Mid-Infrared Observations of the Torus of Active Galactic Nuclei

天体物理学的一个基本问题是活跃星系核（AGN）中的黑洞是如何被燃料激发的，因为黑洞的燃料会影响星系的形成和演化。AGN本身位于星系的正中心，被解释为有一个由气体和尘埃组成的环面，它阻挡了内部的光线，并掩盖了AGN的中心引擎（黑洞）。然而，天文学家并不完全了解环面的确切性质，用望远镜直接观察环面是极其困难的。在这个提议中，PI计划解决以下关键问题：(a)环面是由什么物质构成的，它是如何与宿主星系恒星之间的其他气体和尘埃相连的？(b)环面性质（如几何形状和厚度）如何取决于AGN的亮度？(c)环面尘埃的性质是否随AGN的亮度而改变？(d)星系中心AGN附近的恒星形成在喂养和/或阻断AGN方面的作用是什么？这些问题的答案将使我们深入了解AGN是如何被星系中的气体所推动的，以及这可能对星系本身的形成产生什么影响。通过PI的合作者网络，这项拟议的工作将有助于进一步加强发展中国家墨西哥在天文学方面的联系，并通过与西班牙和墨西哥的联系，促进说西班牙语的美国团队成员（主要是西班牙裔）的参与。PI还计划与当地高中教师合作，提高他们对天文主题的理解和教学。通过这种方式，他希望接触到圣安东尼奥地区的当地学童，这是一个高度多元化的地区，提供高质量的科学内容，并鼓励学生（包括代表性不足的少数民族）追求科学领域。其目的是利用有趣的天文学内容作为STEM学科的“门户”。中红外波段（MIR: 7-26微米）的观测是必不可少的，因为环面拦截了黑洞附近发射的大量电磁辐射，并将其重新辐射到该波段。8米斯巴鲁望远镜和加那利大望远镜（GTC）等MIR设施提供了在MIR波长下以高空间分辨率探测AGN中心的可能性。假设AGN中块状尘埃分布的模型在解释MIR发射方面取得了重大进展。高分辨率观测将有助于约束模型参数，并提供对环面物理特性的洞察。该提案将为GTC上约100小时的保证时间（GT）和额外的180小时ESO-GTC时间（ESO和GTC共同分配的时间，作为西班牙提升为ESO成员的一部分竞争性奖励）的数据分析提供资金。这将与双子座的档案数据相结合，以解决AGN研究中的一个关键问题。详细了解环面，AGN/黑洞燃料过程及其与环面的关系（甚至创造），与宿主星系的相互作用，以及其他星系中的尘埃化学。计划基于当前数据进行模拟，为下一代设施（如SOFIA， JWST， TMT等）准备新的观测结果。

A fundamental question in astrophysics is how black holes in active galactic nuclei (AGN) are fueled, because black hole fueling affects how galaxies are formed and evolve. The AGN themselves, lying at the very center of the galaxies, are explained as having a torus of gas and dust that blocks light from the inside, and can obscure the AGN central engine (the black hole). However, astronomers don't fully understand the exact properties of the torus, and directly viewing the torus with telescopes is extremely difficult. In this proposal, the PI plans to address the key questions of: (a) What material makes up the torus, and how is it connected to the rest of the gas and dust between the stars of the host galaxy? (b) How do the torus properties, such as geometry and thickness, depend on the brightness of the AGN? (c) Do the properties of the dust in the torus change with the AGN brightness? and (d) What is the role of star formation near the AGN in the centers of galaxies in feeding and/or blocking AGN? Answers to these questions will provide insight into how the AGN is fueled by gas in the galaxy and how that might have an impact on the formation of the galaxy itself. Through the PI's network of collaborators, the proposed work will aid in furthering links in astronomy in the developing nation of Mexico, and it promotes involvement of US Spanish-speaking team members, primarily Hispanics, through connections with Spain and Mexico. The PI also plans to work with local high-school teachers to enhance their understanding and teaching of astronomical topics. In this way, he hopes to reach local school children in the San Antonio area, an area of high diversity, providing high quality scientific content, and encouraging the students (including underrepresented minorities) to pursue scientific fields. The intent is to use the interesting astronomical content as a "gateway" to STEM subjects. Observations at mid-infrared (MIR: 7-26 microns) wavelengths are essential, as the torus intercepts a large amount of electromagnetic radiation emitted from near the black hole and re-radiates it in this waveband. MIR facilities such as the 8m Subaru telescope and the Gran Telescope Canarias (GTC) offer the possibility to probe the centers of AGN at MIR wavelengths with high spatial resolution. Models assuming clumpy dust distribution in AGN are making significant progress explaining MIR emission. High-resolution observation will help constrain model parameters and provide insight into torus physical properties. This proposal would fund analysis of data from ~100 hours of guaranteed time (GT) on the GTC and an additional 180 hours of ESO-GTC time (jointly ESO and GTC allocated time, competitively awarded as part of Spain's ascension to ESO membership). This would be combined with archival data from Gemini to tackle a key problem in AGN research. A detailed understanding of the torus, the AGN/black hole fueling process and its relationship to (or even creation of) the torus, the interaction with the host galaxy, and dust chemistry in other galaxies will be constructed. Simulations based on current data to prepare new observations for next generation facilities (such as SOFIA, JWST, TMT, etc.) are planned.