Question

Explain how CMB data can be used to determine the baryon content of the Universe.

Answer 1

The large discrepancy between the amount of baryons that were synthesized in Big-Bang and that we detect at z=0 locked in stars inside galaxies and in hot/cold gas in galaxies. goup and clusters, is a well known crucial issue for present day cosmology. It is also thought that this riddle is at the backbone of how the ordinary matter has formed, inside dark potential wells, the structures we see today.

CMB is the oldest Electromagnetic radiation of the universe but It's BBN(Big Bang Nucleosynthesis), who at first observed the Baryons present in the universe, but then after the evidence of Dark Matter by CMB it was clear that Baryons are there in this universe in large numbers and they are showing gravitational field which affect the CMB radiations. In Dark matter Baryons are in large number and CMB as discovered the Dark matter similarly we can detect Baryons using CMB by studying the CMB data of radiation and interpreting the change in the intensity of radiation at some place due to presence of Baryons. Hence in this way by using CMB we can determine the Baryon content of the universe.