[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?

[dylan604]

https://www.youtube.com/watch?v=rJLtT0QXoPo

This video has answers to your questions.

[tromp]

No idea why this was downvoted. I thought perhaps it's Rick Astley, but no. I found it quite instructive.

[jcims]

Yes, particularly that the first half provides a really nice primer on black holes.

Edit: Looks like a great channel overall.

[dylan604]

I found out about this channel a couple of days ago, and since then, I have watched a large chunk of the content. Rather than looking for something to kill time with on the boobtube, I've killed some time with this channel.

[dylan604]

I probably could have added more context clues, but assumed benefit of the doubt.

[SturgeonsLaw]

Interesting video, thanks for posting it

[dylan604]

That's the same reaction I had a few days ago when someone posted a link from this channel in another thread. Just paying it forward

[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.

[ravar]

The chirp doesn't go to infinite frequency. The last rotation of the two black holes happens in some finite time, a time scale that gets longer the larger the black holes are.

[jcims]

Of course, that's kind of what I was after. Whether or not they would achieve a detectable frequency prior to the merger.