Yes, it is correct that clumping can be solely gravitational effect, though so far we have pretty vague idea about the density in those clumps and halos, which

Yes, it is correct that clumping can be solely gravitational effect, though so far we have pretty vague idea about the density in those clumps and halos, which are mostly derived from N-body simulation, which are obviously model dependent, e.g. NFW profile [1]. If dark matter interacts with itself one can expect deviations from purely gravitational description due to dark matter analogues of pressure, temperature, viscosity, etc. [1] https://en.wikipedia.org/wiki/Navarro%E2%80%93Frenk%E2%80%93White_profile https://en.wikipedia.org/wiki/Navarro%E2%80%93Frenk%E2%80%93...