1999 (IPP)
Permanent URI for this collectionhttp://localhost:4000/handle/11007/2909
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Item Interstellar extinction by porous grains(2015-03-01) Vaidya, D.B.; Gupta, RanjanItem A new class of LRS Bianchi Type –I cosmological models in lyra geometry(2015-03-01) Pradhan, Anirudh; Vishwakarma, Anil KumarLRS Bianchi type-1 models have been studied in the cosmological theory based on Lyra's geometry. A new class of exact solutions has been obtained by considering a time dependent and constant displacement field for constant deceleration parameter models of the universe. The physical behaviour of the models is examined in vacuum and in the presence of perfect fluids.Item The quasi- steady state cosmology: A study of angular size against redshift(2015-03-01) Banerjee, S.K.; Narlikar, J.V.The data on angular sizes and redshifts of ultracompact radio sources used by Jackson and Dodgson in a recent paper have been applied to the various theoretical models in the framework of the quasi-steady state cosmology proposed by Hoyle, Burbidge and Narlikar. It is found that although acceptable fits to the data are available for the fiat models, those with a negative curvature of spatial sections provide a better fit. These latter models require low densities of matter and as such do not demand too high a proportion of dark matter. A comparison is made with the work of Jackson and Dodgson and theoretical implications of the test are discussed.Item Reconstructing the cosmic equation of state from supernova distances(2015-03-01) Saini, Tarun Deep; Raychaudhuri, Somak; Sahni, Varun; Strarobinsky, A.A.Item Structure formation in the Quasi-Steady state cosmology: A toy model(2015-03-01) Nayeri, Ali; Engineer, Sunu; Narlikar, J.V.; Hoyle, F.The problem of formation of large scale structure is discussed within the framework of the Quasi-Steady State Cosmology (QSSC) . The primary process of creation of matter and the resulting dynamics of ejection of matter from regions of strong gravitational fields plays a key role. To understand its working, a toy model is used, in which from a set of randomly distributed creation centres a new generation of centres is created as part of an iterative algorithm. It is shown that the system develops clusters and voids along with filamentary structure, within a few iterations. The two point correlation function and density distribution function for these simulations are shown to reproduce the observed clustering of the large scale structure in the real universe.Item The Z abs~Z em absorption line systems toward QSO J2233-606 in the hubble deep field south: Ne VIIIλλ770,780 absorption and partial coverage(2015-03-01) Petitjean, Patrick; Srianand, R.