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 Plus annual

Presents the access of premium content as premium feature

Premium Content

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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

It is thought that the first generations of massive stars in the Universewere an important, and quite possibly dominant, source of the ultra-violetradiation that reionized the hydrogen gas in the intergalactic medium (IGM); astate in which it has remained to the present day. Measurements of cosmicmicrowave background anisotropies suggest that this phase-change largely tookplace in the redshift range z=10.8 +/- 1.4, while observations of quasars andLyman-alpha galaxies have shown that the process was essentially completed byz=6. However, the detailed history of reionization, and characteristics of thestars and proto-galaxies that drove it, remain unknown. Further progress inunderstanding requires direct observations of the sources of ultra-violetradiation in the era of reionization, and mapping the evolution of the neutralhydrogen fraction through time. The detection of galaxies at such redshifts ishighly challenging, due to their intrinsic faintness and high luminositydistance, whilst bright quasars appear to be rare beyond z~7. Here we reportthe discovery of a gamma-ray burst, GRB 090423, at redshift z=8.26 -0.08 +0.07.This is well beyond the redshift of the most distant spectroscopicallyconfirmed galaxy (z=6.96) and quasar (z=6.43). It establishes that massivestars were being produced, and dying as GRBs, ~625 million years after the BigBang. In addition, the accurate position of the burst pinpoints the location ofthe most distant galaxy known to date. Larger samples of GRBs beyond z~7 willconstrain the evolving rate of star formation in the early universe, whilerapid spectroscopy of their afterglows will allow direct exploration of theprogress of reionization with cosmic time.

A glimpse of the end of the dark ages: the gamma-ray burst of 23 April 2009 at redshift 8.3