Constraining coronal heating with multiwavelength measurements

The high temperature of the corona is one of the outstanding problems in solar physics. Several mechanisms have been proposed to solve this problem, including waves and small reconnection events. Theories are often grouped by frequency into impulsive or steady heating, but which of these mechanisms are at work remains unclear. A growing body of literature examines this problem via investigation of differential emission measures, including an increasing number of studies that utilize multiwavelength data sets. High-energy (hard X-ray) studies are particularly useful for their high sensitivity to flare-temperature plasma, but cannot, in isolation, disambiguate complex DEMs. Soft X-ray and extreme ultraviolet studies can have a wide range of temperature sensitivities, but lack the required sensitivity to detect the highest temperatures in the quiescent corona. Only by combining observations across a wide range of wavelengths with a wide range of temperature sensitivities will definitive answers to this problem emerge.