Self-modulation of cosmic rays in molecular clouds: Imprints in the
  radio observations
  We analyze properties of non-thermal radio emission from the Central
Molecular Zone (CMZ) and individual molecular clouds, and argue that the
observed features can be interpreted in the framework of our recent theory of
self-modulation of cosmic rays (CRs) penetrating dense molecular regions. For
clouds with gas column densities of $\sim10^{23}$ cm$^{-2}$, the theory
predicts depletion of sub-GeV CR electrons, occurring due to self-modulation of
CR protons and leading to harder synchrotron spectra in the sub-GHz range. The
predicted imprints of electron depletion in the synchrotron spectra agree well
with the spectral hardening seen in available radio observations of the CMZ. A
similar, but even stronger effect on the synchrotron emission is predicted for
individual (denser) CMZ clouds, such as the Sgr B2. However, the emission at
frequencies above $\sim$ GHz, where observational data are available, is
completely dominated by the thermal component, and therefore new observations
at lower frequencies are needed to verify the predictions.
