An analytic model for non-spherical lenses in covariant MOdified Newtonian Dynamics |
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| Authors: | Huan Yuan Shan Martin Feix Benoit Famaey HongSheng Zhao |
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| Institution: | National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, 100012 Beijing, China;SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS;Institut d'Astronomie et d'Astrophysique, Universite Libre de Bruxelles, CP226, Bvd du Triomphe, B-1050 Bruxelles, Belgium |
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| Abstract: | Strong gravitational lensing by galaxies in MOdified Newtonian Dynamics (MOND) has until now been restricted to spherically symmetric models. These models were able to account for the size of the Einstein ring of observed lenses, but were unable to account for double-imaged systems with collinear images, as well as four-image lenses. Non-spherical models are generally cumbersome to compute numerically in MOND, but we present here a class of analytic non-spherical models that can be applied to fit double-imaged and quadruple-imaged systems. We use them to obtain a reasonable MOND fit to 10 double-imaged systems, as well as to the quadruple-imaged system Q2237+030 which is an isolated bulge-disc lens producing an Einstein cross. However, we also find five double-imaged systems and three quadruple-imaged systems for which no reasonable MOND fit can be obtained with our models. We argue that this is mostly due to the intrinsic limitation of the analytic models, even though the presence of small amounts of additional dark mass on galaxy scales in MOND is also plausible. |
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| Keywords: | gravitational lensing cosmology: theory dark matter |
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