Bosman, SEI;
Becker, GD;
Haehnelt, MG;
Hewett, PC;
McMahon, RG;
Mortlock, DJ;
Simpson, C;
(2017)
A deep search for metals near redshift 7: the line of sight towards ULAS J1120+0641.
Monthly Notices of the Royal Astronomical Society
, 470
(2)
pp. 1919-1934.
10.1093/mnras/stx1305.
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Abstract
We present a search for metal absorption line systems at the highest redshifts to date using a deep (30 h) Very Large Telescope/X-Shooter spectrum of the z = 7.084 quasi-stellar object (QSO) ULAS J1120+0641. We detect seven intervening systems at z > 5.5, with the highest redshift system being a C IV absorber at z = 6.51. We find tentative evidence that the mass density of C IV remains flat or declines with redshift at z < 6, while the number density of C II systems remains relatively flat over 5 < z < 7. These trends are broadly consistent with models of chemical enrichment by star formation-driven winds that include a softening of the ultraviolet background towards higher redshifts. We find a larger number of weak (Wrest < 0.3 Å) Mg II systems over 5.9 < z < 7.0 than predicted by a power-law fit to the number density of stronger systems. This is consistent with trends in the number density of weak Mg II systems at z ≲ 2.5, and suggests that the mechanisms that create these absorbers are already in place at z ∼ 7. Finally, we investigate the associated narrow Si IV, C IV and N V absorbers located near the QSO redshift, and find that at least one component shows evidence of partial covering of the continuum source.
Type: | Article |
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Title: | A deep search for metals near redshift 7: the line of sight towards ULAS J1120+0641 |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.1093/mnras/stx1305 |
Publisher version: | http://doi.org/10.1093/mnras/stx1305 |
Language: | English |
Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
Keywords: | intergalactic medium – quasars: absorption lines – quasars: individual:ULAS J1120+0641 – dark ages, reionization, first stars. |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
URI: | https://discovery.ucl.ac.uk/id/eprint/10030732 |
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