Vainshtein mechanism in binary pulsars

We compute the scalar gravitational radiation from a binary pulsar system in the simplest model that exhibits the Vainshtein mechanism. The mechanism is successful in screening the effect from scalar fields conformally coupled to matter, although gravitational radiation is less suppressed relative to its general relativity predictions than static fifth forces effects within the pulsar system. This is due to a combination of two effects: firstly, the existence of monopole and dipole radiation; secondly the Vainshtein suppression comes from the hierarchy of scales between the inverse frequency scale and the Vainshtein radius, rather than the orbital radius of the pulsar system. Extensions of these results will have direct relevance to infrared modifications of gravity, such as massive gravity theories, which are known to exhibit a Vainshtein mechanism. Generalization to Galileon models with higher-order interactions are likely to provide stronger constraints.

Figure 1

Numerical evaluation of the sums $\sum _{N=0}^{\infty }|I_n^M(e){|}^2$, $\sum _{N=0}^{\infty }|I_n^D(e){|}^2$ and $\sum _{n=0}^N|I_n^Q(e){|}^2$ with $I_n^{M,D,Q}$ expressed in Eqs. (3.10, 4.9, 5.5), respectively, for the eccentricity of the Hulse-Taylor pulsar $1913+16$ $e=0.617$ [27, 28, 29]. The sums show a rapid convergence as $N\to \infty$.