A connection between obscuration and star formation in luminous quasars

Chien-Ting J Chen, Ryan C Hickox, Stacey Alberts, Christopher Mark Harrison, David M Alexander, Roberto J Assef, Mark Brodwin, Michael James Isles Brown, Agnese Del Moro, William R Forman, Varoujan Gorjian, Andrew D Goulding, Kevin N Hainline, Christine Jones, Christopher S Kochanek, Stephen S Murray, Alexandra Pope, Emmanouel Rovilos, Daniel Stern

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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 Bootessurvey 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 (LIR SF). Correspondingly, we show that the AGN obscured fraction rises from 0.3 to 0.7 between (440) 1011LO. 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.
Original languageEnglish
Pages (from-to)1-15
Number of pages15
JournalThe Astrophysical Journal
Issue number1
Publication statusPublished - 2015


  • galaxies: active
  • galaxies: starburst
  • infrared: galaxies
  • quasars: general
  • X-rays: galaxies

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