# The Mira-Titan Universe II: Matter Power Spectrum Emulation

## TL;DR

This paper presents a new cosmic emulator for the matter power spectrum that accurately predicts across a wide parameter space, including neutrinos and dark energy, with high precision for optical survey applications.

## Contribution

The paper introduces a novel emulator covering eight cosmological parameters with high accuracy, built on extensive simulations and perturbation theory, improving predictions over previous models.

## Key findings

- Achieves approximately 4% accuracy with current models.
- Emulator covers wavenumber k~5/Mpc and redshift z<=2.
- Follow-on models aim for ~1% accuracy with more simulations.

## Abstract

We introduce a new cosmic emulator for the matter power spectrum covering eight cosmological parameters. Targeted at optical surveys, the emulator provides accurate predictions out to a wavenumber k~5/Mpc and redshift z<=2. Besides covering the standard set of LCDM parameters, massive neutrinos and a dynamical dark energy of state are included. The emulator is built on a sample set of 36 cosmological models, carefully chosen to provide accurate predictions over the wide and large parameter space. For each model, we have performed a high-resolution simulation, augmented with sixteen medium-resolution simulations and TimeRG perturbation theory results to provide accurate coverage of a wide k-range; the dataset generated as part of this project is more than 1.2Pbyte. With the current set of simulated models, we achieve an accuracy of approximately 4%. Because the sampling approach used here has established convergence and error-control properties, follow-on results with more than a hundred cosmological models will soon achieve ~1% accuracy. We compare our approach with other prediction schemes that are based on halo model ideas and remapping approaches. The new emulator code is publicly available.