NGC 628 (M 74) radio and X-ray maps images

One of the explanations was the action of the magnetic reconnection, which leads to a higher ordering of the magnetic fields. Because it simultaneously converts the energy of the magnetic fields into thermal energy of the surroundings, magnetic reconnection has been considered as a heating mechanism of the interstellar medium for many years.

Until recently, no clear observational evidence for this phenomenon was found. We search for possible signatures of gas heating by magnetic reconnection effects in the radio and X-ray data for the face-on spiral galaxy NGC 628 (M 74), which presents pronounced magnetic arms and evidence for vertical magnetic fields. The strengths and energy densities of the magnetic field in the spiral and magnetic arms were derived, as were the temperatures and thermal energy densities of the hot gas, for the disk and halo emission.