Article: How fast does a Supermassive Black Hole spin?

[Ricola]

Turns out... really fast.

Covered in an AP story via the local paper hereL http://www.twincities.com/allheadlines/ ... tudy-finds

Also behind a paywall in Nature at http://www.nature.com/nature/journal/v4 ... 11938.html

I looked up NGC 1365. Turns out it's in Fornax, so I guess I'll have to look for it sometime during a trip south. December trip to the Virgin Islands, anyone?

[Dick Jacobson]

This seems to imply that the black hole was created by the merger of two giant black holes. Must have been a really spectacular event, if you like locomotive collisions. Too bad we can't set up a high-energy x-ray telescope to study the results.

[Dave Venne]

I was trying to understand how the unit of spin was a speed (miles per hour)...instead of revolutions or radians per second, so I hunted up something with a little more science content.

If I can get any of this into my head, it looks like the spin of a black hole modifies nearby space in a way that changes the local speed of light, which in turn changes the character of the radiation emitted by matter orbiting the black hole in that area. So measurements of that radiation can be used to infer the amount of distortion, which in turn suggests what the rotation speed is.

Sometimes I think that knowledge itself has an event horizon and that I'm on the wrong side of it.

[Ricola]

...Sometimes I think that knowledge itself has an event horizon and that I'm on the wrong side of it.

I am certainly on the wrong side with you.

Thanks for the additional link.

[sinaroughani1]

I'll rephrase your post as a question. We can find the actual speed if we write an equation including the mass and distance of the stars around it at multiple intervals radially going outwards from the center of the galaxy, and the speed at which they go. Toss in the speed of light, mass of the black hole, a gamma to radio wavelength telescope the size of Jupiter, a 473 terapixel CCD cooled to absolute zero, a new highly advanced version of calculus not discovered by humans, and 83 trillion more dollars to CERN, and then you can calculate the speed of the black hole... But, we haven't discovered that calculus yet, so I'll approximate; a supermassive black hole spins... fast.