A Multi-wavelength Study of the Massive Black Hole Sagittarius A* at the Galactic Center

Yusef-Zadeh博士将使用多波长时间序列观测来测试两种模型，以解释在银河系中心射电源中观测到的耀斑。根据“等离子体”模型，辐射明亮的物质团从中心黑洞向外移动，随着它们在自身的同步加速器辐射下变得光学薄，它们在更长的波长上变得更亮。如果耀斑是由黑洞周围吸积盘中的热点引起的，那么光源应该在所有波长上同时变亮。亚毫米级的观测将用单碟望远镜在北部和南部的天空进行，射电望远镜阵列将使用厘米波长，在几天的时间内测量总强度和偏振。2007年两次这样的活动的数据现在已经到手了，另一次包括NASA的钱德拉太空望远镜在x射线上的观测，计划在2008年中期进行。未来的活动可能包括来自欧空局赫歇尔太空望远镜的中红外数据。来自甚大阵列的存档数据也将被使用。理论工作将包括对等离子体模型的扩展，以预测由各向异性发射区产生的极化。Yusef-Zadeh为本科和成人教育课程开发了一个带有基于问题的练习的交互式网络客户端。他将围绕这个项目为这个系统开发更多的练习。他还将继续协调一个面向公众的跨学科科学讲座项目，在阿德勒天文馆任教，并让学生参与公共宣传。博士后将通过参与研究得到培训。

Dr Yusef-Zadeh will use multiwavelength time-series observations to test two models to explain the flaring observed in the Milky Way's central radio source. According to the 'plasmon' model, blobs of radio-bright material move outwards from the central black hole, brightening at successively longer wavelengths as they become optically thin to their own synchrotron radiation. If the flares are instead caused by hot-spots in an accretion disk around the black hole, the source should brighten simultaneously at all wavelengths. Sub-millimeter observations would be taken in both the northern and southern sky with single-dish telescopes, and radio-telescope arrays would be used at centimeter wavelengths, to measure both total intensity and polarization over periods of several days. Data from two such campaigns in 2007 is now in hand, and another that includes observations with NASA's Chandra space telescope in the X-ray is scheduled for mid-2008. Future campaigns may include mid-infrared data from ESA's Herschel space telescope. Archival data from the Very Large Array will also be used. Theoretical work will include an extension of the plasmon model to predict polarization that arises from the anisotropic emitting region.Dr. Yusef-Zadeh has developed an interactive web client with problem-based exercises for undergraduate and adult-education classes. He will develop further exercises for this system, based around this project. He will also continue to coordinate a program of interdisciplinary science lectures for the public, to teach at Adler Planetarium, and to involve students in public outreach. A postdoc will be trained through involvement in the research.