Spectral Analysis and Energy Estimates in M/X Flares using RHESSI and SXI Amir Caspi 1,2, Säm...
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Transcript of Spectral Analysis and Energy Estimates in M/X Flares using RHESSI and SXI Amir Caspi 1,2, Säm...
Spectral Analysis and Energy Estimates in M/X Flares using
RHESSI and SXI
Amir Caspi1,2, Säm Krucker2, Robert P. Lin1,2
1 Department of Physics, University of California, Berkeley, CA 947202 Space Sciences Laboratory, University of California, Berkeley, CA 94720
June 19, 2003 AAS/SPD Meeting 2
Why is spectral analysis important?
• Provides estimates of energy in thermal and non-thermal electrons
• Provides clues to heating mechanism(s)
• How does SXI help?– Broad band response in soft X-rays– Sensitive to lower-temperature plasmas– Another estimate of thermal energy
June 19, 2003 AAS/SPD Meeting 3
01/24/2003 M1.9 flare
June 19, 2003 AAS/SPD Meeting 4
Fitting the spectra
Forward modeling - which model/fit is best/proper?
June 19, 2003 AAS/SPD Meeting 5
Thermal + Power Law
- Naïve model, poor fit early on, requires small low-energy cutoff at all times
June 19, 2003 AAS/SPD Meeting 6
2 Thermals + Power Law
- Much better fit early on, but ambiguous at later times; still somewhat incomplete
June 19, 2003 AAS/SPD Meeting 7
Analysis - methods and problems
• Low-T component dominant <15 keV– Iron feature is good measure of thermal component
• Power law dominant >30-35 keV– Spectral index fairly easy to fit, but…
• Low-E cutoff very hard to determine– Power law & High-T component interfere
June 19, 2003 AAS/SPD Meeting 8
• Low-T component dominates thermal energy• High-T should vary smoothly - constraint on fit
Spectral parameters, energies
June 19, 2003 AAS/SPD Meeting 9
Conclusions• Forward modeling gives ambiguous results
– Still provides a reasonable first estimate of energies
• High-T component complicates analysis
•Calculate SXI-derived T, EM time profiles•Continue analysis for variety of flares
–More cases may help determine low-E cutoff
Future Work