On the Stability of (M theory) Stars against Collapse : Role of Anisotropic Pressures

Abstract

Unitarity of evolution in gravitational collapses implies existence of macroscopic stable horizonless objects. With such objects in mind, we study the effects of anisotropy of pressures on the stability of stars. We consider stars in four or higher dimensions and also stars in M theory made up of (intersecting) branes. Taking the stars to be static, spherically symmetric and the equations of state to be linear, we study `singular solutions' and the asymptotic perturbations around them. Oscillatory perturbations are likely to imply instability. We find that non oscillatory perturbations, which may imply stability, are possible if an appropriate amount of anisotropy is present. This result suggests that it may be possible to have stable horizonless objects in four or any higher dimensions, and that anisotropic pressures may play a crucial role in ensuring their stability.

Version 3: 44 pages. To be published in International Journal of Modern Physics A

References in corpus (10)

• All static spherically symmetric anisotropic solutions of Einstein's equations
• The fuzzball proposal for black holes
• General relativistic polytropes for anisotropic matter: The general formalism and applications
• Fractional Brane State in the Early Universe
• Relativistic stars with a linear equation of state: analogy with classical isothermal spheres and black holes
• Consequences of U dualities for Intersecting Branes in the Universe
• 10 + 1 to 3 + 1 in an Early Universe with mutually BPS Intersecting Branes
• Stabilisation of Seven Directions in an Early Universe M -- theory Model
• A critical dimension for the stability of perfect fluid spheres of radiation
• Stars in M theory (made up of intersecting branes)