2019/12/31 by Luke Hart, Jens Chluba · 2 citations
Physics and Astronomy · #astro-ph.CO
paper · pdf · doi:10.1093/mnras/staa412
8 pages, 8 figures, 4 tables; modified to copy the accepted MNRAS version
arxiv created 2020/05/22 · arxiv updated 2020/05/25
We present updated constraints on the variation of the fine structure constant, α\rm EM, and effective electron rest mass, m\rm e, during the cosmological recombination era. These two fundamental constants directly affect the ionization history at redshift z≃ 1100 and thus modify the temperature and polarisation anisotropies of the cosmic microwave background (CMB) measured precisely with \it Planck . The constraints on α\rm EM tighten slightly due to improved \it Planck 2018 polarisation data but otherwise remain similar to previous CMB analysis. However, a comparison with the 2015 constraints reveals a mildly discordant behaviour for m\rm e, which from CMB data alone is found below its local value. Adding baryon acoustic oscillation data brings m\rm e back to the fiducial value, m\rm e=(1.0078±0.0067) m\rm e,0, and also drives the Hubble parameter to H0=69.1± 1.2 [in units of \rm km s-1 Mpc-1 ]. Further adding supernova data yields m\rm e=(1.0190±0.0055) m\rm e,0 with H0=71.24±0.96. We perform several comparative analyses using the latest cosmological recombination calculations to further understand the various effects. Our results indicate that a single-parameter extension allowing for a slightly increased value of m\rm e (≃ 3.5σ above m\rm e,0) could play a role in the Hubble tension.