Gravitational lensing shear by an exotic lens object with negative convergence or negative mass

Abstract

Gravitational lens models with negative convergence (surface mass density projected onto the lens plane) inspired by modified gravity theories, exotic matter and energy have been recently discussed in such a way that a static and spherically-symmetric modified spacetime metric depends on the inverse distance to the power of positive n (n=1 for Schwarzschild metric, n=2 for Ellis wormhole) in the weak-field approximation [Kitamura, Nakajima and Asada, PRD 87, 027501 (2013)], and it has been shown that demagnification of images could occur for n > 1 lens models associated with exotic matter (and energy), though they cause the gravitational pull on light rays. The present paper considers gravitational lensing shear by the demagnifying lens models and other models such as negative-mass compact objects causing the gravitational repulsion on light rays like a concave lens. It is shown that images by the lens models for the gravitational pull are tangentially elongated, whereas those by the repulsive ones are radially distorted. This feature of lensed image shapes may be used for searching (or constraining) localized exotic matter or energy with gravitational lensing surveys. It is suggested also that an underdense region such as a cosmic void might produce radially elongated images of background galaxies rather than tangential ones. 95.30.Sf, 98.62.Sb

Finite-distance corrections to the gravitational bending angle of light in the strong deflection limit

“…If the light ray passes near the solar surface, Eq. (22) implies that the finite-distance correction to this case is of the order of…”

“…For instance, strong-field gravitational lensing in a Schwarzschild black hole was investigated by Frittelli, Kling and Newman [8], by Virbhadra and Ellis [9] and more comprehensively by Virbhadra [10]; distinctive lensing features of naked singularities were studied by many authors [11][12][13][14][15][16][17][18][19][20]. Kitamura, Nakajima and Asada proposed a lens model in the inverse powers of the distance as 1/r n [21], such that the Schwarzschild lens, the Ellis wormhole lens and a gravitational lens associated with exotic matter (or energy) that might follow a non-standard equation of state can be discussed in a unified manner of describing these models as a one parameter family [22][23][24][25]. See also Tsukamoto et al (2015) [26] for a possible connection between this inverse power model and the Tangherlini solution to the higher-dimensional Einstein equation.…”

Strong deflection limit analysis and gravitational lensing of an Ellis wormhole

“…[22,23,[39][40][41][42][43]. Micro lens [44][45][46][47], astrometric image centroid displacements [48,49], the Einstein rings [43], the time delay of light rays [50], the signed magnification sum [51], the gravitational lensing shear [52], constraints of the number density from gravitational lensing observations [19,53], a wave effect of gravitational lenses [53], shadows surrounded by a plasma [54] and optically thin dust [55], binary gravitational lenses [56], a particle collision [57], and several observables such as rotation curves [58] in the Ellis wormhole spacetime and in general spacetimes that are coincident with the Ellis wormhole spacetime under the weak-field approximation have been investigated. The visualization of the Ellis wormhole was studied by Muller [59].…”

Gravitational lensing in Tangherlini spacetime in the weak gravitational field and the strong gravitational field

“…Gravitational lensing based on 1/r n fall-off metric, as a one-parameter model that can treat by hand both the Schwarzschild lens (n = 1) and the Ellis wormhole (n = 2) in the weak field, has been recently studied [34,[42][43][44][45]. In particular, Kitamura et al showed that the demagnification of the light curves appears in the case n > 1 [42].…”