SCUBA-2 High Redshift Bright Quasar Survey. II. The Environment of z ∼ 6 Quasars at Submillimeter Band

Qiong Li, Ran Wang, Xiaohui Fan, Xue Bing Wu, Linhua Jiang, Eduardo Bañados, Bram Venemans, Yali Shao, Jianan Li, Jeff Wagg, Roberto Decarli, Chiara Mazzucchelli, Alain Omont, Frank Bertoldi, Sean Johnson, Christopher J. Conselice, Chengpeng Zhang

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1 Scopus citations


The formation of the first supermassive black holes is expected to have occurred in some most pronounced matter and galaxy overdensities in the early universe. We have conducted a submillimeter wavelength continuum survey of 54 z ∼ 6 quasars using the Submillimeter Common-User Bolometre Array-2 on the James Clerk Maxwell Telescope to study the environments around z ∼ 6 quasars. We identified 170 submillimeter galaxies (SMGs) with above 3.5σ detections in 450 or 850 μm maps. Their far-IR luminosities are (2.2-6.4) × 1012 L , and their star formation rates are ∼400-1200 M yr−1. We also calculated the SMGs’ differential and cumulative number counts in a combined area of ∼620 arcmin2. To a 4σ detection (at ∼5.5 mJy), SMGs’ overdensity is 0.68 − 0.19 + 0.21 (±0.19), exceeding the blank-field source counts by a factor of 1.68. We find that 13/54 quasars show overdensities (at ∼5.5 mJy) of δ SMG ∼ 1.5-5.4. The combined area of these 13 quasars exceeds the blank-field counts with the overdensity to 5.5 mJy of δ SMG ∼ 2.46 − 0.55 + 0.64 (±0.25) in the regions of ∼150 arcmin2. However, the excess is insignificant on the bright end (e.g., 7.5 mJy). We also compare results with previous environmental studies of Lyα emitters and Lyman break galaxies on a similar scale. Our survey presents the first systematic study of the environment of quasars at z ∼ 6. The newly discovered SMGs provide essential candidates for follow-up spectroscopic observations to test whether they reside in the same large-scale structures as the quasars and search for protoclusters at an early epoch.

Original languageEnglish (US)
Article number174
JournalAstrophysical Journal
Issue number2
StatePublished - Sep 1 2023

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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