"clumps" of Cold Neutrinos = Dark Matter ??

[Widdekind]

If Neutrinos have a non-zero rest-mass, perhaps of roughly 1.5 eV, then couldn't Neutrinos exist... at rest ??

 

And, if so, couldn't they "clump", into "Neutrino planets" and "Neutrino stars" (as it were) ?? Could that explain Dark Matter ?

 

At only ~1 eV per particle, the self-gravity of Neutrinos might be so weak, they their distribution would be continuously "stirred up", by the motions of planets & stars in galaxies. Could Earth, or our Solar System, be passing through a "thick fog" of cold, and nearly uniformly distributed, Neutrinos ??

Edited April 25, 2010 by Widdekind

[Mr Skeptic]

It's been though of before: http://www.google.com/#hl=en&source=hp&q=neutrino+dark+matter

 

I guess the problem is that they are rather hard to slow down.

[ajb]

The idea that neutrinos could be dark matter has been around for a long time, before it was really established that they are indeed massive.

 

One problem is that the current experiments measure a mass difference between the different species of neutrino rather than their absolute mass.

 

Now, if they are too light then gravity will not slow enough of them down enough to be a serious candidate for cold dark matter. Modified models with cosmic strings for example may have the "near massless" neutrino as hot dark matter.

[Widdekind]

It's been though of before: http://www.google.com/#hl=en&source=hp&q=neutrino+dark+matter

 

I guess the problem is that they are rather hard to slow down.

 

What if they started slow -- what if many were made, "at rest", by the Big Bang ??

[Nano]

It's been shown that neutrinos are most likely not the dark matter, as the amount of them would have to be tremendously high in order to explain all the DM in the universe, which is 5 times more than all the normal matter.

[Widdekind]

If Dark Matter fills the disk, of the Milky Way Galaxy, then our Solar System has had 4.5 billion years to "sweep up" at least some DM particles... could there be "Dark Matter craters" on some of the moons in our Solar System, or could Jupiter have collected a sizeable "Dark Matter core", from 4.5 billion years of "gobbling up" DM ?

[insane_alien]

widdekind, darkmatter would pass through normal matter as if it wasn't there since from what we can tell, it doesn't interact via the electromagnetic force(possibly not even the weak or strong forces either). this means it will happily go through normal matter only exherting a tiny gravitational tug. it will not build up in craters.

[Widdekind]

Thanks for the clarification. (That sounds allot like neutrinos !)

[insane_alien]

Thanks for the clarification. (That sounds allot like neutrinos !)

 

well, neutrinos also do not interact via the electromagnetic force.

 

they do however interact via the weak force which is how we detect them.

 

dark matter appears not to interact via the weak force hence the difficulty in detecting it as we are left with gravity as the only approach.