演化的暗能量密度和宇宙超加速膨胀的直接测量
Direct measurement of evolving dark energy density and super-accelerating expansion of the universe
摘要：
通过对附近Ia型超新星的测量，得到的哈勃常数值比在更高的红移下得到的值要高。由于其宿主的特殊运动，我们发现在如此低的红移下，物质的含量只有在更高红移下的10%左右，这样低的物质密度不可能由ΛCDM膨胀背景下的密度扰动产生.最近，普朗克小组报告了一个较低的哈勃常数和较高的物质含量。我们发现，暗能量密度随宇宙时间的增加而增加，因此其状态方程参数随宇宙时间的增加而减小，在低红移处小于-1。这种暗能量演化是推动宇宙超加速膨胀的原因。在这个扩展的ΛCDM模型中，宇宙学红移代表时间而不是径向坐标，因此宇宙符合哥白尼原理。
英文摘要：
A higher value of Hubble constant has been obtained from measurements with nearby Type Ia supernovae, than that obtained at much higher redshift. With the peculiar motions of their hosts, we find that the matter content at such low redshift is only about 10% of that at much higher redshifts; such a low matter density cannot be produced from density perturbations in the background of the ΛCDM expansion. Recently the Planck team has reported a lower Hubble constant and a higher matter content. We find that the dark energy density increases with cosmic time, so that its equation-of-state parameter decreases with cosmic time and is less than -1 at low redshift. Such dark energy evolution is responsible for driving the super-accelerating expansion of the universe. In this extended ΛCDM model, the cosmological redshift represents time rather than radial coordinate, so that the universe complies to the Copernican Principle.
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