Measurements of the Lyman-alpha (Ly-a) forest in spectra of distant quasars open an additional avenue for probing cosmological parameters and the nature of cosmic expansion. The forest is particularly appealing as it probes higher redshifts than most other methods, z~2-4, but also because the signal comes from sampling lower densities of the cosmic web, with different systematic errors from probes tracing galaxies or galaxy clusters. On large-scales, the Ly-a power-spectrum is used as a standard ruler, measuring the BAO scale at high redshifts. On small-scales (the high-end of the power spectrum), the Ly-a forest allows one to constrain neutrino masses, and offers the promise of distinguishing between modified gravity and dynamical dark energy models. As a part of DOE's SciDAC-3 program, we have developed a new AMR hydro + N-body code called Nyx, with the primary goal of producing accurate predictions for the Ly-a forest under different cosmological models and UV background histories. In this talk I will present details of the code, show results from our first Ly-a simulations, and outline our future simulation campaign.
