Investigations in Theoretical Astrophysics

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Research in three major areas of theoretical astrophysics will be carried out. The areas are: (i) Gravitational Lensing: Several cases of lensing have been discovered where the background source is thought to be an extended galaxy rather than the more common point-like quasar. The characteristics of lensing of extended sources will be explored and compared with observations. (ii) Radio Pulsars: A detailed phenomenological model for the birth and evolution of pulsars in the Galaxy will be developed. Issues to be considered include (a) the timescale of field decay, (b) correlation of pulsar velocity with magnetic field, and (c) the initial rotation periods of pulsars at birth. (iii) Scintillation: Intensity scintillation due to scattering occurs in a variety of astronomical situations: (a) Radio interstellar scintillation, (b) radio interplanetary scintillation, (c) optical scintillation in the earth's atmosphere, (d) optical scintillation in planetary atmospheres, (e) ionospheric scintillation. A variety of phenomena related to (a), (b) and (c) will be explored taking advantage of similarities in the basic theoretical framework. Some observations, using the solar wind as a scintillation laboratory, will be carried out.