Understanding photon sphere and black hole shadow in dynamically evolving spacetimes

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dc.contributor.author Mishra, Akash K.
dc.contributor.author Chakraborty, Sumanta
dc.contributor.author Sarkar, Sudipta
dc.date.accessioned 2019-03-27T06:42:09Z
dc.date.available 2019-03-27T06:42:09Z
dc.date.issued 2019-03
dc.identifier.citation Mishra, Akash K.; Chakraborty, Sumanta and Sarkar, Sudipta, "Understanding photon sphere and black hole shadow in dynamically evolving spacetimes", arXiv, Cornell University Library, DOI: arXiv:1903.06376, Mar. 2019. en_US
dc.identifier.uri http://arxiv.org/abs/1903.06376
dc.identifier.uri https://repository.iitgn.ac.in/handle/123456789/4304
dc.description.abstract We study rheology, microstructure, and response to an applied electric field (E) in suspensions of fumed alumina (Al2O3) nanoparticles in a nematic liquid crystal (NLC) made of N-(4-methoxybenzylidene)-4-butylaniline (MBBA). Fumed Al2O3/MBBA suspensions exhibit flowability with nanoparticle volume fraction (ϕ) = 0.001 and 0.007, and become solid-like gels at a nanoparticle ϕ = 0.014 and beyond. The dynamic rheology of gel-like suspensions follows the soft glass rheology (SGR) model. The effective noise temperature remains close to 1 for these Al2O3/MBBA suspensions, which serves as an indication of the presence of glassy dynamics. Further, the optical microscopy and the differential scanning calorimetry (DSC) reveal that the incorporation of fumed We have derived the differential equation governing the evolution of the photon sphere for dynamical black hole spacetimes with or without spherical symmetry. Numerical solution of the same depicting evolution of the photon sphere has been presented for Vaidya, Reissner-Nordström-Vaidya and de-Sitter Vaidya spacetimes. It has been pointed out that evolution of the photon sphere depends crucially on the validity of the null energy condition by the in-falling matter and may present an observational window to even test it through black hole shadow. We have also presented the evolution of the photon sphere for slowly rotating Kerr-Vaidya spacetime and associated structure of black hole shadow. Finally, the effective graviton metric for Einstein-Gauss-Bonnet gravity has been presented, and the graviton sphere has been contrasted with the photon sphere in this context.
dc.description.statementofresponsibility by Akash K Mishra, Sumanta Chakraborty and Sudipta Sarkar
dc.language.iso en en_US
dc.publisher Cornell University Library en_US
dc.title Understanding photon sphere and black hole shadow in dynamically evolving spacetimes en_US
dc.type Preprint en_US

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