A search for optically quiet quasars

Optically quiet quasars (OQQs) are compact radio-loud and X-ray-bright active galactic nuclei with very weak optical continuum emission. Several explanations have been proposed for the inverted spectral energy distribution (SED) of OQQs, the most likely being reddening and soft X-ray absorption in excess of that expected from the Galaxy. We have made multifrequency observations of three previously known OQQs. The The X-ray spectra are consistent with excess absorption, although we cannot rule out alternative explanations. The wide range of radio and optical properties in these sources suggests that, if excess absorption is important, it arises from a physically unrelated system that intercepts the line of sight. We also observed 10 OQQ candidates selected from two correlations of the ROSAT All-Sky Survey (RASS) with radio surveys. No clear examples of new OQQs were found.