J. V. Narlikar
Articles written in Journal of Astrophysics and Astronomy
Volume 2 Issue 3 September 1981 pp 289-307
We examine a Doppler theory of quasars in which it is assumed that a fraction of the total population of quasars are fired from centres of explosion with moderate cosmological redshifts. It is argued that the substantial part of the redshift of a typical high redshift quasar could be of Doppler origin. If Hoyle’s recent hypothesis that quasars emit the bulk of their radiation in a narrow backward cone is given a quantitative form, it is shown that the kinematic and emission parameters of this model can explain the observed features of the four aligned triplets of quasars discovered by Arp and Hazard (1980) and by Saslaw (personal communication). The model predicts a small but nonzero fraction of quasars with blueshifts. Further observational tests of the model are discussed.
Volume 3 Issue 4 December 1982 pp 393-398
The Newtonian theory of gravitation is modified to include the gravitational energy as a source of gravitational potential, thus making the theory self-coupled and nonlinear. The modified theory can be derived from a Lorentz-invariant action principle. The Kepler problem is discussed in this theory and it is shown that the perihelion of the orbit steadily precesses. The rate of precession is, however, insufficient to account for the observed precession of the perihelion of Mercury. The differences from the Newtonian theory for the bending of light and the gravitational redshift of spectral lines are shown to be marginal.
Volume 5 Issue 1 March 1984 pp 67-78
The concept of the steady-state universe discussed by Hoyle & Narlikar two decades ago is revived in the light of the present discussions of the phase transition in the early big-bang universe. It is shown that with suitable scaling the bubble universe solution bears a striking similarity to the inflationary scenarios being discussed today. The currently discussed idea of cosmic baldness was also anticipated in the C-field cosmology of the steady-state universe.
Volume 5 Issue 4 December 1984 pp 495-506
Over the past fifteen years, observations of some quasars with the techniques of very-long-baseline interferometry have shown that the angular separation between pairs of radio-emitting regions in their cores is increasing year after year. If the quasars are indeed as far away as implied by Hubble’s law, then these angular motions translate into linear speeds several times the speed of light. Several theoretical scenarios have been proposed to show that the observed motions are illusory. The leading contender in this field — the relativistic beam model — and an alternative offered by the concept of a gravitational screen are described and compared in the light of recent observational data.
Volume 6 Issue 1 March 1985 pp 75-75 Erratum
Volume 6 Issue 4 December 1985 pp 171-175
This paper gives a full nonlinear version of Newtonian gravity in which the gravitational energy acts as a source of the gravitational field. The generalized field equation for the scalar gravitational potential is solved for a spherically symmetric localized distribution of matter. It is shown that the perihelia of orbits of test particles in such a field precess steadily. The effect is, however, too small to account for the observed shift in the perihelion of planet Mercury. Further, the bending of light in this theory is zero. It is suggested that these inadequacies of the quasi-Newtonian framework call for more sophisticated approaches to gravity.
Volume 7 Issue 2 June 1986 pp 99-103
It is shown that the luminosity-volume test for optically selected objects has an in-built bias towards increasing the average value of
Volume 12 Issue 1 March 1991 pp 7-16
This paper investigates the effects of the spatial variation of the cosmological constant λ on the spacetime geometry within and outside a massive object. It is seen that the variation of λ with the radial coordinate introduces non-trivial changes leading to spacetime closing on itself around a massive object. It may also be possible to generate interior solutions that lead to flat rotation curves of galaxies
Volume 18 Issue 4 December 1997 pp 465-475
Volume 18 Issue 4 December 1997 pp 477-489
Volume 19 Issue 3-4 December 1998 pp 133-139
Using the metric conformal transformation and simple path integral, Feynman propagator method, for computing its quantum fluctuations, we analyse the radiation dominated anisotropic Bianchi Type I cosmology. We proceed to show that the quantum conformal fluctuations diverge at the classical spacetime singularity, suggesting that a singularity free solution can exist in anisotropic cosmology in the quantum regime.
Volume 19 Issue 3-4 December 1998 pp 141-146
Using simple path integral, Feynman propagator method and the relation between conformal time
Volume 28 Issue 1 March 2007 pp 17-27
There is a growing interest among cosmologists for theories with negative energy scalar fields and creation, in order to model a repulsive gravity. The classical steady state cosmology proposed by Bondi, Gold & Hoyle in 1948, was the first such theory which used a negative kinetic energy creation field to invoke creation of matter. We emphasize that creation plays a very crucial role in cosmology and provides a natural explanation to the various explosive phenomena occurring in local (𝑧 < 0.1) and extra galactic universe.We exemplify this point of view by considering the resurrected version of this theory – the quasi-steady state theory, which tries to relate creation events directly to the large scale dynamics of the universe and supplies more natural explanations of the observed phenomena.
Although the theory predicts a decelerating universe at the present era, it explains successfully the recent SNe Ia observations (which require an accelerating universe in the standard cosmology), as we show in this paper by performing a Bayesian analysis of the data.
Volume 40 | Issue 2
Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.