The effects of velocities and lensing on moments of the Hubble diagram
The effects of velocities and lensing on moments of the Hubble diagram
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速度和透镜效应对哈勃图矩的影响
DOI：
10.1093/mnras/stw3339
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发表时间：
2016
影响因子：
4.8
通讯作者：
R. Nichol
中科院分区：
文献类型：
--
作者：
E. MacAulay;T. Davis;D. Scovacricchi;D. Bacon;T. Collett;R. Nichol
我们考虑了由于特殊速度和引力透镜引起的超新星距离-红移关系的色散，以及这些效应对物质功率谱振幅的敏感性。我们使用Quartin等人发展的矩方法(Memo)透镜似然法，它解释了由透镜放大引起的特征非高斯分布，并测量了星等分布的前四个中心矩。我们建立在备忘录可能性的基础上，将特殊速度的影响直接纳入到时刻的模型中。为了测量稀疏数量的超新星的矩，我们采用了一种新的方法，使用核密度估计来估计星等残差的潜在概率密度函数。我们还描述了一种估计数据协方差矩阵的Bootstrap重采样方法。然后，我们将该方法应用于联合光曲线分析(JLA)超新星星表。当我们只考虑本征色散与红移无关时，我们发现σ=0.44.
在一个标准差水平上，尽管我们注意到在模拟测试中，这个模型往往高估了内在离散度的大小，而低估了σ。我们注意到，当同时考虑透镜效应和速度效应时，本征色散和σ效应之间的简并性更加明显，这是因为当同时考虑这两种效应时，消除了红移依赖。当本征色散模型为宽度为0.14mag的高斯分布时，我们发现σ=1.07
。
We consider the dispersion on the supernova distance-redshift relation due to peculiar velocities and gravitational lensing, and the sensitivity of these effects to the amplitude of the matter power spectrum. We use the Method-of-the-Moments (MeMo) lensing likelihood developed by Quartin et al., which accounts for the characteristic non-Gaussian distribution caused by lensing magnification with measurements of the first four central moments of the distribution of magnitudes. We build on the MeMo likelihood by including the effects of peculiar velocities directly into the model for the moments. In order to measure the moments from sparse numbers of supernovae, we take a new approach using Kernel density estimation to estimate the underlying probability density function of the magnitude residuals. We also describe a bootstrap re-sampling approach to estimate the data covariance matrix. We then apply the method to the joint light-curve analysis (JLA) supernova catalogue. When we impose only that the intrinsic dispersion in magnitudes is independent of redshift, we find σ = 0.44
at the one standard deviation level, although we note that in tests on simulations, this model tends to overestimate the magnitude of the intrinsic dispersion, and underestimate σ. We note that the degeneracy between intrinsic dispersion and the effects of σ is more pronounced when lensing and velocity effects are considered simultaneously, due to a cancellation of redshift dependence when both effects are included. Keeping the model of the intrinsic dispersion fixed as a Gaussian distribution of width 0.14 mag, we find σ = 1.07
.