2000/10/04 by Anna Wolter, Wolter, Anna, Annalisa Celotti +1
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0010086
proceedings of "Blazar Demographics and Physics", ASP Conf. Series, P. Padovani and C. M. Urry eds., 4 pages, 4 ps figures
arxiv created 2000/10/04 · arxiv updated 2009/12/01
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.