Browsing by Author "Dasgupta, P."
Now showing 1 - 4 of 4
- Results Per Page
- Sort Options
Item Counting of radio sources: is evolution necessary?(American Astronomical Society, 1988-01-12) Dasgupta, P.; Narlikar, J. V.; Burbidge, G.This paper suggests a new and clear-cut way of deciding whether evolutionary effects are necessary to interpret the observed radio-source counts. To this end, a method is outlined for constructing the parent radio luminosity function from a complete sample of radio sources whose redshifts are all known. It is argued that if such a luminosity function can be constructed without evolutionary parameters, then evolutionary effects are not required. The method is illustrated by its applications to two well-known samples of radio sources. It is further shown that the non-evolving luminosity function satisfies the constraint of sky brightness and is consistent with the observed redshift-flux-density plot. Thus it appears from these investigations that evolution is not required either in luminosity or in number density.Item Gravitational waves from mini-creation events(Wiley-Blackwell, 1993-03-19) Dasgupta, P.; Narlikar, J. V.This paper examines the possibility of testing the hypothesis recently proposed by some authors that, instead of the one-shot creation of the entire Universe in a big bang, creation of matter takes place in finite bursts at random in a Universe that is without a beginning and whose expansion on the large scale is as given by the steady-state model. It is argued that if the creation events are anisotropic then they generate gravitational waves. Calculations are given to show that a laser interferometric detector of the LIGO type would easily detect an event that generates ˜100-1000 Msun. Further, the cosmological gravitational wave background generated by the mini-creation events is compared with the limits set by the analysis of the arrival time of pulses from millisecond pulsars. The existing data place severe constraints on the mass and anisotropies of the mini-creation events.Item Gravity wave from mini-creation events(2015-01-13) Dasgupta, P.; Narlikar, J. V.This paper examines the possibility of testing the hypothesis recently proposed by some authors that, instead of the one-shot creation of the entire Universe in a big bang, creation of matter takes place in finite bursts at random in a Universe that is without a beginning and whose expansion on the large scale is as given by the steady state model. It is argued that if the creation events are anisotropic then they generate gravitational waves. Calculations are given to show that a laser interferometric detector of the UGO type would easily detect an event that generates -100-1000M0 .Further, the cosmological gravitational wave background generated by the minicreationevents is compared with the limits set by the analysis of the arrival time of pulses from millisecond pulsars. The existing data place severe constraints on the mass and anisotropies of the mini-creation events.Item Statistical tests of peaks and periodicities of the observed redshift distribution of quasi-stellar objects(American Astronomical Society, 1992-01-01) Duari, Debiprosad; Dasgupta, P.; Narlikar, J. V.