Testing consistency of Ωbh2 in the Planck data

We find that the cosmic microwave background temperature and polarization power spectra measurements from Planck constrain the parameter Omega(b)h(2) mostly through (i) the amplitude of Thomson scattering and (ii) a factor that ensures Thomson scattering does not violate momentum conservation of the baryon-photon fluid. This allows us to obtain two distinct but comparably strong constraints on Omega(b)h(2) from the Planck data alone. They are consistent, showing robustness of the Planck Omega(b)h(2) constraint. We can alternatively rephrase these constraints as (i) the change of the Thomson scattering cross section since recombination is less than similar to 2% and (ii) momentum during recombination is conserved to better than similar to 2% by Thomson scattering. Decoupling the eight various ways in which Omega(b)h(2) affects the Planck data leads to H-0 only slightly higher than in the standard analysis, (68.3 +/- 1.6) km/s/Mpc. The overall consistency of all Omega(b)h(2) constraints does not suggest any problem with the standard cosmological model.