New Constraints on Preferred Frame Effects from Binary Pulsars

TL;DR

This paper uses binary pulsar observations to set new, stringent limits on preferred frame effects predicted by alternative gravity theories, improving constraints on key parameters in strong gravitational fields.

Contribution

It provides the first strong-field constraints on PPN parameters  and  using recent pulsar timing data, surpassing previous weak-field bounds.

Findings

Established the best limits on  and  in the strong-field regime.

Demonstrated decoupling of  and  contributions at low eccentricity.

Improved constraints on  beyond weak-field measurements.

Abstract

Preferred frame effects (PFEs) are predicted by a number of alternative gravity theories which include vector or additional tensor fields, besides the canonical metric tensor. In the framework of parametrized post-Newtonian (PPN) formalism, we investigate PFEs in the orbital dynamics of binary pulsars, characterized by the two strong-field PPN parameters, \alpha_1 and \alpha_2. In the limit of a small orbital eccentricity, \alpha_1 and \alpha_2 contributions decouple. By utilizing recent radio timing results and optical observations of PSRs J1012+5307 and J1738+0333, we obtained the best limits of \alpha_1 and \alpha_2 in the strong-field regime. The constraint on \alpha_1 also surpasses its counterpart in the weak-field regime.