Résumé
Primordial magnetic fields (PMFs), long studied as relics of the early Universe, accelerate recombination and have been proposed as a way to relieve the Hubble tension. However, previous studies relied on simplified toy models. Here we use recent evaluations of recombination with PMFs, incorporating full magnetohydrodynamic simulations and detailed Lyman-alpha radiative transfer, to test PMF-enhanced recombination (b Lambda CDM) against observational data for the cosmic microwave background, baryon acoustic oscillations and type Ia supernovae. Focusing on non-helical PMFs with a Batchelor spectrum, we find a preference for present-day total field strengths of approximately 5-10 pG. Depending on the dataset combination, this preference ranges from mild (similar to 1.8 sigma with Planck+DESI) to moderate (similar to 3 sigma with Planck+DESI+SH0ES-calibrated supernovae) significance. The b Lambda CDM has Planck+DESI chi(2) values equal to or better than those for Lambda CDM while predicting a higher Hubble constant. Future high-resolution cosmic microwave background temperature and polarization measurements will be crucial for confirming or further constraining PMFs at recombination. Field strengths of 5-10 pG align closely with those required for cluster magnetic fields to originate entirely from primordial sources, without the need for extra dynamo amplification.