1992 (IPP)

Permanent URI for this collectionhttp://localhost:4000/handle/11007/2663

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Subject: search.filters.subject.Cosmology

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    Generation of seed perturbations from quantum cosmology
    (2014-11-26) Souradeep, Tarun
    The origin of seed perturbations in the Universe is studied within the framework of a specific mini super space model. It is shown that the ‘creation’ of the Universe as a result of a quantum transition from a flat empty space time would lead to a flat FLRW (Friedmann Lemaitre Robertson- Walker) Universe with weak inhomogeneous perturbations at large wavelengths. The power spectrum of these perturbations is found to be scale invariant at horizon crossing (i.e., the Harrison- Zeldovich spectrum). It is also recognised that the seed perturbations generated in our model would be generically of the isocurvature kind.
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    Cylindrically symmetric viscous universes
    (2014-11-26) Patel, L.K.; Dadhich, Naresh
    We have considered here cylindrically symmetric cosmological models with viscous fluid having the Kasnerian time evolution. It turns out that the ‘‘no‐matter’’ limit of our geodetic viscous universes, which can as well be looked upon as string dust universes, is the non-flat empty Kasner spacetime. We thus propose that the universe may be born with the Kasner geometry at t = 0 with matter in the form of viscous fluid, then it may follow the path: geodetic to non-geodetic and finally to the radiation phase when viscosity is fully worn out. We have solutions to describe each phase separately.
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    Singularity free inhomogeneous viscous fluid cosmological models
    (2014-11-23) Patel, L.K.; Dadhich, Naresh
    We obtain two new classes of singularity free inhomogeneous viscous fluid cosmological solutions, which reduce to the Senovilla [1] class when viscosity is switched off. It is interesting to note that inclusion of viscosity does not disturb the singularity free character and general behavior of the models remains qualitatively same.