Millimeter-wave continuum observation of high-z radio quasars

Abstract

Millimeter-wave continuum observations of high redshift (z3) radio loud quasars (RLQs) and radio intermediate quasars (RIQs) have been performed with the 45 m telescope of the Nobeyama Radio Observatory. Sixteen RLQs with S 5GHz > 200 mJy and nine RIQs with 200 mJy > S 5GHz > 20 mJy were observed at four millimeter-wave frequencies. All the observed quasars have synchrotron spectra and their possible dust emission component is obscured by the synchrotron emission in millimeter-wave frequencies, which can be explained by their strong AGN activities. Observed quasars are classified into three spectral classes, according to their millimeter-wave spectral index as steep spectrum, millimeter turn over and extreme flat spectrum quasars. Extreme flat spectrum quasars have relatively flat spectra up to 150 GHz, where the rest frequency is higher than 600 GHz. This is an indication that the objects are in very young stage of quasar evolution and shows higher nuclear activity than lower redshift quasars. One of the QSOs, 2358+189 previously known as a RIQ, is found to have extreme flat spectrum, and is now classified as RLQs.