Measuring Mass Distributions in Moderate-Redshift Galaxies Through Gravitational Lensing

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。Fassnacht博士将使用强大的引力透镜，即光线靠近质量物体时的弯曲，来研究大质量椭圆星系的质量分布，探索回到宇宙大约是现在年龄的一半的时代。前景透镜星系中恒星的速度色散将使用凯克望远镜上的多缝光谱仪在光学和近红外中进行测量。未确定的狭缝将被用来测量位于天空附近的星系的红移，以研究透镜周围的任何星团或星团。哈勃太空望远镜的图像将被用来测量光线从中央透镜通过100kpc或更多的星系的微弱透镜扭曲，探测透镜星系的巨大黑暗光晕。最后，凯克望远镜上的自适应光学成像将被用来寻找透镜星系的暗淡伴星。图像的亮度比通常与光滑椭圆形透镜的预期值不同，这表明可能存在同伴。Fassnacht博士已经使用这项技术找到了一个透镜星系的暗淡伴星。一名研究生和本科生研究人员将参与这项研究。法斯纳赫特博士将继续他的公众外展演讲项目，他将向加州大学戴维斯分校现有的一个面向高中生的项目介绍天文学。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Dr Fassnacht will use strong gravitational lensing, the bending of light as it passes close to a massive object, to study the mass distributions of massive elliptical galaxies, probing back to times when the cosmos was roughly half as old as it is now. The velocity dispersion of the stars in the foreground 'lensing' galaxy will be measured using multislit spectrographs on the Keck telescopes in the optical and in the near-infrared. Uncommitted slits will be used to measure redshifts of galaxies lying nearby on the sky, to study any group or cluster surrounding the lens. Hubble Space Telescope images will be used to measure the weak lensing distortions for galaxies whose light passes 100kpc or more from the central lens, probing the massive dark halo of the lensing galaxy. Finally, adaptive optics imaging on the Keck telescopes will be used to search for faint companions to the lens galaxy. Brightness ratios for the images are often discrepant from what would be expected for a smooth elliptical lens, suggesting that companions may be present. Dr Fassnacht has already used this technique to find a faint companion to one lens galaxy. A graduate student and undergraduate researchers will participate in the research. Dr Fassnacht will continue his program of public-outreach talks, and he will introduce astronomy to an existing program at UC Davis for high school students.