IUCAA Preprints

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Author: search.filters.author.Dadhich, NareshEnd date: 2015

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    On the brown-york quasilocal energy, gravitational charge, and black hole event horizons
    (2015-03-13) Bose, Sukanta; Dadhich, Naresh
    We prove the recently proposed identity for certain black hole spacetimes that relates the difference of the Brown-York quasilocal energy and the Komar charge at the event horizon of the hole to the total energy of the spacetime. We prove this identity for the Kerr-Newman family of black hole spacetimes and for non-static (cosmological) spherically symmetric shear-free perfect fluid solutions of general relativity that contain black hole event horizons. We explicitly demonstrate its validity by applying it to several asymptotically fiat as well as non-fiat black hole solutions, including the case of a black hole with a global monopole charge.
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    On electrogravity duality
    (2015-03-11) Dadhich, Naresh
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    A duality relation for fluid spacetime
    (2015-03-11) Dadhich, Naresh; Patel, L.K.; Tikekar, R.
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    New classes of black hole spacetime in 2+1 gravity
    (2015-03-01) Bose, Sukanta; Dadhich, Naresh; Kar, Syan
    New multi-parameter families of black holes in three-dimensional (3D) gravity are obtained. We apply the electrogravity transformation (which implies an exchange of the Ricci and Einstein tensors) to the 3D field equations to obtain these solutions. Several properties of these geometries, including the nature of the matter that threads them, are discussed. Some of these properties are found to be strikingly different from known black holes in (2+1) dimensions.
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    Domain walls in kaluza-klein spacetime
    (2015-03-01) Patel, L.K.; Dadhich, Naresh; Tikekar, R.
    Three families of exact solutions of Einstein field equations are found. Each family contains three parameters. Two of these families represent thick domain walls in a five dimensional Kaluza-Klein spacetime.The dynamical behaviour of our models is briefly discussed. The spacetime in all the cases is found to be reflection symmetric with respect to the wall.
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    Higher dimensional analogue of McVittie solution
    (2015-03-01) Patel, L.K.; Tikekar, R.; Dadhich, Naresh
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    Exact solutions for null fluid collapse in higher dimensions
    (2015-03-01) Patel, L.K.; Dadhich, Naresh
    A large family of inhomogeneous non-static spherically symmetric solutions of the Einstein equation for null fluid in higher dimensions has been obtained. It encompasses higher dimensional versions of many previously known solutions such as Vaidya, charged Vaidya and Husain solutions and also some new solutions representing global monopole or string dust. It turns out that physical properties of the solutions carry over to higher dimensions.
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    Electromagnetic duality in general relativity
    (2015-03-01) Dadhich, Naresh
    By resolving the Riemann curvature relative to a unit timelike vector into electric and magnetic parts, we consider duality relations analogous to the electromagnetic theory. It turns out that the duality symmetry of the Einstein action implies the Einstein vacuum equation without the cosmological term. The vacuum equation is invariant under interchange of active and passive electric parts giving rise to the same vacuum solutions but the gravitational constant changes sign. Further by modifying the equation it is possible to construct interesting dual solutions to vacuum as well as to flat spacetimes.
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    Gravoelectric-dual of the kerr solution
    (2015-03-01) Dadhich, Naresh; Patel, L.K.
    By decomposing the Riemann curvature into electric and magnetic parts, we define the gravoelectric duality transformation by interchange of active and passive electric parts which amounts to interchange of the Ricci and Einstein tensors. It turns out that the vacuum equation is duality-invariant. We obtain solutions dual to the Kerr solution by writing an effective vacuum equation in such a way that it still admits the Kerr solution but is not duality invariant. The dual equation is then solved to obtain the dual-Kerr solution which can be interpreted as the Kerr black hole sitting in a string dust universe.