## Role of the scalar field in gravitational lensing
^{1} Theoretical Astrophysics Group, Tata Institute of
Fundamental Research, Homi Bhabha Road, Colaba, Mumbai (Bombay)
400005, India^{2} Department of Applied Mathematics, University of
Zululand, Private Bag X1001, Kwa-Dlangezwa 3886, South Africa
A static and circularly symmetric lens characterized by mass and scalar charge parameters is constructed. For the small values of the scalar charge to the mass ratio, the gravitational lensing is qualitatively similar to the case of the Schwarzschild lens; however, for large values of this ratio the lensing characteristics are significantly different. The main features are the existence of two or nil Einstein ring(s) and a radial critical curve, formation of two or four images and possibility of detecting three images near the lens for sources located at relatively large angular positions. Such a novel lens may also be treated as a naked singularity lens.
## Contents- 1. Introduction
- 2. Einstein deflection angle for a general static spherically symmetric metric
- 3. Janis-Newman-Winicour solution and the deflection angle
- 4. Image positions, magnification and critical curves
- 5. Gravitational lens as a diagnostic of scalar charge
- 6. Discussion and summary
- Acknowledgements
- References
© European Southern Observatory (ESO) 1998 Online publication: August 6, 1998 |