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> an invisible collision of invisible objects — black holes — had become briefly visible > it would mark the first time that colliding black holes have produce

by mabbo 6y ago

> an invisible collision of invisible objects — black holes — had become briefly visible > it would mark the first time that colliding black holes have produced light as well as gravitational waves Can someone with a better understanding of astrophysics dumb this down for me a bit? Black holes, by definition, don't let light escape. That's their thing. So how did this collision produce light visible outside of them? I mean, are we talking about a naked singularity? (Someone let Joseph Cooper know). Or is it just that something nearby the collision but outside of the event horizon started producing large amounts of light?

sandworm101 6y ago
Black holes have gravity. That gravity means things orbit them like a star. (Dust, rock, gas, bits of planets etc.) When two black holes merge that orbiting stuff collides really really fast. The light comes from that collision and subsequent heating, not from the actual black holes.
mrkstu 6y ago
Yes, the recoil of the combination event forced the new, larger black hole to zoom through the accretion disk, generating a large amount of energetic interaction with the gas, with a large flare of resultant light, with the flare ending as the black hole escaped the accretion disk. They are predicting that as the main supermassive black hole pulls back the new black hole into the disk, a new flare will form.
nwallin 6y ago
We have a few models about how black holes might merge. The best model was that a massive binary star might end their lives as a pair of black holes, then spiral down into each other. In this model, there will not be any optical counterpart to the merger. But this model can't explain all of the observations by LIGO. When a star ends its life as a black hole, there's a cap on how large the black hole can be; if you make stars larger than that, they end their lives prematurely in pair-instability supernova, which do not leave behind black holes. But LIGO saw black hole mergers where the constituent black holes were larger than that maximum mass, up to twice as large. Binary black hole mergers can't explain those observations. The next idea on the drawing board was that there could be a dense swarm of stars, black holes, and neutron stars in the accretion disks around quasars. In this model, the black holes can grow in the accretion disk, and they can undergo multiple mergers and get much larger. However, when they merge, the new combined black hole should be kicked through the accretion disk at an odd angle, and steal some of the material into a new, more chaotic accretion disk. This new accretion disk should produce a temporary flare up, and then more periodic flareups every few months as the new black hole oscillates up and down through the accretion disk. The new black hole should eventually get dampened into a nearly circular, in-spiraling orbit, where it is available for a subsequent merger. This new observation, if it's confirmed, lends a lot of support that the second model happens too, and teaches us a lot about what exactly is happening around supermassive black holes. So the takeaway from this article isn't just "hey, we saw this cool thing", it's "hey, we saw this thing that increases our understanding" which IMHO is a hell of a lot cooler. The title implies the former, which annoys me. Hopefully, we'll see periodic flareups around the quasar, which would largely confirm the model.

by mabbo 6y ago

sandworm101 6y ago

Black holes have gravity. That gravity means things orbit them like a star. (Dust, rock, gas, bits of planets etc.) When two black holes merge that orbiting stuff collides really really fast. The light comes from that collision and subsequent heating, not from the actual black holes.

mrkstu 6y ago

Yes, the recoil of the combination event forced the new, larger black hole to zoom through the accretion disk, generating a large amount of energetic interaction with the gas, with a large flare of resultant light, with the flare ending as the black hole escaped the accretion disk. They are predicting that as the main supermassive black hole pulls back the new black hole into the disk, a new flare will form.

nwallin 6y ago

We have a few models about how black holes might merge. The best model was that a massive binary star might end their lives as a pair of black holes, then spiral down into each other. In this model, there will not be any optical counterpart to the merger. But this model can't explain all of the observations by LIGO. When a star ends its life as a black hole, there's a cap on how large the black hole can be; if you make stars larger than that, they end their lives prematurely in pair-instability supernova, which do not leave behind black holes. But LIGO saw black hole mergers where the constituent black holes were larger than that maximum mass, up to twice as large. Binary black hole mergers can't explain those observations. The next idea on the drawing board was that there could be a dense swarm of stars, black holes, and neutron stars in the accretion disks around quasars. In this model, the black holes can grow in the accretion disk, and they can undergo multiple mergers and get much larger. However, when they merge, the new combined black hole should be kicked through the accretion disk at an odd angle, and steal some of the material into a new, more chaotic accretion disk. This new accretion disk should produce a temporary flare up, and then more periodic flareups every few months as the new black hole oscillates up and down through the accretion disk. The new black hole should eventually get dampened into a nearly circular, in-spiraling orbit, where it is available for a subsequent merger. This new observation, if it's confirmed, lends a lot of support that the second model happens too, and teaches us a lot about what exactly is happening around supermassive black holes. So the takeaway from this article isn't just "hey, we saw this cool thing", it's "hey, we saw this thing that increases our understanding" which IMHO is a hell of a lot cooler. The title implies the former, which annoys me. Hopefully, we'll see periodic flareups around the quasar, which would largely confirm the model.