We present a new approach to tackling the issue of radio loudness in quasars. We constrain a (simple) prescription for the intrinsic distribution of radio-to-optical ratios by comparing properties of Monte Carlo simulated samples with those of observed optically selected quasars. We find strong evidence for a dependence of the radio luminosity on the optical one, even though with a large scatter. The dependence of the fraction of radio-loud quasars on apparent and absolute optical magnitudes results in a selection effect related to the radio and optical limits of current surveys. The intrinsic distribution of the radio-to-optical ratios shows a peak at R(1.4)(*) similar to 0.3, with only less than or similar to 5 per cent of objects being included in a high-R(1.4)* tail, which identifies the radio-loud regime. No lack or deficit of sources - but only a steep transition region - is present between the radio-loud and radio-quiet populations at any R(1.4)*. Briefly, we discuss possible origins for this behaviour (e.g. an absence of jets in radio-quiet sources, a large range of radiative radio efficiency, different lifetimes for the accretion and jet ejection phenomena, etc.).
|Titolo:||Is there a dichotomy in the radio loudness distribution of quasars?|
|Autori:||Cirasuolo M; Celotti A; Magliocchetti M; Danese L|
|Rivista:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY|
|Data di pubblicazione:||2003|
|Digital Object Identifier (DOI):||10.1046/j.1365-2966.2003.07105.x|
|Appare nelle tipologie:||1.1 Journal article|