  The High Energy Stereoscopic System (HESS), the Major Atmospheric Gamma-ray
Imaging Cherenkov Telescope (MAGIC), and the Very Energetic Radiation Imaging
Telescope Array System (VERITAS) have observed diffuse gamma-ray emission
strongly correlated with the central molecular zone in the Galactic center. The
most accepted scenario to generate this emission is via a hadronic interaction
between cosmic rays (CRs) and ambient gas, where CRs are accelerated from a
central and continuous source of 1 PeV protons (PeVatron). We explore the
influence of the three-dimensional (3D) shape of the central molecular zone on
the indirect observation of the CR energy density via gamma-ray detection. We
simulated synthetic gamma-ray maps using a CR diffusion model with spherical
injection, one isotropic diffusion coefficient, no advection, and
mono-energetic particles of 1 PeV. Also, we used two different 3D gas
distributions considering the observed gas column density, both with and
without an inner cavity. We find that when using a persistent CR source, a
disk-like gas distribution is needed to reproduce the existing CR indirect
observations. This is in agreement with the continuous gas distribution implied
by some dynamical models and studies based on the comparison of emission and
absorption molecular lines. However, it contradicts several models of the
central molecular zone, which imply that this structure has a significant inner
cavity. This tension can be reconciled by an additional, impulsive CR
injection. If the central molecular zone has a cavity, a composite CR
population, coming from the stellar winds of the Wolf-Rayet stars in the
central 0.5 pc and the supernova Sgr A East, produces a good match to the
observed gamma-ray morphology in the Galactic center.
