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）资助的。Gebhardt博士和他的团队将使用麦当劳2.7米望远镜上的纤维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弧分的视野范围内收集漫射光，到达目标星系的外围。这些观测结果将与哈勃太空望远镜和使用自适应光学技术的10米地面望远镜在中心区域的详细测量结果相结合。测量到的运动将与轴对称和三轴轨道模型进行比较，以共同限制暗物质的分布和中心黑洞的质量。这个团队已经证明这两个量很难独立测量，而且从中央星系的模型中忽略暗晕产生的黑洞质量太小。研究小组将把重点放在其他质量测量的星系上，比如那些来自x射线发射气体的质量测量，或者行星状星云或球状星团的运动，这些都可以用于比较。计算成本高昂的建模将在德克萨斯高级计算中心完成。该奖项将支持沈博士后、研究生和本科生研究人员。作为获得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文和西班牙文网页，让公众可以访问他的黑洞研究。他将维护和发展这个网站，与StarDate杂志和麦当劳天文台的游客中心合作。

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.