[josephagoss]

This is insane!

Between 100 days and 3 years we will record what will be the single largest energy release we have ever recorded.

To give an idea of our records so far: our detection of black hole mergers around the 100-150 solar masses scale are just behind a couple gamma ray bursts as the single largest energy release ever.

How big are the black hole mergers around 150 solar masses and the two largest gamma ray bursts?

The energy release converted the mass of between 1-6 solar masses into energy.

With black hole mergers this energy release/conversion is in the form of gravitational waves that we then detect!

So imagine the sun, times 6, every atom, converted into that energy. That’s what we have already recorded.

This predicted one is not even in the same ballpark. Those 1-6 sun matter into energy conversions are ants compared to what’s coming.

These supermassive black holes are thousands to tens of thousands of times the mass of our sun. (Not sure if the ones in this paper are in the billion solar masses class. Yes they do exist)

This event will convert the mass of perhaps a hundred or a thousand suns worth of matter into energy in an instant. (Not sure if the paper gives any accurate predictions I’m lazy!)

[perihelions]

>"With black hole mergers this energy release/conversion is in the form of gravitational waves that we then detect!"

FWIW, these gravitational waves are too low in frequency for LIGO to catch. The paper says it would be within detection range of LISA (the ESA's space-based laser interferometer), but unfortunately they haven't launched that yet.

However, there's a related effect that could be measurable some 5-10 years afterwards:

>"They should, however, leave an imprint on spacetime itself, a sort of relaxation of distance and time dubbed gravitational wave memory, which could be detected over many years by monitoring the metronomic pulses of spinning stellar remnants known as pulsars. “It’s a very tricky signal to measure,” Ransom says, “but that would be definitive, a total smoking gun” of merging supermassive black holes."

https://www.science.org/content/article/crash-titans-imminen...

[l33tman]

Pulsar-based galaxy-wide gravitational wave observing is one of the most intriguing (while being conceptually simple and understandable) concepts I've come across.

https://en.wikipedia.org/wiki/Pulsar_timing_array

[josephagoss]

I didn’t realise that, thanks for clarifying.

I wonder if this predicted supermassive black hole merger is rare for us - once in a lifetime, or we find out after LISA is operational that they happened frequently.

Am I right in thinking that the search area something like LISA and LIGO "see" is essentially the entire observable universe?

Could we could catch a merger from the first billion or so years of the universe?

[jcims]

>FWIW, these gravitational waves are too low in frequency for LIGO to catch.

Will this be true throughout the collision? The ones we've recorded have a sort of 'chirp' right before the merge.

[wrycoder]

If I read this correctly, the black hole binary is about 40 million solar masses and could be five times that. Our own black hole at Sgr A* is only a tenth of that.

This has to be a really rare occurrence. Hopefully, it won’t be behind the sun when it coalesces, though that won’t hide the gravitational effects, of course.

[dylan604]

>This is insane!

You say insane, these guys say, "no, perfectly sane and expected. We have a model predicting it."

But I know what you actually meant! ;-)

[blackhaz]

From the paper: "On the other hand, the SMBH mass (MBH) estimated from broad Hα is ∼ 4 × 10^7 times of solar..." So, looks like each of them is about 40 million solar masses. Other methods estimate 2 × 10^8, so 200 million. Two galactic nuclei are about to be smashed together!

[______-_-______]

Will any of this energy be visible to the naked eye from Earth?

[dylan604]

Depends on where it is located for line of sight. If it's on the other side of the center of our Milky Way galactic core, then it won't be visible in visible light (awkwardly stated). The overall brightness and/or the thick bands of dust prohibit us from seeing some things in the visible spectrum on that side of the galaxy. However, some things can be viewed with other wavelengths.

[dreamcompiler]

Paper says they're assuming the black holes in question are around 10E8 solar masses.