Case for dark radiation

被引：128

作者：

Archidiacono, Maria ^{[1
]}

Calabrese, Erminia

Melchiorri, Alessandro

机构：

[1] Univ Roma La Sapienza, Dept Phys, I-00185 Rome, Italy

来源：

PHYSICAL REVIEW D | 2011年 / 84卷 / 12期

关键词：

COSMOLOGICAL PARAMETERS; POWER SPECTRUM; BULK; CMB;

D O I：

10.1103/PhysRevD.84.123008

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Combined analyses of recent cosmological data are showing interesting hints for the presence of an extra relativistic component, coined dark radiation. Here, we perform a new search for dark radiation, parametrizing it with an effective number of relativistic degrees of freedom parameter, N-eff. We show that the cosmological data we considered are clearly suggesting the presence of an extra relativistic component with N-eff = 4.08(-0.68)(+0.71) at 95% C.L.. Performing an analysis on dark radiation sound speed c(eff) and viscosity c(vis) parameters, we found c(eff)(2) = 0.312 +/- 0.026 and c(vis)(2) = 0.29(-0.16)(+0.21) at 95% C.L., consistent with the expectations of a relativistic free streaming component (c(eff)(2) = c(vis)(2) = 1/3). Assuming the presence of 3 relativistic neutrinos, we constrain the extra relativistic component with N-v(S) = 1.10-0.72+0.79 and c(eff)(2) = 0.24(-0.13)(+0.08) at 95% C. L. while c(vis)(2) results as unconstrained. Assuming a massive neutrino component, we obtain further indications for dark radiation with N-v(S) = 1.12(-0.74)(+0.86) at 95% C.L..

引用

页数：6

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