Disk galaxies and their dark halos as self-organized patterns

Galaxies are built by complex physical processes with significant inherent stochasticity. It is therefore surprising that the inferred dark matter distributions in galaxies are correlated with the observed baryon distributions leading to various 'Baryon-Halo conspiracies'. The fact that no dark matter candidate has been definitively identified invites a search for alternative explanations for such correlations and we present an approach motivated by the behaviors of self organized patterns. We propose a nonlocal relativistic Lagrangian theory for a 'pattern field' which acts as an 'effective dark matter', built on the idea that defects in this pattern field couple to the baryonic matter distribution. The model applies to rotation supported systems and, for them, we compute galactic rotation curves, obtain a radial acceleration relation with two branches, and deduce the Freeman limit for central surface brightness. (C) 2021 The Authors. Published by Elsevier B.V.