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地方。这样的相互作用导致了新恒星的形成，星系中心超大质量黑洞的形成，以及能量的流出。然而，它们背后的详细物理原理仍然知之甚少。虽然银河系的中心离我们很近，很容易被研究，但它却相对安静。这个区域几乎没有恒星形成，黑洞也不活跃。正因为如此，银河系并不是在这些环境中发生的全套过程的代表性例子。这个项目将首次比较银河系中心和更活跃星系的气体特性。这项工作将使我们进一步了解星系中心的气体物理如何与流入和流出过程联系在一起。此外，这项工作将支持与一个监狱教育项目建立伙伴关系，开发和教授数学密集型天文学课程，使被监禁的学生成为精通stem的劳动力的一部分。一个关键的调查领域，也是2010年十年调查确定的优先事项，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地研究这些相互作用：银河系，一个不活跃且相对平静的星系。然而现在，阿塔卡马大型毫米波阵列（ALMA）提供的能力使得对银河系中心与其他星系中心的气体特性和相互作用进行详细比较成为可能。利用对银河系中心的新无线电和毫米观测，该项目将首先对气体特性进行详细研究，以约束吸积本身如何改变气体条件，而不仅仅是它驱动的过程的反馈（例如，银河系中心没有的恒星爆发）。通过将这项研究确定的亚秒差距尺度上的气体特性（只能在我们自己的星系中心探测到的尺度）与秒差距和更大尺度上的特性联系起来，这项工作将测试在其他星系中探测到的全局特性在更小尺度上代表真实特性的程度。最终，该项目将直接比较在秒差距尺度上的特性与ALMA在相同秒差距尺度上对最近的星暴星系的新观测结果。他们的工作是第一次对星系核中详细的气体特性进行“苹果对苹果”的比较：探测星际介质特性在星暴存在下是如何变化的，并在单一案例研究之外推进对我们银河系中心的理解。最后，这个项目将为这些原子核中的极端气体特性生成一个模板库，可以用来解释遥远的高红移星系的条件。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.