[thedoc (OP)]

Donald piniach asked the Naked Scientists:































   Because we have no dark matter planet in our solar system, can we assume that dark matter is not sticking to itself?































What do you think?

[PhysBang]

That's actually a pretty decent inference.

[evan_au]

in our solar system

A study involving n=1 of anything is a pretty small sample from which to draw inferences.

In the case of planetary systems, astronomers were surprised to find that our Solar system is somewhat of an anomaly (but maybe their current observations don't have enough sensitivity to detect systems made of small rocky planets?).

As suggested in another thread, some percentage of Dark Matter will consist of black holes; fortunately, we don't have one of those in our Solar System, either!

can we assume that dark matter is not sticking to itself?

The Bullet Cluster contains the collision of two galaxies, where it seems that the gas of the two galaxies (which interacts strongly) has separated from the Dark Matter (which, it is suggested, has interacted very weakly, if at all).
Other interpretations also exist...
https://en.wikipedia.org/wiki/Bullet_Cluster#Significance_to_dark_matter

[PmbPhy]

Donald piniach asked the Naked Scientists:
   Because we have no dark matter planet in our solar system, can we assume that dark matter is not sticking to itself?
What do you think?

There's no reason to assume that there's no dark matter planet in our solar system. In fact a new planet was recently found orbiting our Sun. The reason we haven't discovered it until just now is because its orbit lies outside that of Pluto meaning that its extremely far away. So I see no reason to assume that there can't be another planet orbiting our Sun that we haven't discovered yet and that could be made out of dark matter. But since I don't know what dark matter is I can't say how likely that is.