As far as I understand the wave-optics effects,such e.g.diffraction at a caustic, are hardly observable in the gravitational lensing. Are there any observations where the diffraction paterns of the visible light have been seen? If not visible, which wavelength?
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$\begingroup$ Where are you expecting to see diffraction? $\endgroup$– ProfRobCommented May 6, 2018 at 20:36
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1$\begingroup$ The inclusion of the word "caustic" suggests iopscience.iop.org/article/10.1086/376896/fulltext/… is relevant $\endgroup$– James KCommented May 7, 2018 at 6:20
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$\begingroup$ I meant: Is something like that is observed in visible light arxiv.org/pdf/1207.4034.pdf $\endgroup$– TruffaldinoCommented May 8, 2018 at 16:32
1 Answer
I'm not sure how to define the "edges" or obscurations in a case of gravitational lensing. The image we produce on Earth is the combination of our local telescope lens elements and the "grav lens" a zillion Kessel Runs away from us. Even if you use the premise that the black hole itself is a central obscuration which should cause a Spot of Arago, I don't think any other diffraction-like effect is observable from such a great distance. All the wavefronts of light which passes thru the GravLens region continue to expand, ending up near-parallel from Earth's viewpoint.