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arXiv · 1510.02907

Efficient calculation of cosmological neutrino clustering with both linear and non-linear gravity

Maria Archidiacono·Steen Hannestad
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Abstract

We study in detail how neutrino perturbations can be followed in linear theory by using only terms up to $l=2$ in the Boltzmann hierarchy. We provide a new approximation to the third moment and demonstrate that the neutrino power spectrum can be calculated to a precision of better than $\sim$ 5% for masses up to $\sim$ 1 eV. The matter and CMB power spectra can be calculated far more precisely and typically at least a factor of a few better than with existing approximations. We then proceed to study how the neutrino power spectrum can be reliably calculated even in the presence of non-linear gravitational clustering by using the full non-linear gravitational potential derived from semi-analytic methods based on $N$-body simulations in the Boltzmann evolution hierarchy. Our results agree extremely well with results derived from $N$-body simulations.

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Maria Archidiacono, Steen Hannestad. 2015-10-10. Efficient calculation of cosmological neutrino clustering with both linear and non-linear gravity. https://doi.org/10.1088/1475-7516%2F2016%2F06%2F018

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