title: A positive-energy theorem for Einstein-aether and Hořava gravity.
abstract: Energy positivity is established for a class of solutions to Einstein-aether theory and the IR limit of Hořava gravity within a certain range of coupling parameters. The class consists of solutions where the aether 4-vector is divergence-free on a spacelike surface to which it is orthogonal (which implies that the surface is maximal). In particular, this result holds for spherically symmetric solutions at a moment of time symmetry.
authors.affiliation: Department of Physics, Oakland University, Rochester, Michigan 48309, USA.
authors.forename: David
authors.initials: D
authors.lastname: Garfinkle
authors.forename: Ted
authors.initials: T
authors.lastname: Jacobson