Gravity theory and gravitational wave phenomenology

In a recent paper published in Physical Review Letters, Xisco Jiménez Forteza (former postdoc in our group, now at MPI), Swetha Bhagwat (former postdoc in our group, now Hawking Fellow at Birmimgham), Sumit Kumar (MPI), and Paolo Pani have developed a novel tests of gravity using ringdown gravitational signals produced after the merger of two compact objects. The main idea is that the amplitudes and phases of the quasinormal modes of the remnants produced in a binary black hole coalescence are uniquely predicted by General Relativity. However, in extensions of Einstein's theory, or if the two merging objects are not black holes, the quasinormal modes are excited differently. In this recent paper, this novel test has been performed using the outstanding event GW190521 and it has been found that the signal is in agreement with General Relativity.  

The test is particularly well suited for accommodating multiple loud ringdown detections as those expected from future detectors such as the Einstein Telescope, and can be used complementarily to standard black-hole spectroscopy as a proxy for modified gravity, compact objects other than black holes, binary precession and eccentricity.

More information:

Novel Ringdown Amplitude-Phase Consistency Test
Xisco Jiménez Forteza, Swetha Bhagwat, Sumit Kumar, and Paolo Pani
Phys. Rev. Lett. 130, 021001 – Published 11 January 2023