Tightness for branching random walk in a space-inhomogeneous random environment

Abstract: We consider the maximum $M_t$ of branching random walk in a space-inhomogeneous random environment on $\mathbb{Z}$. In this model the branching rate while at some location $x\in\mathbb{Z}$ is randomized in an i.i.d. manner. We prove that there is a centering $\widetilde{m}t$ depending only on the environment such that $(M_t-\widetilde{m}_t){t\ge 0}$ is tight in an annealed sense.