Abstract
The linear matter power spectrum $P(k,z)$ connects theory with large scale
structure observations in cosmology. Its scale dependence is entirely encoded
in the matter transfer function $T(k)$, which can be computed numerically by
Boltzmann solvers, and can also be computed semi-analytically by using fitting
functions such as the well-known Bardeen-Bond-Kaiser-Szalay (BBKS) and
Eisenstein-Hu (EH) formulae. However, both the BBKS and EH formulae have some
significant drawbacks. On the one hand, although BBKS is a simple expression,
it is only accurate up to $10\%$, which is well above the $1\%$ precision goal
of forthcoming surveys. On the other hand, while EH is as accurate as required
by upcoming experiments, it is a rather long and complicated expression. Here,
we use the Genetic Algorithms (GAs), a particular machine learning technique,
to derive simple and accurate fitting formulae for the transfer function
$T(k)$. When the effects of massive neutrinos are also considered, our
expression slightly improves over the EH formula, while being notably shorter
in comparison.
Description
Using machine learning to compress the matter transfer function $T(k)$
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