Searching for Solar Shocks

1. Searching for Solar Shocks Including a brief history of X-ray astronomy H. Hudson, SPRC/UCSD/ISAS

2. Beautiful Chandra shock (E0102-72)

3. How X-ray astronomy began • September 21, 1859 (Carrington) • Kew Gardens - magnetic effects • The proper conservatism of L. Kelvin of Largs

6. Latent discoveries • X-rays (Roentgen, 1895) • The ionosphere (Heaviside, 1902) • Collisionless shock waves - ? • “Space weather” - ??

7. Oliver Heaviside • Maxwell’s equations • Laplace transforms • The Heaviside function • Telegraph equation - Pupin Laboratory • Heavy opposition to quaternions • T.S. Eliot, Cats, “Journey to the Heaviside Layer” • Not the father of X-ray astronomy (due credit to B. Rossi, of course) • “Why should I refuse a good dinner simply because I don't understand the digestive processes involved.”

8. We’re in a golden era of coronal observation

10. The dynamic corona

12. The boundary between Photosphere and corona • Density plummets precipitously • Collisionality diminishes • Radiation decouples • Plasma beta drops drastically

13. T.R. T B 0 Height in corona

15. Solar shock: Type II burst

16. A Type II burst is the same thing as a “slow drift” burst - perhaps discovered by early military radars; explained by J. P. Wild and Y. Uchida (recall l-2 ~ ne) III Wavelength II Time

17. Meter-waves and soft X-rays • Megahertz vs Exahertz • Radiative transfer vs direct view • Magnetic effects vs Bremsstrahlung • Inherent fuzziness vs sharp resolution • But - by 1998, we’d seen Types I, III, IV and others

18. But not the simplest and most obvious: Type II!

19. X-ray observation of a global wave • Wave propagation tells us about coronal structure • The innermost (earliest) motions tell us about the flare process itself

20. Moreton-Ramsey wave and EIT wave

21. Why didn’t SXT discover “SXT waves”? • SXT views the whole corona • Fast-mode MHD waves must involve compressional heating • SXT response increases monotonically with temperature • So… why did it take 8 years and the competitive example of EIT?

22. Factors abetting wave detectionin soft X-rays • The wave needn’t be shocked • The SXT response strongly favors detection of a temperature increase (adiabatic law)

23. Sensitivity estimation 2 R (n,T ) = const £ n £ S (T ), i e i e e @ ( l n ( R )) d ( l n ( S )) i i = ¢ ( T ) = 3 + , i e @ ( l n ( T )) d ( l n ( T )) e e

25. SXT and TRACE responses Courtesy N. V. Nitta

26. Factors reducing sensitivity • Poor CCD dynamic range (AEC) • Limited SXT telemetry(“Velocity filter”) • Photon counting statistics • Scattering from grazing-incidence mirror • Flare mode

29. May 6, 1998 FOV 10 arc min

30. FOV 5 arc min

33. Gas pressure in flare loops

35. SOHO/ EIT

36. Uchida’s 1968 model

37. A.R. Uchida S.W.

38. OK, so what caused the wave? • In principle we can see it all in soft X-rays • The earliest manifestation of the wave is within 20,000 km of the flare core • But… it is significantly displaced from the soft X-ray core of the flare

40. Mysteries of low b plasma • Everything seems to expand (cf. Aly) • The Virial Theorem looks goofy too

41. Implosion conjecture • At low b, the coronal energy is purely B2/8p • During a flare, there’s no time for energy transport through the photosphere • Therefore, some field lines must shorten

42. Open field lines Closed field lines Isomagnetobars How low-b implosions must work

43. MHD Virial Theorem

44. The end, thanks

45. The end, thanks