Consistency test of the fine-structure constant from the whole ionization history

Abstract

In cosmology, the fine-structure constant can affect the whole ionization history. However, the previous works confine themselves to the recombination epoch and give various strong constraints on the fine-structure constant. In this paper, we also take the reionization epoch into consideration and do a consistency test of the fine-structure constant from the whole ionization history. From the data combination of Planck 2018, BAO data, SNIa samples, SFR density from UV and IR measurements, and the Q HII constraints, we find the constraint on the fine-structure constant during the recombination epoch is α rec/α EM = 1.001494+0.002041 -0.002063 and its counterpart during the reionization epoch is α rei/α EM = 0.854034+0.031678 0.027209 at 68% C.L.. They are not consistent with each other by 4.64σ. A conservative explanation for such a discrepancy is that there are some issues in the data we used. We prefer a calibration of some important parameters involved in reconstructing the reionization history.