2004 (IPP)

Permanent URI for this collectionhttp://localhost:4000/handle/11007/625

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    Role of the space-time dimensions & the fluid equation of state in spherical gravitational collapse
    (2011-07-06) Dadhich, Naresh; Ghosh, S. G.; Deshkar, D. W.
    We study the spherically symmetric collapse of a fluid with non-vanishing radial pressure in higher dimensional space-time. We obtain the general exact solution in the closed form for the equation of state (Pr = γρ) which leads to the explicit construction of the root equation governing the nature (black hole versus naked singularity) of the central singularity. A remarkable feature of the root equation is its invariance for the three cases: (D + 1, γ = −1), (D, γ = 0) and (D − 1, γ = 1) where D is the dimension of space-time. That is, for the ultimate end result of the collapse, D-dimensional dust, D + 1 - AdS (anti de Sitter)-like and D − 1 - dS-like are absolutely equivalent.
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    Unifying Brane World Inflation with Quintessence
    (2011-07-06) Sami, M.; Dadhich, Naresh
    We review the recent attempts of unifying inflation with quintessence. It appears natural to join the two ends in the framework of brane world cosmology. The models of quintessential inflation belong to the class of non-oscillatory models for which the mechanism of conventional reheating does not work. Reheating through gravitational particle production is inefficient and leads to the excessive production of relic gravity waves which results in the violation of nucleosynthesis constraint. The mechanism of instant preheating is quite efficient and is suitable for brane world quintessential inflation. The model is shown to be free from the problem of excessive production of gravity waves. The prospects of Gauss-Bonnet brane world inflation are also briefly indicated.