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Durham University

Department of Physics

Staff profile

Publication details for Prof Chris Done

Collinson, J.S., Ward, M.J., Done, C., Landt, H., Elvis, M. & McDowell, J.C. (2015). Reaching the peak of the quasar spectral energy distribution - I. Observations and models. Monthly Notices of the Royal Astronomical Society 449(2): 2174-2193.

Author(s) from Durham


We perform a spectral analysis of a sample of 11 medium redshift (1.5 ≲ z ≲ 2.2) quasars. Our sample all have optical spectra from the SDSS, infrared spectra from GNIRS and TripleSpec, and X-ray spectra from XMM–Newton. We first analyse the Balmer broad emission line profiles which are shifted into the IR spectra to constrain black hole masses. Then we fit an energy-conserving, three component accretion model of the broad-band spectral energy distribution (SED) to our multiwavelength data. 5 out of the 11 quasars show evidence of an SED peak, allowing us to constrain their bolometric luminosity from these models and estimate their mass accretion rates. Based on our limited sample, we suggest that estimating bolometric luminosities from L5100A˚L5100A˚ and L2-10 keV may be unreliable, as has been also noted for a low-redshift, X-ray selected active galactic nucleus sample.