Visible light from two Black Holes with the help of a third

[John Clark]

For the first time astronomers think they may have detected the Gravitational Waves from the merger of two black holes and also visible light emissions from the collision; light from neutron star smash ups have been seen before but not from black holes. On May 21 2019 LIGO detected a merger 4 billion light years away of 2 black holes of about equal size that resulted in a new hole of at least 100 solar masses. At first astronomers detected no flash but 34 days later a quasar in the right place in the sky that was 4 billion light years away underwent a very unusual visible flare and there is reason to think the two things may be related. Gravitational waves carry an enormous amount of energy but for them to heat up gas to incandescence it would have to be extremely close to the source of those waves and be very dense, there is only one place that fits that bill, the accretion disk around an even larger black hole.

A model was developed in which the two black holes were in orbit in the accretion disk around a third black hole, a supermassive one of about 100 million solar masses. In such a situation the Gravitational Waves would heat the gas to enormous temperatures but it would take about a month for that spike of heat energy to work its way to the outside of the accretion disk so it could be radiated away and let us see it. They made a testable prediction to figure out if the model is correct. The black holes were spinning very rapidly so If the model is right the new merged hole would shoot up at right angles to the accretion disk at about 120 miles a second which would shut off the flare, but the black hole would then fall back down through the disk again in 1.6 years, so they predict we should see the quasar give out another unusual flair around Christmas time of this year.

Candidate Electromagnetic Counterpart to the Binary Black Hole Merger Gravitational-Wave Event S190521g

John K Clark

[Lawrence Crowell]

This appears to be different from another announcement of a BH merger that was associated with emission of photons.

https://www.forbes.com/sites/startswithabang/2020/06/25/shocking-new-observation-merging-black-holes-really-can-emit-light/#5cc33c7817bf

This is the merger of two black holes of 36 and 29 solar masses. It is generally thought the accretion disks around them interacted with each other in ways that released gamma ray photons,

LC