The standard paradigm of cosmology is that the mass in the Universe is dominated by ``cold” dark matter.
Surprisingly, new observations indicate a dearth of dark matter in flat dark-matter cores in certain types of galaxies, in particular massive galaxies at early epochs.
Current simulations fail to reproduce this phenomenon, possibly raising doubts concerning the nature of the dark matter or the validity of Einstein's gravity.
We challenge this puzzle within the standard model, via the gravitational Interplay between the dark matter and the regular, baryonic matter. 

We find that the dark matter can be pushed out from the main body of the galaxy by the combination of two processes: kinematically heating the dark matter by the dynamical friction on compact merging satellites, followed by the response of the heated dark matter to ejection of gas from the vicinity of the super-massive black hole.
A similar puzzle in dwarf galaxies may be solved in an analogous way via supernova-driven outflows.