Probing Turbulence in the Interstellar Medium of Galaxies

TL;DR

This paper introduces a new radio interferometry method to estimate the HI intensity fluctuation power spectrum in galaxies, revealing turbulence characteristics in the interstellar medium of both spiral and dwarf galaxies.

Contribution

A novel visibility correlation technique for measuring HI power spectra, especially effective for faint dwarf galaxies, and analysis of turbulence regimes in different galaxy types.

Findings

Power-law behavior of the HI power spectrum in observed galaxies

Evidence of 2D and 3D turbulence based on spectral slope

Method successfully applied to multiple galaxy types

Abstract

The power spectrum of HI intensity fluctuation of the interstellar medium carries information of the turbulence dynamics therein. We present a method to estimate the power spectrum of HI intensity fluctuation using radio interferometric observations. The method involves correlating the visibilities in the u-v plane at different baselines. This method is particularly use full for evaluating the power spectrum for the faint dwarf galaxies. We apply this method to 3 spiral galaxies and 5 dwarf galaxies. The measured power spectrum seem to follow a power law P_HI(U) = A U^\alpha, suggesting turbulence to be operational. Further, depending on the slope of the power spectrum, we expect the presence of 2D and 3D turbulence in those galaxies.