The Evolution of the HeII-Ionizing Background at Redshifts 2.3<z<3.8 Inferred from a Statistical Sample of 24 HST/COS HeII Ly$\alpha$ Absorption Spectra

Gábor Worseck, Frederick B. Davies, Joseph F. Hennawi +1

We present measurements of the large-scale (~40 comoving Mpc) effective optical depth of HeII Ly$\alpha$ absorption, ${\tau }_{\mathrm{eff}}$, at 2.54<z<3.86 toward 16 HeII-transparent quasars obs…