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 a search for galaxies at  7.6 &lt;  z  &lt; 9.8  using the latest  Hubble Space Telescope /Wide Field Camera 3 (WFC3) near‐infrared data, based on the Lyman‐break technique. We search for galaxies which have large  ( Y − J )  colours (the ‘  Y  ‐drops’) on account of the Lyman α forest absorption, and with  ( J − H )  colours inconsistent with being low‐redshift contaminants. We identify 24 candidates at redshift   z ≈ 8–9  (15 are robust and a further nine more marginal but consistent with being high redshift) over an area of  ≈50  arcmin  2  . Previous searches for   Y  ‐drops with WFC3 have focused only on the  Hubble Ultra Deep Field , and our larger survey (involving two other nearby deep fields and a wider area survey) has trebled the number of robust   Y  ‐drop candidates. For the first time, we have sufficient   z ≈ 8–9  galaxies to fit both  φ*  and   M *  of the UV Schechter luminosity function. There is evidence for evolution in this luminosity function from   z = 6–7  to   z = 8–9 , in the sense that there are fewer UV‐bright galaxies at   z ≈ 8–9 , consistent with an evolution mainly in   M * . The candidate   z ≈ 8–9  galaxies we detect have insufficient ionizing flux to reionize the Universe, and it is probable that galaxies below our detection limit provide a significant UV contribution. The faint‐end slope, α, is not well constrained. However, adopting a similar faint‐end slope to that determined at   z = 3–6  ( α=−1.7 ) and a Salpeter initial mass function (IMF), then the ionizing photon budget still falls short if   f  esc  &lt; 0.5 , even integrating down to   M  UV =−8 . A steeper faint‐end slope or a low‐metallicity population (or a top‐heavy IMF) might still provide sufficient photons for star‐forming galaxies to reionize the Universe, but confirmation of this might have to await the  James Webb Space Telescope .

Star‐forming galaxies at z ≈ 8–9 from Hubble Space Telescope /WFC3: implications for reionization