All Figures

$\begin{figure} \par\includegraphics[width=17.8cm,clip]{8103fig1.eps} \end{figure}$ Figure 1: Actual shapes of non-thermal f-b and f-f spectra for different temperature regimes and non-thermal electron parameters. Note that the cool, hot and ultra-hot totals are almost identical and the dashed curves nearly indistinguishable for $E_{\rm c} = 25$ keV.
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In the text

$\begin{figure} \par\includegraphics[width=17.5cm,clip]{8103fig2.eps} \end{figure}$ Figure 2: Photon flux ratio of non-thermal f-b to f-f emission for different temperature regimes and parameters. Line styles have the same meaning as in Fig. 1.
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In the text

$\begin{figure} \par\includegraphics[width=12cm,clip]{8103fig3.eps} \end{figure}$ Figure 3: Spatially localised spectra from a loop with the 2002 April 14 event plasma parameters for two values of $E_{\rm c}$ . The left plot shows a very distinct iron edge at $\approx$ 22 keV $({=}E_{\rm c} + V_{\rm Fe 24+})$ and a much less predominant oxygen edge at $\approx$ 15 keV $({=}E_{\rm c})$ , whereas the second plot shows very distinct oxygen ( $\approx$ 21 keV $({=}E_{\rm c})$ ) and iron ( $\approx$ 28 keV) edges. This shows the value of recombination as an $E_{\rm c}$ diagnostic. The ``edges'' appear to be of finite slope because of the finite (1 keV) resolution used.
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In the text

$\begin{figure} \par\includegraphics[width=17cm,clip]{8103fig4.eps} \end{figure}$ Figure 4: The spectral components for 4 different hypothetical situations. We show these spectra by varying the parameters around the results in the Veronig & Brown (2004) paper that analyses the coronal thick target 2002 April 14 event. In all cases we keep the same values of $\delta = 6.7$ , $E_{\rm c}=10$ keV and T=19.6 MK. Plot A is for the thick-target coronal case with the actual event parameters $n_{\rm p},{\cal F}_{\rm oc}$ according to Veronig and Brown. Plot B was obtained for the same event parameters but with $n_{\rm p}$ reduced 25 times to make the loop collisionally thin above 10 keV and with footpoint emission occulted. The injection rate is the same as Plot A so the density fraction of fast electrons is 25 times higher. The non-thermal emission is down by 25 times while the thermal is down by a factor of 625. Plot C is the same as B but with cold thick target footpoints included. The cold footpoint emission (motsly f-f) is dominant. Plot D is the same as C, but with an injection rate reduced by a factor of 25 so that the density fraction of fast electrons is the same as in Plot A. Evidently the detectability of the f-b contribution and of associated features in F(E) is sensitive to plasma parameters and observing conditions/geometry.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{8103fig5.eps} \end{figure}$ Figure 5: Spectral components for a resolution of 0.01 keV. The f-b edges of all elements involved are clearly noticeable. The parameters are T = 19.6 MK, $E_{\rm c}=10$ keV and $\delta = 6.7$ . This plot can be compared to Plot A of Fig. 4, which has the same parameters but for 1 keV binning resolution.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{8103fig6.eps} \end{figure}$ Figure 6: Fractional error ( $\Delta G/G$ ) in G (Eq. (25)) as discussed in Sect. 5 for E_* = 5, 10, 20 keV respectively for a shifted power-law due to inference of G from H ignoring the presence of recombination.
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In the text

$\begin{figure} \par\includegraphics{8103fig7.eps} \end{figure}$ Figure A.1: The f-b electron efficiency compared to f-f for the 4 elements discussed in Appendix A. It is evident from the graph that, if present, highly ionised Fe is the most efficient source of f-b HXRs in terms of the F(E) needed followed by Si, O and Mg.
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In the text

$\begin{figure} \par\includegraphics{8103fig8.eps} \end{figure}$ Figure A.2: The $\Psi _{\rm smooth}$ as discussed in Appendix A and Eq. (A.5). It is the ratio of $j_{\rm R}$ to $j_{\rm B}$ for the smooth $F(E) \propto E(E+E_*)^{-\delta -1}$ for E_*=5, 10, 20 keV respectively.
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In the text

$\begin{figure} \par\includegraphics[width=17cm,clip]{8103fig9.eps} \end{figure}$ Figure B.1: Non-thermal f-f and f-b spectra for the thick target case (Eqs. (B.11) and (B.12)) shown for 2 different temperatures: 20 MK that is pertinent to events such as the 2002 April 14 event and 10 MK, which is more in the range of ``microflare'' temperatures. It is interesting to note the three distinct energy regimes for the f-b spectrum, namely: $\epsilon < V_{\rm Fe}; V_{\rm Fe} \le \epsilon \le V_{\rm Fe} + E_{\rm c}; \epsilon > V_{\rm Fe} + E_{\rm c}$ . Clearly f-b is very important in the 10-50 keV range, precisely where albedo issues are also important.
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In the text

$\begin{figure} \par\includegraphics[width=17.8cm,clip]{8103fig1.eps} \end{figure}$	Figure 1: Actual shapes of non-thermal f-b and f-f spectra for different temperature regimes and non-thermal electron parameters. Note that the cool, hot and ultra-hot totals are almost identical and the dashed curves nearly indistinguishable for $E_{\rm c} = 25$ keV.
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$\begin{figure} \par\includegraphics[width=17.5cm,clip]{8103fig2.eps} \end{figure}$	Figure 2: Photon flux ratio of non-thermal f-b to f-f emission for different temperature regimes and parameters. Line styles have the same meaning as in Fig. 1.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{8103fig5.eps} \end{figure}$	Figure 5: Spectral components for a resolution of 0.01 keV. The f-b edges of all elements involved are clearly noticeable. The parameters are T = 19.6 MK, $E_{\rm c}=10$ keV and $\delta = 6.7$ . This plot can be compared to Plot A of Fig. 4, which has the same parameters but for 1 keV binning resolution.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{8103fig6.eps} \end{figure}$	Figure 6: Fractional error ( $\Delta G/G$ ) in G (Eq. (25)) as discussed in Sect. 5 for E_* = 5, 10, 20 keV respectively for a shifted power-law due to inference of G from H ignoring the presence of recombination.
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$\begin{figure} \par\includegraphics{8103fig7.eps} \end{figure}$	Figure A.1: The f-b electron efficiency compared to f-f for the 4 elements discussed in Appendix A. It is evident from the graph that, if present, highly ionised Fe is the most efficient source of f-b HXRs in terms of the F(E) needed followed by Si, O and Mg.
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$\begin{figure} \par\includegraphics{8103fig8.eps} \end{figure}$	Figure A.2: The $\Psi _{\rm smooth}$ as discussed in Appendix A and Eq. (A.5). It is the ratio of $j_{\rm R}$ to $j_{\rm B}$ for the smooth $F(E) \propto E(E+E_)^{-\delta -1}$ for E_=5, 10, 20 keV respectively.
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