Correlations between turbulent velocity and density fields in the local interstellar medium

TL;DR

This study re-evaluates the correlation between velocity and density fluctuations in the interstellar medium using HI4PI data, correcting previous errors and concluding that these fields are uncorrelated, which alters earlier interpretations.

Contribution

The paper corrects a software error in the velocity decomposition algorithm, clarifying that velocity and density fields in the ISM are uncorrelated, revising previous conclusions.

Findings

Velocity and density fields are uncorrelated in the ISM.

Correction of the VDA software error changed previous correlation results.

Previous claims of anti-correlation are invalid.

Abstract

Kalberla et al. used HI4PI data to analyze velocity and density fluctuations in the interstellar medium (ISM). They applied the Yuen et al. (2021) velocity decomposition algorithm (VDA) for separating such fluctuations in the position-position-velocity (PPV) space. In the first version of this manuscript they came to the conclusion that velocity and density fields are statistically correlated. Yuen et al. (2021) tried to reproduce these results and pointed to a likely mistake in the VDA expression that was used. We confirm that there was such a software problem. The statement that VDA derived density and velocity fields from HI4PI are anti-correlated needs to be withdrawn. Correct is that these density and velocity fields are uncorrelated. In turn major parts of the conclusions in the first version of this manuscript, based on an erroneous correlation, are invalid. The submission to A&A was withdrawn on 24 February 2022.