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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 742823.0, MPI für Astronomie / Publikationen_mpia
A deep search for metals near redshift 7: the line of sight towards ULAS J1120+0641
Authors:Bosman, S. E. I.; Becker, G. D.; Haehnelt, M. G.; Hewett, P. C.; McMahon, R. G.; Mortlock, D. J.; Simpson, C.; Venemans, B. P.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:Monthly Notices of the Royal Astronomical Society
Start Page:1919
End Page:1934
Audience:Not Specified
Abstract / Description:We present a search for metal absorption line systems at the highest redshifts to date using a deep (30h) VLT/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 ( W_rest < 0.3A ) 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.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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