In September 2015, detectors at the LIGO observatory in Livingston (LLO) and Hanford (LLH) detected, for the first time, evidence of a gravitational wave, an event that Einstein had predicted a century earlier, but had not been predicted by the scientific community. been able to demonstrate until then. Gravitational waves are waves in space-time that travel at the speed of light and spread out in a characteristic pattern . Thus, before the explosion of a supernova or a collision of black holes, ripples are generated that expand throughout the space-time in the universe.
Now, a work published in The Astrophysical Journal Letters describes the detection of gravitational waves arising from the collision of a neutron star with a black hole. The event was caught not once, but twice, by the LIGO observatory in the US and the Virgo in Italy, and the researchers responsible announce that their observations will help describe some of the most complex mysteries in the universe, including the basic components of the universe. matter and the workings of space and time.
It happened a billion years ago
Susan Scott, a co-author of the study and a researcher at the Australian National University, has explained that the events occurred approximately one billion years ago, but were so massive that we can still observe their gravitational waves today. “These collisions have shaken the universe to its core and we have detected the waves that have sent at full speed through the cosmos,” he says.
“Each collision is not just the union of two massive and dense objects. It’s really like Pac-Man, with a black hole completely swallowing its companion neutron star, ”says the researcher. One of the events captured includes a black hole with a mass nine times that of our own Sun and a neutron star that is twice its mass. The protagonists of the other event were a black hole with approximately six times the mass of our Sun and a neutron star with 1.5 times its mass.
Previously, this international team of scientists had already captured many events related to the collision of two black holes and two neutron stars colliding with each other. “Now, we have completed the last piece of the puzzle with the first confirmed observations of gravitational waves from a black hole and the collision of a neutron star,” the authors explain.
Both detections were made between January 5 and 15, 2020. ” We have not detected these events once, but twice and ten days apart, ” explains Johannes Eichholz, another of the authors. “Like the ripples from these two events, which have been felt a billion years later, these findings will have a profound impact on our understanding of the universe.”
