Microlensed image centroid motions by an exotic lens object with negative convergence or negative mass
Abstract
Gravitational lens models with negative convergence inspired by modified gravity theories, exotic matter, and energy have been recently examined in such a way that a static and spherically symmetric modified spacetime metric depends on the inverse distance to the nth power (n=1 for Schwarzschild metric, n=2 for Ellis wormhole, and n≠1 for an extended spherical distribution of matter such as an isothermal sphere) in the weakfield approximation. Some of the models act as if a convex lens, whereas the others are repulsive on light rays like a concave lens. The present paper considers microlensed image centroid motions by the exotic lens models. Numerical calculations show that, for large n cases in the convextype models, the centroid shift from the source position might move on a multiply connected curve like a bow tie, while it is known to move on an ellipse for the n=1 case and to move on an oval curve for n=2. The distinctive feature of the microlensed image centroid may be used for searching (or constraining) localized exotic matter or energy with astrometric observations. It is shown also that the centroid shift trajectory for concavetype repulsive models might be elongated vertically to the source motion direction like a prolate spheroid, whereas that for convextype models such as the Schwarzschild one is tangentially elongated like an oblate spheroid.
 Publication:

Physical Review D
 Pub Date:
 April 2014
 DOI:
 10.1103/PhysRevD.89.084020
 arXiv:
 arXiv:1307.6637
 Bibcode:
 2014PhRvD..89h4020K
 Keywords:

 04.40.b;
 95.30.Sf;
 98.62.Sb;
 Selfgravitating systems;
 continuous media and classical fields in curved spacetime;
 Relativity and gravitation;
 Gravitational lenses and luminous arcs;
 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 22 pages, 8 figures, 3 tables. accepted by PRD. arXiv admin note: substantial text overlap with arXiv:1305.5037