Research Publications

Permanent URI for this communityhttp://localhost:4000/handle/11007/1

Browse

Subject: search.filters.subject.Gravitational lenses

Search Results

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    General relativity and astrophysics
    (Springer, 2010-11-27) Narlikar, J. V.
  • Thumbnail Image
    Item
    3C 273 : A gravitationally lensed quasar?
    (EDP Sciences, 1984-05-30) Chitre, S. M.; Narasimha, D.; Narlikar, J. V.; et al.
    It is suggested that the abnormal brightness of the quasar 3C 273, coupled with the observations of superluminal motions in its radio core B as well as the misalignment of its VLBI jet with the optical jet, can be understood by postulating a faint spheroidal lensing galaxy located about halfway along the line of sight to the quasar. The lens model also helps to understand why the quasar is found slightly off-centre with respect to its nebulosity. The probability for such a lens system to arise for 3C 273 by chance is shown to be no less than that computed on the basis of the relativistic beaming hypothesis. Further tests of the lens model are discussed.
  • Thumbnail Image
    Item
    Quasars Q 2345 + 007 A,B and 3C 273 : Gravitational Lenses?
    (Liege University Press, Liege, 1983-01-14) Narlikar, J. V.; Subramanian, Kandaswamy; Narasimha, D.; et al.
  • Thumbnail Image
    Item
    Associations between quasi-stellar objects and galaxies
    (American Astronomical Society, 1990-11-12) Burbidge, G.; Hewitt, A.; Narlikar, J. V.; et al.
  • Thumbnail Image
    Item
    Is gravitational lensing a local phenomenon caused by Pop - III objects?
    (Gordon and Breach Science Publishers, 1986-01-31) Padmanabhan, T.; Chitre, S. M.
  • Thumbnail Image
    Item
    Focusing equations, caustics and the condition for multiple imaging by thick gravitational lenses
    (Royal Astronomical Society, 1987-12-27) Padmanabhan, T.; Subramanian, Kandaswamy
    The condition for the production of multiple images by an arbitrary (thick or thin) gravitational lens are studied. We show that the necessary and sufficient condition for the production of multiple images by a lens is the following: The lens should produce a point conjugate to the observer, along some null geodesic, at an affine distance smaller than that of the source. It is shown that previous results on multiple imaging by thin lenses can be obtained as a special case. We also show that a thick lens cannot be more efficient than a suitably designed thin lens for the production of multiple images.