We present the first joint-likelihood analysis of Big Bang Nucleosynthesis (BBN) and Cosmic Microwave Background (CMB) data. Bayesian inference is performed on the baryon abundance and the effective number of neutrino species, $N_{ \rm eff}$, using a CMB Boltzmann solver in combination with LINX, a new flexible and efficient BBN code. We marginalize over Planck nuisance parameters and nuclear rates to find $N_{ \rm{ eff}} = 3.08_{ -0.13}^{ +0.13},\,2.94 _{ -0.16}^{ +0.16},$ or $2.98_{ -0.13}^{ +0.14}$, for three separate reaction networks. This framework enables robust testing of the Lambda Cold Dark Matter paradigm and its variants with CMB and BBN data.
Categories: astro-ph.CO hep-ph