http://arxiv.org/abs/1611.02632
The data release 1 (DR1) of milliarcsecond-scale accurate optical positions of stars and galaxies was recently published by the space mission Gaia. We analyze the offsets of highly accurate absolute radio (very long baseline interferometry, VLBI) and optical positions of active galactic nuclei (AGN) to check whether a signature of wavelength-dependent parsec-scale structure can be seen. We use in the analysis astrometric positions of thousands of AGNs from the VLBI and Gaia observations as well as reconstructed VLBI images. We have found that there is a statistically significant excess of sources with VLBI-to-Gaia positional offset directions along the jet for a full range of offset values as well as an excess for the direction opposite to the jet if offset values are less than 3 mas. An existence of strong extended parsec-scale optical jet structure in many AGNs is required to explain the observed VLBI-Gaia offsets along the jet direction. The 1-mas offsets in the opposite direction are explained by a non-point-like VLBI jet structure or the “core-shift” effect due to synchrotron opacity.
Y. Kovalev, L. Petrov and A. Plavin
Wed, 9 Nov 16
39/56
Comments: 4 pages, 4 figures; submitted to A&A Letters
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