A post-Keplerian parameter to test gravito-magnetic effects in binary pulsar systems

TL;DR

This paper investigates the gravito-magnetic correction to the Shapiro time delay in binary pulsar systems, introducing a new post-Keplerian parameter related to the stars' angular momentum, and evaluates its magnitude.

Contribution

It introduces a novel post-Keplerian parameter linked to the intrinsic angular momentum of stars in binary pulsars, expanding gravitational tests.

Findings

The gravito-magnetic correction to the Shapiro delay is quantifiable.

The new parameter's magnitude is small but significant for gravitational tests.

The effects are evaluated for known binary pulsar systems.

Abstract

We study the pulsar timing, focusing on the time delay induced by the gravitational field of the binary systems. In particular, we study the gravito-magnetic correction to the Shapiro time delay in terms of Keplerian and post-Keplerian parameters, and we introduce a new post-Keplerian parameter which is related to the intrinsic angular momentum of the stars. Furthermore, we evaluate the magnitude of these effects for the binary pulsar systems known so far. The expected magnitude is indeed small, but the effect is important per se.