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QSO near-zones are an important probe of the the ionization state of the IGMat z ~ 6-7, at the end of reionization. We present here high-resolutioncosmological 3D radiative transfer simulations of QSO environments for a widerange of host halo masses, 10$^{10-12.5}$ M_sun. Our simulated near-zonesreproduce both the overall decrease of observed near-zone sizes at 6 < z < 7and their scatter. The observable near-zone properties in our simulationsdepend only very weakly on the mass of the host halo. The size of the H IIregion expanding into the IGM is generally limited by (super-)Lyman Limitsystems loosely associated with (low-mass) dark matter haloes. This leads to astrong dependence of near-zone size on direction and drives the large observedscatter. In the simulation centred on our most massive host halo, manysightlines show strong red damping wings even for initial volume averagedneutral hydrogen fractions as low as ~ 10$^{-3}$. For QSO lifetimes long enoughto allow growth of the central supermassive black hole while optically bright,we can reproduce the observed near-zone of ULAS J1120+0641 only with an IGMthat is initially neutral. Our results suggest that larger samples of z > 7QSOs will provide important constraints on the evolution of the neutralhydrogen fraction and thus on how late reionization ends.

Probing the end of reionization with the near-zones of z > 6 QSOs