Supermassive black holes have immense gravity due to their rotation speed. In fact, many black holes have an accretion disk around them made up of dust and debris due to their rotation. However, researchers have found exactly what the rotation rate is of one of the most massive black holes in the universe.
In this study, researchers used more than two dozen optical telescopes and NASA's space-based SWIFT X-ray telescope to accurately measure the rotational rate of a massive black hole. The black hole, in this case, lies about 3.5 billion light-years away from Earth, has a mass of about 18 billion solar masses and helps power a quasar called OJ287.
This particular quasar is located close to the apparent path of the sun's motion on the celestial sphere seen from Earth, which means that its optical photometric measurements already cover more than 100 years. The quasar was further shown to have produced quasi-periodic optical outbursts at intervals of about 12 years dating back to around 1891. The research team also found double peaks in these outbursts.
Because of these findings, the researchers created a model where the quasar harbored two black holes. One of the black holes was massive, while the other was smaller and revolved around it. In this model, there was a slow accretion of matter, which allowed the quasar to be visible. The black hole passes through this dusty disk during its orbit, which causes the disk material to become scorching hot. This material then jets out from both sides of the disk and radiates strongly for weeks, which causes peaks in brightness, and the double peaks are due to the fact that the orbit is elliptical.
The researchers then launched an observational campaign to catch a predicted outburst, which helped researchers measure the spin rotation of the black hole. In the end, they found that the massive black hole had a rotation rate of one-third of the maximum spin rate allowed in General Relativity.
The findings reveal a bit more about these types of systems and may help with understanding gravitational waves.
The study was published in the March 10 issue of the Astrophysical Journal Letters.
