Interstellar Scintillation Monitoring of the RadioAstron Blazars

Abstract

The RadioAstron space radio telescope provides a unique opportunity to study the extreme brightness temperatures (${\mathrm{T}}_{\mathrm{B}}$) in AGNs with unprecedented long baselines of up to 28 Earth diameters. Since interstellar scintillation (ISS) may affect the visibilities observed with space VLBI (sVLBI), a complementary ground based flux density monitoring of the RadioAstron targets, which is performed near in time to the VLBI observation, could be beneficial. The combination/comparison with the sVLBI data can help to unravel the relative influence of source intrinsic and ISS induced effects, which in the end may alter the conclusions on the ${\mathrm{T}}_{\mathrm{B}}$ measurements from sVLBI. Since 2013, a dedicated monitoring program has been ongoing to observe the ISS of RadioAstron AGN targets with a number of radio telescopes. Here we briefly introduce the program and present results from the statistical analysis of the Effelsberg monitoring data. We discuss the possible effects of ISS on ${\mathrm{T}}_{\mathrm{B}}$ measurements for the RadioAstron target B0529+483 as a case study.

Proceedings for the 14th European VLBI Network Symposium & Users Meeting (EVN 2018) 8-11 October 2018, Granada, Spain