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π 0 Decay

Composite Solar Flare Spectrum. Thermal Bremsstrahlung. T = 2 x 10 7 K. T = 4 x 10 7 K. Nonthermal Bremsstrahlung. π 0 Decay. Positron and Nuclear Gamma-Ray lines. ~ 10 32 ergs in ~ 10 3 seconds = ~10 29 ergs/s => ~10 36 electrons/s! => empty entire flare loop!!

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π 0 Decay

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  1. Composite Solar Flare Spectrum Thermal Bremsstrahlung T = 2 x 107 K T = 4 x 107 K Nonthermal Bremsstrahlung π0 Decay Positron and Nuclear Gamma-Ray lines

  2. ~ 1032 ergs in ~ 103 seconds = ~1029 ergs/s => ~1036 electrons/s! => empty entire flare loop!! => ~1017 amps!! What about thermal emission from confined ~108 K plasma?

  3. e+ - e- n-capture bremsstrahlung narrow lines broad lines RHESSI solar count spectrum from 11:06:20 – 11:10:04 on Oct. 28, 2003 (Smith et al. Poster 2.01)

  4. Loop-top source Stochastic Acceleration throughout the loop - Miller/Petrosian

  5. RHESSI Science Objective To explore the basic physics of particle acceleration and explosive energy release in solar flares • Impulsive Energy Release in the Corona • Acceleration of Electrons, Protons, and Ions • Plasma Heating to Tens of Millions of degrees • Energy and Particle Transport and Dissipation A1309.03

  6. HESSI Primary Observations • Hard X-ray Images • Angular resolution as fine as 2 arcseconds • Temporal resolution as fine as 10 ms • Energy resolution of <1 keV to ~5 keV (FWHM) • High Resolution X-ray and Gamma-ray Spectra • ~keV energy resolution • To energies as high as 15 MeV A1309.05

  7. RHESSI’S PHOTON-BASED IMAGING DATA : * Energy & Time (~μsec) of EVERY Photon Interaction * Aspect Information – Six solar limbs to ~arcsec, 16 times per spin (4s), & roll angle to ~arcmin => ~ ARCSEC IMAGING WITH ARCMIN STRUCTURE * Field of View ~ 1 ° > full Sun, ~0.2 ° pointing * DATA Stored in 4 Gigabyte memory (> largest flare) & dumped at 4 Mbps to Berkeley (& Wallops) => FULLY AUTONOMOUS OPERATION

  8. X-Class Flare of 2002 July 23 • 00:27:20–00:43:20 UT • GOES X4.8 • Location: S13E72 (Lin et al. 2003)

  9. Derived Parent Electron Spectrum for 23 July 2003, 00:30:00 -00:30:20(Johns-Krull 2003) • White: Johns & Lin (1992) • Red: Piana et al. 2002, 0th order regularization

  10. WITH IMAGING DOWN TO THE 1% LEVEL AND ZERO NOISE Contours of an 8”'' FWHM Gaussian source with its associated albedo patch. (factor of 2 contours) 1.5% RHESSI-NESSI-II -- 24-27 March 2004 3% 6% The green contours show the levels of integrated albedo flux. The 2nd green (~35''x100'') contour contains 75% of the albedo flux, assumed here to be 50% of the primary source flux. E J Schmahl (2004)

  11. 23 July 2002 flare nuclear de-excitation lines (Smith et al. 2003),see Smith et al poster 2.01, Shih et al talk 47.08

  12. Smith et al., 2003

  13. Particle Acceleration by the Sun Lower corona: Solar Flares - Large, small, microflares, nanoflares (?) High Corona: Coronal radio phenomena – Metric type I, II, III, IV, V Low energy (sometimes down to ~0.1 keV) impulsive electron events, associated with 3He-rich ion events Continuous (?) electron acceleration (~1-100keV superhalo) Inner heliosphere: Fast Coronal Mass Ejections (CMEs) with shock waves

  14. Microflares from Active RegionsKrucker et al. 2002

  15. Flares/Microflares in Active Regions Observed frequency distribution of flares is flat (slope below 2), i.e. there is not enough energy in flares to heat the solar corona (e.g. Crosby et al. 1993, Shimizu et al. 1997) Steeper distribution? at lower energies?  microflare/ nanoflare heating? Instrumental energy cutoff & sensitivity are important! (from Krucker, 2003) See Christe et al. talk 87.03

  16. Panel 1,2: GOES (Class A3 above B8 bkgd) VERY small! Panel 3: RHESSI Spectrogram Panel 4: RHESSI non-thermal (12-15 keV) Panel 5: thermal (3-12 keV) channel Panel 6: Radio Spectrogram from WIND/WAVES

  17. April 15, 2002, Solar FlareSui & Holman 2003, Ap. J. 596, L251 RHESSI Light Curve RHESSI Images (10-25 keV) 12-25keV 25-50 keV • Evolution of the coronal source above the loop : • Separation • Stationary ~ 2 mins • Outward motion at300 km/s

  18. RHESSI SpectraThin Shutters (A1)Thin + Thick (A3)Detector #41-minute accumulations

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