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。这种相互作用是形成新恒星、星系中心超大质量黑洞生长和驱动能量外流的原因。然而，它们背后的详细物理学仍然知之甚少。虽然银河系的中心很近，很容易研究，但它相对安静。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。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。这项工作将导致我们对星系中心气体物理学如何与流入和流出过程联系起来的理解的进步。此外，这项工作将支持与监狱教育计划的伙伴关系，以开发和教授数学密集型天文学课程，这些课程将使被监禁的学生成为STEM识字劳动力的一部分。2010年十年调查确定的一个关键调查领域和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，一个不活跃且相对平静的星系。然而现在，阿塔卡马大型毫米波阵列（阿尔马）提供的能力使我们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无线电和毫米波观测，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，而不仅仅是它驱动的过程的反馈（例如，在银河系中心不存在的星暴）。通过将本研究确定的亚秒差距尺度（只能在我们自己的银河系中心探测的尺度）上的气体性质与秒差距和更大尺度上的性质相关联，这项工作将测试在其他星系中探测的全球性质在多大程度上代表了较小尺度上的真实性质。最后，这个项目将直接比较在秒差距尺度上的属性与新的阿尔马观测最近的星爆星系在相同的秒差距尺度。他们的工作是第一次对星系核中详细的气体性质进行“苹果对苹果”的比较：探索星际介质的性质如何在存在星暴的情况下发生变化，并将我们对银河系中心的理解推进到单个案例研究之外。最后，该项目将为这些原子核中的极端气体性质建立一个模板库，这些模板可用于解释遥远的高红移星系的条件。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

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.