The Scale Height of NGC 1058 Measured from its HI Power Spectrum

We have measured the HI power spectrum of the nearly face-on spiral galaxy NGC 1058 from radio-interferometric observations using a visibility based estimator. The power spectrum is well fitted by two different power laws P (U) = AUα, one with α = − 2.5± 0.6 at small length-scales (600 pc to 1.5 kpc) and another with α = − 1.0± 0.2 at large length-scales (1.5 kpc to 10.0 kpc). We interpret this change in the slope of the power spectrum as a transition from 3D turbulence at small length-scales to 2D turbulence in the plane of the galaxy’s disk at large length-scales. We use the observed break in the power spectrum to estimate the galaxy’s scale-height, which we find to be 490± 90