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Blackbody Spectrum Example

The expected (50% in detect cell) count rate from a source with a blackbody spectrum (perhaps a neutron star) needs to be estimated. The source has L tex2html_wrap_inline17741  ergs s tex2html_wrap_inline17743 in the ROSAT\ energy band (0.1 to 2.4 keV), and is at a distance of 2 kpc with N tex2html_wrap_inline17745  cm tex2html_wrap_inline17747 (log(N tex2html_wrap_inline17749 ). The assumed temperature is equivalent to 0.1 keV. The unabsorbed flux for this source is tex2html_wrap_inline17751  ergs cm tex2html_wrap_inline17753  s tex2html_wrap_inline17755 , or in units of tex2html_wrap_inline17757 the flux is tex2html_wrap_inline17759 . From the Table 11.5 or Figure 11.7 the appropriate ECF is tex2html_wrap_inline17761 , and the expected count rate is tex2html_wrap_inline17763  counts s tex2html_wrap_inline17765 . We estimate that a detection of this source at the tex2html_wrap_inline17767 level will require an observation time of about 4,000 seconds.


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