The Radio-loud Fraction of Quasars with Faint Optical Luminosities
Session 88 -- Mulit-Wavelength Observations of Blazars and BL Lacertae Obj Objects
Oral presentation, Wednesday, 11, 1995, 10:00am - 11:30am

## [88.08] The Radio-loud Fraction of Quasars with Faint Optical Luminosities

E. J. Hooper, C. D. Impey (SO), C. B. Foltz (MMTO), P. C. Hewett (IoA, Cambridge, UK)

The observed radio-loud fraction of optically selected quasars decreases for absolute blue magnitudes fainter than $M_{B} \approx -24$, a phenomenon which has been attributed to a selection effect in quasar surveys (e.g., Peacock et al. 1986, MNRAS, 218, 265). A similar decrease was found (Hooper et al. 1995, ApJ submitted) in a sample of the optically-selected Large Bright Quasar Survey (LBQS; Hewett et al. 1995, in preparation) observed at radio wavelengths. The change in radio-loud fraction within the LBQS cannot be explained by the proposed selection bias against quasars with large radio luminosities and small optical luminosities, implying that the effect is a real physical change in the quasar population. An additional sample of LBQS quasars was observed with the VLA and combined with the earlier data to verify this effect and to better determine the form of the change in radio-loud fraction. The radio-loud (8.4 GHz luminosity $> 10^{25}$ W ${\rm Hz}^{-1}$) fraction is 2/70 (3\%) for $M_{B}$ fainter than $-24$, compared to 30/289 (10\%) among the more optically luminous objects, a difference significant at the 98\% confidence level.