On the sensitivity of the GOES flare classification to properties of the electron beam in the thick target model

Abstract

The collisional thick target model, wherein a large number of electrons are accelerated down a flaring loop, can be used to explain many observed properties of solar flares. In this study, we focus on the sensitivity of GOES flare classification to the properties of the thick target model. Using a hydrodynamic model with RHESSI-derived electron beam parameters, we explore the effects of the beam energy flux (or total non-thermal energy), the cut-off energy, and the spectral index of the electron distribution on the soft X-rays (SXRs) observed by GOES. We conclude that (1) the GOES class is proportional to the non-thermal energy $E^{\alpha}$ for $\alpha \approx 1.7$ in the low energy passband (1-8 \AA) and $\approx 1.6$ in the high energy passband (0.5-4 \AA); (2) the GOES class is only weakly dependent on the spectral index in both passbands; (3) increases in the cut-off will increase the flux in the 0.5-4 \AA\ passband, but decrease the flux in the 1-8 \AA\ passband, while decreases in the cut-off will cause a decrease in the 0.5-4 \AA\ passband and a slight increase in the 1-8 \AA\ passband.