The EMSS Radio Loud Quasar Sample

Abstract

We construct the first X-ray selected sample of radio-loud quasars from the EMSS survey. The X-ray selection allows us to explore the properties of radio-loud quasars 10-100 weaker than classical samples in the radio band. There are no radio-loud quasars whose synchrotron peak reaches the UV-soft X-ray band at these (radio) flux levels (as occurs for BL Lac objects selected in the X-ray band), but they appear to have comparatively stronger optical-UV emission. We suggest that this can be ascribed to a significant contribution from a quasi-thermal optical-UV component, emerging due to the comparatively weak non-thermal emission. The detection of sources at low radio fluxes also shows the presence of a large population of steep spectrum quasars, and the lack of the predicted turnover in the quasar counts.