A Connection between Obscuration and Star Formation in Luminous Quasars
Gorjian, Varoujan; Alberts, Stacey; Jones, Christine; Kochanek, Christopher S.; Hainline, Kevin N.; Pope, Alexandra; Stern, Daniel; Forman, William R.; Hickox, Ryan C.; Brodwin, Mark; Brown, Michael J. I.; Murray, Stephen S.; Chen, Chien-Ting J.; Alexander, David M.; Del Moro, Agnese; Goulding, Andrew D.; Harrison, Chris M.; Assef, Roberto; Rovilos, Emmanouel
United States, United Kingdom, Chile, Australia
Abstract
We present a measurement of the star formation properties of a uniform sample of mid-IR-selected, optically unobscured, and obscured quasars (QSO1s and QSO2s) in the Boötes survey region. We use a spectral energy distribution analysis for photometric data spanning optical to far-IR wavelengths to separate the active galactic nucleus (AGN) and host galaxy components. We find that when compared to a matched sample of QSO1s, the QSO2s have roughly twice the far-IR detection fractions, far-IR fluxes, and infrared star formation luminosities (LIRSF). Correspondingly, we show that the AGN obscured fraction rises from 0.3 to 0.7 between (4-40) × {{10}11}{{L}⊙ }. We also find evidence associating X-ray absorption with the presence of far-IR-emitting dust. Overall, these results are consistent with galaxy evolution models in which quasar obscuration is associated with dust-enshrouded starburst galaxies.