Searching For Quiet Sun X-ray Emission With RHESSI
Abstract
In this work we are searching for X-ray emission from the Sun that is not associated with active regions. RHESSI has greater sensitivity in the 5-25 keV range than previous missions, but since the quiet Sun sources may be well-dispersed spatially across the disk, RHESSI's normal imaging technique is not well suited to the task. An alternate observational technique involves pointing RHESSI slightly away from the Sun. The resulting time-dependent transmission of the signal through RHESSI's rotating modulation collimators allows the quiet Sun signal to be distinguishable from the background. However, a large sample of data is required in this mode so that we can determine whether the observations are noise limited or quiet Sun signal. This novel offpointing technique has been used 4 times since July 2005, during which the GOES background level dropped below A1. From the data acquired we have been able to obtain limits to the quiet Sun X-ray flux between 3-100 keV. At the lowest energies, below 7 keV, the limits correlate with the observed GOES flux, suggesting a signal. We will discuss the consequences of interpreting this emission as originating from either a thermal or non-thermal electron population, and the relevance to coronal heating.
- Publication:
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AAS/Solar Physics Division Meeting #37
- Pub Date:
- June 2006
- Bibcode:
- 2006SPD....37.1402H