Accretion and Star Formation Induced by the Galactic Center Supermassive Black Hole Sgr A*

天体物理学中的一个长期问题是了解我们的银河系是如何在其一生中形成和发展的。了解银河系形成和演化的一个重要方面是研究其中心的超大质量黑洞(称为SgrA*)，以及该黑洞如何与银河系的其他部分相互作用。SgrA*的接近为研究两个相互交织的过程提供了一个极好的实验室：恒星是如何在黑洞附近形成的，以及它们的恒星风随后是如何被捕获的。该项目将应用观测和理论来确定当前恒星形成的地点，距离SgrA*非常近(在2秒内)，并将测试关于恒星如何在这种环境中形成的想法。研究人员在向公众交流科学和研究方面有着广泛的历史，并致力于在整个项目过程中继续这些努力。该团队还包括两名研究生，他们为芝加哥地区的高中和社区大学教室开发了银河中心课程，其中一些课程包含了全球望远镜(WWT)可视化系统。该团队将创建并分享两个以银河中心和银河系为主题的WWT之旅。团队成员将在关于银河中心黑洞的公开演讲中使用数据、WWT之旅和视频，这是学校和许多天文学会非常流行的话题。该团队将向专业人士和公民科学界提供与该项目相关的Fits图像。他们将从FITS文件中制作JPEG图像，并将天文视觉元数据信息嵌入到图像标题中。FITS和JPEG图像、WWT之旅和视频将托管在西北大学，并将通过可搜索的内容管理网站访问。该项目将研究SgrA*的潮汐和辐射效应显著的恒星形成。他们的多波长方法(例如，VLA、ALMA、VLT、SMA和CARMA)将检查水脉泽、致密的H-II区、原恒星的SED拟合，以及分子环中的Proplyds和SiO流出，并将识别位于SGR A*的2个pC范围内的原恒星流出。此外，该团队将通过使用无线电技术测量年轻恒星电离风的质量损失率来确定SgrA*的质量吸积率。导致吸积的过程与我们银河系核心以及拥有大质量黑洞的星系核心的恒星形成密切相关。对银河系中心内部分秒的详细观测主要是使用Keck和VLT望远镜在红外波长进行的。最近VLA的升级和ALMA的启用提供了一个在无线电和毫米波段应用新技术的机会，以研究两个相关的主题--恒星形成和SgrA*的吸积。这些新功能将使该团队能够使用大质量恒星以毫秒级的精度记录无线电和红外线图像，并确定恒星绕SgrA*轨道的正确运动。超大质量黑洞附近恒星的准确定位将通过测量周星移位来探测时空的广义相对论曲率。研究人员将使用一种新的实用方法来研究SgrA*潮汐压力环境附近恒星形成的圆盘模式。该项目可能对恒星形成的性质和拥有大质量黑洞的更活跃星系核中的活动星系核活动产生深远的影响。

A longstanding problem in astrophysics is to understand how our own Milky Way Galaxy formed and developed throughout its lifetime. One important aspect of understanding the formation and evolution of the Milky Way is to study the supermassive black hole (called Sgr A*) at its center and how the black hole interacts with the rest of the Galaxy. The proximity of Sgr A* provides an excellent laboratory in which to investigate two intertwined processes: how stars are formed in the vicinity of the black hole and how their stellar winds are subsequently captured. This project will apply observation and theory to identify sites of current star formation very close to Sgr A* (within 2 parsecs) and will test ideas about how stars are formed in this environment.The investigators have an extensive history in communicating science and research to the public and are committed to continuing these efforts over the course of this project. The team also includes two graduate students who have developed Galactic center lessons, some of which incorporate the WorldWide Telescope (WWT) visualization system, for high school and community college classrooms throughout the Chicago area. The team will create and share two WWT tours on the topic of the Galactic center and the Milky Way Galaxy. Team members will use data, WWT tours and videos in public talks on the Galactic center black hole, a very popular topic to schools and numerous astronomical societies. The team will make FITS images related to this project available to professional and citizen science communities. They will make JPEG images from the FITS files and embed Astronomical Visual Metadata information into the image headers. The FITS and JPEG images, WWT tours and videos will be hosted at Northwestern University and will be accessible through a searchable content-managed web site.This project will examine star formation where the tidal and radiative effects by Sgr A* are significant. Their multi-wavelength approach (e.g., VLA, ALMA, VLT, SMA and CARMA) will examine water masers, compact H-II regions, SED fitting of protostars, proplyds and SiO outflows in the molecular ring and will identify protostellar outflows lying within 2 pc of Sgr A*. In addition, the team will determine the mass accretion rate onto Sgr A* by measuring the mass loss rate of ionized winds from young stars using radio techniques. The processes that lead to accretion are closely related to star formation in the nucleus of our Galaxy as well as in the nuclei of galaxies that host massive black holes.Detailed observations of the inner parsec of the Galactic center have primarily been conducted at infrared wavelengths using Keck and VLT telescopes. The recent upgrading of the VLA and commissioning of ALMA present an opportunity to apply novel techniques at radio and millimeter wavelengths to examine two related topics, star formation and accretion onto Sgr A*. These new capabilities will allow the team to use massive stars to register the radio and infrared frames with milliarcsecond accuracy and to determine the proper motion of stars orbiting Sgr A*. The accurate positioning of stars near the supermassive black hole will probe general-relativistic curvature of space-time by measuring periastron shift. The investigators will use a novel pragmatic approach to studying the disk mode of star formation near the tidally stressed environment of Sgr A*. The project may have far reaching implications on the nature of star formation and AGN activity in the nuclei of more active galaxies hosting massive black holes.