Homogeneous Ricci solitons

Abstract

In this work, we study metrics which are both homogeneous and Ricci soliton. If there exists a transitive solvable group of isometries on a Ricci soliton, we show that it is isometric to a solvsoliton. Moreover, unless the manifold is flat, it is necessarily simply-connected and diffeomorphic to ${\mathbb{R}}^n$. In the general case, we prove that homogeneous Ricci solitons must be semi-algebraic Ricci solitons in the sense that they evolve under the Ricci flow by dilation and pullback by automorphisms of the isometry group. In the special case that there exists a transitive semi-simple group of isometries on a Ricci soliton, we show that such a space is in fact Einstein. In the compact case, we produce new proof that Ricci solitons are necessarily Einstein. Lastly, we characterize solvable Lie groups which admit Ricci soliton metrics.

25pp. The second half of the paper has been dramatically revised. Now included is a characterization of solvable Lie groups admitting Ricci solitons. Final version to appear in Crelle

References in corpus (2)

• On homogeneous Ricci solitons
• Ricci flow of homogeneous manifolds

Cited by in corpus (3)

• Strongly solvable spaces
• Warped product Einstein metrics on homogeneous spaces and homogeneous Ricci solitons
• Ricci flow of homogeneous manifolds