Gravitational collapse of a self-gravitating unidirectional fluid flow

This paper explores the collapsing process of a unidirectional isotropic matter configuration. The junction conditions for a static exterior geometry and the non-static interior geometry are expressed in terms of the cosmological constant. The time-lapse for the appearance of the black hole and the cosmological horizon is calculated. It is observed that in the de-Sitter space, the unidirectional perfect fluid flow does not make the collapse disappear. The vacuum energy of the cosmological constant makes the collapsing process quite slow and affects the time-lapse of horizon formation. Moreover, the presence of string tension increases the time-lapse of horizon formation.