On mathematical analysis for bianchi type–I string cosmological model in modified theory of relativity

The study of cosmic strings has been a subject of much interest for cosmologists. It is believed that these strings give rise to density perturbations leading to the formation of galaxies.1 String theory is a hypothetical framework in which the point-like particles are replaced by one-dimensional objects called strings. On distance scales larger than the string scale, a string in believed to work just like an ordinary particle. In the early universe (strings dominated era), the strings produce fluctuations in the density of particles. We may speculate that as strings vanish and particles become important, then the fluctuations grow in such a way that finally we shall end up with galaxies. The presence of string in the early universe can be explained using grand unified theories (GUT) as already discussed.2‒4 These strings have stress energy and are classified as geometric and massive strings.