Testing Gravity with Binary Pulsars in the SKA Era

TL;DR

The paper discusses how the SKA telescope will enhance tests of gravity using binary pulsars, potentially revealing deviations from general relativity and discovering new relativistic systems.

Contribution

It outlines the capabilities needed for SKA to improve gravity tests with pulsars and predicts the discovery of new relativistic pulsar systems, including pulsar-black hole binaries.

Findings

SKA will significantly improve pulsar timing precision.

Potential discovery of pulsar-black hole binaries.

Enhanced tests of strong-field gravity and general relativity.

Abstract

Binary (and trinary) radio pulsars are natural laboratories in space for understanding gravity in the strong field regime, with many unique and precise tests carried out so far, including the most precise tests of the strong equivalence principle and of the radiative properties of gravity. The Square Kilometre Array (SKA) telescope, with its high sensitivity in the Southern Hemisphere, will vastly improve the timing precision of recycled pulsars, allowing for a deeper search of potential deviations from general relativity (GR) in currently known systems. A Galactic census of pulsars will, in addition, will yield the discovery of dozens of relativistic pulsar systems, including potentially pulsar -- black hole binaries, which can be used to test the cosmic censorship hypothesis and the ``no-hair'' theorem. Aspects of gravitation to be explored include tests of strong equivalence principles, gravitational dipole radiation, extra field components of gravitation, gravitomagnetism, and spacetime symmetries. In this chapter, we describe the kinds of gravity tests possible with binary pulsar and outline the features and abilities that SKA must possess to best contribute to this science.