Dark matter annihilation feedback in cosmological simulations - I: Code convergence and idealized haloes

We describe and test a novel dark matter annihilation feedback (DMAF) scheme that has been implemented into the well-known cosmological simulation code GADGET-2. In the models considered here, dark matter can undergo self-annihilation/ decay into radiation and baryons. These products deposit energy into the surrounding gas particles and then the dark matter/baryon fluid is self-consistently evolved under gravity and hydrodynamics. We present tests of this new feedback implementation in the case of idealized dark matter haloes with gas components for a range of halomasses, concentrations and annihilation rates. For some dark matter models, DMAF's ability to evacuate gas is enhanced in lower mass, concentrated haloes where the injected energy is comparable to its gravitational binding energy. Therefore, we expect the strongest signs of dark matter annihilation to imprint themselves on to the baryonic structure of concentrated dwarf galaxies through their baryonic fraction and star formation history. Finally, we present preliminary results of the first self-consistent DMAF cosmological box simulations showing that the small-scale substructure is washed out for large annihilation rates.