Discovery of the first heavily obscured QSO candidate at $z>6$ in a close galaxy pair

Understand

While theoretical arguments predict that most of the early growth of supermassive black holes (SMBHs) happened during heavily obscured phases of accretion, current methods used for selecting $z>6$ quasars (QSOs) are strongly biased against obscured QSOs, thus considerably limiting our understanding of accreting SMBHs during the first Gyr of the Universe from an observational point of view.

• We report the $Chandra$ discovery of the first heavily obscured QSO candidate in the early universe, hosted by a close ($\approx5$ kpc) galaxy pair at $z=6.515$.
• One of the members is an optically classified type 1 QSO, PSO167-13.
• The companion galaxy was first detected as a [C II] emitter by ALMA.