As is known, black holes are so named because they do not emit or reflect light or any type of electromagnetic radiation. However, a group of scientists says they have explained a single flash of light generated by the fusion of two black holes. When two black holes spiral around each other and finally fuse together, they emit waves into space-time called gravitational waves. However, this process does not emit light, so until recently these fusions were especially difficult to identify. Now, for the first time, astronomers have observed one that produces light.
With the help of the Zwicky Transient Facility (ZTF) at Caltech University , located at the Palomar Observatory near San Diego, scientists have detected what could be a flare of light from a pair of fused black holes. Their merger was captured by the LIGO Gravitational Wave Observatory and the European Virgo detector on May 21, 2019 at an event called S190521g. As black holes merged, shaking space and time, they sent gravitational waves.
While this was happening, the ZTF was studying the sky and captured an eruption generated by a distant active supermassive black hole, or quasar, called J1249 + 3449 in the region where the S190521g event occurred .