1.Introduction :
CAMB (Code for Anisotropies in Microwave Background) is a numerical tool designed to best describe anisotropies in microwave background, i.e the first light emitted by the Universe 380.000 years after the Bigbang. This code is avalaible on cosmologist.info website. You will able to find also the theoretical part and the implemented numerical method.
2.Use of CAMB :
Once the archive decompressed, look at the compilation. We can build 2 types of executable : "camb" et "camb_fits". The first is the basics version of the code, which only generates raw output data files. Among these files, the most important is the one which contains temperature as a function of the multipole "l" parameter : "test_scalCls.dat" file by default.
The second one allows to get, with in addition of the previous ones, a FITS formatted output file : "test_scalCls.fits" file by default.
Depending on the version of the code you have, you may experience problems with compilation. For any questions, you can subscribe to the following dedicated forum : cosmocoffee.info, and post into the "Computers and software" part.
3.Results examples :
Below a comparison of three power angular spectrums got by CAMB with WMAP et PLANCK experimental data : the first one represents the concordance model also called ΛCDM model, the second and the third one are Einsteinde Sitter (EdS) model where density is equal to critical density (with Ω_{ν}=0.12 and Ω_{Q}=0.12), and the two last ones are data collected by WMAP and PLANCK missions.
Here the gnuplot script for plotting the power angular spectrums :
You can notice the logarithmic scale for 0 < l < 200 and linear scale for 200 < l < 2000.
