The "slow LDEs" look thermal, but the hard X-rays show that they are not.
We suspect a relationship between these hard X-rays and other coronal
sources (Hudson, ApJ 224, 235, 1978; Masuda et al., Nature 371, 495,
If the most impulsive flares and the most gradual flares
both have comparable non-thermal components, it is likely
that CME-launching arcade events also are non-thermal.
We don't know yet if there is a relationship between
slow LDEs and the infall signature seen in spiky arcades.