Beamed radio-intermediate quasars

In this paper, using the two-epoch radio data obtained during the Faint Images of the Radio Sky at Twenty cm (FIRST) and NRAO VLA Sky Survey (NVSS), we identified 89 radio-variable sources in the Sloan Digital Sky Survey (SDSS). Among them, more than half are radio-intermediate quasars (RL=f_20cm_/f_2500{AA}_<250).

For all objects with available multiple-band radio observations, the radio spectra are either flat or inverted. The brightness temperature inferred from the variability is larger than the synchrotron self-Compton limit for a stationary source in 87 objects, indicating relativistic beaming. Considering the sample selection and the viewing angle effect, we conclude that relativistic jets probably exist in a substantial fraction of radio-intermediate quasars.