Emission-lines from AGN&Starbursts: new steps to understanding their message

许多现代天体物理学涉及到电磁辐射(光)与恒星周围、星系中以及它们之间的空间中弥漫的气体云的相互作用。辐射与气体中的原子相互作用，加热气体，有时电离和激发原子。然后，气体发出光，进而与气体相互作用。这些相互作用中涉及的详细物理过程极其复杂，并且随着气体的温度、密度和化学丰度的不同而变化。了解这些过程及其与辐射的相互作用，使天体物理学家能够推断气体云中的物理条件和辐射源的特征。费兰德博士是研究光和电离气体相互作用的世界专家之一，三十年来，他一直在开发一种开源的、公开可用的计算机模拟工具，名为“Cloudy”。数以百计的天文学家和天体物理学家使用云彩来研究不同的区域，从恒星形成区域到活动星系(活动星系核或AGN)和类星体中心的超大质量黑洞周围的发光区域并由其激发。Cloudy已用于几代学生和青年科研人员的培训和研究。该奖项将支持Cloudy代码的重大升级，以提高其性能和适用范围。这次升级可能会让它用于模拟恒星形成区等致密等离子体中的气体，并可以更好地计算类星体中心附近气体的光发射。在理解活动星系核和星暴星系的整个电磁光谱的中心区域方面，这是一个史无前例的发现时刻。利用低红移的光学H-I复合线和高红移的碰撞激发线对宽线区域进行混响映射，形成了超大质量黑洞质量表。这些反过来又使得对关键问题的研究成为可能，例如黑洞质量的演化，活动星系核反馈的作用，以及黑洞和周围星系演化之间的相互作用。阿塔卡马大毫米/亚毫米阵列(ALMA)使常规研究活动星系核和恒星爆发星系的射电复合线成为可能，探测尘埃覆盖区域的电离辐射源。ALMA可以进一步探测恒星形成区和活动星系核分子环的分子发射。这个项目将开发理解这些发射线观测所需的理论工具，并将它们纳入Cloudy中，Cloudy旨在以单个原子和分子过程的基础为基础，同时自始至终地解决这些等离子体、化学、辐射传输和动力学问题。最近与高密度等离子体/磁聚变界的讨论推动了将要取得的进展。他们开发的方法和数据将以令人惊讶的低成本极大地改进数值模拟。这些显著改进的模拟将应用于BLR、恒星形成区域和相关分子区域的模型。

Much of modern astrophysics involves the interaction of electromagnetic radiation (light) with diffuse clouds of gas around stars, in galaxies and in the spaces between them. The radiation interacts with the atoms in the gas, heats the gas and sometimes ionizes and excites the atoms. The gas then emits light which, in turn, interacts with the gas. The detailed physical processes involved in these interactions are enormously complex and vary with the gas' temperature, density and chemical abundance. Understanding these processes and their interplay with the radiation allows astrophysicists to deduce the physical conditions in the gas clouds and the characteristics of the source of the radiation. Dr. Ferland is one of the world's experts in the study of the interplay of light and ionized gas and for thirty years he has been developing an open-source, publicly-available computer simulation tool called "Cloudy." Cloudy is used by hundreds of astronomers and astrophysicists in studies of diverse regions from star-forming regions to the light-emitting regions surrounding and excited by the supermassive black holes at the centers of active galaxies (Active Galactic Nuclei or AGN) and quasars. Cloudy has been used in the training and research of several generations of students and young researchers. This award will support a major upgrade of the Cloudy code that will improve its performance and range of applicability. The upgrade will potentially allow it to be used in simulations of gas in dense plasmas such as star-forming regions and will allow better calculation of the emission of light from gas near the heart of quasars.This is a time of unprecedented discovery in understanding the central regions of Active Galactic Nuclei and Starburst galaxies across the electromagnetic spectrum. Reverberation mapping of the Broad Lined Region, using optical H I recombination lines at low redshift, and collisionally excited lines at high redshift, have led to catalogs of supermassive black hole masses. These in turn make possible investigations of key questions such as the evolution of black hole mass, the role of AGN feedback, and the interplay between the evolution of the black hole and surrounding galaxy. The Atacama Large Millimeter/Sub-millimeter Array (ALMA) makes it possible to routinely study radio recombination lines from both AGN and Starburst galaxies, probing sources of ionizing radiation in dust-shrouded regions. ALMA can further probe molecular emission from both star-forming regions and the AGN molecular torus. This project will develop the theoretical tools needed to understand these emission-line observations and incorporate them into Cloudy, which has been designed to solve these plasma, chemistry, radiation transport, and dynamics problems simultaneously and self consistently, building from the foundation of individual atomic and molecular processes. The advances to be undertaken are motivated by recent discussions with the dense plasma / magnetic fusion communities. Methods and data they have developed will dramatically improve the numerical simulations at surprisingly low cost. These significantly improved simulations will be applied to models of the BLR, star-forming regions,and to associated molecular regions.