Pulsar Constraints on Screened Modified Gravity

TL;DR

This paper investigates how scalar fields in screened modified gravity models affect energy loss in binary pulsar systems, deriving new bounds on scalar interactions but concluding pulsar tests are less competitive than existing constraints.

Contribution

It provides the first detailed analysis of scalar radiation effects in screened modified gravity models using pulsar data, establishing new bounds on scalar charge variation.

Findings

Pulsar observations set bounds on the time variation of scalar charge.

The bounds translate into limits on the scalar interaction range in the Milky Way.

Current pulsar constraints are weaker than existing observational limits.

Abstract

We calculate the rate of energy loss from compact astrophysical objects due to a scalar field in screened modified gravity models of the chameleon, dilaton and symmetron types. The cosmological evolution of the field results in a time-variation of the scalar charge of screened objects implying the emission of scalar radiation. Focusing on binary objects, this leads to an additional decay in the orbital period complementing that due to the emission of gravitational waves. Using the Hulse-Taylor binary pulsar, the double pulsar PSR J0737-3039 and the pulsar-white dwarf system PSR J1738+033, we find a new observational bound on the time variation of the scalar charge of the earth in the Milky Way. We then translate this into a new bound on the range of the scalar interaction in the Milky Way. Ultimately, we find that pulsar tests are not competitive with current observational constraints.