Orateur
Description
Cosmological forecasts and likelihood analyses increasingly need two ingredients at once: the linear matter power spectrum, and the abundance of dark matter haloes. Computing them exactly is far too slow for parameter inference, and computing them from unrelated approximations quietly introduces inconsistencies between the two.
In this presentation, I will introduce two emulators built to solve both problems together: emu_pk and emu_hmf, in their first public releases. Both are fast, both are automatically differentiable — so gradients with respect to cosmology come for free — and both are designed to be used side by side.
I will show the accuracy they achieve on cosmologies never seen during training. emu_pk reproduces the power spectrum to about 0.1 %, over a wider range of cosmologies than comparable public emulators, including massive neutrinos and evolving dark energy, and it recovers the derivatives that forecasts actually consume — two of them exactly. emu_hmf recalibrates the standard Tinker (2008) halo mass function as a function of cosmology and redshift, reducing its error from roughly 7 % to 0.5 %, a factor of more than ten.
I will close on why consistency matters as much as accuracy: the two emulators share the same conventions and the same definition of the matter field, so going from cosmology to a halo mass function is a single, coherent, differentiable chain. Both are publicly released and installable in one line.