2011MNRAS.411..792C

The spectra emitted from clouds near the Galactic Centre (GC) are investigated calculating the UV-optical-IR lines using the physical parameters and the element abundances obtained by the detailed modelling of mid-IR observations. Graphical representation of the spectra reveals strong lines. Characteristic line ratios calculated at the nebula provide information about the dereddened spectra emitted from regions near the GC. These line ratios are compared with those observed in active galaxies. We have found that the physical conditions in the nebulae near the GC are different from those of starburst galaxies and active galactic nuclei, namely, gas velocities and densities as well as the photoionization fluxes are relatively low. The geometrical thickness of the emitting filaments is particularly small suggesting that matter is strongly fragmented by instabilities leading to an underlying shock-generated turbulence. This is revealed by the power spectra of the radial velocities, of the mid-IR continuum flux and of the computed Si/H relative abundances. Moreover, turbulence could amplify the initial magnetic fields.