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arXiv 1101.0650astro-ph.CO
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大半径下详细的星系团透镜轮廓和对星系团弱透镜研究的影响

Detailed cluster lensing profiles at large radii and the impact on cluster weak lensing studies

Masamune Oguri, Takashi Hamana

摘要:

在N体模拟中使用大量的射线追踪,我们详细研究了大规模暗晕周围的透镜轮廓,特别强调了维里半径周围的轮廓。我们将径向收敛轮廓与我们简单的分析模型预测进行了比较,径向收敛轮廓是在射线追踪模拟中通过堆叠许多暗晕而准确测量的。我们的分析模型包括一个主晕,这是由Navarro-Frenk-White(NFW)密度剖面与三种不同形式的截断,加上相关的物质(2晕项)周围的主晕。我们发现,平滑截断的NFW配置文件最好地再现模拟透镜配置文件,超过10倍的维里半径。然后,我们使用这个分析模型来研究集群弱透镜效应研究中的潜在偏差,其中一个单一的,未截断的NFW组件通常是假设在解释观测到的信号。我们发现,集群的质量,推断通过拟合减少切向剪切剖面与NFW剖面,往往被低估了约5-10%,如果拟合进行到约10 '-30'。相反,对于相同的拟合范围,浓度参数通常高估约20%。我们还研究了计算弱透镜质量峰的信噪比的偏差,发现对于显著的质量峰,它们<4%。在附录中,我们提供了光滑截断NFW剖面的有用公式。

英文摘要:

Using a large set of ray-tracing in N-body simulations, we examine lensing profiles around massive dark haloes in detail, with a particular emphasis on the profile at around the virial radii. We compare radial convergence profiles, which are measured accurately in the ray-tracing simulations by stacking many dark haloes, with our simple analytic model predictions. Our analytic models consist of a main halo, which is modelled by the Navarro-Frenk-White (NFW) density profile with three different forms of the truncation, plus the correlated matter (2-halo term) around the main halo. We find that the smoothly truncated NFW profile best reproduces the simulated lensing profiles, out to more than 10 times the virial radius. We then use this analytic model to investigate potential biases in cluster weak lensing studies in which a single, untruncated NFW component is usually assumed in interpreting observed signals. We find that cluster masses, inferred by fitting reduced tangential shear profiles with the NFW profile, tend to be underestimated by ~5-10% if fitting is performed out to ~10'-30'. In contrast, the concentration parameter is overestimated typically by ~20% for the same fitting range. We also investigate biases in computing the signal-to-noise ratio of weak lensing mass peaks, finding them to be <4% for significant mass peaks. In the Appendices, we provide useful formulae for the smoothly truncated NFW profile.

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