EIGER. VI. The Correlation Function, Host Halo Mass, and Duty Cycle of Luminous Quasars at z ≳ 6

Abstract

We expect luminous (M ₁₄₅₀ ≲ ‑26.5) high-redshift quasars to trace the highest-density peaks in the early Universe. Here, we present observations of four z ≳ 6 quasar fields using JWST/NIRCam in the imaging and wide-field slitless spectroscopy mode and report a wide range in the number of detected [O III]-emitting galaxies in the quasars' environments, ranging between a density enhancement of δ ≈ 65 within a 2 cMpc radius—one of the largest protoclusters 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 autocorrelation function, we infer a correlation length of quasars at <z> = 6.25 of r0QQ=22.0‑2.9+3.0cMpch‑1 , while we obtain a correlation length of the [O III]-emitting galaxies of r0GG=4.1±0.3cMpch‑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 log10(Mhalo,min/M⊙)=12.43‑0.15+0.13 (and log10(Mhalo,min[OIII]/M⊙)=10.56‑0.03+0.05 for the [O III] 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 _duty ≪ 1. 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.