Abstract
Observations of neutron star mergers in the late Universe have given significant restrictions to the class of viable scalar-tensor theories. In this paper we construct black holes within the "self-tuning" class of this restricted set, whereby the bare cosmological constant is absorbed by the dynamics of the scalar, giving a lower effective cosmological constant. We use analytic expansions at the singularity, black hole and cosmological horizon, and asymptotic region, coupled with numerical solutions, to find well-behaved black holes that asymptote to the self-tuned de Sitter geometry. The geometry differs from standard general relativity black holes near the horizon, and the scalar field velocity provides a hair for the black holes.
Highlights
It is a remarkable success of the theory of General Relativity (GR) that it has so far withstood the onslaught of ever more precise astrophysical and cosmological data, and at present remains our best low-energy description of gravity
The recent gravitational wave data [8,9,10,11,12,13] has dealt a strong blow to such models, proving that in the late Universe light and gravity propagate at identical speeds, and ruling out large regions of the parameter space of these theories
We present the only self-tuning model left in the class of Horndeski theories that pass the gravitational wave tests, together with an exact cosmological solution
Summary
It is a remarkable success of the theory of General Relativity (GR) that it has so far withstood the onslaught of ever more precise astrophysical and cosmological data, and at present remains our best low-energy description of gravity. That is not to say, that GR is without its problems, in providing a robust description of the dark sector of the universe These outstanding issues have motivated research into modifications of GR, the prototypical example being scalar-tensor theory, in which one introduces an additional scalar degree of freedom into the gravitational sector. With gravitational wave detectors and electromagnetic observations, we have entered an era that makes it possible to explore the strong field regime of gravity It is more important than ever to understand the behaviour of scalar-tensor theories in this sector. We present the only self-tuning model left in the class of Horndeski theories that pass the gravitational wave tests, together with an exact cosmological solution.
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