Research Publications
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Item On the apparent superluminal separation of radio sources components(Willy-Blackwell, 1979-01-13) Chitre, S. M.; Narlikar, J. V.Item Applications of statistical techniques to the angular size-flux density relation for extraglactic radio sources(Willy-Blackwell, 1977-01-14) Narlikar, J. V.; Chitre, S. M.The data on the angular sizes (theta) and flux densities (S) of extragalactic radio sources selected from two surveys are subjected to two independent statistical tests in order to determine whether the data warrant the conclusion that the universe is evolving. The nature of the observed scatter in the (theta, S) relation is examined, and a minimum chi-squared test is used to compare the observed (theta, S) plot with three theoretical models (one evolutionary and two nonevolutionary). A median test is then applied to compare the median angular sizes of two source samples in a narrow range of flux density. The results obtained indicate that due to the existing large scatter in the (theta, S) data, it is not possible to distinguish clearly between the evolutionary and the nonevolutionary models.Item Effect of intergalactic dust on the measurement of the cosmological deceleration parameter qo(Indian Academy of Sciences, 1976-01-11) Chitre, S. M.; Narlikar, J. V.In a recent attempt to explain the cosmic microwave background without the big bang, a thermalization mechanism involving intergalactic whisker grains of graphite was proposed. The effect of absorption by the intergalactic medium in general, and of the above type in particular, on the measurement of the deceleration parameter q0 of the expanding universe is discussed. Its effect is shown to be comparable in magnitude but opposite to that of the luminosity evolution in galaxies. A consequential selection effect is also discussed.Item Astrophysical applications of the gravitational searchlight(Plenum Publishing Corporation, 1976-01-15) Chitre, S. M.; Narlikar, J. V.The astrophysical consequences of the blue-shifted radiation emitted in the forward direc- tion by a source moving in an equatorial orbit with radius slightly in excess of 1.5 times the Schwarzschild radius of a highly collapsed central object are examined with special reference to quasistellar objects.Item Blueshift and spectral features of the gravitational searchlight(Plenum Publishing Corporation, 1975-01-17) Chitre, S. M.; Narlikar, J. V.; Kapoor, R. C.It is shown that a photon emitted in the forward direc- tion by a charged particle moving in an equatorial cir- cular orbit centred on a highly collapsed mass M, the radius being slightly in excess of one and a half times the Schwarzschild radius, is strongly blueshifted when it arrives at a distant receiver. A ring shaped emit- ting region composed of such orbiting particles has a power law spectrum of the form d~/~ as seen by a distant stationary observer.Item Neutral currents and the cooling of neutron stars(Kluwer Academic Publishers, 1975-01-06) Chitre, S. M.; Narlikar, J. V.; Ramadurai, S.Although the neutrino cooling rate by purely leptonic processes is altered by the neutral currents, the overall cooling of model neutron stars is shown to remain practically unaffected.Item Gravitational searchlight effect(Astronomical Society of India, 1975-01-11) Chitre, S. M.; Narlikar, J. V.; Kapoor, R. C.Item Gravitational searchlight and its astrophysical applications(Nature Publishing Group, 1974-12-06) Chitre, S. M.; Narlikar, J. V.; Kapoor, R. C.