Loop corrections to the power spectrum for massive neutrino cosmologies with full time- and scale-dependence. (arXiv:2008.00013v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Garny_M/0/1/0/all/0/1">Mathias Garny</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Taule_P/0/1/0/all/0/1">Petter Taule</a>
Loop corrections to the power spectrum are frequently computed using
approximate non-linear kernels adopted from an Einstein de-Sitter (EdS)
cosmology. We present an algorithm that allows us to take the full time- and
scale-dependence of the underlying fluid dynamics into account, and apply it to
assess the impact of neutrino free-streaming on the 1- and 2-loop matter power
spectrum. Neutrino perturbations are described by a hybrid Boltzmann/two-fluid
model, that we show to agree with the CLASS Boltzmann solution at the linear
level when using an appropriate effective neutrino sound velocity. We then use
this scheme at 1- and 2-loop to perform a precision comparison of the matter
power spectrum with simplified treatments of massive neutrinos. For a commonly
adopted scheme using cold dark matter+baryon perturbations and EdS kernels to
compute non-linear corrections, we find deviations above 1% for k > 0.15 h/Mpc
at z=0, and sub-percent agreement on weakly non-linear scales at z=0.5. We also
demonstrate the impact of the EdS approximation on the 2-loop power spectrum
for massless neutrinos.
Loop corrections to the power spectrum are frequently computed using
approximate non-linear kernels adopted from an Einstein de-Sitter (EdS)
cosmology. We present an algorithm that allows us to take the full time- and
scale-dependence of the underlying fluid dynamics into account, and apply it to
assess the impact of neutrino free-streaming on the 1- and 2-loop matter power
spectrum. Neutrino perturbations are described by a hybrid Boltzmann/two-fluid
model, that we show to agree with the CLASS Boltzmann solution at the linear
level when using an appropriate effective neutrino sound velocity. We then use
this scheme at 1- and 2-loop to perform a precision comparison of the matter
power spectrum with simplified treatments of massive neutrinos. For a commonly
adopted scheme using cold dark matter+baryon perturbations and EdS kernels to
compute non-linear corrections, we find deviations above 1% for k > 0.15 h/Mpc
at z=0, and sub-percent agreement on weakly non-linear scales at z=0.5. We also
demonstrate the impact of the EdS approximation on the 2-loop power spectrum
for massless neutrinos.
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