Anthropic explanation of the dark matter abundance
Anthropic explanation of the dark matter abundance
复制标题
暗物质丰度的人为解释
DOI：
10.1088/1475-7516/2010/03/021
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发表时间：
2008
影响因子：
6.4
通讯作者：
Ben Freivogel
中科院分区：
文献类型：
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作者：
Ben Freivogel
我使用Bousso的因果钻石措施，使暗物质丰度的统计预测，假设一个大的衰变常数fa >> 1012 GeV的轴子。使用观察者形成的粗略近似，预测与观测结果吻合得很好：30%的观察者形成在暗物质比我们观察到的少的区域，而70%的观察者形成在暗物质更多的区域。暗物质比率的大值不受基本效应的影响：增加暗物质的数量，同时保持重子与光子的比率不变，会减少一个视界体积内的重子数量。因此，这个预测对宇宙中观测者形成的假设相当不敏感，因为宇宙中的暗物质比我们自己的多得多。关键假设是，对于接近观测值的比率，每个重子的观察者数量大致与暗物质比率无关。
I use Bousso's causal diamond measure to make a statistical prediction for the dark matter abundance, assuming an axion with a large decay constant fa >> 1012 GeV. Using a crude approximation for observer formation, the prediction agrees well with observation: 30% of observers form in regions with less dark matter than we observe, while 70% of observers form in regions with more dark matter. Large values of the dark matter ratio are disfavored by an elementary effect: increasing the amount of dark matter while holding fixed the baryon to photon ratio decreases the number of baryons inside one horizon volume. Thus the prediction is rather insensitive to assumptions about observer formation in universes with much more dark matter than our own. The key assumption is that the number of observers per baryon is roughly independent of the dark matter ratio for ratios near the observed value.