Kavli Affiliate: Robert A. Simcoe
| First 5 Authors: Anna-Christina Eilers, Ruari Mackenzie, Elia Pizzati, Jorryt Matthee, Joseph F. Hennawi
| Summary:
We expect luminous ($M_{1450}lesssim-26.5$) high-redshift quasars to trace
the highest density peaks in our universe, and therefore to reside in
proto-clusters encompassing an abundance of galaxies in close vicinity. Here,
we present observations of four $zgtrsim6$ quasar fields using JWST/NIRCam in
imaging and widefield slitless spectroscopy mode and report a wide range in the
number of detected [OIII]-emitting galaxies in the quasars’ environments,
ranging between a density enhancement of $delta>100$ within a $2$ cMpc radius
– one of the largest proto-clusters during the Epoch of Reionization discovered
to date – to a density contrast consistent with zero, indicating the presence
of a UV-luminous quasar in a region comparable to the average density of the
universe. By measuring the two-point cross-correlation function of quasars and
their surrounding galaxies, as well as the galaxy auto-correlation function, we
infer a correlation length of quasars at $langle zrangle=6.25$ of $r_0^{rm
QQ}=21.3^{+2.7}_{-2.6}~{rm cMpc},h^{-1}$, while we obtain a correlation
length of the [OIII]-emitting galaxies of $r_0^{rm GG}=4.2pm0.1~{rm
cMpc},h^{-1}$. By comparing the correlation functions to dark-matter-only
simulations we estimate the minimum mass of the quasars’ host dark matter halos
to be $log_{10}(M_{rm halo, min}/M_odot)=12.30pm0.14$ (and
$log_{10}(M_{rm halo, min}^{rm [OIII]}/M_odot) = 10.72pm0.03$ for the
[OIII]-emitters), indicating that (a) luminous quasars do not necessarily
reside within the most overdense regions in the early universe, and that (b)
the UV-luminous duty cycle of quasar activity at these redshifts is $f_{rm
duty}ll1$. Such short quasar activity timescales challenge our understanding
of early supermassive black hole growth and provide evidence for highly
dust-obscured growth phases or episodic, radiatively inefficient accretion
rates.
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