• DOI:10.1111/j.1365-2966.2005.09043.x
• Corpus ID: 15298984

The luminosity dependence of the type 1 active galactic nucleus fraction

@article{Simpson2005TheLD,
  title={The luminosity dependence of the type 1 active galactic nucleus fraction},
  author={Chris Simpson},
  journal={Monthly Notices of the Royal Astronomical Society},
  year={2005},
  volume={360},
  pages={565-572}
}

• C. Simpson
• Published 23 March 2005
• Physics
• Monthly Notices of the Royal Astronomical Society

Using a complete, magnitude-limited sample of active galaxies from the Sloan Digital Sky Survey, we show that the fraction of broad-line (type 1) active galactic nuclei (AGNs) increases with luminosity of the isotropically emitted [O III] narrow emission line. Our results are quantitatively in agreement with, and far less uncertain than, similar trends found from studies of X-ray and radio-selected active galaxies. While the correlation between broad-line fraction and luminosity is qualitatively consistent with the receding torus model, its slope is shallower and we therefore propose a modification to this model where the height of the torus increases slowly with AGN luminosity. We demonstrate that the faint-end slope of the AGN luminosity function steepens significantly when a correction for 'missing' type 2 objects is made, and that this can substantially affect the overall AGN luminosity density extrapolated from samples of more luminous objects.