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Supermassive black holes locked in a stable orbit around each other

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27 points DaveZale | 2 comments | 13 Oct 25 14:59 UTC | HN request time: 0.417s | source
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pavel_lishin ◴[13 Oct 25 15:08 UTC] No.45569161[source]▶
> The existence of two black holes in OJ287 was first suggested in 1982. Aimo Sillanpää, then a graduate student at the University of Turku, observed that the brightness of the quasar changed regularly over a 12-year cycle.

Damn, that's about the time it takes Jupiter to orbit the sun. That feels wildly close together for objects that mass 18 billion & 150 million times that of our own sun.

These black holes (according to a calculator I found online) have radii of 53 billion km and 400 million km, so I'm guessing they must be orbiting significantly further away, and significantly faster than Jupiter (which is ~800 million km away from the sun) - which makes sense, given the monstrous 18b figure. I wonder how far apart they are, but I don't really know how to easily calculate that right now.

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hinkley ◴[13 Oct 25 15:20 UTC] No.45569325[source]▶
How much time dilation do you get at those masses though?

I’m having more trouble visualizing how accretion disks would work for a binary black hole. Because the light is coming from the disks, not the black holes. So those are what are actually pulsing/girating.

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1. pavel_lishin ◴[13 Oct 25 15:23 UTC] No.45569366[source]▶
Yeah, good point on that, too. I bet someone's written a simulator that I could run locally, but I've got a busy day ahead of me :(

I thought that in this case, the light that they detected was coming from the jets coming from the poles, not the disk itself directly.

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2. hinkley ◴[13 Oct 25 15:35 UTC] No.45569516[source]▶
Since black holes are black holes, the jets are generated by the disk.