Electromagnetic outflows in a class of scalar-tensor theories: Binary neutron star coalescence

Marcelo Ponce , Carlos Palenzuela , Enrico Barausse (1) , Luis Lehner

1 IAP - Institut d'Astrophysique de Paris

As we showed in previous work, the dynamics and gravitational emission of binary neutron-star systems in certain scalar-tensor theories can differ significantly from that expected from general relativity (GR) in the coalescing stage. In this work we examine whether the characteristics of the electromagnetic counterparts to these binaries—driven by magnetosphere interactions prior to the merger event—can provide an independent way to test gravity in the most strongly dynamical stages of binary mergers. We find that the electromagnetic flux emitted by binaries in these scalar-tensor theories can show deviations from the GR prediction in particular cases. These differences are quite subtle, thus requiring delicate measurements to differentiate between GR and the type of scalar-tensor theories considered in this work using electromagnetic observations alone. However, if coupled with a gravitational-wave detection, electromagnetic measurements might provide a way to increase the confidence with which GR will be confirmed (or ruled out) by gravitational observations.

Mots clés: perturbation theory; related approximations; Wave generation and sources; General Relativity and Quantum Cosmology; Astrophysics - High Energy Astrophysical Phenomena; 04.50.Kd; 04.25.D-; 04.25.Nx; 04.30.Db; Modified theories of gravity; Numerical relativity; Post-Newtonian approximation

Domaines: Planète et Univers [physics]

Marcelo Ponce, Carlos Palenzuela, Enrico Barausse, Luis Lehner. Electromagnetic outflows in a class of scalar-tensor theories: Binary neutron star coalescence. Physical Review D, 2015, 91, ⟨10.1103/PhysRevD.91.084038⟩. ⟨insu-03644969⟩