Talk:The Rise and Fall of The Low Energy Cut Off

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Revision as of 20:53, 18 November 2008 by Pshilaire (Talk | contribs)
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It appears to me a bit premature to say that the low-energy cutoff issue is dead: As pointed out in Holman et al. (2003) the "traditional" method yields a lower limit of 2.6x10^31 ergs in injected non-thermal electrons, a factor 3 or so above the instantaneous thermal energy content, a fact often observed in flares (see e.g. Emslie et al., 2004; Saint-Hilaire et al., 2005; ...). Using Emslie's "Death to the low-energy cutoff" approach (Emslie, 2003), and using for kT that given by isothermal fitting of the X-ray spectrum, Gordon Holman finds 4x10^34 ergs as the upper limit on the energy in injected non-thermal electrons. I.e. *three* orders of magnitude more. Where does all that energy go to? Which method is closest to the Truth? Assuming this is indeed too much energy, it is clear that we need another, higher, kT value than the one given by isothermal fitting.

I think Emslie (2003) is a definite step forward, but might have simply pushed the problem sideways for observers interested in flare energetics: instead of determining a proper low-energy cutoff, it seems it is an appropriate super-hot kT that has to be determined...

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