http://arxiv.org/abs/1704.07365
We interpret the recent discovery of a preferable VLBI/Gaia offset direction for active galactic nuclei (AGNs) along the parsec-scale radio jet as a manifestation of their optical structure on scales of 1 to 100 milliarcseconds. The extended jet structure affects the Gaia position stronger than the VLBI position due to the difference in observing techniques. Gaia detects total power while VLBI measures the correlated quantity, visibility. The synergy of VLBI that is sensitive to the position of the most compact source component, usually associated with the opaque radio core, and Gaia that is sensitive to the centroid of optical emission, opens a window of opportunity to study optical jets at milliarcsecond resolution, two orders of magnitude finer than the resolution of most existing optical instruments. We have demonstrated that strong variability of optical jets is able to cause a jitter comparable to the VLBI/Gaia offsets at a quiet state, i.e. several milliarcseconds. We have shown that VLBI/Gaia position jitter correlation against the AGN optical light curve may help to locate the region where the flare occurred, estimate its distance from the super-massive black hole and the ratio of the flux density in the flaring region to the total flux density.
L. Petrov and Y. Kovalev
Wed, 26 Apr 17
35/60
Comments: Submitted to Monthly Notices of the Royal Astronomical Society; 12 pages, 8 figures