Primordial magnetic field from non-inflationary cosmic expansion in Horava-Lifshitz gravity
Primordial magnetic field from non-inflationary cosmic expansion in Horava-Lifshitz gravity
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DOI：
10.1103/physrevd.80.123538
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发表时间：
2009-09
影响因子：
5
通讯作者：
S. Maeda;S. Mukohyama;T. Shiromizu
中科院分区：
文献类型：
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作者：
S. Maeda;S. Mukohyama;T. Shiromizu
宇宙大尺度磁场的起源是现代宇宙学中最大的谜团之一。基于Horava最近提出的幂次计数引力重整化理论，我们提出了一种新的大尺度磁场产生机制。与广义相对论中的通常情况相反，在这个理论中，麦克斯韦作用量的U（1）规范对称性允许在紫外线中破坏共形不变性。此外，对于高频模式，理论固有的各向异性标度不可避免地使声音视界远离哈勃视界。因此，早期宇宙中的非暴胀宇宙膨胀自然会产生磁场的超视界量子涨落。专门考虑的情况下，动力学临界指数z = 3，我们显示了一组明确的参数，其中（i）产生的磁场的振幅是足够大的发电机机制的种子;（ii）宇宙膨胀的反反应是足够小的;和（iii）高能量色散关系是一致的，从MAGIC和费米合作的最新观测极限。
The origin of large-scale magnetic field in the Universe is one of the greatest mysteries in modem cosmology. We present a new mechanism for generation of large-scale magnetic field, based on the power-counting renormalizable theory of gravitation recently proposed by Horava. Contrary to the usual case in general relativity, the U(1) gauge symmetry of a Maxwell action in this theory permits terms breaking conformal invariance in the ultraviolet. Moreover, for high frequency modes, the anisotropic scaling intrinsic to the theory inevitably makes the sound horizon far outside the Hubble horizon. Consequently, noninflationary cosmic expansion in the early Universe naturally generates superhorizon quantum fluctuations of the magnetic field. Specializing our consideration to the case with the dynamical critical exponent z = 3, we show an explicit set of parameters for which (i) the amplitude of generated magnetic field is large enough as a seed for the dynamo mechanism; (ii) backreaction to the cosmic expansion is small enough; and (iii) the high-energy dispersion relation is consistent with the most recent observational limits from MAGIC and Fermi collaborations.