| Type |
Journal Article |
| Names |
Blakesley Burkhart, Snežana Stanimirović, A. Lazarian, Grzegorz Kowal |
| Publication |
The Astrophysical Journal |
| Volume |
708 |
| Issue |
2 |
| Pages |
1204-1220 |
| Date |
January 1, 2010 |
| URL |
http://adsabs.harvard.edu/abs/2010ApJ...708.1204B |
| Library Catalog |
NASA ADS |
| Abstract |
We investigate the nature and spatial variations of turbulence in the
Small Magellanic Cloud (SMC) by applying several statistical methods on
the neutral hydrogen (H I) column density image of the SMC and a
database of isothermal numerical simulations. By using the third and
fourth statistical moments we derive the spatial distribution of the
sonic Mach number ({\cal M}_s) across the SMC. We find that about 90% of
the H I in the SMC is subsonic or transonic. However, edges of the SMC
"bar" have {\cal M}_s\sim 4 and may be tracing shearing or turbulent
flows. Using numerical simulations we also investigate how the slope of
the spatial power spectrum depends on both sonic and Alfvén Mach
numbers. This allows us to gauge the Alfvén Mach number of the
SMC and conclude that its hydrodynamic pressure dominates over the
magnetic pressure. The trans-Alfvénic nature of the H I gas in
the SMC is also highlighted by the bispectrum, a three-point correlation
function which characterizes the level of non-Gaussianity in wave modes.
We find that the bispectrum of the SMC H I column density displays
similar large-scale correlations as numerical simulations; however, it
has localized enhancements of correlations. In addition, we find a break
in correlations at a scale of ~160 pc. This may be caused by numerous
expanding shells of a similar size. |
| Tags |
Galaxies: ISM, ISM: structure, MAGELLANIC CLOUDS, MHD, turbulence |