Open AccessSubmillimetre detection of a high‐redshift type 2 QSO
Author(s) -
Mainieri V.,
Rigopoulou D.,
Lehmann I.,
Scott S.,
Matute I.,
Almaini O.,
Tozzi P.,
Hasinger G.,
Dunlop J. S.
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08600.x
Subject(s) - physics , astrophysics , galaxy , spectral energy distribution , active galactic nucleus , redshift , photometry (optics) , star formation , flux (metallurgy) , astronomy , supermassive black hole , stars , materials science , metallurgy
We report on the first SCUBA detection of a type 2 QSO at z = 3.660 in the Chandra Deep Field South. This source is X‐ray‐absorbed, shows only narrow emission lines in the optical spectrum and is detected in the submillimetre: it is the ideal candidate in an evolution scheme for active galactic nuclei (AGN) (e.g. Fabian 1999; Page et al. 2004) of an early phase corresponding to the main growth of the host galaxy and formation of the central black hole. The overall photometry (from the radio to the X‐ray energy band) of this source is well reproduced by the spectral energy distribution (SED) of NGC 6240, while it is incompatible with the spectrum of a type 1 QSO (3C 273) or a starburst galaxy (Arp 220). Its submillimetre (850 μm) to X‐ray (2 keV) spectral slope (α SX ) is close to the predicted value for a Compton‐thick AGN in which only 1 per cent of the nuclear emission emerges through scattering. Using the observed flux at 850 μm we have derived a star formation rate of 550–680 M ⊙ yr −1 and an estimate of the dust mass M dust = 4.2 × 10 8 M ⊙ .