Random matrix products when the top Lyapunov exponent is simple

In the present paper, we treat random matrix products on the general linear group GL(V), where V is a vector space over any local field, when the top Lyapunov exponent is simple, without the irreducibility assumption. In particular, we show the existence and uniqueness of the stationary measure nu on P(V) that is related to the top Lyapunov exponent and we describe the projective subspace generated by its support. We observe that the dynamics takes place in an open subset of P(V) which has the structure of a skew product space. Then, we relate this support to the limit set of the semigroup T-mu of GL(V) generated by the random walk. Moreover, we show that nu has Holder regularity and give some limit theorems concerning the behavior of the random walk and the probability of hitting a hyperplane. These results generalize known ones when T-mu acts strongly irreducibly and proximally (i-p for short) on V. In particular, when applied to the affine group in the so-called contracting case or more generally when the Zariski closure of T-mu is not necessarily reductive, the Holder regularity of the stationary measure together with the description of the limit set are new. We mention that we do not use results from the i-p setting; rather we see it as a particular case.