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Neutrino Anisotropies after Planck | | Martina Gerbino
; Eleonora Di Valentino
; Najla Said
; | | Date: |
27 Apr 2013 | | Abstract: | We present new constraints on the rest-frame sound speed, c_eff^2, and the
viscosity parameter, c_vis^2, of the Cosmic Neutrino Background from the recent
measurements of the Cosmic Microwave Background anisotropies provided by the
Planck satellite. While broadly consistent with the ex- pectations of c_eff^2 =
c_vis^2 = 1/3 in the standard scenario, the Planck dataset hints for a higher
value of the viscosity parameter, with c_vis^2 = 0.60 +/- 0.18 at 68% c.l., and
a lower value of the sound speed, with c_eff^2 = 0.304 +/- 0.013 at 68% c.l..
We find a correlation between the neutrino parameters and the lensing amplitude
of the temperature power spectrum A_L. When the latter parameter is allowed to
vary, we find a better consistency with the standard model with c_vis^2 = 0.51
+/- 0.22, c_eff^2 = 0.311 +/- 0.019 and A_L = 1.08 +/- 0.18 at 68% c.l.. This
result indicates that the anomalous large value of A_L measured by Planck could
be connected to non-standard neutrino properties. Including additional datasets
from Baryon Acoustic Oscillation surveys and the Hubble Space Telescope
constraint on the Hubble constant, we obtain c_vis^2 = 0.40 +/- 0.19, c_eff^2 =
0.319 +/- 0.019, and A_L = 1.15 +/- 0.17 at 68% c.l.. | | Source: | arXiv, 1304.7400 | | Services: | Forum | Review | PDF | Favorites | |
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