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arXiv 0901.1119gr-qcastro-ph.CO
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CMB极化与有质量引力子的引力理论

CMB Polarization and Theories of Gravitation with Massive Gravitons

Dennis Bessada, Oswaldo D. Miranda

摘要:

本文研究了在Minkowski背景和平坦FRW背景下的三种不同的有质量引力子的引力理论--修正的Fierz-Pauli(FP)模型、质量引力和Visser提出的双度规理论。对于TT张量扰动,我们证明了这三种理论在广义相对论(GR)中产生相同的动力学方程和相同形式的辐射转移Boltzmann方程。然后,我们分析这些理论中的向量扰动,并表明它们不会给出与前一种情况相同的结果。我们首先表明,矢量扰动在大质量引力中呈现出与广义相对论中相同的形式,而在修正的FP理论中,矢量引力波(GW)偏振模式(纽曼-彭罗斯(NP)形式主义中的$Ψ_{3}$振幅)不会像在前一种情况下那样衰减得太快。相反,我们表明,这种$Ψ_{3}$偏振模式引起一个不寻常的矢量萨克斯-沃尔夫效应,留下一个签名的四极形式$Y_{2,\pm 1}(θ,φ)$的CMB偏振。然后,我们推导出这些$Ψ_{3}$模式的CMB光子汤姆森散射的详细信息,然后构造相应的玻尔兹曼方程。基于这些结果,我们然后定性地表明,$Ψ_{3}$模式矢量签名-如果它们确实存在-可以清楚地区分从通常的$Ψ_4$张量模式的CMB偏振。

英文摘要:

We study in this paper three different theories of gravitation with massive gravitons - the modified Fierz-Pauli (FP) model, Massive Gravity and the bimetric theory proposed by Visser - in linear perturbation theory around a Minkowski and a flat FRW background. For the TT tensor perturbations we show that the three theories give rise to the same dynamical equations and to the same form of the Boltzmann equations for the radiative transfer in General Relativity (GR). We then analyze vector perturbations in these theories and show that they do not give the same results as in the previous case. We first show that vector perturbations in Massive Gravity present the same form as found in General Relativity, whereas in the modified FP theory the vector gravitational-wave (GW) polarization modes ($Ψ_{3}$ amplitudes in the Newman-Penrose (NP) formalism) do not decay too fast as it happens in the former case. Rather, we show that such $Ψ_{3}$ polarization modes give rise to an unusual vector Sachs-Wolfe effect, leaving a signature in the quadrupole form $Y_{2,\pm 1}(θ,φ)$ on the CMB polarization. We then derive the details for the Thomson scattering of CMB photons for these $Ψ_{3}$ modes, and then construct the correspondent Boltzmann equations. Based upon these results we then qualitatively show that $Ψ_{3}$-mode vector signatures - if they do exist - could clearly be distinguished on the CMB polarization from the usual $Ψ_4$ tensor modes.

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