Model-independent cosmological constraints from the CMB

Abstract

We analyse CMB data in a manner which is as model-independent as possible. We encode the effects of late-time cosmology into a single parameter which determines the distance to the last scattering surface. We exclude low multipoles $\ell<40$ from the analysis. We consider the WMAP5 and ACBAR data. We obtain the cosmological parameters $100\omega_b =2.13\pm 0.05$, $\omega_c=0.124\pm 0.007$, $n_s=0.93\pm 0.02$ and $\theta_A=0.593\pm 0.001$ degrees (68% C.L.). The last number is the angular scale subtended by the sound horizon at decoupling. There is a systematic shift in the parameters as more low $\ell$ data is omitted, towards smaller values of $\omega_b$ and $n_s$ and larger values of $\omega_c$. The scale $\theta_A$ remains stable and very well determined.