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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present results of a survey of Lyα emitters (LAEs) at   z = 6.5  which is thought to be the final epoch of the cosmic re‐ionization. In a ≈530 arcmin 2  deep image of the SSA22 field taken through a narrow‐band filter NB912 installed in the Subaru/Suprime‐Cam, we have found only 14 LAE candidates with   L  Lyα ≳ 3 × 10 42  erg s −1  . Even applying the same colour selection criteria, the number density of the LAE candidates is a factor of 3 smaller than that found at the same redshift in the Subaru Deep Field (SDF). Assuming the number density in the SDF is a cosmic average, the probability to have a number density equal to or smaller than that found in the SSA22 field is only 7 per cent if we consider fluctuation by the large‐scale structure (i.e. cosmic variance) and Poisson error. Therefore, the SSA22 field may be a rare void at   z = 6.5 . On the other hand, we have found that the number density of  i ′‐drop galaxies with  25.5 &lt;  z ′ &lt; 26.0  in the SSA22 field agrees well with that in the SDF. If we consider a scenario that a larger neutral fraction of intergalactic hydrogen,   x  H I  , in the SSA22 field obscures a part of Lyα emission,   x  H I   in the SSA22 field should be about two times larger than that in the SDF. This can be translated into   x  H I  &lt; 0.9  at   z = 6.5  in the SSA22 field. A much larger survey area than previous ones is required to overcome a large fluctuation reported here and to obtain a robust constraint on   x  H I   at the end of the re‐ionization from LAEs.

Lyα emitters at z = 6.5 in the SSA22 field: an area more neutral or void at the end of the re‐ionization epoch ★