Outputs (28)

Stability of scalarized black hole solutions in scalar-Gauss-Bonnet gravity (2019)
Journal Article
Silva, H. O., Macedo, C. F., Sotiriou, T. P., Gualtieri, L., Sakstein, J., & Berti, E. (2019). Stability of scalarized black hole solutions in scalar-Gauss-Bonnet gravity. Physical Review D, 99(6), 1-9. https://doi.org/10.1103/physrevd.99.064011

Scalar-tensor theories of gravity where a new scalar degree of freedom couples to the Gauss-Bonnet invariant can exhibit the phenomenon of spontaneous black hole scalarization. These theories admit both the classic black hole solutions predicted by g... Read More about Stability of scalarized black hole solutions in scalar-Gauss-Bonnet gravity.

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), Article 024034. https://doi.org/10.1103/PhysRevD.98.024034

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 about Dynamical obstruction to perpetual motion from Lorentz-violating black holes.

Spontaneous scalarization of black holes and compact stars from a Gauss-Bonnet coupling (2018)
Journal Article
Silva, H. O., Sakstein, J., Gualtieri, L., Sotiriou, T. P., & Berti, E. (2018). Spontaneous scalarization of black holes and compact stars from a Gauss-Bonnet coupling. Physical Review Letters, 120(13), Article 131104. https://doi.org/10.1103/PhysRevLett.120.131104

We identify a class of scalar-tensor theories with coupling between the scalar and the Gauss-Bonnet invariant that exhibit spontaneous scalarization for both black holes and compact stars. In particular, these theories formally admit all of the stati... Read More about Spontaneous scalarization of black holes and compact stars from a Gauss-Bonnet coupling.

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), https://doi.org/10.1103/PhysRevD.97.064020

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 about Revisiting the cuscuton as a Lorentz-violating gravity theory.

Constructing neutron stars with a gravitational Higgs mechanism (2018)
Journal Article
Franchini, N., Coates, A., & Sotiriou, T. P. (2018). Constructing neutron stars with a gravitational Higgs mechanism. Physical Review D, 97(6), https://doi.org/10.1103/PhysRevD.97.064013

In scalar-tensor theories, spontaneous scalarization is a phase transition that can occur in ultradense environments such as neutron stars. The scalar field develops a non-trivial configuration once the stars exceeds a compactness threshold. We recen... Read More about Constructing neutron stars with a gravitational Higgs mechanism.

Detecting Lorentz violations with gravitational waves from black hole binaries (2018)
Journal Article
Sotiriou, T. P. (2018). Detecting Lorentz violations with gravitational waves from black hole binaries. Physical Review Letters, 120(4), https://doi.org/10.1103/PhysRevLett.120.041104

Gravitational wave observations have been used to test Lorentz symmetry by looking for dispersive effects that are caused by higher order corrections to the dispersion relation. In this Letter I argue on general grounds that, when such corrections ar... Read More about Detecting Lorentz violations with gravitational waves from black hole binaries.

Hořava gravity after GW170817 (2018)
Journal Article
Emir Gümrükçüoğlu, A., Saravani, M., & Sotiriou, T. P. (in press). Hořava gravity after GW170817. Physical Review D, 97(2), https://doi.org/10.1103/PhysRevD.97.024032

The recent detection of gravitational wave GW170817 has placed a severe bound on the deviation of the speed of gravitational waves from the speed of light. We explore the consequences of this detection for Hořava gravity.

Black hole horizons at the extremal limit in Lorentz-violating gravity (2017)
Journal Article
Franchini, N., Saravani, M., & Sotiriou, T. P. (2017). Black hole horizons at the extremal limit in Lorentz-violating gravity. Physical Review D, 96(10), Article 104044. https://doi.org/10.1103/PhysRevD.96.104044

Lorentz-violating gravity theories with a preferred foliation can have instantaneous propagation. Nonetheless, it has been shown that black holes can still exist in such theories and the relevant notion of an event horizon has been dubbed “universal... Read More about Black hole horizons at the extremal limit in Lorentz-violating gravity.

Gravitational Higgs mechanism in neutron star interiors (2017)
Journal Article
Coates, A., Horbatsch, M. W., & Sotiriou, T. P. (2017). Gravitational Higgs mechanism in neutron star interiors. Physical Review D, 95(8), Article 084003. https://doi.org/10.1103/PhysRevD.95.084003

We suggest that nonminimally coupled scalar fields can lead to modifications of the microphysics in the interiors of relativistic stars. As a concrete example, we consider the generation of a non-zero photon mass in such high-density environments. Th... Read More about Gravitational Higgs mechanism in neutron star interiors.

Black hole hair formation in shift-symmetric generalised scalar-tensor gravity (2017)
Journal Article
Benkel, R., Sotiriou, T. P., & Witek, H. (2017). Black hole hair formation in shift-symmetric generalised scalar-tensor gravity. Classical and Quantum Gravity, 34(6), Article 064001. https://doi.org/10.1088/1361-6382/aa5ce7

A linear coupling between a scalar field and the Gauss–Bonnet invariant is the only known interaction term between a scalar and the metric that: respects shift symmetry; does not lead to higher order equations; inevitably introduces black hole hair i... Read More about Black hole hair formation in shift-symmetric generalised scalar-tensor gravity.