Statistics of Satellite Galaxies Around Milky Way-Like Hosts
  We calculate the probability that a Milky-Way-like halo in the standard
cosmological model has the observed number of Magellanic Clouds (MCs). The
statistics of the number of MCs in the LCDM model are in good agreement with
observations of a large sample of SDSS galaxies. Under the sub-halo abundance
matching assumption of a relationship with small scatter between galaxy r-band
luminosities and halo internal velocities v_max, we make detailed comparisons
to similar measurements using SDSS DR7 data by Liu et al. (2010). Models and
observational data give very similar probabilities for having zero, one, and
two MC-like satellites. In both cases, Milky Way-luminosity hosts have just a
\sim 10% chance of hosting two satellites similar to the Magellanic Clouds. In
addition, we present a prediction for the probability for a host galaxy to have
Nsats satellite galaxies as a function of the magnitudes of both the host and
satellite. This probability and its scaling with host properties is
significantly different from that of mass-selected objects because of scatter
in the mass- luminosity relation and because of variations in the star
formation efficiency with halo mass.
