Dips and Waves

Introduction

There has been some heated discussion as to whether the "dip" seen in the mean electron spectrum derived from RHESSI flare observations is a real feature as it can often be removed be correcting for albedo. But for flares with relatively low thermal mission the standard "thick-target" interpretation says that the "dip" must be there. This model only accounts for Coulomb collisions between the propagating beam of accelerated electrons and the background plasma. In this nugget we present simulation results from our recent paper, where we show what happens to the dip when you also include wave-particle interactions between the beam and background plasma.

Wave-particle Interactions

This is because this model, in which the accelerated electron beam propagates to the chromosphere only having Coulomb collisions with the background plasma

The standard interpretation of RHESSI's hard x-ray emission is of electrons accelerated in the corona that propgated down to the chromosphere, colliding with the background plasma and eventually stopping.

Conclusions

The work shown here is a step towards a more complete treatment of electron transport in solar flares and highlights that the inclusion of wave-particle interactions flattens sharp low energy cutoffs in the inital accelerated electron distribution.