Horndeski theory meets the McVittie solution: A scalar field theory for accretion onto cosmological black holes

• Published in: Physical review. D, Particles, fields, gravitation, and cosmology Vol. 90; no. 8
• Main Authors: Afshordi, Niayesh, Fontanini, Michele, Guariento, Daniel C.
• Format: Journal Article
• Language: English
• Published: 13-10-2014
• Subjects: Black holes (astronomy); Constants; Cosmology; Field theory; Gravitation; Mathematical analysis; Scalars; Transformations
• ISSN: 1550-7998; 1550-2368
• DOI: 10.1103/PhysRevD.90.084012

We show that the generalized McVittie spacetime, which represents a black hole with time-dependent mass in an expanding universe, is an exact solution of a subclass of the Horndeski family of actions. The heat-flow term responsible for the energy transfer between the black hole and the cosmological background is generated by the higher-order kinetic gravity braiding term, which generalizes the cuscuton action that yields McVittie with constant mass as a solution. Finally, we show that this generalization can be understood in terms of a duality realized by a disformai transformation, connecting the cuscuton field theory to an extension of the Horndeski action which does not propagate any scalar degrees of freedom. Our finding opens a novel window into studies of nontrivial interactions between dark energy/modified gravity theories and astrophysical black holes.