Collaborative Research: CDS&E: Constraining the uncertain physics of galaxy formation: cosmic rays, black holes, and beyond

星系形成的计算机模拟是帮助理解、测试和预测在本地和极遥远宇宙中观测到的星系特性的强大工具。鉴于最近开始（或即将进行）的大量敏感的广域星系调查，迫切需要以最高精度模拟星系的形成和演化。拟议中的研究将建立在该小组早期的转型星系模拟的基础上，通过将气体吸积的影响添加到大质量黑洞、超高能量原子核（宇宙射线）和磁场上。此外，还将对研究生和本科生进行培训，对地区高中生进行指导，并制作动画供公众观看。该小组将继续为监狱囚犯开展教育项目。这项研究代表了几年前FIRE（现实环境反馈）合作项目的进一步发展，该项目创建了最先进的星系形成和演化的流体动力学模拟，其中包括对来自大质量恒星和超新星的“反馈”的详细处理。这项工作成功地再现了观测到的广泛的星系特性——质量、化学丰度趋势和缩放关系——矮星系一直到大约银河系大小（L*）的系统。对于更大质量的星系，需要对快速吸积的大质量黑洞（即活动星系核；AGN）所注入的能量进行精确处理。这是本文提出的原始FIRE模拟代码的主要更新之一。其他潜在的重要过程，包括磁场和宇宙射线，以及跟踪化学丰度的新框架也将实施。这些有望产生新的星系模拟，具有更精确的秒差距尺度分辨率，并允许对广泛的物理现象进行预测（即“正演建模”），包括分辨无线电和伽马射线发射，宇宙射线光谱，星系内部和周围的法拉第旋转，Sunyaev-Zeldovich效应，以及环星系介质的动力学。FIRE团队将向科学界公开提供作为这项工作的一部分开发的GIZMO模拟代码的新模块，以及该项目的数据产品。在更广泛的影响领域，该项目将支持四名研究生，十几名本科生和一些高中生参与制作科学动画。该小组还将通过与Stateville惩教中心的合作，让囚犯参与教育活动。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。

Computer simulations of galaxy formation are powerful tools to help understand, test, and predict the observed properties of galaxies in the local and extremely distant Universe. Given the large number of sensitive wide-area galaxy surveys that have recently started (or are soon to be underway) there is a critical need for simulations that model the formation and evolution of galaxies with the highest accuracy. The proposed research will build upon the group’s earlier transformative galaxy simulations by adding the effects of gas accretion onto massive black holes, extremely high energy atomic nuclei (cosmic rays), and magnetic fields. These efforts will additionally train graduate and undergraduate students, mentor area high school students, and produce animations for public shows. The team will continue an educational program for prison inmates.This research represents the further development of a project started several years ago by the FIRE (Feedback in Realistic Environments) collaboration to create state-of-the-art hydrodynamic simulations of galaxy formation and evolution that included a detailed treatment of “feedback” from massive stars and supernovae. That work successfully reproduced a wide range of observed galaxy properties – masses, chemical abundances trends, and scaling relations – for dwarf galaxies up to approximately Milky Way sized (L*) systems. For more massive galaxies, an accurate treatment of the energy injected by rapidly accreting massive black holes (i.e., active galactic nuclei; AGN) is required. This is one of the primary updates to the original FIRE simulation code proposed here. Other potentially important processes, including magnetic fields and cosmic rays, and a new framework to track chemical abundances are to be implemented as well. These promise to result in new galaxy simulations with parsec-scale resolution that are more accurate and that allow predictions (i.e., “forward modeling”) for a wide range of physical phenomena, including resolved radio and gamma-ray emission, cosmic ray spectra, Faraday rotation in and around galaxies, the Sunyaev-Zeldovich effect, and the dynamics of the circum-galactic medium. The FIRE team will make publicly available to the scientific community new modules for the GIZMO simulation code developed as part of this work, as well as data products from the project. In the area of Broader Impacts this project will support four graduate students, a dozen undergraduate students, and a number of high-school students involved in creating scientific animations. The team will also engage inmates in educational activities via a partnership with the Stateville Correctional Center.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.