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Item On searches for gravitational waves from mini-creation events by laser interferometric detectors(Wiley-Blackwell, 2006-02-27) Sarmah, B. P.; Banerjee, S.K.; Dhurandhar, Sanjeev; et al.As an alternative view to the standard big bang cosmology, the quasi-steady-state cosmology argues that the Universe was not created in a single great explosion: it did not have a beginning, nor will it ever come to an end. The creation of new matter in the Universe is a regular feature occurring through finite explosive events. Each creation event is called a mini-bang, or a mini-creation event. Gravitational waves are expected to be generated as a result of any anisotropy present in this process of creation. A mini-creation event that ejects matter in two oppositely directed jets is thus a source of gravitational waves, which can in principle be detected by laser interferometric detectors. In the present work we consider the gravitational waveforms propagated by linear jets and then estimate the response of laser interferometric detectors such as LIGO and LISA.Item Inhomogeneities in the microwave background radiation interpreted within the framework of the quasi-steady state cosmology(American Astronomical Society, 2003-03-01) Narlikar, J. V.; Vishwakarma, R. G.; Hajian, Amir; et al.We calcul ate the expected angular power spectrum of the temperature fluctuations in the microwave background radiation (MBR) generated in the quasi–steady state cosmology (QSSC ). The paper begins with a brief description of how the background is produced and thermalized in the QSSC. We then discuss within the framework of a simple model the likely sources of fluctuations in the background due to astrophysical and cosmological causes. Power spectrum peak s at l=6–10, 180–220, and 600–900 are shown to be respectively related in this cosmology to curvature effects at the last minimum of the scale factor, clusters, and groups of galaxies. The effect of clusters is shown to be related to their distribution in space as indicated by a toy model of structure formation in the QSSC. We derive and parameterize the angular power spectrum using six parameters related to the sources of temperature fluctuations at three characteristic scales. We are able to obtain a satisfactory fit to the observational band power estimates of the MBR temperature fluctuation spectrum. Moreover, the values of the best-fit parameters are consistent with the range of expected values .Item Structure formation in the quasi-steady state cosmology : A toy model(American Astronomical Society, 1999-11-01) Nayeri, Ali; Engineer, Sunu; Narlikar, J. V.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 Ðelds play a key role. To understand their workings, a toy model is used, in which from a set of randomly distributed creation centers a new generation of centers 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 Quasi-steady state cosmology: A study of angular size against redshift(Wiley-Blackwell, 1999-02-25) Banerjee, Shyamal K.; Narlikar, J. V.The data on angular sizes and redshifts of ultracompact radio sources used by Jackson & 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 & Narlikar. It is found that although acceptable fits to the data are available for the flat 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 & Dodgson and theoretical implications of the test are discussed.Item On the Hubble and the cosmological constant(Wiley-Blackwell, 1996-10-28) Hoyle, F.; Burbidge, G.; Narlikar, J. V.We review the observational determinations of the Hubble constant which have been made in recent years. We conclude that the most likely value of H_0 is 58 km s^-1 Mpc^-1 with uncertainties of +10 and -5. Thus the age of the standard big bang model is 11.2Gyr. The discrepancy between this value and the ages of the oldest observed stars, 13-16Gyr, appears to be real, necessitating some change in the standard model. A currently favoured procedure for coping with this widely-admitted difficulty for the theory which has been favoured by many cosmologists in recent years is a rebirth of the cosmological constant lambda. Even with this constant, the observations constrain the model very severely. There are theoretical considerations as well. The problem with this constant, as it has been seen over much of the past half-century, is that it is required to have a physical dimensionality of (length)^-2 and to have a magnitude of about 10^-56cm^-2. Theoreticians have not favoured introducing such a quantity ab initio into cosmology, but attempts to explain the genesis of lambda from particle physics have yielded results that are wide of what is required by immense factors (~10^50 to ~10^100). Using an approach from a scale-invariant theory of gravity, we show that lambda can be derived correct to a factor of ~2 within the modern Universe. This derivation does not appear to be applicable to earlier phases of the Universe, which give lambda~=H^2 rather than the relation lambda~=H^2_0 that a true cosmological constant would require.Item Quasi-steady state cosmology: A problem of stability(American Astronomical Society, 1997-09-20) Banerjee, Shyamal K.; Narlikar, J. V.This paper examines the gravitational stability against small perturbations of the -. This model was first introduced by Hoyle et al., who in subsequent papers looked at its various theoretical and observational implications. Here we carry out a perturbation analysis of the exact solution of the field equations obtained by Sachs et al. in the noncreative mode which describes the oscillatory feature of this model. We show that the perturbations grow only to a limited amount and then fall o†, thus confirming the stability of the solution. We discuss the implications of this result for structure formation in this cosmologyItem Quasi-steady state cosmology: analytical solutions of field equations and their relationship to observations(EDP Sciences, 1996-03-02) Sachs, R.; Narlikar, J. V.; Hoyle, F.We solve the cosmological equations obtained by Hoyle, Burbidge and Narlikar (1995a) from a Machian theory of gravity in the case where the universe satisfies the Weyl postulate and the cosmological principle. The equations in effect are the Einstein equations of general relativity together with a negative cosmological constant and a trace-free zero rest-mass scalar field. We find a wide range of solutions for spatial sections of zero, positive and negative curvature. The solution for the quasi-steady state cosmology used by Hoyle, Burbidge and Narlikar (1994 a,b) is shown to be an approximation to the simplest of the above solutions. We apply the simplest solution to work out the redshift-magnitude relation and the radio source count. We show that there are marginal differences from the results obtained by Hoyle et al (1994a), although the present exact solution provides a better rationale for the parameters of the model.Item Evolution of the Correlation Function for a Class of Processes involving Non Local Self - Replication(American Astronomical Society, 2002-11-01) Padmanabhan, T.Alarge class of evolutionary processes can be modeled by a rule that involves self-replication of some physical quantity with a nonlocal rescaling. We show that a class of such models is exactly solvable in the discrete as well as the continuum limit and can represent several physical situations, as varied as from the formation of galaxies in some cosmological models to growth of bacterial cultures. This class of models, in general, has no steady state solution and evolves unstably as as t → ∞ for generic initial conditions. The models can, however, exhibit an (unstable) power-law correlation function in the continuum limit, for an intermediate range of times and length scales.Item Gravitational collapse in an expanding universe: scaling relations for two-dimensional collapse revisited(Wiley-Blackwell, 2005-03-21) Ray, Suryadeep; Bagla, J. S.; Padmanabhan, T.We investigate non-linear scaling relations for two-dimensional (2D) gravitational collapse in an expanding background using a 2D TreePM code, and study the strongly non-linear regime ( ¯ξ 200) for power-law models. Evolution of these models is found to be scale invariant in all our simulations. We find that the stable clustering limit is not reached, but there is a model independent non-linear scaling relation in the asymptotic regime. This confirms results from an earlier study that only probed the mildly non-linear regime( ¯ξ 40). The correlation function in the extremely non-linear regime is a less steep function of scale than reported in earlier studies. We show that this is due to coherent transverse motions in massive haloes. We also study density profiles, and find that the scatter in the inner and outer slopes is large and that there is no single universal profile that fits all cases. We find that the difference in typical density profiles for different models is smaller than expected from similarity solutions for halo profiles, and transverse motions induced by substructure are a likely reason for this difference being small.