On December 18, 2024, an international team of scientists announced a breakthrough in detecting a unique phenomenon related to supernova explosions—the gravitational wave memory effect. This effect, predicted by Einstein's theory of relativity, had previously evaded observation. The findings were published in Physical Review Letters.
Gravitational waves are ripples in spacetime generated by cosmic events. The memory effect implies that after a gravitational wave passes, the distance between cosmic objects changes permanently. However, capturing this effect has proven challenging with existing instruments.
Supernovae are massive stars that end their life cycle in powerful explosions, releasing vast amounts of energy, producing neutrinos, emitting light, and generating gravitational waves. Unlike waves from other events, such as black hole mergers, those from supernovae have lower amplitudes and more complex characteristics, complicating their detection. Nonetheless, they provide insights into both external and internal processes of stars that cannot be observed otherwise.
The researchers employed three-dimensional modeling of supernova explosions using a new mathematical framework, focusing on stars with masses up to 25 solar masses. They identified a characteristic slow increase in the signal associated with the memory effect.
Calculations indicate that waves from such stars could be detected by current gravitational wave detectors from distances of up to 30,000 light-years. While contemporary observatories can register weak waves, new instruments like the space-based LISA interferometer are necessary for more precise detection.
Dr. Colter Richardson from the University of Tennessee, the project leader, stated, 'Our method opens new horizons for studying the internal processes in stars, and we hope to expand the frontiers of gravitational astronomy.'