I've been pondering this for a while.
Is it possible for a gamma ray to undergo Inverse Compton Scattering causing it to decrease in wavelength (increase in energy) and this causes it to change its direction to earth with even more energy than it started with?
ronwizfr
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Yes. This is how black hole accretion disks produce their X-rays. Initially the photon spectrum is thermal (energies of eVs), but backscattering off electrons upgrade them to X-rays (energies of eVs).
And this particle physic experiment http://www.lnf.infn.it/~levisand/graal/graal.html scatters green photons of a GeV electron beam, to produce a gamma photon beam.