Diffractive microlensing  III. Astrometric signatures
Abstract
Gravitational lensing is generally treated in the geometric optics limit; however, when the wavelength of the radiation approaches or exceeds the Schwarzschild radius of the lens, diffraction becomes important. Although the magnification generated by diffractive gravitational lensing is well understood, the astrometric signatures of diffractive microlensing are first derived in this paper along with a simple closedform bound for the astrometric shift. This simple bound yields the maximal shifts for substellar lenses in solar neighbourhood observed at 20 GHz, accessible to high sensitivity, high angular resolution radio telescopes such as the proposed Square Kilometre Array (SKA).
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 March 2011
 DOI:
 10.1111/j.13652966.2010.17814.x
 arXiv:
 arXiv:1003.0250
 Bibcode:
 2011MNRAS.411.1787H
 Keywords:

 gravitational lensing: micro;
 techniques: high angular resolution;
 astrometry;
 Astrophysics  Astrophysics of Galaxies;
 Astrophysics  Instrumentation and Methods for Astrophysics
 EPrint:
 6 pages, 3 figures, added calculations of expected rates, number of sources and lenses