RHESSI Microflare Statistics

I Hannah

S. Christe, H. Hudson, S. Krucker, M. A. Hendry and L. Fletcher

We present preliminary results from the first microflare survey using the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). RHESSI is ideally suited for observing microflares due to its unprecedented sensitivity and spectral resolution of the low energy X-rays (3-15 keV) produced by the thermal and non-thermal electron bremsstrahlung emitted by microflares. We have developed automated code that can survey a large sample of microflares, providing thermal (temperature and emission measure) and non-thermal (power-law index) characterisation of each event. We are also considering the effect of threshold selection bias on the observed microflare distributions and working on a semi-analytical technique to correct for the discrepancy between observed and intrinsic distributions - so far this has been tested on TRACE micro- and nanoflare observations. The improved sensitivity of RHESSI and consideration of bias in the microflare statistics will provide us with a more accurate estimate of the power input into the corona from microflares. This work is supported by PPARC.