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

TL;DR

This paper explores how dissipative dark matter from multiple Standard Model sectors can address small-scale structure issues in cosmology, proposing a specific kinetic mixing parameter value that aligns with observations.

Contribution

It introduces a model with multiple Standard Model copies interacting via gravity and kinetic mixing, offering explanations for small-scale cosmic structures not addressed by previous models.

Findings

Model consistent with large-scale structure and CMB measurements

Potential explanation for satellite galaxy distribution and halo structures

Estimated kinetic mixing parameter around 1.2 x 10^{-10} for five sectors

Abstract

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.