(a) Dependence of the ionising photon production efficiency ξ_ion on the UV absolute magnitude M_FUV. The LAEs at z ∼ 3 (Nakajima et al. 2020), z ∼ 6.6 SFGs with Lyα emission (Endsley et al. 2020), mean ξ_ion values for z = 3.8–5.4 galaxies (Bouwens et al. 2016), mean ξ_ion values for z = 4–5 galaxies (Lam et al. 2019b), and a mean ξ_ion value for z = 3.8–5.4 faint galaxies with high EW(Lyα) (Maseda et al. 2020) are shown by filled circles. The relation for z ∼ 2 galaxies (Shivaei et al. 2018), for z ∼ 9–10 galaxies (Bouwens et al. 2019) and for z ∼ 3 faint Lyα emitters (Nakajima et al. 2018) are shown by green dashed, dash-dotted and solid lines, respectively. (b) Dependence of the ionising photon production efficiency ξ_ion on the intrinsic UV slope β. (c) Dependence of the ionising photon production efficiency ξ_ion on the intrinsic UV slope β reddened with R(V) = 3.1. Filled circles are z ∼ 3.8–5.4 galaxies (Bouwens et al. 2016) and z ∼ 6.6 SFGs with Lyα emission (Endsley et al. 2020), asterisks are mean ξ_ion values of z = 4–5 galaxies (Lam et al. 2019b). The relation for z ∼ 2 galaxies (Shivaei et al. 2018) is shown by a green dashed line. Values of ξ_ion assumed in canonical Universe reionisation models are shown (as in Figs. 11 and 12 in grey; e.g., Bouwens et al. 2016). The meanings of symbols for the SDSS CSFGs are the same as in Fig. 1.