Supermassive black holes and the growth of galaxies

天文学家最近发现，基本上每个大质量星系的中心都包含一个超大质量黑洞（SMBH），并且SMBH的性质与其宿主星系的性质密切相关。这些相关性表明，SMBH和它们的宿主的宇宙演化从根本上是联系在一起的，但这种联系的细节仍然不清楚。作为STFC研究员，我建议在达勒姆大学工作三年，使用来自尖端天文台（如哈勃太空望远镜，钱德拉X射线天文台，斯皮策太空望远镜，赫歇尔和SCUBA 2）的数据来解决有关SMBH和星系演化的关键问题。这项工作旨在通过观察早期宇宙中关键时期的星系和黑洞生长来了解星系，黑洞和暗物质之间的相互作用。第一个项目探索SMBH吸积和星星形成是如何被推动的。这项工作将由Herschel和SCUBA 2的数据驱动，这些强大的新红外和亚毫米观测站将使我们能够观察到比以往任何时候都更暗，更深的星系。一个流行的理论是，星系和黑洞的增长是由富含气体的星系的主要合并推动的，这导致了活跃的星星形成，并将气体推向黑洞，产生了被气体和尘埃高度遮蔽的活动星系核（AGN）。最近已经发现了红移为2的遥远星系，它们有很高的星星形成率和模糊的活动星系核，但是还没有直接的证据表明它们是由合并提供动力的。Herschel和SCUBA 2的数据将使我们能够通过测量高度模糊的AGN和周围星系的大样本之间的空间相关性，对合并燃料假说进行首次直接测试。我目前研究的初步结果表明，适度模糊的活动星系核确实与合并有关，因为它们在小尺度上有过多的邻近星系。我的工作将对深埋的活动星系核进行同样的测试，这些活动星系核被认为是合并的直接产物。第二个项目将讨论大规模结构对SMBH和星系演化的作用。最近的理论和观测表明，有一个特征的暗物质晕质量合并是最常见的和活动星系核反馈积极淬火恒星的形成。一些在低红移的研究，包括我自己最近的研究，与这张图片是一致的，但它还没有在大质量结构中进行测试，在高红移的AGN活动处于峰值。利用达勒姆小组最近对一个红移为3的原星团进行的超深X射线观测，我将测量X射线探测到的活动星系核周围的局部星系密度，以测试在合并最常见的环境中吸积是否增强。我还计划分析原星系团活动星系核的近红外光谱，以限制可能阻止星星形成和加热星系际气体的能量外流的性质和丰度。这两个项目，通过利用尖端的观测和理论工具，将帮助我们了解我们的银河系和我们在本地宇宙中观察到的其他星系是如何存在的。除了研究，我还计划努力帮助提高公众对宇宙历史的理解。在过去，我喜欢给美国的天文学团体和学校做公开讲座，并期待着向英国公众展示最新的结果。我已经与英格兰北方的一些业余天文学会通信，并希望在奖学金期间能够每1- 2个月安排一次讲座，以直接促进公众对这项令人兴奋的研究和科学的热情。

Astronomers have recently discovered that the center of essentially every massive galaxy contains a supermassive black hole (SMBH), and that the properties of SMBHs are tightly correlated with those of their host galaxies. These correlations suggest that the cosmic evolution of SMBHs and their hosts are fundamentally linked, but the details of this connection are still unclear. As an STFC Fellow, I propose to work for three years at Durham University, using data from cutting-edge observatories (such as the Hubble Space Telescope, Chandra X-ray Observatory, Spitzer Space Telescope, Herschel, and SCUBA2) to address key questions about the evolution of SMBHs and galaxies. This work seeks to understand the interplay between galaxies, black holes, and dark matter by observing galaxy and black hole growth at crucial epochs in the early Universe. The first project explores how SMBH accretion and star formation are fueled. This work will be driven by data from Herschel and SCUBA2, powerful new infrared and submillimeter observatories that will allow us to observe fainter and more deeply obscured galaxies than ever before. A prevailing theory is that galaxy and black hole growth is fueled by the major mergers of gas-rich galaxies, which induce vigorous star formation and drive gas down onto the black hole, producing an active galactic nucleus (AGN) that is highly obscured by gas and dust. There have recently been discovered distant galaxies at redshift 2 that have high rates of star formation and obscured AGN, but there is not yet direct evidence that they are powered by mergers. Herschel and SCUBA2 data will allow us to perform the first direct tests of the merger-fueling hypothesis, by measuring the spatial correlations between large samples of highly obscured AGN and surrounding galaxies. Preliminary results from my current research suggest that moderately obscured AGN are indeed associated with mergers, since they have an excess of nearby galaxies on small scales. My proposed work will perform the same test for deeply buried AGN that are expected to be the immediate products of mergers. The second project will address the role of large-scale structures on SMBH and galaxy evolution. Recent theory and observations suggest that there is a characteristic dark matter halo mass for which mergers are most common and AGN feedback actively quenches the formation of stars. Some studies at low redshifts, including my own recent research, are consistent with this picture, but it has not been tested in massive structures at high redshifts where AGN activity is at its peak. Making use of the Durham group's recent ultradeep X-ray observations of a protocluster at redshift 3, I will measure the local galaxy density around X-ray detected AGN to test if accretion is enhanced in environments where mergers are most common. I also plan to analyze near-infrared spectra of the AGN in the protocluster, to constrain the nature and abundance of energetic outflows that could halt star formation and heat intergalactic gas. Both these projects, by making use of cutting-edge observational and theoretical tools, will help us understand how our Milky Way galaxy, and other galaxies we observe in the local Universe, came to exist. In addition to research, I also plan to work to help enhance the public's understanding of the cosmic history of the Universe. In the past I have enjoyed giving public lectures to astronomy groups and schools in the U.S., and would look forward to presenting the latest results to the British public as well. I have corresponded with a number of amateur astronomy societies in northern England, and expect to be able to schedule talks every 1--2 months during the term of the Fellowship, in order to directly promote public enthusiasm for this exciting research and for science in general.