Relating graph energy and Sombor index

Abstract

The energy of a graph (ε) is the sum of absolute values of its eigenvalues, thus it is a graph-spectrum-based quantity. The Sombor index (SO) is a recently conceived vertex-degree-based topological index. We establish various relations between ε and SO, among which are lower and upper bounds. These relations improve and extend earlier results communicated in the paper [A. Ülker, A. Gürsoy, N. K. Gürsoy, MATCH Commun. Math. Comput. Chem. 87 (2022) 51–58].