Can a matter-dominated model with constant bulk viscosity drive the accelerated expansion of the universe?
Can a matter-dominated model with constant bulk viscosity drive the accelerated expansion of the universe?
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DOI：
10.1088/1475-7516/2009/04/006
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发表时间：
2008-11
影响因子：
6.4
通讯作者：
A. Avelino;U. Nucamendi
中科院分区：
文献类型：
--
作者：
A. Avelino;U. Nucamendi
我们测试了一个宇宙模型，其中唯一的组成部分是具有恒定体积粘度的无压流体，作为目前宇宙加速膨胀的解释。我们根据模型预测的宇宙的过去、现在和未来的演变对所有可能的情景进行分类，并使用SCP '‘ Union’数据集（307 SNe Ia）进行贝叶斯统计分析，对无量纲常数体积粘性系数施加热力学第二定律，并将模型预测的宇宙年龄与来自最古老的球状星团的约束进行比较，以测试其可行性。哈勃常数H0和H0的最佳估计值分别为：= 1.922±0.089和H0 = 69.62±0.59 (km/s)Mpc−1,χ2min = 314 （χ2 .o）。F = 1.031)。宇宙的年龄为14.95±0.42吉珥。我们可以看到H0的估计值以及χ2 . 0的估计值。f与使用相同的snia数据集从ΛCDM模型中获得的结果非常相似。宇宙的估计年龄与来自最古老的球状星团的限制是一致的。的估计值为正，符合热力学第二定律。另一方面，我们对参数H0进行了不同形式的边缘化，以研究结果对H0边缘化方式的敏感性。我们发现，在目前的工作中，该模型的自由参数的最佳估计值与H0被边缘化的方式之间的依赖关系几乎可以忽略不计。因此，这个简单的模型可能是解释目前宇宙加速膨胀的可行候选模型。
We test a cosmological model which the only component is a pressureless fluid with a constant bulk viscosity as an explanation for the present accelerated expansion of the universe. We classify all the possible scenarios for the universe predicted by the model according to their past, present and future evolution and we test its viability performing a Bayesian statistical analysis using the SCP ``Union'' data set (307 SNe Ia), imposing the second law of thermodynamics on the dimensionless constant bulk viscous coefficient and comparing the predicted age of the universe by the model with the constraints coming from the oldest globular clusters. The best estimated values found for and the Hubble constant H0 are: = 1.922±0.089 and H0 = 69.62±0.59 (km/s)Mpc−1 with a χ2min = 314 (χ2d.o.f = 1.031). The age of the universe is found to be 14.95±0.42 Gyr. We see that the estimated value of H0 as well as of χ2d.o.f are very similar to those obtained from ΛCDM model using the same SNe Ia data set. The estimated age of the universe is in agreement with the constraints coming from the oldest globular clusters. Moreover, the estimated value of is positive in agreement with the second law of thermodynamics (SLT). On the other hand, we perform different forms of marginalization over the parameter H0 in order to study the sensibility of the results to the way how H0 is marginalized. We found that it is almost negligible the dependence between the best estimated values of the free parameters of this model and the way how H0 is marginalized in the present work. Therefore, this simple model might be a viable candidate to explain the present acceleration in the expansion of the universe.