Impact of H0 prior on the evidence for dark radiation

被引:54
作者
Calabrese, Erminia [1 ]
Archidiacono, Maria [2 ,3 ]
Melchiorri, Alessandro [2 ,3 ]
Ratra, Bharat [4 ]
机构
[1] Univ Oxford, Subdept Astrophys, Oxford OX1 3RH, England
[2] Univ Roma La Sapienza, Dept Phys, I-00185 Rome, Italy
[3] Univ Roma La Sapienza, Ist Nazl Fis Nucl, I-00185 Rome, Italy
[4] Kansas State Univ, Dept Phys, Manhattan, KS 66506 USA
基金
美国国家科学基金会;
关键词
GAS MASS FRACTION; COSMOLOGICAL CONSTRAINTS; MEDIAN STATISTICS; HUBBLE CONSTANT; POWER SPECTRUM; FIELD; PARAMETERS; TELESCOPE; EVOLUTION; ENERGY;
D O I
10.1103/PhysRevD.86.043520
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Recent analyses that include cosmic microwave background (CMB) anisotropy measurements from the Atacama Cosmology Telescope and the South Pole Telescope have hinted at the presence of a dark radiation component at more than two standard deviations. However, this result depends sensitively on the assumption of an Hubble Space Telescope prior on the Hubble constant, where H-0 = 73.8 +/- 2.4 km/s/Mpc at 68% c.l.. Here we repeat this kind of analysis assuming a prior of H-0 = 68 +/- 2.8 km/s/Mpc at 68% c.l., derived from a median statistics (MS) analysis of 537 non-CMB H-0 measurements from Huchra's compilation. This prior is fully consistent with the value of H-0 = 69.7 +/- 2.5 km/s/Mpc at 68% c.l. obtained from CMB measurements under assumption of the standard ACDM model. We show that with the MS H-0 prior the evidence for dark radiation is weakened to similar to 1.2 standard deviations. Parametrizing the dark radiation component through the effective number of relativistic degrees of freedom N-eff, we find N-eff 3.98 +/- 0.37 at 68% c.l. with the Hubble Space Telescope prior and N-eff 3.52 +/- 0.39 at 68% c.l. with the MS prior. We also discuss the implications for current limits on neutrino masses and on primordial Helium abundances.
引用
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页数:8
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