Vol. 248, No. 2, 2010

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The nonexistence of quasi-Einstein metrics

Jeffrey S. Case

Vol. 248 (2010), No. 2, 277–284
Abstract

We study complete Riemannian manifolds satisfying the equation

Ric+∇2f − -1df ⊗ df = 0
m

by studying the associated PDE Δff + exp(2f∕m) = 0 for μ 0. By developing a gradient estimate for f, we show there are no nonconstant solutions. We then apply this to show that there are no nontrivial Ricci flat warped products with fibers that have nonpositive Einstein constant. We also show that for nontrivial steady gradient Ricci solitons, the quantity R + |∇f|2 is a positive constant.

Keywords
Einstein, warped product, quasi-Einstein
Mathematical Subject Classification 2000
Primary: 53C21
Secondary: 58J60
Milestones
Received: 9 September 2009
Revised: 23 January 2010
Accepted: 4 February 2010
Published: 1 December 2010
Authors
Jeffrey S. Case
Department of Mathematics
University of California
Santa Barbara, CA 93106
United States
http://math.ucsb.edu/~casej