The HELLAS2XMM survey – XII. The infrared/submillimetre view of an X-ray selected type 2 quasar at z≈ 2 |
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| Authors: | C Vignali F Pozzi J Fritz A Comastri C Gruppioni E Bellocchi F Fiore M Brusa R Maiolino M Mignoli F La Franca L Pozzetti G Zamorani A Merloni |
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| Institution: | Dipartimento di Astronomia, Universitàdegli Studi di Bologna, Via Ranzani 1, I-40127 Bologna, Italy;INAF –Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna, Italy;INAF –Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy;INAF –Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monteporzio, Roma, Italy;Max-Planck-Institut für Extraterrestrische Physik (MPE), Giessenbachstr. 1, 85748 Garching, Germany;Dipartimento di Fisica, Universitàdi Roma Tre, Via della Vasca Navale 84, I-00146 Roma, Italy;Excellence Cluster Universe, Boltzmannstr. 2, D-85748 Garching, Germany |
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| Abstract: | We present multiwavelength observations (from optical to submillimetre, including Spitzer and Submillimetre Common-User Bolometer Array) of H2XMMJ 003357.2?120038 (also GD 158_19), an X-ray selected, luminous narrow-line (type 2) quasar at z = 1.957 selected from the HELLAS2XMM survey. Its broad-band properties can be reasonably well modelled assuming three components: a stellar component to account for the optical and near-infrared (IR) emission; an active galactic nucleus (AGN) component (i.e. dust heated by an accreting active nucleus), dominant in the mid-IR, with an optical depth at 9.7  along the line of sight (close to the equatorial plane of the obscuring matter) of τ(9.7) = 1 and a full covering angle of the reprocessing matter (torus) of 140° and a far-IR starburst component (i.e. dust heated by star formation) to reproduce the wide bump observed longward of 70  .
The derived star formation rate is ≈1500 M⊙ yr?1 . The overall modelling indicates that GD 158_19 is a high-redshift X-ray luminous, obscured quasar with coeval powerful AGN activity and intense star formation. It is probably caught before the process of expelling the obscuring gas has started, thus quenching the star formation. |
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| Keywords: | galaxies: active galaxies: nuclei quasars: general quasars: individual: GD 158_19 |
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