Multi-Fidelity Emulation for the Matter Power Spectrum using Gaussian Processes

Understand

We present methods for emulating the matter power spectrum by combining information from cosmological $N$-body simulations at different resolutions.

• An emulator allows estimation of simulation output by interpolating across the parameter space of a limited number of simulations.
• We present the first implementation in cosmology of multi-fidelity emulation, where many low-resolution simulations are combined with a few high-resolution simulations to achieve an increased emulation accuracy.
• The power spectrum's dependence on cosmology is learned from the low-resolution simulations, which are in turn calibrated using high-resolution simulations.