Braneworld black holes as gravitational lenses

Eiroa, Ernesto F.

doi:10.1590/s0103-97332005000700026

Cited by 23 publications

(7 citation statements)

References 18 publications

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“…Other spherically-symmetric and static black hole models have found some interest because their existence is predicted by alternative theories of gravity. E.g., the bending properties have been worked out for black holes from string theory [39], from braneworld gravity [224,433,122,123,41], from Einstein-Born-Infeld theory [124], from dilaton theory [286,168] and from Hořava-Lifshitz gravity [76]. Up to now there is no observational indication that any of these black holes exist in nature.…”

Section: Historical Notesmentioning

confidence: 99%

Gravitational Lensing from a Spacetime Perspective

Perlick

2004

Living Rev. Relativ.

421

501

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The theory of gravitational lensing is reviewed from a spacetime perspective, without quasi-Newtonian approximations. More precisely, the review covers all aspects of gravitational lensing where light propagation is described in terms of lightlike geodesics of a metric of Lorentzian signature. It includes the basic equations and the relevant techniques for calculating the position, the shape, and the brightness of images in an arbitrary general-relativistic spacetime. It also includes general theorems on the classification of caustics, on criteria for multiple imaging, and on the possible number of images. The general results are illustrated with examples of spacetimes where the lensing features can be explicitly calculated, including the Schwarzschild spacetime, the Kerr spacetime, the spacetime of a straight string, plane gravitational waves, and others.

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Section: Historical Notesmentioning

confidence: 99%

Gravitational Lensing from a Spacetime Perspective

Perlick

2004

Living Rev. Relativ.

421

501

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“…However, it was Bozza et al [49] who first defined the strong-field deflection limit to analytically investigate the Schwarzschild black hole lensing. This technique has been applied to static, spherically symmetric metrics which includes Reissner−Nordstrom black holes [50], braneworld black holes [51][52][53][54], charged black hole of heterotic string theory [55], and was also generalized to an arbitrary static, spherically symmetric metric by Bozza [56]. On the other hand, lensing in the strong gravitational field is a powerful tool to test the nature of compact objects, therefore, it continues to receive significant attention, and more recent works include lensing from other black holes [57][58][59][60].…”

Section: Introductionmentioning

confidence: 99%

Gravitational lensing by black holes in the 4D Einstein-Gauss-Bonnet gravity

Islam

Kumar

Ghosh

2020

J. Cosmol. Astropart. Phys.

148

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Recently, a non-trivial 4D Einstein-Gauss-Bonnet (EGB) theory of gravity, by rescaling the GB coupling parameter as α/(D−4), was formulated in [1], which bypasses Lovelock's theorem and avoids Ostrogradsky instability. The theory admits a static spherically symmetric black hole, unlike 5D EGB or general relativity counterpart, which can have both Cauchy and event horizons. We generalize previous work, on gravitational lensing by a Schwarzschild black hole, in the strong and weak deflection limits to the 4D EGB black holes to calculate the deflection coefficients ā and b̄, while former increases and later decrease with increasing α. We also find that the deflection angle αD, angular position θ∞ and um decreases, but angular separation s increases with α. The effect of the GB coupling parameter α on positions and magnification of the source relativistic images is discussed in the context of SgrA* and M87* black holes. A brief description of the weak gravitational lensing using the Gauss-Bonnet theorem is presented.

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“…Later, Bozza [6] used the strong field limit approximation to obtain analytical expressions for the positions and magnification of the relativistic images and extended his method of lensing for a general class of static and spherically symmetric space-times to show that the logarithmic divergence of the deflection angle at photon sphere is a generic feature for such space-times. Bozza's [6] methods was extended to several static, spherically symmetric metrics which includes Reissner−Nordstrom black holes [7], braneworld black holes [8][9][10][11], charged black hole of heterotic string theory [12]. The strong gravitational field continues to receive significant attention, more recent works include lensing from other black holes [13][14][15][16] and from various modifications of Schwarzschild geometry [17][18][19][20][21][22][23], and more recently in 4D Einstein-Gauss-Bonnet gravity [24,25,27].…”

Section: Introductionmentioning

confidence: 99%

Investigating strong gravitational lensing effects by suppermassive black holes with Horndeski gravity

Kumar,

Islam,

Ghosh

2021

Preprint

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We study gravitational lensing in strong field limit by a static spherically symmetric hairy black hole in quartic scalar field Horndeski theory. We find an increase in the deflection angle αD, photon sphere radius xps, and angular position θ∞ that increases more quickly while angular separation s more slowly, but ratio of the flux of the first image to all other images rmag decreases rapidly with increasing magnitude of the hair q. We find that the angular position or the the separation of the first and second order images is very insensitive to the changes in the source position β. Therefore, the separation of these images could give accurate estimation of the distance of black hole of known mass. We also discuss the astrophysical consequences in the supermassive black holes at the centre of several galaxies and note that the hairy black holes in Horndeski gravity can be quantitatively distinguished from the Schwarzschild black hole. Notably, we find that the deviation ∆θ∞ of hairy black holes in Horndeski gravity from their general relativity (GR) counterpart, for supermassive black holes Sgr A* and M87, respectively, can reach as much as 25.192 µas and 18.92 µas (for q = −0.5) while ∆s is about 1.121 µas for Sgr A* and 0.8424 µas for M87*. The ratio of the flux of the first image to all other images suggest that the Schwarzschild images are brighter than those of the hairy black holes in Horndeski gravity wherein the deviation |∆rmag| is as much as 3.082. The results suggest that observational tests of hairy black holes in Horndeski gravity are indeed feasible.

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Braneworld black holes as gravitational lenses

Cited by 23 publications

References 18 publications

Gravitational Lensing from a Spacetime Perspective

Gravitational Lensing from a Spacetime Perspective

Gravitational lensing by black holes in the 4D Einstein-Gauss-Bonnet gravity

Investigating strong gravitational lensing effects by suppermassive black holes with Horndeski gravity

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