All Outputs (27)

Ringdowns for black holes with scalar hair: The large mass case (2024)
Journal Article
D’Addario, G., Padilla, A., Saffin, P. M., Sotiriou, T. P., & Spiers, A. (2024). Ringdowns for black holes with scalar hair: The large mass case. Physical Review D, 109(8), Article 084046. https://doi.org/10.1103/physrevd.109.084046

Deviations from general relativity can alter the quasinormal mode (QNM) ringdown of perturbed black holes. It is known that a shift-symmetric (hence massless) scalar can only introduce black hole hair if it couples to the Gauss-Bonnet invariant, in w... Read More about Ringdowns for black holes with scalar hair: The large mass case.

Stable spontaneously-scalarized black holes in generalized scalar-tensor theories (2022)
Journal Article
Antoniou, G., Macedo, C. F., McManus, R., & Sotiriou, T. P. (2022). Stable spontaneously-scalarized black holes in generalized scalar-tensor theories. Physical Review D, 106(2), Article 024029. https://doi.org/10.1103/physrevd.106.024029

It has been shown that the synergy of a scalar field coupling with both the Ricci scalar and the Gauss-Bonnet invariant significantly affects the properties of scalarized black holes and neutron stars, including their domain of existence and the amou... Read More about Stable spontaneously-scalarized black holes in generalized scalar-tensor theories.

Black hole scalarization with Gauss-Bonnet and Ricci scalar couplings (2021)
Journal Article
Antoniou, G., Lehébel, A., Ventagli, G., & Sotiriou, T. P. (2021). Black hole scalarization with Gauss-Bonnet and Ricci scalar couplings. Physical Review D, 104(4), Article 044002. https://doi.org/10.1103/PhysRevD.104.044002

Spontaneous scalarization is a gravitational phenomenon in which deviations from general relativity arise once a certain threshold in curvature is exceeded, while being entirely absent below that threshold. For black holes, scalarization is known to... Read More about Black hole scalarization with Gauss-Bonnet and Ricci scalar couplings.

Spin-Induced Scalarized Black Holes (2021)
Journal Article
Herdeiro, C. A., Radu, E., Silva, H. O., Sotiriou, T. P., & Yunes, N. (2021). Spin-Induced Scalarized Black Holes. Physical Review Letters, 126(1), Article 011103. https://doi.org/10.1103/PhysRevLett.126.011103

It was recently shown that a scalar field suitably coupled to the Gauss-Bonnet invariant G can undergo a spin-induced linear tachyonic instability near a Kerr black hole. This instability appears only once the dimensionless spin j is sufficiently lar... Read More about Spin-Induced Scalarized Black Holes.

Detecting Scalar Fields with Extreme Mass Ratio Inspirals (2020)
Journal Article
Maselli, A., Franchini, N., Gualtieri, L., & Sotiriou, T. P. (2020). Detecting Scalar Fields with Extreme Mass Ratio Inspirals. Physical Review Letters, 125(14), Article 141101. https://doi.org/10.1103/PhysRevLett.125.141101

We study extreme mass ratio inspirals (EMRIs), during which a small body spirals into a supermassive black hole, in gravity theories with additional scalar fields. We first argue that no-hair theorems and the properties of known theories that manage... Read More about Detecting Scalar Fields with Extreme Mass Ratio Inspirals.

Prospects for fundamental physics with LISA (2020)
Journal Article
Barausse, E., Berti, E., Hertog, T., Hughes, S. A., Jetzer, P., Pani, P., …Zumalacarregui, M. (2020). Prospects for fundamental physics with LISA. General Relativity and Gravitation, 52(8), Article 81. https://doi.org/10.1007/s10714-020-02691-1

In this paper, which is of programmatic rather than quantitative nature, we aim to further delineate and sharpen the future potential of the LISA mission in the area of fundamental physics. Given the very broad range of topics that might be relevant... Read More about Prospects for fundamental physics with LISA.

Onset of spontaneous scalarization in generalized scalar-tensor theories (2020)
Journal Article
Ventagli, G., Lehébel, A., & Sotiriou, T. P. (2020). Onset of spontaneous scalarization in generalized scalar-tensor theories. Physical Review D, 102(2), Article 024050. https://doi.org/10.1103/PhysRevD.102.024050

In gravity theories that exhibit spontaneous scalarization, astrophysical objects are identical to their general relativistic counterpart until they reach a certain threshold in compactness or curvature. Beyond this threshold, they acquire a nontrivi... Read More about Onset of spontaneous scalarization in generalized scalar-tensor theories.

Self-interactions and spontaneous black hole scalarization (2019)
Journal Article
Macedo, C. F., Sakstein, J., Berti, E., Gualtieri, L., Silva, H. O., & Sotiriou, T. P. (2019). Self-interactions and spontaneous black hole scalarization. Physical Review D, 99(10), 1-11. https://doi.org/10.1103/physrevd.99.104041

It has recently been shown that nontrivial couplings between a scalar and the Gauss-Bonnet invariant can give rise to black hole spontaneous scalarization. Theories that exhibit this phenomenon are among the leading candidates for testing gravity wit... Read More about Self-interactions and spontaneous black hole scalarization.

Black holes and binary mergers in scalar Gauss-Bonnet gravity: Scalar field dynamics (2019)
Journal Article
Witek, H., Gualtieri, L., Pani, P., & Sotiriou, T. P. (2019). Black holes and binary mergers in scalar Gauss-Bonnet gravity: Scalar field dynamics. Physical Review D, 99(6), 1-24. https://doi.org/10.1103/physrevd.99.064035

We study the nonlinear dynamics of black holes that carry scalar hair and binaries composed of such black holes. The scalar hair is due to a linear or exponential coupling between the scalar and the Gauss-Bonnet invariant. We work perturbatively in t... Read More about Black holes and binary mergers in scalar Gauss-Bonnet gravity: Scalar field dynamics.

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.

Ho?ava 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 Ho?ava 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.

Dynamical scalar hair formation around a Schwarzschild black hole (2016)
Journal Article
Benkel, R., Sotiriou, T. P., & Witek, H. (2016). Dynamical scalar hair formation around a Schwarzschild black hole. Physical Review D, 94(12), https://doi.org/10.1103/PhysRevD.94.121503

Scalar fields coupled to the Gauss-Bonnet invariant evade the known no-hair theorems and have nontrivial configurations around black holes. We focus on a scalar field that couples linearly to the Gauss-Bonnet invariant and hence exhibits shift symmet... Read More about Dynamical scalar hair formation around a Schwarzschild black hole.