arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1208.3000astro-ph.CO
收藏

用引力透镜约束源的红移分布

Constraining Source Redshift Distributions with Gravitational Lensing

D. Wittman, W. A. Dawson

摘要:

介绍了一种利用弱引力透镜剪切来约束星系红移分布的新方法。我们不使用观察到的剪切和红移来约束宇宙学参数,而是询问在假设宇宙学参数固定的情况下,星系团周围的剪切可以在多大程度上约束红移。这提供了一个检查光度红移,独立的源光谱能量分布特性,因此没有混淆因素,如光谱突变的错误识别。我们发现,~40个大质量($σ_v=1200$ km/s)的集群透镜是足够的,以确定在每六个粗红移箱的源的分数~ 11%,给定弱(20%)的先验的质量最高的红移透镜,紧(5%)的先验的质量最低的红移透镜,只有适度(20-50%)的先验的校准和演化效果。额外的大质量透镜降低了不确定性,如$N_{lens}^0.5$,但随着人们被迫使用质量函数更低的透镜,改善速度减慢。未来的大型调查包含足够的集群,以达到1%的精度,在bin分数,如果紧透镜质量先验可以保持大样本的镜头。在实践中,这将是难以实现的,但该方法可能是有价值的,作为其他更精确的方法的补充,因为它是基于不同的物理,因此具有不同的系统误差。

英文摘要:

We introduce a new method for constraining the redshift distribution of a set of galaxies, using weak gravitational lensing shear. Instead of using observed shears and redshifts to constrain cosmological parameters, we ask how well the shears around clusters can constrain the redshifts, assuming fixed cosmological parameters. This provides a check on photometric redshifts, independent of source spectral energy distribution properties and therefore free of confounding factors such as misidentification of spectral breaks. We find that ~40 massive ($σ_v=1200$ km/s) cluster lenses are sufficient to determine the fraction of sources in each of six coarse redshift bins to ~11%, given weak (20%) priors on the masses of the highest-redshift lenses, tight (5%) priors on the masses of the lowest-redshift lenses, and only modest (20-50%) priors on calibration and evolution effects. Additional massive lenses drive down uncertainties as $N_{lens}^0.5$, but the improvement slows as one is forced to use lenses further down the mass function. Future large surveys contain enough clusters to reach 1% precision in the bin fractions if the tight lens mass priors can be maintained for large samples of lenses. In practice this will be difficult to achieve, but the method may be valuable as a complement to other more precise methods because it is based on different physics and therefore has different systematic errors.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑