Galaxy Clusters in a New Relativistic Theory of Modified Newtonian Dynamics: Preliminary Results
Abstract
Galaxy clusters are generally accepted to be a problem for Modified Newtonian Dynamics (MOND), since a dark component is still needed to fit galaxy cluster observations. But MOND is a non-relativistic theory and necessarily incomplete, leaving open whether its incompleteness is related to its failure to account for galaxy cluster observations. Recently, a new relativistic theory (Aether-Scalar-Tensor theory, AeST) has been proposed that embeds MOND on small scales and has a ΛCDM limit on the largest scales, with unknown behaviour on intermediate scales. We consider static, spherically symmetric solutions of the weak-field limit of AeST. A new term appears in addition to the MOND equation, with new phenomenology in addition to MOND. Along the way we encounter mathematical difficulties that are only apparent, and which are solved after finding a variational formulation of the original problem. We consider the vacuum solution, the fixed prescribed source and self-gravitating isothermal gaseous source (a galaxy cluster model) in this truncation of AeST. We discuss possible phenomenology. It seems that the new term in AeST produces an apparent dark component in addition to MOND.