Tuesday

Lyman alpha absorption spectra from quasars have been a powerful tool to probe the intergalactic medium (IGM). At the end of the epoch of reionisation (z>5.5), however, the residual neutral fraction is so high that it often causes absorption to saturate. The only places where we can detect unsaturated absorption are within the quasar proximity zones, where the neutral fraction is lower than average, thanks to the ionizing radiation from the quasar itself. Therefore, the quasar proximity zone plays a crucial, irreplaceable role in probing cosmic reionisation. In our study, we first use simulations to investigate how to recover the density field around z~6 quasars with Lyman alpha absorption spectra. We find that the density field can be accurately recovered with our method. Moreover, we apply this method to a sample of observed high-quality quasar spectra to study the large-scale environment where they reside. In this talk, I will present the method to recover the density and our progress in understanding the large-scale environment of quasars in reionisation.