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 (≥10^47 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 × 10^44 erg s-1 is a fraction (<10%) of the intrinsic one, which is estimated to be ≳ 5 × 10^45 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.
Piconcelli E., Vignali C., Bianchi S., Zappacosta L., Fritz J., Lanzuisi G., et al. (2015). The hidden quasar nucleus of a WISE-selected, hyperluminous, dust-obscured galaxy at z~2.3. ASTRONOMY & ASTROPHYSICS, 574, L9-L9 [10.1051/0004-6361/201425324].
The hidden quasar nucleus of a WISE-selected, hyperluminous, dust-obscured galaxy at z~2.3
VIGNALI, CRISTIAN;LANZUISI, GIORGIO;
2015
Abstract
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 (≥10^47 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 × 10^44 erg s-1 is a fraction (<10%) of the intrinsic one, which is estimated to be ≳ 5 × 10^45 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
