Moderate Steepening of Galaxy Cluster Dark Matter Profiles by Baryonic Pinching

Understand

To assess the effect of baryonic ``pinching'' of galaxy cluster dark matter (DM) haloes, cosmological (LCDM) TreeSPH simulations of the formation and evolution of two galaxy clusters have been performed, with and without baryons included.

• The simulations with baryons invoke star formation, chemical evolution with non-instantaneous recycling, metallicity dependent radiative cooling, strong star-burst, driven galactic super-winds and the effects of a meta-galactic UV field, including simplified radiative transfer.
• The two clusters have T_X~3 and 6 keV, respectively, and, at z~0, both host a prominent, central cD galaxy.
• Comparing the simulations without and with baryons, it is found for the latter that the inner DM density profiles, r<50-100 kpc, steepen considerably: Delta(alpha)~0.5-0.6, where -alpha is the logarithmic DM density gradient.