Towards High-Resolution Cosmological Simulations of Ultralight Dark Matter

Over the past three decades, ΛCDM has gained acceptance as the concordance model of cosmology, owing to its predictive successes and theoretical simplicity. Still, the question of what exactly dark matter is remains open. Additionally, tensions at small scales between N-body simulations and observation motivate research into alternative dark matter models. Ultralight dark matter (ULDM), a bosonic dark matter candidate with a mass around 1e-22 eV/c^2, can potentially explain these tensions. In ULDM models, the de Broglie wavelength is of kiloparsec scales, which subsequently leads to a suppression of structure below galactic scales. Though compelling, few cosmological scale simulations of ULDM have been performed to-date. Furthermore, by taking advantage of the quantum-classical transition, ULDM simulations show promise of reproducing classical N-body results without many of the complicating discreteness effects. We have developed an ULDM solver by leveraging the Hardware/Hybrid Accelerated Cosmology Code (HACC), an exascale N-body code, and a topological halo finder. Our solver uses a Fourier pseudo-spectral split-operator method to integrate the Schrödinger-Poisson equations. In this work, this code will be presented, alongside convergence studies and early science results.