applying redshift to apec spectrum

[nicolas-cerardi]

Hi,
Not sure this is the good place for this issue as this is more a physical question, but I'll give it a shot. Related to #44

The spectra computed with PyatomDB are in the object rest frame. If the object lies at redshift z, how to compute its spectra in the observer frame ?

As I understand :

• If the band of interest is X1 to X2 keV in the observer frame, then one should compute the raw spectrum in the rest frame in the band X1*(1+z) - X2*(1+z) keV
• Then because the units are photons and bins^-1, there is no need to divide the spectrum by (1+z) (?) (usually one would do that for the K-correction). So the X1*(1+z) - X2*(1+z) keV spectrum is directly the X1 to X2 keV spectrum.
• So the only transformation needed is f * ne * np * Volume / (4*pi*DL(z)^2) * Aeff
• (If needed, rmf & arf have to be applied in last)

Is there anything wrong with this ?