Fit to radio data from the CMZ region. The solid line refers to the total predicted synchrotron emission from CR electrons. The dashed line shows the contribution from electrons accelerated inside the CMZ. The dotted line shows the contribution from the background sea of CR electrons (LIS) with a low-energy exponential cut-off to take into account the suppressed penetration of background CR electrons into the CMZ. We consider an average magnetic field strength of B_CMZ ∼ 150 μG.