  Relativistic shocks propagating into a medium with low magnetization are
generated and sustained by small-scale but very strong magnetic field
turbulence. This so-called "microturbulence" modifies the typical shock
acceleration process, and in particular that of electrons. In this work we
perform Monte Carlo (MC) simulations of electrons encountering shocks with
microturbulent fields. The simulations cover a three-dimensional parameter
space in shock speed, acceleration efficiency, and peak magnetic field
strength. From these, a Markov Chain Monte Carlo (MCMC) method was employed to
estimate the maximum electron momentum from the MC-simulated electron spectra.
Having estimated this quantity at many points well-distributed over an
astrophysically relevant parameter space, an MCMC method was again used to
estimate the parameters of an empirical formula that computes the maximum
momentum of a Fermi-accelerated electron population anywhere in this parameter
space. The maximum energy is well-approximated as a broken power-law in shock
speed, with the break occurring when the shock decelerates to the point where
electrons can begin to escape upstream from the shock.
