  We use a recently developed order parameter expansion method to study the
transition to synchronous firing occuring in a system of coupled active
rotators under the exclusive presence of quenched noise. The method predicts
correctly the existence of a transition from a rest state to a regime of
synchronous firing and another transition out of it as the intensity of the
quenched noise increases and leads to analytical expressions for the critical
noise intensities in the large coupling regime. It also predicts the order of
the transitions for different probability distribution functions of the
quenched variables. We use numerical simulations and finite size scaling theory
to estimate the critical exponents of the transitions and found values which
are consistent with those reported in other scalar systems in the exclusive
presence of additive static disorder.
