[Comment on “The case for protons powering solar flares”] The case for electron dominance in solar flare energy transport



“Facts are stubborn things,” A. R. Lesage (1668–1747), once said. The accompanying article claims that “the crux of the argument is one of global energetics,” in other words that the existence of an energy content in protons comparable to that in electrons is enough to uproot the time-honored notion that electrons are the principal mediator of energy transport during solar flares. However, simply having a large enough reservoir of energy in high-energy particles is not sufficient; one must also make sure that this energy is distributed amongst the high-energy particles in a manner that accounts for the intense hard X ray bursts that are such a ubiquitous signature of the impulsive phase of flares. Further, the energy must be deposited at the right place to account for a host of other observable signatures, such as the dramatic increase in the amount of 107K plasma that characterizes the main phase of the flare. Only deka-keV electrons and ˜MeV protons satisfy the energy deposition requirements and, while such electrons naturally account for the impulsive-phase hard X ray burst, MeV protons do not.