Power Spectra with CAMB
3 posts • Page 1 of 1
I was going through the tutorial for CAMB (http://camb.readthedocs.io/en/latest/CAMBdemo.html ) and I notice the TT spectrum is shifted downward compared with the Planck 2015 results( https://arxiv.org/pdf/1502.02114.pdf ) . For example, the first peak in the demo is around 5300 [tex] \mu K^2[/tex], while for Planck the peak is around 5700 [tex] \mu K^2[/tex]. I notice the same thing when trying to compare the BB spectrum with the best fit values (third entry in the data set column in http://irsa.ipac.caltech.edu/data/Planc ... lary-data/ ). In both cases it seems multiplying the CAMB results by a constant factor would make them match the Planck observation, but I do not see why that is the case.
The demo is just using some random parameters. Specifically it probably doesn't set a realistic value of A_s. Always check with print(pars) that everything is correct after setting values.