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arXiv 0910.4098astro-ph.CO
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用引力透镜超新星称量暗物质晕

Weighing dark matter haloes with gravitationally lensed supernovae

Jakob Jonsson, Tomas Dahlen, Isobel Hook, Ariel Goobar, Edvard Mortsell

摘要:

高红移的Ia型超新星(SNe Ia)很可能被前景星系的暗物质晕引力透镜化。由于超新星Ia在经过光变曲线形状和颜色校正后色散非常小,它们的亮度可以通过引力放大来测量暗物质晕的性质。利用大天文台起源深度巡天(GOODS)对星系和Ia超新星的观测,测量了星系光度与暗物质晕质量之间的关系。我们研究的关系是速度色散和星系光度之间的标度律在B波段。这种关系的最佳拟合值(速度弥散归一化和指数)分别为136 km/s和0.27。我们发现,在95%的置信水平下,速度弥散归一化小于190公里/秒。这种方法提供了一个独立的交叉检查测量星系星系透镜研究的暗物质晕属性。我们的结果与星系-星系透镜效应的结果一致,但有更大的不确定性。Ia型SNe的GOODS样本相对较小(我们包括24个SNe),因此结果取决于单个Ia型SNe。我们已经研究了一些潜在的系统性影响。光变曲线拟合是影响Ia超新星亮度推断的最重要的方法。使用不同的光变曲线拟合程序获得的结果在68.3%的置信水平上存在差异。

英文摘要:

High redshift Type Ia supernovae (SNe Ia) are likely to be gravitationally lensed by dark matter haloes of galaxies in the foreground. Since SNe Ia have very small dispersion after light curve shape and colour corrections, their brightness can be used to measure properties of the dark matter haloes via gravitational magnification. We use observations of galaxies and SNe Ia within the Great Observatories Origins Deep Survey (GOODS) to measure the relation between galaxy luminosity and dark matter halo mass. The relation we investigate is a scaling law between velocity dispersion and galaxy luminosity in the B-band. The best-fitting values to this relation (velocity dispersion normalisation and exponent) are 136 km/s and 0.27. We find the velocity dispersion normalisation to be less than 190 km/s at the 95 per cent confidence level. This method provides an independent cross-check of measurements of dark matter halo properties from galaxy-galaxy lensing studies. Our results agree with the galaxy-galaxy lensing results, but have much larger uncertainties. The GOODS sample of SNe Ia is relatively small (we include 24 SNe) and the results therefore depend on individual SNe Ia. We have investigated a number of potential systematic effects. Light curve fitting, which affects the inferred brightness of the SNe Ia, appears to be the most important one. Results obtained using different light curve fitting procedures differ at the 68.3 per cent confidence level.

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