Journal Article

Spectra from the shocked nebulae revealing turbulence near the Galactic Centre

M. Contini and I. Goldman

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 411, issue 2, pages 792-806
Published in print February 2011 | ISSN: 0035-8711
Published online February 2011 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1111/j.1365-2966.2010.17719.x
Spectra from the shocked nebulae revealing turbulence near the Galactic Centre

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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.

Keywords: shock waves; radiation mechanisms: general; turbulence; ISM: abundances; Galaxy: centre; galaxies: active

Journal Article.  8430 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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