We use cookies to ensure that we give you the best experience on our website. You can change your cookie settings at any time. Otherwise, we'll assume you're OK to continue.

Department of Physics

# Staff profile

## Publication details for Prof David Alexander

Chen, C.-T.J., Hickox, R.C., Alberts, S., Harrison, C.M., Alexander, D.M., Assef, R., Brodwin, M., Brown, M.J.I., Del Moro, A., Forman, W.R., Gorjian, V., Goulding, A.D., Hainline, K.N., Jones, C., Kochanek, C.S., Murray, S.S., Pope, A., Rovilos, E. & Stern, D. (2015). A Connection between Obscuration and Star Formation in Luminous Quasars. The Astrophysical Journal 802(1): 50.

### 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 ($L_{{\rm IR}}^{{\rm SF}}$). Correspondingly, we show that the AGN obscured fraction rises from 0.3 to 0.7 between (4–40) × ${{10}^{11}}{{L}_{\odot }}$. 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.