  Protons gain energy in short range collisions with heavier dark matter
particles (DMPs) of comparable velocity dispersion. We examine the conditions
under which the heating of baryons by scattering off DMPs can offset radiative
cooling in the cores of galaxy clusters. Collisions with a constant cross
section independent of the relative velocity of the colliding particles, cannot
produce stable thermal balance. In this case, avoiding an unrealistic increase
of the central temperatures yields the upper bound on the cross-section,
\sigma_xp<10^-25 cm^2 (m_x/m_p), where m_x and m_p are the DMP and proton mass,
respectively. A stable balance, however, can be achieved for a power law
dependence on the relative velocity, V, of the form \sigma_xp \propto V^a with
a<-3. An advantage of this heating mechanism is that it preserves the metal
gradients observed in clusters.
