Mid-Infrared Observations of the Torus of Active Galactic Nuclei

活动星系核环面的中红外观测

• 批准号: 1616828
• 负责人: Christopher Packham
• 金额: $ 38.72万
• 依托单位: University of Texas at San Antonio
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1616828&HistoricalAwards=false
• 关键词: Mid; Infrared; Observations; Torus; Active

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.

天体物理学中的一个基本问题是活动星系核（AGN）中的黑洞是如何被填充的，因为黑洞填充会影响星系的形成和演化。 活动星系核本身位于星系的中心，被解释为具有气体和尘埃的环面，阻挡了来自内部的光线，并可以掩盖活动星系核的中央引擎（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）什么材料构成了环面，它如何与宿主星系恒星之间的其余气体和尘埃连接？(b)活动星系核的亮度如何决定环的性质，如几何形状和厚度？(c)活动星系核亮度的变化是否会影响环面上尘埃的性质？（d）星系中心活动星系核附近的星星形成在供给和/或阻塞活动星系核方面起什么作用？ 这些问题的答案将提供对AGN如何由星系中的气体提供燃料以及如何对星系本身的形成产生影响的见解。通过PI的合作者网络，拟议的工作将有助于进一步加强发展中国家墨西哥的天文学联系，并通过与西班牙和墨西哥的联系，促进美国西班牙语团队成员的参与，主要是西班牙裔。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，这是一个高度多样性的地区，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。其目的是使用有趣的天文学内容作为STEM科目的“门户”。 在中红外（MIR：7-26微米）波长的观测是必不可少的，因为环面拦截了大量从黑洞附近发射的电磁辐射，并在这一波段重新辐射。8米斯巴鲁望远镜和加那利群岛大望远镜（GTC）等和平号望远镜设施提供了在和平号波段以高空间分辨率探测活动星系核中心的可能性。假设活动星系核中尘埃分布的模型在解释MIR辐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。该提案将资助对GTC上约100小时的保证时间（GT）和另外180小时的ESO-GTC时间（ESO和GTC共同分配的时间，作为西班牙Ascension ESO成员的一部分竞争性授予）的数据进行分析。 这将与双子座的档案数据相结合，以解决活动星系核研究中的一个关键问题。详细了解的环面，活动星系核/黑洞的燃料供应过程及其关系（甚至创建）的环面，与宿主星系的相互作用，并在其他星系的尘埃化学将被构建。基于当前数据的模拟，为下一代设施（如索菲亚、JWST、TMT等）准备新的观测数据都计划好了