Mitigating the noise of DESI mocks using analytic control variates

Understand

In order to address fundamental questions related to the expansion history of the Universe and its primordial nature with the next generation of galaxy experiments, we need to model reliably large-scale structure observables such as the correlation function and the power spectrum.

• Cosmological $N$-body simulations provide a reference through which we can test our models, but their output suffers from sample variance on large scales.
• Fortunately, this is the regime where accurate analytic approximations exist.
• To reduce the variance, which is key to making optimal use of these simulations, we can leverage the accuracy and precision of such analytic descriptions using Control Variates (CV).