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

TL;DR

This study measures the HI power spectrum of galaxy NGC 1058, revealing a transition from 3D to 2D turbulence and estimating the galaxy's scale height at approximately 490 parsecs.

Contribution

It provides the first measurement of the HI power spectrum in NGC 1058 and uses it to estimate the galaxy's scale height based on turbulence transition.

Findings

Power spectrum fits two power laws with different slopes

Transition from 3D to 2D turbulence identified

Estimated galaxy scale height is 490 ± 90 pc

Abstract

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 $P(U)=AU^{\alpha}$, one with $\alpha =- 2.5\pm 0.6$ at small length-scales $(600 {\rm pc} {\rm to} 1.5 {\rm kpc})$ and another with $\alpha =- 1.0\pm 0.2$ at large length-scales $(1.5 {\rm kpc} {\rm to} 10.0 {\rm kpc})$. 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 \pm 90 $ pc.