Baryon-driven decontraction in Milky Way-mass haloes

We select a sample of Milky Way (MW) mass haloes from high-resolution version the EAGLE simulation to study their inner dark matter (DM) content and how baryons alter it. As in previous studies, we find that all are more massive at centre compared DM-only (DMO) counterparts present day as result dissipational collapse during assembly galaxy. However, identify two processes can reduce central halo evolution Firstly, gas blowouts induced by AGN feedback lead substantial decrease DM mass. Secondly, formation stellar bar its interaction with induce secular expansion halo; rate which is evacuated region this process related average strength timescale on it acts determines much has decontracted. Although regions have investigated still than DMO $z = 0$, they significantly less past expected classic adiabatic contraction model. Since MW both supermassive black hole bar, extent contracted uncertain. This may affect estimates signals direct indirect detection experiments.