The Sherwood simulation suite: overview and data comparisons with the Lyman α forest at redshifts 2 ≤z≤ 5

We introduce a new set of large-scale, high-resolution hydrodynamical simulations of the intergalactic medium: the Sherwood simulation suite. These are performed in volumes of 10 3 -160 3 h -3 comoving Mpc 3 , span almost four orders of magnitude in mass resolution with up to 17.2 billion particles, and employ a variety of physics variations including warm dark matter and galactic outflows. We undertake a detailed comparison of the simulations to highresolution, high signal-to-noise observations of the Ly forest over the redshift range 2 z 5. The simulations are in very good agreement with the observational data, lending further support to the paradigm that the Ly forest is a natural consequence of the web-like distribution of matter arising in cold dark matter cosmological models. Only a small number of minor discrepancies remain with respect to the observational data. Saturated Ly absorption lines with column densities N H I > 10 14.5 cm -2 at 2 4. Finally, the temperature of intergalactic gas in the simulations may be slightly too low at z = 2.7 and a flatter temperaturedensity relation is required at z = 2.4, consistent with the expected effects of non-equilibrium ionization during He II reionization.