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arXiv 1006.3274gr-qchep-th
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de Sitter时空中自由下落电荷的经典辐射

Classical radiation by free-falling charges in de Sitter spacetime

E. T. Akhmedov, Albert Roura, A. Sadofyev

摘要:

本文研究了de Sitter时空中自由下落电荷与不同类型场耦合时的经典辐射。具体地,我们考虑的情况下,电磁场,线性化的重力和标量场与任意质量和曲率耦合。给定任意一组这样的电荷,对于足够晚的时间,对应于每个电荷被场区包围,而其他电荷的影响可以忽略不计,这是一个通用的结果。此外,我们明确地发现一个静态的解决方案,在静态补丁适应的费用(这意味着没有能量损失的费用),可以定期扩展到视界以外的完整的德西特时空,并表明,任何其他解决方案在后期衰减到这一个。另一方面,对于非共形的标量场,惯性观测者自然地与空间平坦坐标相关联,他们将看到一个远离视界的非零通量,对于足够轻的场(m^2 + Δ R < 5H^2/4),该通量的衰减比距离的平方反比慢,并产生一个随半径无限增长的总积分通量。这可以定性地解释为一个经典的参数放大的领域所产生的费用,由于依赖于时间的背景时空的结果。这些结果大多不适用于无质量的最小耦合标量场,其特殊行为是单独分析的。

英文摘要:

We study the classical radiation emitted by free-falling charges in de Sitter spacetime coupled to different kinds of fields. Specifically we consider the cases of the electromagnetic field, linearized gravity and scalar fields with arbitrary mass and curvature coupling. Given an arbitrary set of such charges, there is a generic result for sufficiently late times which corresponds to each charge being surrounded by a field zone with negligible influence from the other charges. Furthermore, we explicitly find a static solution in the static patch adapted to a charge (implying no energy loss by the charge) which can be regularly extended beyond the horizon to the full de Sitter spacetime, and show that any other solution decays at late times to this one. On the other hand, for non-conformal scalar fields the inertial observers naturally associated with spatially flat coordinates will see a non-vanishing flux far from the horizon, which will fall off more slowly than the inverse square of the distance for sufficiently light fields (m^2 + ξR < 5H^2/4) and give rise to a total integrated flux that grows unboundedly with the radius. This can be qualitatively interpreted as a consequence of a classical parametric amplification of the field generated by the charge due to the time-dependent background spacetime. Most of these results do not hold for massless minimally coupled scalar fields, whose special behavior is analyzed separately.

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