PIRSA:18020083

Two-body problem in modified gravities and EOB theory

Julie, F. (2018). Two-body problem in modified gravities and EOB theory. Perimeter Institute. https://pirsa.org/18020083

Julie, Felix. Two-body problem in modified gravities and EOB theory. Perimeter Institute, Feb. 08, 2018, https://pirsa.org/18020083 

          @misc{ pirsa_PIRSA:18020083,
            doi = {10.48660/18020083},
            url = {https://pirsa.org/18020083},
            author = {Julie, Felix},
            keywords = {Strong Gravity},
            language = {en},
            title = {Two-body problem in modified gravities and EOB theory},
            publisher = {Perimeter Institute},
            year = {2018},
            month = {feb},
            note = {PIRSA:18020083 see, \url{https://pirsa.org}}
          }

Felix Julie

University of Paris-Saclay

Talk number
PIRSA:18020083
Collection
Talk Type
Subject
Abstract

In general relativity, the effective-one-body (EOB) approach, which consists in reducing the two-body dynamics to the motion of a test particle in an effective static, spherically symmetric metric, has proven to be a very powerful framework to describe analytically the coalescence of compact binary systems.

In this seminar, we address its extension to modified gravities, considering first the example of massless scalar-tensor theories (ST). We reduce the ST two-body dynamics, which is known at second post-Keplerian order, to a simple parametrized deformation of the general relativistic EOB Hamiltonian, and estimate the ST corrections to the strong-field regime; in particular, the ISCO location and orbital frequency.

We then discuss the class of Einstein-Maxwell-dilaton (EMD) theories, which provide simple examples of "hairy" black holes. We compute the EMD post-Keplerian two-body Lagrangian, and show that it can, as well, be incorporated within the EOB framework. Finally, we highlight that, depending on their scalar environment, EMD black holes can transition to a regime where they strongly couple to the scalar and vector fields, inducing large deviations from the general relativistic two-body dynamics.