As i see it, light behaves in certain ways, as the Double Slit experiement shows, So when light comes into contact with dark matter, it becomes both a wave and a particle, the wave is bent around the dark matter, which we see as gravitational lensing, but the particle will go through the dark matter, but will also leave our frame of reference, follow the particle through dark matter and its speed would not change staying at $c$, but only relative to the the space it travels through, it would eventually pass through dark matter, we would see this first as a red or blue shift as it slowly emerges (from our perspective), and continues on it way, Never knowing it had passed through any medium, where as the wave had passed around the dark matter thousands, millions, or billions of years before, depending upon the mass of the dark matter.
3 Answers
Light interacts with dark matter only through gravitation. That is why we try to map dark matter distribution in the universe by statistically studying the small distortions in the images of background galaxies (weak lensing regime).
Whole redshift-sliced 3D maps of dark matter have been traced for some small regions of the sky, by means of weak lensing distortion. In all cases, the observed properties of the background objects are in a statistical sense the same (apart from shape distortion) for objects observed through, and not through, dark matter clumps.
That is one of the proofs for dark matter not interacting with photons.
Another proof is in the strong lensing regime of multiple lensed quasars. The Hubble parameter can be derived by measuring time delays between flux changes of a background quasar, as detected in two lensed images. That time delays happen because the photons travel through different paths, both through the dark matter halo of the lens galaxy and the Universe. But the measured line waveleght redshifts agree perfectly with the optical paths derived from the geometry of the lens, and no additional frequency shift has ever been observed. As expected from GR, photons leaving a dark matter clump behind recover the colour they had when they entered it.
That is, dark matter affects light only by means of the metric tensor, but doesn't interact with the photons. Otherwise it would had been already observed.
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This is another version of the "tired light" hypothesis. This doesn't work for a variety of reasons, among which are the facts that there are no absorption or emission peaks evident in light, there is no blurring of the light from distant objects (stars look like points, not globs), and there appears to be no dependence on the angular view from the sky when looking for redshifts (while dark matter DOES appear to be clumped).
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Dark matter--as the term is understood--does not interact electromagnetically. Light only interacts electromagnetically.
So, no it could not.
