Black holes. They were formerly thought to be hypothetical until the first one was discovered and proven in the late twentieth century. Astronomers now discover them all over the place. We even have direct radio views of two black holes: one in M87 and one in Sagittarius A* at the core of our galaxy.
So, what do we know about them? A lot. But there's more to discover.
Using Chandra X-ray Observatory data, a team of astronomers revealed a shocking finding regarding a core supermassive black hole in a quasar nested in a faraway galaxy cluster. What they discovered sheds light on the formation and development of supermassive black holes.
Two-factor identification of black holes
There are several hurdles to studying a black hole, particularly a supermassive one. Every huge galaxy, it turns out, contains a center monster black hole. As a result, we must learn everything we can about them. Millions, if not billions, of solar masses are contained within these cosmic behemoths.
They have powerful gravitational forces, and nothing, not even light, can escape their grasp. This has an impact on our capacity to examine them and their surrounding areas.
One thing is still unclear: how do these monsters develop and evolve?
The solution may be found in two of their qualities. "Every black hole can be defined by just two numbers: its spin and its mass," said Julia Sisk-Reynes of the Institute of Astronomy (IoA) at the University of Cambridge in the United Kingdom, who conducted a new study of a supermassive black hole 3.6 billion years distant.
"While that sounds fairly simple, figuring those values out for most black holes has proved to be incredibly difficult."
X-raying a black hole
Measuring the masses is tough, but there are methods. Measuring spin is a difficult task. Sisk-Reynes and colleagues used Chandra X-ray Observatory data to learn more about giant black holes.
They investigated data of the quasar H1821+primary 643's supermassive black hole engine in order to determine its spin rate. It has a mass 30 billion times that of the Sun. (By comparison, the center supermassive black hole of the Milky Way possesses only approximately 4 million solar masses.)
Why are X-rays used? A spinning black hole drags space with it, allowing matter to circle closer to it than a non-spinning one. The speed of the black hole is revealed by X-ray measurements.
The spectrum of H1821+643 reveals that its black hole rotation rate is unusual when compared to other less massive black holes that spin at near to the speed of light. The crew was taken aback by the quasar's black hole's slower pace.
"We found that the black hole in H1821+643 is spinning about half as quickly as most black holes weighing between about a million and ten million suns," astronomer Christopher Reynolds said (also of the Institute of Astronomy).
He is co-author of the paper reporting the results of the Chandra measurements. "The million-dollar question is: why?"
Black holes: Origin and evolution
According to co-author James Matthews, the history of H1821+643 may hold the key to understanding its slower spin rate (also at the Institute of Astronomy).
He believes that supermassive black holes like the one in H1821+643 formed by mergers with other black holes when galaxies colliding.
Because galaxy collisions build up bigger galaxies throughout time, the same activities (including dwarf galaxies colliding) are fair game as possible contributors.
It's also feasible that this black hole's outer disk was damaged in a collision, sending gas in all directions throughout the event.
These actions would have an effect on the black hole's spin rate, slowing it down or perhaps torquing it in a totally different direction. As a result, depending on their recent histories, such black holes may exhibit a range of spin rates.
"The moderate spin for this ultramassive object may be a testament to the violent, chaotic history of the universe's biggest black holes," Matthews added.
"It may also give insights into what will happen to our galaxy's supermassive black hole billions of years in the future when the Milky Way collides with Andromeda and other galaxies."
This article was originally published by Universe Today. Read the original article.
