Nearly every galaxy in the cosmos houses a supermassive black hole at its center; our own Milky Way Galaxy contains Sagittarius A*, a black hole four million times as massive as our sun. Although Sagittarius A* is by far the closest supermassive black hole to Earth, it is not the only one that is ripe for study.
A team at Durham University in the United Kingdom, led by Professor Chris Done, has conducted observations of a supermassive black hole even more massive than Sagittarius A* – 10 million times more massive than the sun. This particular supermassive black hole, PG1244+026, is located in a spiral galaxy 500 million light years from Earth. PG1244+026 is surrounded by an accretion disc of material being consumed by the black hole.
Done and colleagues gathered data on x-rays and optical and ultraviolet light generated as the black hole devours the disc; they used this information, obtained by the European Space Agency’s XMM-Newton satellite, to determine the distance between the black hole and the disc. This distance depends on the rate of the black hole’s spin; the faster the black hole spins, the closer it pulls the disc towards itself. Having determined the distance separating PG1244+026 and its accretion disc, the team was able to determine the spin of the black hole.
Although it is immense compared to our sun, PG1244+026 is tiny compared to the mass of its host galaxy. “We know the black hole in the center of each galaxy is linked to the galaxy as a whole, which is strange because black holes are tiny in relation to the size of the galaxy,” Done explained in a press release. “This would be like something the size of a large boulder (10 [meters across]) influencing something the size of the Earth.”
Supermassive black holes, such as PG1244+026, eject high energy particles that can hinder the cooling of intergalactic gases and impede the formation of new stars in the outer reaches of a galaxy. The reason black holes emit these jets of particles is not known, but Done and team think they could be connected to the spin of the black hole.
A spinning black hole also pulls space and time and the accretion disc along with it; as the accretion disc moves inward, closer to the black hole, the spin of the black hole increases. By accurately measuring the spins of black holes such as PG1244+026, Done and colleagues aspire to reveal how supermassive black holes affect the evolution of their galaxies. The new research has been published in the journal Monthly Notices of the Royal Astronomical Society.