We present the first cosmological simulations of dwarf galaxies , which include dark matter self-interactions and baryons .
We study two dwarf galaxies within cold dark matter , and four different elastic self-interacting scenarios with constant and velocity-dependent cross sections , motivated by a new force in the hidden dark matter sector .
Our highest resolution simulation has a baryonic mass resolution of 1.8 \times 10 ^ { 2 } { M _ { \odot } } and a gravitational softening length of 34 { pc } at z = 0 .
In this first study we focus on the regime of mostly isolated dwarf galaxies with halo masses \sim 10 ^ { 10 } { M _ { \odot } } where dark matter dynamically dominates even at sub-kpc scales .
We find that while the global properties of galaxies of this scale are minimally affected by allowed self-interactions , their internal structures change significantly if the cross section is large enough within the inner sub-kpc region .
In these dark-matter-dominated systems , self-scattering ties the shape of the stellar distribution to that of the dark matter distribution .
In particular , we find that the stellar core radius is closely related to the dark matter core radius generated by self-interactions .
Dark matter collisions lead to dwarf galaxies with larger stellar cores and smaller stellar central densities compared to the cold dark matter case .
The central metallicity within 1 { kpc } is also larger by up to \sim 15 \% in the former case .
We conclude that the mass distribution , and characteristics of the central stars in dwarf galaxies can potentially be used to probe the self-interacting nature of dark matter .