Effects of Weak Gravitational Lensing from Large-Scale Structure on the Determination of q0
Effects of Weak Gravitational Lensing from Large-Scale Structure on the Determination of q0
复制标题
大尺度结构弱引力透镜对 q0 确定的影响
DOI：
10.1086/310470
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
J. Ostriker
中科院分区：
文献类型：
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作者：
J. Wambsganss;R. Cen;Guohong Xu;J. Ostriker
大尺度结构的弱引力透镜效应影响宇宙学减速参数q0的确定。我们发现，在 Ω0 = 0.40、Λ0 = 0.6、H = 65 km s-1 Mpc-1 和 σ8 = 0.79 的 COBE 归一化冷暗物质宇宙中，真正标准蜡烛上的透镜引起的色散在红移 z = 1 和 z = 0.5 时分别为 0.04 和 0.02 mag。结果表明，与真实的 q0 = -0.400 相比，在红移 z = 1 和 z = 0.5 处，使用具有零内在色散的标准蜡烛，可以观察到 q0 = -0.395−0.095+0.125 和 q0 = -0.398−0.077+0.048（误差线为 2 σ 限制）。标准 COBE 归一化 Ω0 = 1 CDM 模型将产生三倍的方差，而混合（热和冷）暗物质模型将产生中间结果。这种色散效应的一个独特特征是其非高斯性。尽管在较低红移处的透镜引起的色散仍然明显小于目前在 Ia 型超新星样本中观察到的最佳（总）色散 0.12 星等（采用多色光曲线形状方法选择），但在较高红移处它变得显着。我们表明，存在一个最佳红移，范围为 z ~ 0.5-2.0，具体取决于标准烛光固有色散的幅度，在此可以最准确地确定 q0。
Weak gravitational lensing by large-scale structure affects the determination of the cosmological deceleration parameter q0. We find that the lensing induced dispersions on truly standard candles are 0.04 and 0.02 mag at redshift z = 1 and z = 0.5, respectively, in a COBE-normalized cold dark matter universe with Ω0 = 0.40, Λ0 = 0.6, H = 65 km s-1 Mpc-1, and σ8 = 0.79. It is shown that one would observe q0 = -0.395−0.095+0.125 and q0 = -0.398−0.077+0.048 (the error bars are 2 σ limits) with standard candles with zero intrinsic dispersion at redshift z = 1 and z = 0.5, respectively, compared to the truth of q0 = -0.400. A standard COBE normalized Ω0 = 1 CDM model would produce three times as much variance and a mixed (hot and cold) dark matter model would lead to an intermediate result. One unique signature of this dispersion effect is its non-Gaussianity. Although the lensing induced dispersion at lower redshift is still significantly smaller than the currently best observed (total) dispersion of 0.12 mag in a sample of type Ia supernovae, selected with the multicolor light curve shape method, it becomes significant at higher redshift. We show that there is an optimal redshift, in the range z ~ 0.5-2.0 depending on the amplitude of the intrinsic dispersion of the standard candles, at which q0 can be most accurately determined.