Counting Dark Matter Sub-halos: Gaps in Star Streams. Ray Carlberg University of Toronto. Millions of sub-halos. Sub-Halos. N(M) ~ M -1.9 N~10 6 for M> 10 6 M_sun inside r<~400kpc ~5-10% of the halo mass Most of the mass in the top 30 or so Known dwarf galaxies
University of Toronto
~106 simulations of encounters of sub-halos with streams varying M, b, v, angles.
Results for cold streams apply to streams with width random Jr (radial velocities).
Real streams have some Jθ which can shear away gap.
Gap density profile with distance of closest encounter
A little steeper at small r