Merging galaxies which contain supermassive black holes offer a unique spectacle, as the black holes will consume a high amount of material at a very fast pace, leading to the appearance of a quasar, which emits a massive amount of light.
Astronomers have observed several pairs of merging galaxies with the help of three observatories located in Maunakea. As the galaxies merge, dual quasars will appear, an event which is quite rare as it estimated that less than 0.3% of all quasars contain supermassive black holes on a collision trajectory.
Since quasars are fueled by supermassive black holes, which are billions of times larger than the sun, they emit the brightest light in the known universe. The material found around a supermassive black hole is exposed to immense temperature, releasing a light that is so intense that the quasar can outshine the host galaxy.
Due to heir nature, it is quite difficult to divide the light, which is emitted by two quasars, especially when the tend to be close. It is also hard to survey a sufficient amount of the sky to catch such events.
Hard to find
During the initial stage of the survey, 421 candidates were identified. It was known from the start that most of them wouldn’t be real dual quasars, as they might be projections of starlight from the Milky Way. With the help of two highly-sensitive instruments, the team spotted three pairs of dual quasars, and two of them are new.
Each of the objects observed by the researchers featured the tell-tale sign of cosmic gas, which moves at high speed under the forces exerted by a supermassive black hole. The discovery of dual quasars paves the way for the use of wide-area imaging and advanced spectroscopy observations to track down elusive objects found and learn more about what can be found in the universe.