As a dark matter candidate, what should be the temperature and kinetic energy (or also the speed) of the WIMPs (weakly interacting massive particles) to agree with the observed distribution of dark matter and not to accumulate so much in the inner part (40 AU radius) of the Solar System that the change in the orbits of the planets would be observable? Is it in equilibrium with the microwave background radiation or not yet or never will?

EDIT: I have replaced some part into another question, Evidence of dark matter in our galaxy, and I have deleted some other part.

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    $\begingroup$ The sub-parts of this question are not very strongly related. Please consider cutting all but one part from this question and pasting them into separate questions. You will get answers more focused on the content in which you are most interested. $\endgroup$ – Andrew Jul 8 '11 at 14:42

In a classic two-body situation, the WIMPs can't accumulate in the solar system no matter how slowly they are travelling; they will leave the solar system at the same speed at which they entered the solar system. Add a passing star or interstellar cloud, and it's possible that a few slow WIMPS would get captured; and interactions with the planets, principally Jupiter, could also capture a few. But once captured, they would be subject to being thrown out of the solar system by the same mechanisms, so I would guess that the total mass of WIMPs captured by the solar system in an equilibrium situation would be rather low. See:

Dark matter in the Solar System. III. The distribution function of WIMPs at the Earth from gravitational capture. Annika H. G. Peter. Phys. Rev. D 79, 103533 (2009), arXiv:0902.1348.

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