Apples to Apples: Comparing the Cores of Nearby Galaxies

星系的中心是恒星、气体和黑洞之间独特相互作用的家园。这种相互作用负责形成新的恒星，形成星系中心的超大质量黑洞，并驱动能量外流。然而，人们对它们背后的详细物理原理仍然知之甚少。虽然银河系的中心很近，也很容易被研究，但它的中心相对安静。在这一区域形成的恒星很少，黑洞也不活跃。正因为如此，银河系并不是发生在这些环境中的一整套过程的典型例子。该项目将首次将银河系中心的气体性质与更活跃的星系中的气体性质进行比较。这项工作将促进我们对星系中心气体的物理如何与流入和流出过程相联系的理解。此外，这项工作将支持与一个监狱教育项目的合作，开发和教授数学密集型天文学课程，为被监禁的学生成为STEM熟练劳动力的一部分做准备。一个关键的研究领域，也是2010年十年调查中确定的优先事项，是星系中心发生的事情：恒星、黑洞和气体之间的相互作用。直到最近，只有一个星系可以详细研究这些相互作用：银河系，一个不活跃、相对平静的星系。然而，现在，阿塔卡马大毫米阵列(ALMA)提供的能力使得有可能对银河系中心与其他星系中心的气体性质和相互作用进行详细的比较。利用对银河系银河系中心的新的射电和毫米观测，该项目将首先对气体性质进行详细研究，以限制吸积本身如何改变气体条件，而不仅仅是来自它所驱动的过程的反馈(例如，银河系中心不存在的恒星爆发)。通过将这项研究确定的亚帕秒尺度(只能在我们银河系中心探测的尺度)上的气体性质与帕秒和更大尺度上的性质联系起来，这项工作将测试在其他星系中探测的全局性质在更小尺度上代表真实性质的程度。最终，这个项目将直接比较在帕秒尺度上的性质与ALMA在相同的帕秒尺度上对最近的恒星爆发星系的观测结果。他们的工作是首次对星系核中详细的气体性质进行“苹果对苹果”的比较：探索星际介质性质如何在恒星爆发存在的情况下发生变化，并推动对我们银河系中心的理解超越单一的案例研究。最后，该计划将为这些原子核中的极端气体属性建立一个模板库，可以用来解释遥远、高红移星系的条件。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The centers of galaxies are home to unique interactions between stars, gas, and black holes. Such interactions are responsible for forming new stars, growing a galaxy's central supermassive black hole, and driving energetic outflows. However, the detailed physics behind them is still poorly understood. Though nearby and easily studied, the Milky Way's center is relatively quiet. Few stars are forming in this region, and the black hole is not active. Because of this, the Milky Way is not a representative example of the full suite of processes that occur in these environments. This project will make the first comparison of gas properties in the Milky Way center with those in a more active galaxy. This work will lead to advances in our understanding of how the physics of the gas in galaxy centers is linked to inflow and outflow processes. In addition, this work will support a partnership with a prison education program to develop and teach math-intensive astronomy courses that will prepare incarcerated students to be part of a STEM-literate workforce. A key area of investigation, and a priority identified in the 2010 Decadal Survey, is what goes on in galaxy centers: the interactions between stars, black holes and gas. Until recently there has only been one galaxy where these interactions can be investigated in detail: The Milky Way, an inactive and relatively sedate galaxy. Now however, the capabilities offered by the Atacama Large Millimeter Array (ALMA) make it possible to conduct detailed comparisons of gas properties and interactions in the Milky Way center with those in other galaxy centers. Using new radio and millimeter observations of the Milky Way's Galactic center, this project will first make detailed studies of gas properties to constrain how accretion itself modifies gas conditions, and not just feedback from processes it drives (e.g., starbursts which are absent in the Galactic center). By relating the gas properties on sub-parsec scales determined by this study (scales that can only be probed in our own Galaxy center) to the properties on the parsec and larger scales, this work will test how well global properties probed in other galaxies represent the true properties on smaller scales. Ultimately, this project will directly compare the properties on parsec scales with new ALMA observations of the nearest starburst galaxy on identical parsec scales. Their work is the first 'apples to apples' comparison of detailed gas properties in galaxy nuclei: probing how interstellar medium properties change in the presence of a starburst, and advancing the understanding of our Galaxy center beyond a single case study. Finally, this program will produce a library of templates for the extreme gas properties in these nuclei that can be used to interpret conditions in distant, high redshift galaxies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.