Constraining the cosmological constant and the DGP gravity with the double pulsar PSR J0737-3039

TL;DR

This study uses the double pulsar PSR J0737-3039 to test the effects of the cosmological constant and DGP gravity on orbital dynamics, finding no detectable influence within current measurement errors.

Contribution

It introduces a novel ratio-based method to compare observed orbital discrepancies with theoretical predictions for Lambda and DGP gravity effects in a pulsar system.

Findings

Observed ratio R is consistent with zero within errors.

Theoretical effects of Lambda and DGP are incompatible with observed data.

Results support previous Solar System tests negating local effects of these theories.

Abstract

We consider the double pulsar binary system as a laboratory to locally test the orbital effects induced by an uniform cosmological constant $\Lambda$ in the framework of the known general relativistic laws of gravity, and the DGP braneworld model of gravity independently of the cosmological acceleration itself for which they were introduced. We, first, construct the ratio R=Delta\dot\omega/Delta P of the discrepancies between the phenomenologically determined periastron rate \dot\omega and orbital period and their predicted values from the 1PN approximation and the third Kepler law. Then, we compare its value R = (0.3 +/- 4) \times 10^-11 s^-2, compatible with zero within the errors, to the ratios R_Lambda and R_DGP of the effects induced on the apsidal rate and the orbital period by Lambda and the DGP gravity; we find them neatly incompatible with R being R_Lambda = (3.4 +/- 0.3) \times 10^-8 s^-2 and R_DGP = (1.4 +/- 0.1) \times 10^-7 s^-2, respectively. Such a result, which for the case of Lambda is valid also for any other Hooke-like exotic force proportional to r, is in agreement with other negative local tests recently performed in the Solar System with the ratios of the non-Newtonian/Einsteinian perihelion precessions for several pairs of planets.