In September 2015, gravitational waves were detected for the first time by the Ligo detector in the United States. The phenomenon at the origin: a collision of black holes. Since then, researchers have been trying to model these cataclysms. And a recent study comes closer than ever to the reality of these astrophysical events.
In 2015, gravitational waves were captured for the first time by the Ligo interferometer, located in the United States. Since then, Ligo and Virgo (in Italy) have led to the discovery of nearly 100 black hole mergers, astrophysical cataclysms that distort space-time enough to send gravitational waves all the way to us. At the same time, models are progressing more and more to account for the phenomenon.
And a new study published in Physical Review Letters and available on ArXiv has just greatly improved the computational reproduction of black hole mergers. “This is a big step forward in preparing us for the next phase of gravitational wave detection, which will deepen our understanding of gravity and these incredible phenomena that take place in the outer reaches of the cosmos”Macarena Lagos said in a communiqué, co-author of the study. For this, the researchers took into account certain non-linear effects, which were not integrated into the models until today.
New nonlinear effects taken into account in the simulations
More precisely, the team explains that they have added second-order effects of perturbation theory, used to reproduce the collisions of black holes. They describe these essential additions for modeling depreciation. Because gravitational waves can be seen like other types of waves, especially like waves! The principle is the same: the waves influence each other, just like the waves. And linear contributions do not take these interactions into account.
“Nonlinear effects are what happens when waves peak and break on the beachexplained Keefe Mitman, first author of the study and Caltech graduate student. The waves interact and influence each other rather than rolling by themselves. With something as violent as a black hole merger, we expected these effects but hadn’t seen them in our models so far. New methods of extracting the waveforms from our simulations made it possible to see the non-linearities. »
Ligo will be able to detect one black hole merger per hour
According to the authors, this new model might offer up to 10% improvement in the overall accuracy of black hole models. “Supercomputers are needed to perform an accurate calculation of the entire signal: the inspiration of the two orbiting black holes, their merging and stabilization into a single residual black hole at rest, added Saul A. Teukolsky, co-author of the study and one of the pioneers of computer simulation of general relativity equations. The linear treatment of the installation phase was the subject of my doctoral thesis under Kip a long time ago. The new nonlinear processing of this phase will allow for more accurate wave modeling and possibly new tests of whether general relativity is, in fact, the correct theory of gravity for black holes. »
And their results are timely, because the Ligo observatory will restart shortly, following three years of shutdown caused by the Covid-19 pandemic! Its sensitivity has been increased such that it should be able to detect one black hole merger per hour. “We are preparing for the time when we will be detectives of gravitational waves, when we dig deeper to understand everything we can regarding their nature,” concluded in a Columbia University press release Leo C. Stein, co-author of the study.
