0. The complete sample shows that sub-DLAs contribute 8–20% to the total Ωg from 1.5 < z < 5.0. In agreement with previous studies, no evolution of Ωg was observed from low to high redshift (i.e., 1.5 < z < 5.0), suggesting that star formation alone cannot explain this non-evolution and replenishment of gas and that recombination of ionized gas is needed.

KW - galaxies: abundances

KW - galaxies: evolution

KW - galaxies: high-redshift

KW - quasars: absorption lines

KW - quasars: general

U2 - 10.1051/0004-6361/201321154

DO - 10.1051/0004-6361/201321154

M3 - Article

VL - 556

SP - 1

EP - 20

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A141

ER -

The ESO UVES advanced data products quasar sample: II. Cosmological evolution of the neutral gas mass density

Abstract

Keywords

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