Scientists have verified an essential property of black holes

 

Scientists have verified an essential property of black holes

The research team conducted an analysis of data from the most massive black hole merger ever recorded. Black holes, characterized by their mass and angular momentum, are remarkably simple entities compared to the more intricate matter distributions found in stars or planets.

These mysterious cosmic entities emit a unique gravitational wave spectrum with distinct frequencies that gradually decay over time. When two black holes merge, the final phase of gravitational wave emission manifests as a mixture of rapidly damped sinusoids. The black hole no-hair theorem, an important property governing black holes, postulates that the quasi normal mode spectrum of a black hole should be highly constrained. This is because only two parameters, mass and spin, are expected to determine the entire spectrum.

A global team of researchers from Radboud University has validated this fundamental characteristic of black holes through meticulous analysis of gravitational wave observations. Their focus was on re-evaluating data from the binary black hole merger event known as GW190521, the heaviest merger detected to date, which was observed by LIGO and the Virgo observatory in May 2019.

Employing more sensitive techniques, the researchers uncovered an unexpected revelation in the data—a second, considerably weaker quasinormal mode that had eluded previous investigations. The revelation defied expectations, as it was previously believed that detecting such an event would require significantly more sensitive detectors, possibly not available until the mid-2030s.

Professor Badri Krishnan of Radboud University expressed his surprise, saying, “More than 20 years ago, we proposed these observations to verify the nature of black holes. At the time, we doubted that the current capabilities of the LIGO and Virgo detectors would enable the observation of multiple ringdown modes. Therefore, these results are particularly satisfying for me. To date, we have found no deviations from the predictions of general relativity, confirming Einstein's accuracy. Our analysis indicates that the frequencies and damping times of the quasinormal modes align with the expectations of general relativity.

Journal Reference:

1.     Collin D. Capano, Miriam Cabero, Julian Westerweck, Jahed Abedi, Shilpa Kastha, Alexander H. Nitz, Yi-Fan Wang, Alex B. Nielsen, and Badri Krishnan. Multimode Quasinormal Spectrum from a Perturbed Black Hole. Physical Review Letters. DOI: 10.1103/PhysRevLett.131.221402