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3.3.3 Raymond-thermal spectrum example
What is the conversion factor from counts per second to energy flux
for a particular spectrum? For example, consider a Raymond-Smith
Plasma with a temperature corresponding to 1 keV and a column of 5 x 1021 cm-2 (log(N
H) = 21.7). The ECF for this
spectral model is taken from Table 10 or Figure 32, it is
8.84 x 109. That is, a flux of 1 x 10-11 ergs cm-2 s-1
in the ROSAT energy band (0.1 to 2.4
keV) will give a count rate of 0.0884 ct s-1 in the HRI. Inverting
this relationship gives the result that 1 ct s-1 = 1.13
x 10-10 ergs cm-2 s-1.
Figure 30:
The ECF (energy-to-counts
conversion factor) is plotted as a function of the energy index for
the powerlaw spectral model. The values are shown for a range of
absorbing column densities (log(NH)).
![\includegraphics[width=\textwidth]{power.ps}](power.gif) |
LINK TO POSTSCRIPT FILE
for
Figure 30
Figure 31:
The ECF
(energy-to-counts conversion factor) is plotted as a function of the
temperature (Log(kT)) for a Thermal Bremsstrahlung spectral model.
The values are shown for a range of absorbing column densities
(log(NH)).
![\includegraphics[width=\textwidth]{thermal.ps}](thermal.gif) |
LINK TO POSTSCRIPT FILE
for
Figure 31
Figure 32:
The ECF
(energy-to-counts conversion factor) is plotted as a function of the
temperature (Log(kT)) for a Raymond-Smith spectral model. The values
are shown for a range of absorbing column densities (log(NH)).
![\includegraphics[width=\textwidth]{raymond.ps}](raymond.gif) |
LINK TO POSTSCRIPT FILE
for
Figure 32
Figure 33:
The ECF
(energy-to-counts conversion factor) is plotted as a function of
the temperature (Log(kT)) for a blackbody spectral model. The values
are shown for a range of absorbing column densities (log(NH)).
![\includegraphics[width=\textwidth]{black.ps}](black.gif) |
LINK TO POSTSCRIPT FILE
for
Figure 33
Next: 3.4 Time Variability Studies
Up: 3.3 Expected Count Rates
Previous: 3.3.2 Power-law spectrum example
rsdc@cfa.harvard.edu
1999-05-25