Comment on "Dispersion relation for MHD waves in homogeneous plasma"

TL;DR

This paper critiques Pandey & Dwivedi's claim that the dispersion relation for MHD waves is a sixth degree polynomial, clarifying that only five roots are relevant for wave propagation analysis.

Contribution

The authors demonstrate that Pandey & Dwivedi's derivation introduces an unnecessary root, emphasizing that only five roots are necessary for understanding wave modes.

Findings

Pandey & Dwivedi's sixth degree polynomial includes an extraneous root.

Five roots of the dispersion relation are sufficient for wave analysis.

The additional root is insignificant for the physical interpretation of wave modes.

Abstract

Pandey & Dwivedi (2007) again tried to claim that the dispersion relation for the given set of equations must be a sixth degree polynomial. Through a series of papers, they are unnecessarily creating confusion. In the present communication, we have shown how Pandey & Dwivedi (2007) are introducing an additional root, which is insignificant. Moreover, five roots of both the polynomials are common and they are sufficient for the discussion of propagation of slow-mode and fast-mode waves.