There’s no evidence of anything odd happening in our data. We check the consistency of the early part of the signal with the late part (the inspiral–merger–ringdown consistency test), which might show up if the energy loss was greater than expected. That’s not quite the same as measuring the energy loss is as predicted, but the best we can do. A louder signal would let is actually measure this.

However, that doesn’t necessarily answer your question, as there could still be something happening inside the merger where the internal luminosity is high, but that’s not reflected in the gravitational wave signal. I don’t think such high mass flows occur, but I think you’d need to offer your dinner to a numerical relativist to get a definitive answer. They’d be able to examine their simulations to calculate these things.

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]]>About the mass flow limit c^3/G, my friend Chris believes that c^3/G is a limit that is independent of the surface and the observer coordinates chosen. I am skeptical. So my question is: Does LIGO data allow to test whether the limit is broken or is followed? I would offer a free dinner in exchange of any evidence that a higher mass flow than c^3/G is possible for any freely chosen surface and observer!

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]]>In general, c^5/G is a good limit on a luminosity. To estimate this, consider that if you put lots of energy into a small space, you’ll eventually form a black hole. Let’s say you have energy E = Mc^2, so that it’ll form a black hole with mass M once squashed together. The size of this black hole is about r ~ GM/c^2, where we’ll ignore factors of 2 due to rotation, as we just want an approximate size. Now let us move this energy around at the fastest possible speed, the speed of light. It takes a time t ~ r/c ~ GM/c^3 to travel across the size of the black hole (again ignoring things like factors of 2). If looking at the black hole moving, it would take about this time for it to pass by. Therefore, we could at most gain an energy E in time t, meaning a maximum luminosity of L ~ E/t = (Mc^2)/(GM/c^3) = c^5/G. That’s a little hand-wavy, but hopefully gives you a quick sketch of why c^5/G is a good limit.

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]]>What is your personal take on this?

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