Generating approximate halo catalogues for blind challenges in precision cosmology


Garrison LH, Eisenstein DJ. Generating approximate halo catalogues for blind challenges in precision cosmology. Monthly Notices of the Royal Astronomical Society [Internet]. 2019;485 :2407-2416.

Date Published:

May 01, 2019


We present a method for generating suites of dark matter halo catalogueswith only a few N-body simulations, focusing on making small changes tothe underlying cosmology of a simulation with high precision. In thecontext of blind challenges, this allows us to re-use a simulation bygiving it a new cosmology after the original cosmology is revealed.Starting with full N-body realizations of an original cosmology and atarget cosmology, we fit a transfer function that displaces haloes inthe original so that the galaxy/HOD power spectrum matches that of thetarget cosmology. This measured transfer function can then be applied toa new realization of the original cosmology to create a new realizationof the target cosmology. For a 1 per cent change in σ8, weachieve 0.1 per cent accuracy to k = 1 h Mpc^{-1} in the real-spacepower spectrum; this degrades to 0.3 per cent when the transfer functionis applied to a new realization. We achieve similar accuracy in theredshift-space monopole and quadrupole. In all cases, the result isbetter than the sample variance of our 1.1 h^{-1} Gpc simulation boxes.