Prospects for probing strong gravity with a pulsar-black hole system

TL;DR

Discovering a pulsar orbiting a black hole could revolutionize tests of relativistic gravity and black hole properties, especially with supermassive black holes, enabling precise measurements and tests of general relativity.

Contribution

This paper highlights the potential of pulsar-black hole systems as powerful tools for testing strong gravity and black hole characteristics, emphasizing future observational prospects.

Findings

Potential for precise black hole mass measurements

Verification of space-time dragging by black hole spin

Testing the no-hair theorem with supermassive black holes

Abstract

The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems, utilizing present and future radio telescopes, like FAST and SKA.