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peteshimmon
2006-Jan-22, 11:42 AM
I hesitate to post here as I have to reply
but it seems worthwhile. If you accept radio
noise emanates from any galactic disk, would
you accept the possibility that the
"ionosphere" of a foreground galaxy might
bend this radio energy forming some kind of
image? I had this idea and on the principle
that "violet light is most violently bent"
thought that some radio lobes would be wider
at higher frequencies. This was just what was
found some years ago! But there seems to be
erroneous ideas about refraction of radio waves
around! The bending of radio waves in the
Earths ionosphere is a messy, involved subject
but I think my simple model is correct.
Hope this is of interest and I may be slow in
replying.

Nereid
2006-Jan-23, 03:15 AM
You might like to consider starting a thread in the Q&A section on this (it's an interesting topic ... in general).

However, I suggest that you first read up on 'pulsar dispersion' (use those two words in Google) - the ISM (interstellar medium) does have an effect on the propogation of electromagnetic waves in the radio (and sometimes microwave?). This effect is well-observed, and can be used to give a handle on all kinds of interesting things, especially about the ISM itself.

A similar set of interesting hits come from 'pulsar scintillation' - same underlying mechanism.

peteshimmon
2006-Jan-23, 04:32 PM
Thanks Nereid! I think extragalactic space is generally empty of charged
particles so that the ionosphere of a galaxy fades out and causes
bending of radio waves passing through. This is the bare idea and some
radio images may be caused by this. BTW some of those images showing
beams impinging on gas look too good to be true. But I accept them:)