Question

THIS IS AN ASTRONOMY QUESTION:

Question 1: An observer uses an X-ray telescope with an effective area of 500 cm^2 to search for X-ray emission lines in the spectrum of an accreting neutron star. At the energy of the target line, 6.7 keV, the continuum (arising from accretion) contributes 1.2 × 10^−3 counts/s/cm2/keV. In a spectrum accumulated over a 1 ks observation, the observer measures a total of 162 counts from within a 0.2 keV range centred on the target line energy.

What is the background contribution to the measurement in the 6.6 to 6.8 keV range? Estimate the strength of the line (i.e. the number of photons in excess of the continuum level) and the uncertainty. Ensure to correctly propagate the errors, and quote the confidence level for the uncertainty. What is the signal-to-noise ratio of the line?

Answer 1