Synhrotron radiation from positrons University of Maryland 同步辐射从正电子马里兰大学.pptVIP

More phenomena difficult to observe A MacKinnon More phenomena difficult to observe synchrotron radiation of positrons: sub-mm observations? inner bremsstrahlung of secondary neutrons Positron energy distribution from ?+ decay Effective distribution in thick target source Cumulative e+ distribution – ‘mean distribution’ in source Synchrotron spectrum – monoenergetic e Synchrotron spectrum Rough estimate Inner Bremsstrahlung spectrum Angular distribution of IBXR’s Briefly: X-ray flux integrates over all neutron energies present along the line of sight looking further from the Sun samples more energetic neutrons because lower energy ones decay Approximately, the distribution of X-ray flux with angle is the Laplace transform of the neutron energy distribution at the Sun invert integral equation to deduce neutron energy distribution F(E) Example Sun’s X-ray halo Seckel et al. (1992) modelled turbulent transport of cosmic rays in inner heliosphere + interaction with small-scale magnetic fields near solar surface (lots of assumptions!) predicted 2.3×10-8 neutrons.cm-2.s-1 above 100 MeV at 1 AU assume F(E)?(E+10)-? at the Sun and normalise to this prediction ? IB flux at 1% of cosmic XRB in 2 – 10 keV range After flares? look near large, limb flares…….. * really, this is what is injected into the source by colliding p’s, ?’s ?=2, Tmax = 3 GeV/nucl dE/dt : collisions (logarithmic energy dependence – constant!) synchrotron (?2) bremsstrahlung (? - above 100 MeV) divide these by dE/dt ?c = 4.3×106 B ?2 sin? 1032 protons above 300 MeV × 10-2 e+ per proton 4×10-22 1000 erg.s-1 .Hz-1 × 10-2 s lifetime spread out over e.g. 100 s and divided by 4 ? AU2 ~ 10-20 erg.cm-2.s-1 .Hz-1 = 10-23 W.m-2.Hz-1 = 10-1 s.f.u. TOO SMALL Knipp and Uhlenbeck (1936); Bloch (1936); Petrosian and Ramaty (1972) r = solar distance z = distance from Earth distances in AU * * *