Volume 574, February 2015
|Number of page(s)||4|
|Published online||05 February 2015|
The hidden quasar nucleus of a WISE-selected, hyperluminous, dust-obscured galaxy at z ~ 2.3
Osservatorio Astronomico di Roma (INAF),
via Frascati 33, 00040
Monte Porzio Catone ( Roma),
2 Dipartimento di Fisica e Astronomia, Università di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
3 Osservatorio Astronomico di Bologna (INAF), via Ranzani 1, 40127 Bologna, Italy
4 Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
5 Sterrenkundig Observatorium Universiteit Gent, Krijgslaan 281, S9, 9000 Gent, Belgium
6 Centro de Astrobiologia (CSIC-INTA), Dep. de Astrofísica, ESAC, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
7 Institute de Radioastronomie Millimétrique, 300 rue de la Piscine, 38406 St. Martin d’Hères, Grenoble, France
8 Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge CB3 0HE, UK
Received: 12 November 2014
Accepted: 5 December 2014
We present the first X-ray spectrum of a hot dust-obscured galaxy (DOG), namely W1835+4355 at z ~ 2.3. Hot DOGs represent a very rare population of hyperluminous (≥1047 erg s-1), dust-enshrouded objects at z ≥ 2 recently discovered in the WISE All Sky Survey. The 40 ks XMM-Newton spectrum reveals a continuum as flat (Γ ~ 0.8) as typically seen in heavily obscured AGN. This, along with the presence of strong Fe Kα emission, clearly suggests a reflection-dominated spectrum due to Compton-thick absorption. In this scenario, the observed luminosity of L2−10~ 2 × 1044 erg s-1 is a fraction (<10%) of the intrinsic one, which is estimated to be ≳ 5 × 1045 erg s-1 by using several proxies. The Herschel data allow us to constrain the SED up to the sub-mm band, providing a reliable estimate of the quasar contribution (~75%) to the IR luminosity as well as the amount of star formation (~2100 M⊙ yr-1). Our results thus provide additional pieces of evidence that associate Hot DOGs with an exceptionally dusty phase during which luminous quasars and massive galaxies co-evolve and a very efficient and powerful AGN-driven feedback mechanism is predicted by models.
Key words: galaxies: individual: WISE J183533.71+435549.1 / galaxies: active / galaxies: nuclei / submillimeter: galaxies / X-rays: galaxies
© ESO, 2015
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