Strong gravitational lensing—a probe for extra dimensions and Kalb-Ramond field

Chakraborty, Sumanta; SenGupta, Soumitra

doi:10.1088/1475-7516/2017/07/045

Cited by 86 publications

(49 citation statements)

References 96 publications

(162 reference statements)

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“…Spherically symmetric spacetimes constitute an essential part of black hole physics because all the fundamental properties of the black holes can be explained and can further be used to recognize and hence generalize in any eligible more general scenario [116]. In this paper, we discussed two main issues.…”

Section: Discussionmentioning

confidence: 99%

Charged spherically symmetric black holes inf(R)gravity and their stability analysis

2019

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A new class of analytic charged spherically symmetric black hole solutions, which behave asymptotically as flat or (A)dS spacetimes, is derived for specific classes of f (R) gravity, i.e., fwhere Λ is the cosmological constant. These black holes are characterized by the dimensional parameter α that makes solutions deviate from the standard solutions of general relativity. The Kretschmann scalar and squared Ricci tensor are shown to depend on the parameter α which is not allowed to be zero. Thermodynamical quantities, like entropy, Hawking temperature, quasi-local energy and the Gibbs free energy are calculated. From these calculations, it is possible to put a constrain on the dimensional parameter α to have 0 < α < 0.5, so that all thermodynamical quantities have a physical meaning. The interesting result of these calculations is the possibility of a negative black hole entropy. Furthermore, present calculations show that for negative energy, particles inside a black hole, behave as if they have a negative entropy. This fact gives rise to instability for f RR < 0. Finally, we study the linear metric perturbations of the derived black hole solution. We show that for the odd-type modes, our black hole is always stable and has a radial speed with fixed value equal to 1. We also, use the geodesic deviation to derive further stability conditions.

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Section: Discussionmentioning

confidence: 99%

Charged spherically symmetric black holes inf(R)gravity and their stability analysis

2019

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“…where η LR is the impact parameter of the (unstable) LR and {a, b} are constants [72]. We remark that, despite not being an angle, the impact parameter η ≡ L/E can be used to parametrize the initial angle in O (e.g.…”

Section: Lensing By a Horizonless Ucomentioning

confidence: 99%

Shadows and strong gravitational lensing: a brief review

Cunha¹,

Herdeiro²

2018

Gen Relativ Gravit

451

289

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For ultra compact objects (UCOs), Light Rings (LRs) and Fundamental Photon Orbits (FPOs) play a pivotal role in the theoretical analysis of strong gravitational lensing effects, and of BH shadows in particular. In this short review, specific models are considered to illustrate how FPOs can be useful in order to understand some non-trivial gravitational lensing effects. This paper aims at briefly overviewing the theoretical foundations of these effects, touching also some of the related phenomenology, both in General Relativity (GR) and alternative theories of gravity, hopefully providing some intuition and new insights for the underlying physics, which might be critical when testing the Kerr black hole hypothesis.

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“…In particular, f (R) theories of gravity has drawn significant interest in the past few years due to its ability to explain the late time cosmic acceleration [21][22][23][24][25][26][27][28][29][30][31][32][33] and its close correspondence with scalar-tensor theories of gravity [34][35][36][37][38][39][40][41]. In addition Lovelock theories of gravity [42][43][44][45][46][47][48][49], f (T ) gravity [50][51][52][53][54][55], higher dimensional along with higher curvature modifications to gravitational dynamics [56][57][58][59][60][61] play crucial roles in explaining various scenarios among the alternative gravity theories. On the other hand, among the scalar coupled gravity theories (also known as the scaler-tensor theories) Horndeski theories are of particular interest.…”

Section: Introductionmentioning

confidence: 99%

Horndeski theories confront the Gravity Probe B experiment

Mukherjee

Chakraborty

2018

Phys. Rev. D

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In this work we have investigated various properties of a spinning gyroscope in the context of Horndeski theories. In particular, we have focused on two specific situations -(a) when the gyroscope follows a geodesic trajectory and (b) when it is endowed with an acceleration. In both these cases, besides developing the basic formalism, we have also applied the same to understand the motion of a spinning gyroscope in various static and spherically symmetric spacetimes pertaining to Horndeski theories. Starting with the Schwarzschild de-Sitter spacetime as a warm up exercise, we have presented our results for two charged Galileon black holes as well as for a black hole in scalar coupled Einstein-Gauss-Bonnet gravity. In all these cases we have shown that the spinning gyroscope can be used to distinguish black holes from naked singularities. Moreover, using the numerical estimation of the geodetic precession from the Gravity Probe B experiment, we have constrained the gauge/scalar charge of the black holes in these Horndeski theories. Implications are also discussed. * sm13ip029@iiserkol.ac.in

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Strong gravitational lensing—a probe for extra dimensions and Kalb-Ramond field

Cited by 86 publications

References 96 publications

Charged spherically symmetric black holes inf(R)gravity and their stability analysis

Charged spherically symmetric black holes inf(R)gravity and their stability analysis

Shadows and strong gravitational lensing: a brief review

Horndeski theories confront the Gravity Probe B experiment

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