Structure Formation in Nonlocal MOND

Abstract

We consider structure formation in a nonlocal, metric-based realization of Milgrom's MOdified Newtonian Dynamics (MOND). We derive the general equations for linearized scalar perturbations about the $Λ$CDM expansion history. These equations are considerably simplified for sub-horizon modes, and it becomes obvious (in this model) that the MOND enhancement is not sufficient to allow ordinary matter to drive structure formation. We discuss ways in which the model might be changed to correct the problem.

26 pages, 4 figures, uses LaTeX 2e, Version 2 revised for publication with some errors corrected and new references