schriste@ssl

Iain Hannah[1], S. Christe[1,2], S. Krucker[1], H. Hudson[1], R.P. Lin[1,2], E. DeLuca[3]
1 Space Sciences Lab, U.C. Berkeley
2 Physics Department, U.C. Berkeley
3 Harvard-Smithsonian Center for Astrophysics

Presented at Fall AGU Meeting 2007 (presentation link).

Abstract:
We present analysis of microflares (small active region associated flares below GOES C class) using RHESSI and Hinode/XRT. RHESSI has observed well over 1,000 microflares since Hinode launched late in 2006 and of these over 150 have good Hinode/XRT coverage. We use RHESSI to obtain the temperature, emission measure and non-thermal power-law parameters from spectral fitting. We compare RHESSI and Hinode/XRT images to locate the thermal and non-thermal emissions. Taking advantage of the sensitive high-resolution capability of XRT for the softer X-rays, we investigate the resulting heating and evaporation from the accelerated electrons observed via the non-thermal emission by RHESSI.

Steven Christe[1,2], I. Hannah[1], S. Krucker[1], G. Hurford[1], J. McTiernan[1], R.P. Lin[1,2]
1 Space Sciences Lab, U.C. Berkeley
2 Physics Department, U.C. Berkeley

Presented at Fall AGU Meeting 2007 (presentation link)

Abstract:
We present the first in-depth statistical survey of all X-ray microflares observed by RHESSI between March 2002 and March 2007, a total of 25,705 events. These microflares were found using a new flare-finding algorithm designed to search the 6–12~keV count rate when RHESSIs full sensitivity was available in order to find the smallest events. These microflares are small flares, from low GOES C Class to below A Class (background subtracted) and associated with active regions. Each microflare is automatically analyzed at the peak time of the 6–12~keV emission. Spectral parameters are determined both by considering ratios between energy channels and by forward fitting a thermal plus non-thermal model. Flare images are created using back-projection and centroids and by forward fitting the complex visibilities. The combination of imaging and spectral parameters allow for the first time analysis of the thermal and non-thermal energy at the peak time of these microflares.