questions about dark matter density

[36grit]

Obviously we co-exist with dark matter, so the question is; Can dark matter be as as large and dense and/or a part of as a neutron star?

How about as small and dense as a proton?

 

Is dark matter predicted to have a strong nuclear force holding it's constiuants together?

[derek w]

As far as I know the answer is that nobody knows.

[Enthalpy]

There are different models of dark matter - enough ones that, if we're lucky, one will be seen to fit some day...

 

Several models (the most common, not the only ones) invoke wimps to constitute dark matter. These Weakly Interating Massive Particles do not respond to the strong force. Interacting (only?) by gravity, they would make rather diffuse halos in galaxies, or possibly have constituted black holes.

 

A new force, felt only by dark matter, that would make clumps of it? This model would have the same limit as the ones that propose clumps of ordinary matter to explain the missing mass: such clumps would be detectable for they would bend light; most possible scales for such objects (brown dwarves, extinct suns, stellar black holes...) have been disproven experimentally.

 

What's sure: the missing mass, for which a dark matter explanation is wanted, can't reside at normal matter, because the mass of observable matter is known (...well enough...) and this mass doesn't suffice. We need mass elsewhere, because we know the one of visible objects.

 

Even more precise: gravitational lensing, which tells where matter is in galaxies, is sometimes observed where normal matter is not. This is one strong argument for dark matter and against modified gravitational laws.