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arXiv 1207.3293astro-ph.CO
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利用来自WMAP和SPT的PDKEEPAAA数据对耦合暗能量的约束

Constraints on coupled dark energy using CMB data from WMAP and SPT

Valeria Pettorino, Luca Amendola, Carlo Baccigalupi, Claudia Quercellini

摘要:

我们考虑的情况下,在暗宇宙学部门的耦合,其中暗能量标量场修改的引力之间的吸引暗物质粒子。我们发现,使用当前的宇宙微波背景(CMB)数据,包括WMAP 7和SPT,耦合的强度β被约束为小于0.063(0.11)在68%(95%)的置信水平。此外,我们考虑了CMB透镜振幅、曲率、相对论性物质和大质量中微子的有效数量的附加效应,并表明当前数据对β的约束已经足够强,相对于任何这些变量都相当稳定。当我们考虑大质量中微子时,得到最强的效应,在这种情况下,束缚变得稍微弱一些,β < 0.084(0.14)。相对论自由度的有效数值越大,暗物质和暗能量之间的耦合越大,光谱指数越接近1。加上目前对哈勃常数的限制,以及从重子声学振荡和超新星Ia,我们发现β < 0.050(0.074)。在这种情况下,我们还发现了β = 0.041的一个有趣的似然峰值(在1σ处仍然与0相容)。这个峰值主要来自哈勃参数HST结果和WMAP 7 +SPT最佳拟合之间的微小差异。最后,我们表明,普朗克+SPT模拟数据的预测可以牵制耦合的精度优于1%,并检测我们发现在小的非零耦合的边缘峰值是否是一个真正的效果。

英文摘要:

We consider the case of a coupling in the dark cosmological sector, where a dark energy scalar field modifies the gravitational attraction between dark matter particles. We find that the strength of the coupling β is constrained using current Cosmic Microwave Background (CMB) data, including WMAP7 and SPT, to be less than 0.063 (0.11) at 68% (95%) confidence level. Further, we consider the additional effect of the CMB-lensing amplitude, curvature, effective number of relativistic species and massive neutrinos and show that the bound from current data on β is already strong enough to be rather stable with respect to any of these variables. The strongest effect is obtained when we allow for massive neutrinos, in which case the bound becomes slightly weaker, β < 0.084(0.14). A larger value of the effective number of relativistic degrees of freedom favors larger couplings between dark matter and dark energy as well as values of the spectral index closer to 1. Adding the present constraints on the Hubble constant, as well as from baryon acoustic oscillations and supernovae Ia, we find β < 0.050(0.074). In this case we also find an interesting likelihood peak for β = 0.041 (still compatible with 0 at 1σ). This peak comes mostly from a slight difference between the Hubble parameter HST result and the WMAP7+SPT best fit. Finally, we show that forecasts of Planck+SPT mock data can pin down the coupling to a precision of better than 1% and detect whether the marginal peak we find at small non zero coupling is a real effect.

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