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

Research output: Contribution to journalArticle

  • James S. Bolton
  • Ewald Puchwein
  • Debora Sijacki
  • Martin G. Haehnelt
  • Tae-Sun Kim
  • Avery Meiksin
  • John A. Regan
  • Matteo Viel

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Original languageEnglish
Pages (from-to)897-914
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 21 Sep 2016


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 103-1603h-3 comoving Mpc3, 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 high-resolution, high signal-to-noise observations of the Ly α 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 α forest is a natural consequence of the web-like distribution of matter arising in Λcold dark matter cosmological models. Only a small number of minor discrepancies remain with respect to the observational data. Saturated Ly α absorption lines with column densities N_{H I}>10^{14.5} cm^{-2} at 2 <z <2.5 are underpredicted in the models. An uncertain correction for continuum placement bias is required to match the distribution and power spectrum of the transmitted flux, particularly at z > 4. Finally, the temperature of intergalactic gas in the simulations may be slightly too low at z = 2.7 and a flatter temperature-density relation is required at z = 2.4, consistent with the expected effects of non-equilibrium ionization during He II reionization.

    Research areas

  • methods: numerical, intergalactic medium, quasars: absorption lines

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