  A subcritical transition to turbulence in magnetized Keplerian shear flows is
investigated using a statistical approach. Three-dimensional numerical
simulations of the shearing box equations with zero net magnetic flux are
employed to determine the transition from decaying to sustained turbulence as a
function of the magnetic Reynolds number Rm. The results reveal no clear
transition to sustained turbulence as the average lifetime of the transients
grows as an exponential function of Rm, in accordance with a type-II
supertransient law.
