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Moving charged particles generally emmit energy in form of radiation.

Assume a charged particle that is situated in a zone that can join the Hubble flow and therefore starts moving away from us.

As it moves away, and accelerates, due to the accelerating expansion of the universe, would that charged particle emmit radiation?

Would this situation be similar to this article (https://iopscience.iop.org/article/10.1088/1475-7516/2006/11/013)?

And how much energy would it emmit before crossing the Hubble horizon?

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  • $\begingroup$ If you surround your charge with detectors in its local rest system, then you will not detect any radiation. This means that the charge itself can not radiate. At most the stretching of the field lines far away from the charge could produce radiation. OTOH, if we treat it as an accelerated charge problem, then the radiation will be emitted into a forward cone. An observer behind the charge would see nothing. However, because of isotropy of the expansion there is no such thing as a forward observer. Everybody sees the charge accelerate away from them. $\endgroup$
    – FlatterMann
    Commented Oct 3, 2022 at 21:23
  • $\begingroup$ @FlatterMann So, then, the charge wouldn't radiate? $\endgroup$
    – vengaq
    Commented Oct 3, 2022 at 22:59
  • $\begingroup$ Not if we believe the local observer. The question is at most whether an electromagnetic field (or a quantum field in general) in an accelerated background metric will radiate... if we believe that inflation is what causes primordial matter, then the answer is positive. I don't know if one can coax that out of QFT with absolute certainty. I doubt it can be experimentally tested at the current rate of acceleration (if there is any at all). But then, I am usually wrong, so there is that. $\endgroup$
    – FlatterMann
    Commented Oct 4, 2022 at 3:18
  • $\begingroup$ Here is a speculation of how to detect it if it exists arxiv.org/abs/astro-ph/0306574 $\endgroup$
    – anna v
    Commented Oct 4, 2022 at 5:40

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