English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We present a search for metal absorption line systems at the highestredshifts to date using a deep (30h) VLT/X-Shooter spectrum of the z = 7.084quasi-stellar object (QSO) ULAS J1120+0641. We detect seven intervening systemsat 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 ordeclines with redshift at z < 6, while the number density of C II systemsremains relatively flat over 5 < z < 7. These trends are broadly consistentwith models of chemical enrichment by star formation-driven winds that includea softening of the ultraviolet background towards higher redshifts. We find alarger number of weak ( W_rest < 0.3A ) Mg II systems over 5.9 < z < 7.0 thanpredicted by a power-law fit to the number density of stronger systems. This isconsistent 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 inplace at z = 7. Finally, we investigate the associated narrow Si IV, C IV, andN V absorbers located near the QSO redshift, and find that at least onecomponent shows evidence of partial covering of the continuum source.

A deep search for metals near redshift 7: the line-of-sight towards ULAS J1120+0641