DM: dark matter; OM: ordinary matter
I know that DM has a distribution which is mostly concentrated in the center of galaxies. This was mainly deduced by accounting for gravitational effects on the motion of galaxies which weren't due to any visible matter.
1) a: What property of DM which isn't present in OM caused it to clump up at the center of galaxies and cause this in-homogeneous distribution of dark and ordinary matter?
b) Is it because DM interacts with itself so weakly compared to OM that allows it to clump up whereas ordinary matter would start repelling itself ? (This would imply that the average density of DM in its clumps would be much higher than that of OM in a galaxy because otherwise even OM would be able to do it.)
2) Also, if interacts so weakly with OM does ordinary matter pass freely through the clumps? Can we study the interactions between OM and DM from objects that have passed through the clumps a long time ago and that are now much nearer to us?