AT1 - Extended Theories of Gravity and Quantum Cosmology |
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Speaker |
Gergely, László Árpád |
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Coauthors |
Racskó, Bence |
| Talk Title |
Shock-waves in the gravitational wave compatible Horndeski theories with linear kinetic term |
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Abstract |
Propagating shock-waves can be discussed in terms of junction conditions between space-time regions separated by a hypersurface. Recent observations of gravitational waves and their electromagnetic counterparts established that the former also propagate with the speed of light. Hence energetic gravitational waves could be perceived as shock-waves on null hypersurfaces. The most generic scalar-tensor theories with at most second order dynamics, the Horndeski-theories were severely constrained. We derive generic junction conditions for the subclass of allowed Horndeski-theories with linear kinetic term dependence, exploring a formalism based on a transverse vector, rather than normal, which can be applied to any type of hypersurfaces, including null. In the particular case of a non-null hypersurface we obtain a generalised Lanczos equation, with the jump of the extrinsic curvature induced by both the distributional energy-momentum tensor of the wavefront of the shock-wave, and by the jump in the transverse derivative of the scalar. For null hypersurfaces we derive constraints on the surface density, current and pressure of a distributional light-like shock-wave. |
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