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

Cosmic hydrogen reionization and cosmic production of first metals are majorphase transitions of the Universe occurring during the first billion yearsafter the Big Bang, but still poorly explored observationally. Using the JWSTNIRSpec prism spectroscopy, we report the discovery of a sub-$L_{\ast}$ galaxyat $z_{\rm spec}=8.1623_{-0.0008}^{+0.0007}$, dubbed RXJ2129-z8HeII, via thedetection of a series of strong rest-frame UV/optical nebular emission linesand the clear Lyman break. A strong He II $\lambda$1640 emission is present,the highest redshift He II line currently known. Its high rest-frame equivalentwidth (EW $=19.4\pm3.2$ Angstrom) and extreme flux ratios with respect to UVmetal lines and Balmer lines raise the possibility that part ofRXJ2129-z8HeII's stellar populations could be Pop III-like. RXJ2129-z8HeII alsoshows a pronounced UV continuum with an extremely steep (i.e. blue) spectralslope of $\beta=-2.50\pm0.08$, the steepest amongst all spectroscopicallyconfirmed galaxies at $z\gtrsim7$, in support of its very hard ionizingspectrum that could lead to a significant leakage of its ionizing flux.Therefore, RXJ2129-z8HeII is representative of the key galaxy populationdriving the cosmic reionization. To date, this is also the most compelling casewhere trace Pop III stars might coexist with more metal-enriched stars.

A strong He II $\lambda$1640 emitter with extremely blue UV spectral slope at $z=8.16$: presence of Pop III stars?