Evidence for a Population of Beamed Radio‐intermediate Quasars

Whether radio intermediate quasars possess relativistic jets as radio-loudquasars is an important issue in the understanding of the origin of radioemission in quasars. In this letter, using the two-epoch radio data obtainedduring Faint Image of Radio Sky at Twenty centimeter sky (FIRST) and NOAO VLASky Survey (NVSS), we identify 89 radio variable sources in the Sloan DigitalSky Survey. Among them, more than half are radio intermediate quasars(RL=f2cm/f2500A<250). For all objects with available multiple band radioobservations, the radio spectra are either flat or inverted. The brightnesstemperature inferred from the variability is larger than the synchrotron-selfCompton limit for a stationary source in 87 objects, indicating of relativisticbeaming. Considering the sample selection and viewing angle effect, we concludethat relativistic jets probably exist in a substantianl fraction of radiointermediate quasars.Comment: 15 pages, 4 figures, 1 table, Accepted to the Astrophysical Journa