arXiv 1503.058022015-03astro-ph.COhep-phhep-th

轴子暴胀模型中磁场的一致产生

Consistent generation of magnetic fields in axion inflation models

Tomohiro Fujita, Ryo Namba, Yuichiro Tada, Naoyuki Takeda, Hiroyuki Tashiro

备注：: 19 pages, 5 figures, reference added
DOI：: 10.1088/1475-7516/2015/05/054

摘要：

越来越多的证据表明，银河系外区域存在磁场，而试图将其起源与暴胀时代联系起来的尝试则极具挑战性。因此，我们考虑到一致的后暴胀演变的磁场，起源于真空涨落在通货膨胀。在我们感兴趣的模型中，电磁场通过特征项$ϕF\tilde F$耦合到赝标量暴胀子$ϕ$，打破了共形不变性。这种相互作用动态地打破了宇称，并通过快子不稳定性使电磁场的偏振态之一的连续生产成为可能。由此产生的磁场是螺旋形的。我们发现，在这个模型中观测到的磁场的主要贡献来自模式，离开视界附近的结束膨胀，进一步增强的快子不稳定性结束后的膨胀。在暴胀子振荡期间，电磁场随后被参数共振放大。一旦热等离子体形成（再加热），所产生的螺旋磁场经历称为逆级联的湍流过程，其将它们的峰值相关尺度从较小的尺度移动到较大的尺度。我们一贯考虑到所有这些影响内的政权的扰动$ϕ$是可以忽略不计的，并获得$B_{\rm eff} \sim 10^{-19}$ G，表明额外的机制，以适应的意见的必要性。

英文摘要：

There has been a growing evidence for the existence of magnetic fields in the extra-galactic regions, while the attempt to associate their origin with the inflationary epoch alone has been found extremely challenging. We therefore take into account the consistent post-inflationary evolution of the magnetic fields that are originated from vacuum fluctuations during inflation. In the model of our interest, the electromagnetic (EM) field is coupled to a pseudo-scalar inflaton $ϕ$ through the characteristic term $ϕF\tilde F$, breaking the conformal invariance. This interaction dynamically breaks the parity and enables a continuous production of only one of the polarization states of the EM field through tachyonic instability. The produced magnetic fields are thus helical. We find that the dominant contribution to the observed magnetic fields in this model comes from the modes that leave the horizon near the end of inflation, further enhanced by the tachyonic instability right after the end of inflation. The EM field is subsequently amplified by parametric resonance during the period of inflaton oscillation. Once the thermal plasma is formed (reheating), the produced helical magnetic fields undergo a turbulent process called inverse cascade, which shifts their peak correlation scales from smaller to larger scales. We consistently take all these effects into account within the regime where the perturbation of $ϕ$ is negligible and obtain $B_{\rm eff} \sim 10^{-19}$G, indicating the necessity of additional mechanisms to accommodate the observations.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文