Ground-space interferometer RadioAstron provides unique opportunity to probe
detail structure of the distant active galactic nuclei at μas scales. Here
we report on RadioAstron observations of the BL Lac object S5 0716+71,
performed in a framework of the AGN Polarization and Survey Key Science
Programs at 22 GHz during 2012-2018. We obtained the highest angular resolution
image of the source to date, at 57×24μas. It reveals complex
structure of the blazar jet in the inner 100 μas, with emission regions
that can be responsible for the blazar variability at timescales of a few days
to week. Linear polarization is detected in the core and jet areas at the
projected baselines up to about 5.6 Earth diameters. The observed core
brightness temperature in the source frame of ≥2.2×1013 K is in
excess of theoretical limits, suggesting the physical conditions are far from
the equipartition between relativistic particles and magnetic field.Comment: 11 pages, 4 figures; Unedited, Advances in Space Research, in press;
Proceedings of the COSPAR 2018 42nd Assembly (Pasadena, CA, July 14-22 2018