EVN observations of weak blazars

We undertook a survey with the European Very Long Baseline Interferometry Network at 5 GHz of a complete sample of weak blazars, aiming to a follow-up comparison between high- and lowpower samples of blazars. We observed 87 sources extracted from the “Deep X-ray Radio Blazar Survey”. All of the sources observed were detected. Point-like sources on milli-arcsecond scale are found in 39 cases, 45 show core-jet structure, and 3 possibly have triple structure. According to their spectral indices, 56 sources show a flat or inverted spectral index. They can be considered blazars. Twenty-nine sources show a steep spectrum or a spectrum peaking at a frequency around 1−2 GHz. Fourteen flat spectrum plus 1 steep spectrum sources are also γ-ray emitters detected by the Fermi Gamma-ray Space Telescope. About 50% of them are BL Lacs. The DXRBS containes about 13% of BL Lacs in total. This supports the finding that BL Lacs are more preferably detected by Fermi. We confirm the correlation found between the source core flux density and the γ-ray photon fluxes down to fainter flux densities. We found that weak blazars are also weaker γ-ray emitters compared to bright blazars. 12th European VLBI Network Symposium and Users Meeting