I'm trying to do a simple calculation, but there must be something wrong.(adsbygoogle = window.adsbygoogle || []).push({});

The wavelength ##\lambda_1## corresponding to first acoustic peak of the CMB is related to the sound horizon at last scattering, ##d_{hs}##, by :

## \lambda_1 = 2d_{hs} ## (see for instance slide 14 on Wayne Hu PDF slides).

Now, the multipole ##l## of the first acoustic peak can be related to its wavelength and to the distance to last scattering surface, ##D##, by :

##l_1 = \frac{2 \pi}{\lambda_1} D## (see slide 15)

From that I deduce the following equation :

##l_1 = \frac{\pi}{d_{hs}}D##

I find in the litterature that ##D \approx 14000 Mpc##, and ##d_{hs} \approx 150 Mpc##. I plug those values into the previous equation, and I find ##l_1 \approx 293##, which is quite far from the ##l_1 \approx 200## I should get for the first peak. What's wrong ?

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# I Getting the wrong multipole for 1st acoustic peak

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