Key points are not available for this paper at this time.
Using a sample of optically-selected quasars from the Sloan Digital Sky Survey, we have determined the radio-loud fraction (RLF) of quasars as a function of redshift and optical luminosity. The sample contains more than 30, 000 objects and spans a redshift range of 010 to define radio-loud quasars, we find that b₀=-0. 132+/-0. 116, bᵦ=-2. 052+/-0. 261, and bM=-0. 183+/-0. 025. The RLF at z=0. 5 declines from 24. 3% to 5. 6% as luminosity decreases from M₂₅₀₀=-26 to M₂₅₀₀=-22, and the RLF at M₂₅₀₀=-26 declines from 24. 3% to 4. 1% as redshift increases from 0. 5 to 3, suggesting that the RLF is a strong function of both redshift and luminosity. We also examine the impact of flux-related selection effects on the RLF determination using a series of tests, and find that the dependence of the RLF on redshift and luminosity is highly likely to be physical, and the selection effects we considered are not responsible for the dependence.
Jiang et al. (Wed,) studied this question.