The wedding of modified dynamics and non-exotic dark matter in galaxy clusters

Understand

We summarize the status of Modified Newtonian Dynamics (MOND) in galaxy clusters.

• The observed acceleration is typically larger than the acceleration threshold of MOND in the central regions, implying that some dark matter is necessary to explain the mass discrepancy there.
• A plausible resolution of this issue is that the unseen mass in MOND is in the form of ordinary neutrinos with masses just below the experimentally detectable limit.
• In particular, we show that the lensing mass reconstructions of the clusters 1E0657-56 (the bullet cluster) and Cl0024+17 (the ring) do not pose a new challenge to this scenario.