Sounds a bit naive but I read somewhere that neutrinos were thought to account for dark matter to an extent and I think Zwicki came up with the idea before cosmic rays were announced (not sure though). Any help would be great.

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    $\begingroup$ It doesn't really sound naive. Instead it seems to imply that you think all the professionals working on the subject for the last few decades are a bunch of idiots. It would have been rather more politic to ask about the fraction of the non-luminous mass made up of radiation, cosmic rays, and neutrinos. $\endgroup$ – dmckee --- ex-moderator kitten Jun 1 '16 at 1:39
  • $\begingroup$ The missing mass has been conjectured as a result of their being insufficient mass in galaxies to create the gravity responsible for keepin the galaxy together. If someone were to come along and try to evaluate the number of cosmic ray particles trapped by that gravity within a galaxy since its formation I doubt they'd be considered an idiot, as far as I'm aware nobody has done so, if you'd like to point to an example of someone who has id be interested because that's what I asked in the first place. $\endgroup$ – Sam Cottle Jun 1 '16 at 1:44
  • $\begingroup$ Also I did mention that professionals have been considering neutrinos for some of dark matter, I was wondering about cosmic rays, sorry. $\endgroup$ – Sam Cottle Jun 1 '16 at 1:56
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    $\begingroup$ Have a look in the calculations here astro.ucla.edu/~wright/neutrinos.html this w.astro.berkeley.edu/~mwhite/darkmatter/hdm.html for neutrinos . Cosmic rays are composed of hadronic matter, protons mostly which have electromagnetic interactions and cannot be part of a "dark" component. If there were as many as necessary to explain dark matter effects they would shine. $\endgroup$ – anna v Jun 14 '16 at 4:03
  • $\begingroup$ Possible duplicates: physics.stackexchange.com/q/1008/2451 and links therein. $\endgroup$ – Qmechanic Apr 14 '18 at 15:55

It is highly unlikely. Neutrinos are known to account for a small part. The problem with neutrinos is that they are low mass and usually highly relativistic. DM needs to be made up of particles or objects that are slow and non relativistic. DM concentrates around galaxies, and tends to stay around, DM needs to be cold to stay around.

As for cosmic rays it's even worse. They are basically highly relativistic protons, also certainly not cold. They also electromagnetically interact, it is known that DM interacts little (eg when a galaxy goes through another the DM is hardly affected). Charged particles could not do that.

The best remaining idea on DM is that they are unknown WIMPS, weakly interacting,massive particles. The problem is of course we still don't know what those may be. Black holes, small or medium sized, were also considered and they would have to be Early universe remnants, calculations are also that they just can't be a significant percentage of DM.

Some ssuperparticles were also considered, but with no light superparticles found at LHC people are looking for other alternatives.

So, don't know but unlikely any of those.

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