A Multi-Fidelity Emulator for the Lyman-$\alpha$ Forest Flux Power Spectrum

Understand

In this work we extend our recently developed multi-fidelity emulation technique to the simulated Lyman-$\alpha$ forest flux power spectrum.

• Multi-fidelity emulation allows interpolation of simulation outputs between cosmological parameters using many cheap low-fidelity simulations and a few expensive high-fidelity simulations.
• Using a test suite of small box (30 Mpc/h) simulations, we show that multi-fidelity emulation is able to reproduce the Lyman-$\alpha$ forest flux power spectrum well, achieving an average accuracy when compared to a test suite of $0.8\%$.
• We further show that it has a substantially increased accuracy over single-fidelity emulators, constructed using either the high or low-fidelity simulations only.