“School of Physics”

Back to Papers Home
Back to Papers of School of Physics

Paper   IPM / P / 12277
School of Physics
  Title:   Revisiting Cosmic No-Hair Theorem for Inflationary Settings
  Author(s): 
1.  A. Maleknejad
2.  M.M. Sheikh-Jabbari
  Status:   Published
  Journal: Phys. Rev. D
  Vol.:  85
  Year:  2012
  Pages:   123508
  Supported by:  IPM
  Abstract:
In this work we revisit Wald's cosmic no-hair theorem in the context of accelerating Bianchi cosmologies for a generic cosmic fluid with non-vanishing anisotropic stress tensor and when the fluid energy momentum tensor is of the form of a cosmological constant term plus a piece which does not respect strong or dominant energy conditions. Such a fluid is the one appearing in inflationary models. We show that for such a system anisotropy may grow, in contrast to the cosmic no-hair conjecture. In particular, for a generic inflationary model we show that there is an upper bound on the growth of anisotropy. For slow-roll inflationary models our analysis can be refined further and the upper bound is found to be of the order of slow-roll parameters. We examine our general discussions and our extension of Wald's theorem for three classes of slow-roll inflationary models, generic multi-scalar field driven models, anisotropic models involving U(1) gauge fields and the gauge-flation scenario.

Download TeX format
back to top
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
Clients Logo
scroll left or right