Numerical models of the galactic dynamo

Abstract

Abstract Axisymmetric αω‐dynamo models are investigated numerically for the galactic dynamo. Contrasting to the eigenvalue formulation of the problem by S TIX (1976), an initial‐value formulation is developed in a manner which is a generalization of the approach to the solar dynamo by J EPPS (1975). It is found, for S TIX's model, that the critical dynamo numbers, P c , obtained by this approach do not agree with those obtained by S TIX . In order to resolve this disagreement S OWARD (1977) has evaluated an asymptotic formula for P c which confirm the results presented here. Having established this approach, the dependence of the models upon boundary conditions and the relevant astrophysical parameters is investigated, and an attempt is made to simulate nonlinear effects. Finally a comparison is made between predictions of the dynamo models and the observed radiation of certain external galaxies which provides insight into the nature of the intergalactic medium.