Non-thermal recombination - a neglected source of flare hard X-rays and fast electron diagnostics (Corrigendum)

J. C. Brown, P. C. V. Mallik, N. R. Badnell

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Brown and Mallik (BM) recently claimed that non-thermal recombination (NTR) can be a dominant source of flare hard X-rays (HXRs) from hot coronal and chromospheric sources. However, major discrepancies between the thermal continua predicted by BM and by the Chianti database as well as RHESSI flare data, led us to discover substantial errors in the heuristic expression used by BM to extend the Kramers expressions beyond the hydrogenic case. Here we present the relevant corrected expressions and show the key modified results. We conclude that, in most cases, NTR emission was overestimated by a factor of 1-8 by BM but is typically still large enough (as much as 20-30% of the total emission) to be very important for electron spectral inference and detection of electron spectral features such as low energy cut-offs since the recombination spectra contain sharp edges. For extreme temperature regimes and/or if the Fe abundance were as high as some values claimed, NTR could even be the dominant source of flare HXRs, reducing the electron number and energy budget, problems such as in the extreme coronal HXR source cases reported by e. g. Krucker et al.

LanguageEnglish
PagesC1
Number of pages3
JournalExperimental Astronomy
Volume515
DOIs
Publication statusPublished - Jun 2010

Fingerprint

flares
recombination
electron
electrons
x rays
energy budgets
energy budget
heuristics
inference
budgets
continuums
energy
temperature

Keywords

  • atomic processes
  • corona
  • flares
  • X-rays
  • errata, addenda
  • ionization
  • plasmas
  • rates
  • gamma rays
  • sun

Cite this

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abstract = "Brown and Mallik (BM) recently claimed that non-thermal recombination (NTR) can be a dominant source of flare hard X-rays (HXRs) from hot coronal and chromospheric sources. However, major discrepancies between the thermal continua predicted by BM and by the Chianti database as well as RHESSI flare data, led us to discover substantial errors in the heuristic expression used by BM to extend the Kramers expressions beyond the hydrogenic case. Here we present the relevant corrected expressions and show the key modified results. We conclude that, in most cases, NTR emission was overestimated by a factor of 1-8 by BM but is typically still large enough (as much as 20-30{\%} of the total emission) to be very important for electron spectral inference and detection of electron spectral features such as low energy cut-offs since the recombination spectra contain sharp edges. For extreme temperature regimes and/or if the Fe abundance were as high as some values claimed, NTR could even be the dominant source of flare HXRs, reducing the electron number and energy budget, problems such as in the extreme coronal HXR source cases reported by e. g. Krucker et al.",
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Non-thermal recombination - a neglected source of flare hard X-rays and fast electron diagnostics (Corrigendum). / Brown, J. C.; Mallik, P. C. V.; Badnell, N. R.

In: Experimental Astronomy, Vol. 515, 06.2010, p. C1.

Research output: Contribution to journalArticle

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