Resolution of the small scale structure issues with dissipative dark matter from multiple Standard Model sectors

Dissipative dark matter arising from a hidden sector consisting of $N_{\rm sec}$ exact copies of the Standard Model is discussed. The particles from each sector interact with those from the other sectors by gravity and via the kinetic mixing interaction, described by the dimensionless parameter, $\epsilon$. It has been known for some time that models of this kind are consistent with large scale structure and the cosmic microwave background measurements. Here, we argue that such models can potentially explain various observations on small scales, including the observed paucity and planar distribution of satellite galaxies, the flat velocity function of field galaxies, and the structure of galaxy halos. The value of the kinetic mixing parameter is estimated to be $\epsilon \approx 1.2 \times 10^{-10}$ for $N_{\rm sec} = 5$, the example studied in most detail here. We also comment on cluster constraints such as those which arise from the Bullet cluster.