Our Galaxy's Monster Black Hole Is Spinning Almost As Fast As Physics Allows (sciencealert.com) 11
alternative_right shares a report from ScienceAlert: The colossal black hole lurking at the center of the Milky Way galaxy is spinning almost as fast as its maximum rotation rate. That's just one thing astrophysicists have discovered after developing and applying a new method to tease apart the secrets still hidden in supermassive black hole observations collected by the Event Horizon Telescope (EHT). The unprecedented global collaboration spent years working to give us the first direct images of the shadows of black holes, first with M87* in a galaxy 55 million light-years away, then with Sgr A*, the supermassive black hole at the heart of our own galaxy. [...]
Their results show, among other things, that Sgr A* is not only spinning at close to its maximum speed, but that its rotational axis is pointed in Earth's direction, and that the glow around it is generated by hot electrons. Perhaps the most interesting thing is that the magnetic field in the material around Sgr A* doesn't appear to be behaving in a way that's predicted by theory. M87*, they discovered, is also rotating rapidly, although not as fast as Sgr A*. However, it is rotating in the opposite direction to the material swirling in a disk around it -- possibly because of a past merger with another supermassive black hole. The findings have been detailed in three papers published in the journal Astronomy & Astrophysics. They can be found here, here, and here.
Their results show, among other things, that Sgr A* is not only spinning at close to its maximum speed, but that its rotational axis is pointed in Earth's direction, and that the glow around it is generated by hot electrons. Perhaps the most interesting thing is that the magnetic field in the material around Sgr A* doesn't appear to be behaving in a way that's predicted by theory. M87*, they discovered, is also rotating rapidly, although not as fast as Sgr A*. However, it is rotating in the opposite direction to the material swirling in a disk around it -- possibly because of a past merger with another supermassive black hole. The findings have been detailed in three papers published in the journal Astronomy & Astrophysics. They can be found here, here, and here.
Six terabytes (Score:3)
The study of the black hole in our galaxy has taken years to analyze.
A large number of images were taken during an observing campaign in 2017, producing six terabytes of data. These data had to be processed and analyzed – a process that took years, and the development of new algorithms to compensate for the rapid changeability.
They also found we are at about 90 degrees from the accretion disc, almost on the axis of rotation. This should provide an interesting viewpoint for observation and analysis.
13.25: Christian Fromm of Würzburg University in Germany is now stepping up to tell us what the image tells us about Sgr A*.
The team used supercomputers around the world to model black holes. When compared with their models, the image tells us that Sgr A* is rotating and that we are looking at it face-on. https://www.sciencealert.com/l... [sciencealert.com]
Re: (Score:2)
Yeah I think the rotating bit is to be taken for granted. It would be *very* strange to find a black hole without any angular momentum (being that its one of only three properties a black hole has, angular momentum, electrical charge and mass, aka the no-hair theorem).
The text of the actual papers is a little terse and mathematical for my brain, did you manage to figure out what that "close to the maximum allowed by physics" speed actually was, the pop-sci article seemed a bit short on details.
Re:Six terabytes (Score:5, Informative)
did you manage to figure out what that "close to the maximum allowed by physics" speed actually was, the pop-sci article seemed a bit short on details.
I didn't understand exactly, but a quick summary of a few articles indicated that when stars collapse into smaller objects (white dwarfs, neutron stars, etc) their angular momentum is preserved so the smaller objects must rotate faster. With Sgr A* containing mass 4.3 million times the mass of the Sun, the angular momentum is huge and the mass spins extremely fast. The limiting factor seems to be the outer edge of the mass exceeding the speed of light which instead gets converted into gravity waves, keeping the mass from spinning any faster. Slower rotational speeds have been observed on other black holes, but Sgr A* seems to be spinning near the theoretical maximum as it absorbs more mass and rotational energy.
That was my layman's understanding of what was happening. Other stellar experts can probably explain it better.
Re: Six terabytes (Score:2)
Do you know whether this might relate to the masses of those galaxies or whether faster speeds have been observed?
Re: (Score:2)
Re: galaxy rotational speed variation (Score:2)
Do you know how this might relate to the masses of those galaxies and whether faster speeds have been observed?
Nice (Score:2)
Re: (Score:2)
Latch one to the moon first, it is also rotating. With appropriate choice of gears, you can turn a generator as fast as you want.
Re: Nice (Score:2)
Need to make sure that our Ringworld... (Score:1)
Rotates in the right plane so that the scrith can block as much of the astrophysical jets as possible.
Just saying :-)