1. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova On Broken-up Spectra of RHESSI Flares Y. P. Li & W. Q. Gan Purple Mountain Observatory

2. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova Hard X-ray sources Ashwanden (2004) I II III IV V

3. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova HXR Flux= I + II + III + IV + V +…… One obvious example is that two power-law spectra sum A 1 E -δ 1 +A 2 E -δ 2  a broken-up spectrum

4. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova We use RHESSI imaging capability to check the spectral relationships between the individual HXR sources and the integrated HXRs. This study could provide a reference in explaining non-imaging HXR observations

5. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova 1N/M7.6 flare on Oct. 24, 2003 02:48:32-02:48:52 UT GOES light curves

6. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova F1 F2 F1+F1 looptop

7. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova Broken-up spectrum with a broken energy at 26.1 keV; the power-law spectral index at lower energy end is about 2 bigger than that at higher energy end Coronal contri. Footpoint contri.

8. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova Discussion For X7.1 flare on Jan. 20, 2005 (Krucker at al. 2008) corona footpoints 2.9 1.5

9. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova Although the broken-up spectra in these two flares all resulted from a summation of looptop source and footpoint sources (conclusion 1), the different broken energy, 26 keV versus 400 keV, suggests a difference in physics (conclusion 2): the former indicates a sum of emissions produced by thin-target and thick-target electrons, while the later indicates a sum of emissions produced by trapped and precipitation electrons.

10. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova footpoint contribution corona contribution 1.5 2.9

11. 9th RHESSI Workshop, Sept. 1-5, 2009, Genova Thank you!