Production of energy-dependent time delays in impulsive solar flare hard X-ray emission by short-duration spectral index variations

摘要

Cross-correlation techniques have been used recently to study the relative timing of solar flare hard X-ray emission at different energies. These studied find that for the majority of the impulsive flares Observed with BATSE there is a systematic time delay of a few tens of milliseconds between low(≈50 KeV) and higher energy emission(≈100 keV). These time delays have been interpreted as energy- Dependent time-of-flight differences for electron propagation from the corona, where they are accelerated, To the chromosphere, where the bulk of the hard X-rays are emitted.