The mean transmission of the neutral intergalactic medium in the LYα -line from a sample of high-resolution quasar spectra

Abstract

We present our measurements of the mean transmission $$\overline F \left( z \right)$$ of the neutral intergalactic medium in the Lyα line. For this purpose we used the sample of 33 high-resolution (R = 5300…45 000) spectra selected from the public available archive of the European Southern Observatory with the help of the Virtual Observatory tools. For continuum determination in each spectra the points with maximum flux in Lyα-forest region were selected and fitted by spline. The obtained values of the mean transmission $$\overline F \left( z \right)$$ was fitted by power-law τeff = α(1 + z)β, where α = (4.4 −0.2 +4.4 )× 10–3, β = 3.278 −0.054 +0.083 for averaging of the F(z) over the redshift bins Δz = 0.1 and α = (10.6 −1.0 +1.1 )× 10–3, β = 2.685 −0.071 +0.081 for averaging over each quasar. The results were compared with those ones from previous studies of high- and low-resolution quasar spectra.