arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0911.4972astro-ph.CO
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由弱透镜效应精确确定团簇质量

Precision cluster mass determination from weak lensing

Rachel Mandelbaum, Uros Seljak, Tobias Baldauf, Robert E. Smith

摘要:

弱引力透镜在过去的十年中被广泛用于限制星系团的质量,并且是最有前途的观测技术,可以为精确的星系团宇宙学提供必要的质量校准。在估算星团质量时有几个挑战,特别是(a)对天体物理效应和观测系统学的敏感性,这些效应和观测系统学相对于理论预期修改了信号,以及(b)由于质量估算方法中的假设而可能产生的偏差,例如假设的星团径向轮廓。所有这些挑战在集群的内部区域都更成问题,这表明它们的影响在理想情况下会被抑制,以便进行质量估计。然而,在任何给定的半径,通过透镜测量的微分表面密度对该半径内的所有质量都很敏感,并且来自内部部件的损坏信号被分散到所有尺度。我们开发了一个新的统计,是理想的集群质量估计,因为它完全消除了质量贡献低于选定的规模(我们建议应该是维里半径的20%左右),从而降低了系统和天体物理效应的敏感性。我们使用模拟和分析配置文件来量化系统偏差的质量估计的几个标准方法的质量估计,发现这些可能会导致显着的质量偏差,范围从10%到超过50%.The质量的不确定性时,使用我们的新的统计减少了高达10倍的标准方法,而只有适度增加的统计误差。这种新的质量估计方法将使未来的科学工作更高水平的精度与弱透镜质量估计的星系团。

英文摘要:

Weak gravitational lensing has been used extensively in the past decade to constrain the masses of galaxy clusters, and is the most promising observational technique for providing the mass calibration necessary for precision cosmology with clusters. There are several challenges in estimating cluster masses, particularly (a) the sensitivity to astrophysical effects and observational systematics that modify the signal relative to the theoretical expectations, and (b) biases that can arise due to assumptions in the mass estimation method, such as the assumed radial profile of the cluster. All of these challenges are more problematic in the inner regions of the cluster, suggesting that their influence would ideally be suppressed for the purpose of mass estimation. However, at any given radius the differential surface density measured by lensing is sensitive to all mass within that radius, and the corrupted signal from the inner parts is spread out to all scales. We develop a new statistic that is ideal for estimation of cluster masses because it completely eliminates mass contributions below a chosen scale (which we suggest should be about 20 per cent of the virial radius), and thus reduces sensitivity to systematic and astrophysical effects. We use simulated and analytical profiles to quantify systematic biases on the estimated masses for several standard methods of mass estimation, finding that these can lead to significant mass biases that range from ten to over fifty per cent. The mass uncertainties when using our new statistic are reduced by up to a factor of ten relative to the standard methods, while only moderately increasing the statistical errors. This new method of mass estimation will enable a higher level of precision in future science work with weak lensing mass estimates for galaxy clusters.

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