Astrometric microlensing with the RadioAstron space mission

摘要

According to a revised schedule of the Russian Space Agency, in October 2008the 10 m space telescope RadioAstron will be launched in a high eccentric orbit around theEarth. Acting together with ground based radio telescopes, the VLBI interferometer with aground-space arm will operate. The interferometer will have extraordinary angular resolutionof a few microarcsecond (μas) at the shortest wavelength (1.35 cm). Since typical angularscales for gravitational microlensing are at the pas level for cosmological locations of sourcesand microlenses, in principle there is a chance to resolve microimages and (or) at least, detectastrometrical shift of bright point like images. In particular, gravitationally lensed systems, suchas B1600+434, where in radio band a signature of microlensing is found, look suitable for directobservations of microlensing, since microlensing with the RadioAstron interferometer may bedetected in the future (considering its high angular resolution and a relatively high sensitivityand assuming a ground support by the advanced radio telescopes).