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

QSOs have been thought to be important for tracing highly biased regions inthe early universe, from which the present-day massive galaxies and galaxyclusters formed. While overdensities of star-forming galaxies have been foundaround QSOs at 2<z<5, the case for excess galaxy clustering around QSOs at z>6is less clear. Previous studies with HST have reported the detection of smallexcesses of faint dropout galaxies in some QSO fields, but these surveys probeda relatively small region surrounding the QSOs. To overcome this problem, wehave observed the most distant QSO at z=6.4 using the large field of view ofthe Suprime-Cam (34' x 27'). Newly-installed CCDs allowed us to select Lymanbreak galaxies (LBG) at z~6.4 more efficiently. We found seven LBGs in the QSOfield, whereas only one exists in a comparison field. The significance of thisapparent excess is difficult to quantify without spectroscopic confirmation andadditional control fields. The Poisson probability to find seven objects whenone expects four is ~10%, while the probability to find seven objects in onefield and only one in the other is less than 0.4%, suggesting that the QSOfield is significantly overdense relative to the control field. We find someevidence that the LBGs are distributed in a ring-like shape centered on the QSOwith a radius of ~3 Mpc. There are no candidate LBGs within 2 Mpc from the QSO,i.e., galaxies are clustered around the QSO but appear to avoid the verycenter. These results suggest that the QSO is embedded in an overdense regionwhen defined on a sufficiently large scale. This suggests that the QSO wasindeed born in a massive halo. The central deficit of galaxies may indicatethat (1) the strong UV radiation from the QSO suppressed galaxy formation inits vicinity, or (2) that star-formation closest to the QSO occurs mostly in anobscured mode that is missed by our UV selection.

A Large Number of z > 6 Galaxies around a QSO at z = 6.43: Evidence for a Protocluster?