Southern Galactic Plane Survey Measurements of the Spatial Power Spectrum of Interstellar H I in the Inner Galaxy
J. M. Dickey, N. M. McClure-Griffiths, S. Stanimirovic, B. M. Gaensler, A. J. Green;
ApJ, 2001, 561, 264
ABSTRACT:Using data from the Southern Galactic Plane Survey, we have measured the spatial power spectrum of the interstellar neutral atomic hydrogen in
the fourth Galactic quadrant.
This function shows the same power-law
behavior that has been found for H I in the second quadrant of the Milky Way and in
the Magellanic Clouds with the same slope.
When we average over velocity
intervals broader than the typical small-scale velocity dispersion, we find
that the slope steepens, from ~=-3 to ~=-4 for the warm gas, as predicted by
theories of interstellar turbulence if the column density fluctuations are
dominated by variations in the gas density on small spatial scales.
The cool gas
shows a different increase of slope, which suggests that it is in the regime of
turbulence dominated by fluctuations in the velocity field.
Overall, these
results confirm that the small-scale structure and motions in the neutral
atomic medium are well described by a turbulent cascade of kinetic energy.
KEYWORDS: galaxy: structure, ism: atoms, ism: structure, radio lines: ism
PERSOKEY:turbulence, ,
CODE: dickey2001