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arXiv 1006.0931astro-ph.COgr-qchep-phhep-th
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宇宙弦环在所有长度尺度和任何红移下的分布

Cosmic string loop distribution on all length scales and at any redshift

Larissa Lorenz, Christophe Ringeval, Mairi Sakellariadou

摘要:

我们分析得出预期的数密度分布的南部-后藤宇宙弦环在任何红移后不久的字符串形成的时间到今天。我们的方法是基于Polchinski-Rocha模型的循环形成从长字符串,我们调整,以适应数值模拟和补充的引力反作用的唯象模型。在辐射和物质时代,宇宙演化驱动着环分布在所有长度尺度上的缩放。任何合理的辐射时代的初始环分布的记忆被证明是擦除之前大爆炸核合成。在物质时代,圈分布达到全尺度,直到辐射时代的一些残余圈,这些圈可能存在于极低的弦张力中。最后,低于重力截止的循环的数密度被证明是规模独立的,成比例的负功率的弦张力和不敏感的细节的反作用建模。作为一个应用,我们证明了在目前允许的弦张力值下,现今的圈的能量密度参数不能超过10^(-5),而圈数密度不能小于10^(-6)/Mpc ^3。我们的结果应该为研究宇宙弦环的宇宙学后果提供一个更坚实的基础。

英文摘要:

We analytically derive the expected number density distribution of Nambu-Goto cosmic string loops at any redshift soon after the time of string formation to today. Our approach is based on the Polchinski-Rocha model of loop formation from long strings which we adjust to fit numerical simulations and complement by a phenomenological modelling of gravitational backreaction. Cosmological evolution drives the loop distribution towards scaling on all length scales in both the radiation and matter era. Memory of any reasonable initial loop distribution in the radiation era is shown to be erased well before Big Bang Nucleosynthesis. In the matter era, the loop distribution reaches full scaling, up to some residual loops from the radiation era which may be present for extremely low string tension. Finally, the number density of loops below the gravitational cutoff is shown to be scale independent, proportional to a negative power of the string tension and insensitive to the details of the backreaction modelling. As an application, we show that the energy density parameter of loops today cannot exceed 10^(-5) for currently allowed string tension values, while the loop number density cannot be less than 10^(-6) per Mpc^3. Our result should provide a more robust basis for studying the cosmological consequences of cosmic string loops.

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