Black Holes vs. Dark Matter

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。格布哈特博士和他的团队将使用麦克唐纳2.7米望远镜上的光纤馈送光谱仪来测量附近椭圆星系外部的恒星运动。这些大纤维将在2角分钟的视野内聚集漫反射光，到达目标星系的外围。这些观测将与中心地区的详细测量结合起来，使用哈勃太空望远镜和使用自适应光学的10米地面望远镜。测量到的运动将与轴对称和基于三轴轨道的模型进行比较，以共同限制暗物质的分布和中央黑洞的质量。这个团队已经证明，这两个量很难单独测量，而且从中央星系的模型中省略暗晕会产生对黑洞来说太小的质量。该团队将专注于其他质量测量可供比较的星系，如X射线发射气体的质量测量，或行星状星云或球状星团的运动。计算成本高昂的建模将在德克萨斯高级计算中心进行。该奖项将支持博士后沈阳、研究生和本科生研究人员。作为他的美国国家科学基金会职业奖AST-0349095的一部分，格布哈特博士建立了一个英语和西班牙语的网页，以使公众能够访问他的黑洞研究。他将与StarDate杂志和麦当劳天文台的游客中心合作，维护和开发这个网站。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Dr Gebhardt and his team will use a fiber-fed spectrograph at the McDonald 2.7-meter telescope to measure stellar motions in the outer parts of nearby elliptical galaxies. The large fibers will gather diffuse light over a 2-arcminute field of view, which reaches the outskirts of the target galaxy. These observations will be combined with detailed measurements in the central regions with the Hubble Space Telescope and with 10-meter ground-based telescopes using adaptive optics. The measured motions will be compared with both axisymmetric and triaxial orbit-based models, to place limits jointly on the distribution of dark matter and the mass of a central black hole. This team has already shown that these two quantities are difficult to measure independently, and that omitting the dark halo from models of the central galaxy yields too small a mass for the black hole. The team will concentrate on galaxies for which other mass measures, such as those from X-ray-emitting gas, or the motions of planetary nebulae or globular star clusters, are available for comparison. The computationally expensive modeling will be done at the Texas Advanced Computing Center. This award will support postdoctoral scholar Shen, a graduate student, and undergraduate researchers. As part of his NSF CAREER award AST-0349095, Dr Gebhardt built a web page, available both in English and in Spanish, to make his black hole research accessible to the public. He will maintain and develop this website, in association with StarDate magazine and the McDonald Observatory's visitor center.