Inflationary universe with anisotropic hair

Masa Aki Watanabe, Sugumi Kanno, Jiro Soda

Research output: Contribution to journalArticlepeer-review

310 Citations (Scopus)


We study an inflationary scenario with a vector field coupled with an inflaton field and show that the inflationary Universe is endowed with anisotropy for a wide range of coupling functions. This anisotropic inflation is a tracking solution where the energy density of the vector field follows that of the inflaton field irrespective of initial conditions. We find a universal relation between the anisotropy and a slow-roll parameter of inflation. Our finding has observational implications and gives a counterexample to the cosmic no-hair conjecture.

Original languageEnglish
Article number191302
JournalPhysical review letters
Issue number19
Publication statusPublished - May 14 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


Dive into the research topics of 'Inflationary universe with anisotropic hair'. Together they form a unique fingerprint.

Cite this