Constraining models of modified gravity with the double pulsar PSR J0737-3039A/B system

TL;DR

This paper uses precise measurements of the double pulsar system PSR J0737-3039A/B to place constraints on various modified gravity models, including f(R), Yukawa-like fifth force, and MOND, with current data limiting certain parameters.

Contribution

It introduces a novel method of constraining modified gravity models using the orbital period discrepancy in the double pulsar system, independent of the third Kepler law.

Findings

Constraints on f(R) parameter ||< 0.8 10^-26 m^-2

Limits on fifth-force strength ||< 5.5 10^-4 for   =0.006 AU

Strong-acceleration MOND effects are currently too small to constrain

Abstract

In this paper we use Delta P = -1.772341 +/- 13.153788 s between the phenomenologically determined orbital period P_b of the PSR J0737-3039 double pulsar system and the purely Keplerian period P^(0)=2\pi\sqrt{a^3/G(m_A+m_B)} calculated with the system's parameters, determined independently of the third Kepler law itself, in order to put constraints on some models of modified gravity (f(R), Yukawa-like fifth force, MOND). The major source of error affecting Delta P is not the one in the phenomenologically measured period (\delta P_b=4 10^-6 s), but the systematic uncertainty \delta P^(0) in the computed Keplerian one due to the relative semimajor axis a mainly caused, in turn, by the errors in the ratio R of the pulsars' masses and in sin i. We get |\kappa|< 0.8 10^-26 m^-2 for the parameter that in the f(R) framework is a measure of the non linearity of the theory, |\alpha|< 5.5 10^-4 for the fifth-force strength parameter (for \lambda\approx a=0.006 AU). The effects predicted by the strong-acceleration regime of MOND are far too small to be constrained with some effectiveness today and in the future as well. In view of the continuous timing of such an important system, it might happen that in the near future it will be possible to obtain somewhat tighter constraints.