I imagine electrons being accelerated by passing gravitational waves, say from a nearby kilonova, so I would expect the electrons to emit light. Am I right?
Answer
A gravitational wave does not exert a force on a point particle. By this I mean if you were that point particle and you were holding an accelerometer then you would measure no acceleration as the wave passed through you. More precisely your proper acceleration remains zero at all times.
This may seem a bit odd, but it happens because the gravitational wave changes the separation of objects by changing the geometry of the spacetime around them, not by exerting a force on the objects to move them.
The situation you describe is essentially the same as whether an electron falling in a gravitational field radiates. If you watch a freely falling electron then you see it accelerate so from your perspective it should radiate. However the freely falling electron is weightless, like all freely falling objects, and therefore experiences no acceleration. So from the electron's perspective it shouldn't radiate. This is a longstanding paradox and has been addressed several times on the site - the definitive question appears to be:
Having said this, I'm unsure to what extend the paradox has been satisfactorily resolved. I believe the solution is that it does radiate as observed from a stationary frame but does not radiate as observed from a comoving frame. The difference is because observers in different frames disagree about the QED ground state. This is the same argument as used for Unruh radiation.
So, arguing by comparison with the freely falling charge I think the gravitational wave does cause electrons to radiate as observed by an observer outside the area affected by the gravitational wave. However an observer comoving with the electron would not measure any radiation.
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