Research Repository

See what's under the surface


Dynamical obstruction to perpetual motion from Lorentz-violating black holes (2018)
Journal Article
Benkel, R., Bhattacharyya, J., Louko, J., Mattingly, D., & Sotiriou, T. P. (2018). Dynamical obstruction to perpetual motion from Lorentz-violating black holes. Physical Review D, 98(2), doi:10.1103/PhysRevD.98.024034. ISSN 2470-0010

Black holes in Lorentz-violating theories have been claimed to violate the second law of thermodynamics by perpetual motion energy extraction. We revisit this question for a Penrose splitting process in a spherically symmetric setting with two specie... Read More

Revisiting the cuscuton as a Lorentz-violating gravity theory (2018)
Journal Article
Bhattacharyya, J., Coates, A., Colombo, M., Gümrükçüoğlu, A. E., & Sotiriou, T. P. (2018). Revisiting the cuscuton as a Lorentz-violating gravity theory. Physical Review D, 97(6), doi:10.1103/PhysRevD.97.064020. ISSN 2470-0010

The cuscuton is a scalar field with infinite speed of propagation. It was introduced in the context of cosmology but it has also been claimed to resemble Horava gravity in a certain limit. Here we revisit the cuscuton theory as a Lorentz-violating gr... Read More

Causality and black holes in spacetimes with a preferred foliation (2016)
Journal Article
Bhattacharyya, J., Colombo, M., & Sotiriou, T. P. (2016). Causality and black holes in spacetimes with a preferred foliation. Classical and Quantum Gravity, 33(23), doi:10.1088/0264-9381/33/23/235003

We develop a framework that facilitates the study of the causal structure of spacetimes with a causally preferred foliation. Such spacetimes may arise as solutions of Lorentz-violating theories, e.g. Hořava gravity. Our framework allows us to rigorou... Read More

Evolution and spherical collapse in Einstein-Æther theory and Hořava gravity (2016)
Journal Article
Bhattacharyya, J., Coates, A., Colombo, M., & Sotiriou, T. P. (2016). Evolution and spherical collapse in Einstein-Æther theory and Hořava gravity. Physical Review D, 93(6), doi:10.1103/PhysRevD.93.064056

We compare the initial value formulation of the low-energy limit of (nonprojectable) Hořava gravity to that of Einstein-æther theory when the æther is assumed to be hypersurface orthogonal at the level of the field equations. This comparison clearly... Read More