Star Formation in the Turbulent ISM with Realistic Large-Scale Forcing

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。这项研究的目的是用高动态范围模拟来约束恒星形成模型。目前的恒星形成模拟是基于非物理初始条件或人造驱动力，模拟来自大范围湍流级联的能量注入。在这个项目中，加州大学圣地亚哥分校的Paolo Padoan博士将通过开发恒星形成模拟来克服这一限制，该模拟可以解决单个原恒星核心的坍塌问题，同时包括驱动湍流和控制恒星形成云生命周期的大规模物理过程。该项目将通过嵌入恒星形成模拟，在垂直于银盘的1×1×20千帕秒区域内，达到200个天文单位的坍塌核心的分辨率，包括大尺度物理学。该区域的星际介质将使用三维、可压缩的理想磁流体(MHD)模拟，包括银河系引力场中的密度分层、气体自重、辐射冷却、光电和宇宙射线加热、大规模银河系剪切、恒星形成以及Ia、Ib+c和II型超新星爆炸的热和机械反馈。这些模拟产生的恒星形成云的大样本将用辐射传输代码处理，以产生模拟尘埃连续和线发射观测的数据集。恒星的形成是许多天体物理学和宇宙学的核心。该项目的结果将与研究星系的形成和演化以及宇宙的恒星形成历史有关。它们将被用于制定星系形成的宇宙学模拟的亚格子模型，其中恒星反馈是重要的。辐射传输计算将产生恒星形成云的模拟观测的大数据集，这将有助于解释实际观测。由于该项目将产生一些迄今为止最大的超音速湍流模拟，它还将允许对超新星驱动的MHD湍流的统计特性进行高分辨率研究。帕多安博士与圣地亚哥超级计算机中心合作，最近启动了计算天体物理数据分析中心(CADAC)，这是一项收集、共享和分析数值模拟数据集的新服务。CADAC向天体物理界提供了强大的数据存储和数据分析资源，鼓励及早公布数字数据集和数据分析工具。通过CADAC，该项目的数据和计算资源将提供给科学界，包括研究生。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The objective of this research is to constrain star formation models with high dynamic range simulations. Current star formation simulations are based on unphysical initial conditions or artificial driving forces that mimic the energy injection from a large-scale turbulent cascade. In this project, Dr. Paolo Padoan (University of California - San Diego) will overcome this limitation by developing star formation simulations that resolve the collapse of individual protostellar cores, while including the large-scale physical processes that drive the turbulence and control the life cycle of star-forming clouds. The project will include the large-scale physics by embedding the star-formation simulations, reaching a resolution of 200 astronomical units in collapsing cores, in a 1 × 1 × 20 Kiloparsec region perpendicular to the Galactic disk. The interstellar medium in this region will be modeled using three-dimensional, compressible, ideal magneto-hydrodynamic (MHD) simulations, including density stratification in the Galactic gravitational field, gas self-gravity, radiative cooling, photoelectric and cosmic-ray heating, large-scale Galactic shear, star formation, and thermal and mechanical feedback from Type Ia, Ib+c, and Type II supernova explosions. The large samples of star-forming clouds generated by these simulations will be processed with radiative transfer codes to produce datasets of simulated dust-continuum and line emission observations. Star formation is central to much of astrophysics and cosmology. Results from this project will be relevant to studies of the formation and evolution of galaxies and to the star formation history of the universe. They will be used to formulate sub-grid models for cosmological simulations of galaxy formation, where stellar feedback is important. The radiative transfer calculations will result in large datasets of simulated observations of star-forming clouds that will be helpful in the interpretation of real observations. Because this project will generate some of the largest simulations of supersonic turbulence to date, it will also allow high resolution studies of the statistical properties of supernova-driven MHD turbulence. Dr. Padoan, in collaboration with the San Diego Supercomputer Center, has recently started the Computational Astrophysics Data Analysis Center (CADAC), a new service to collect, share, and analyze datasets from numerical simulations. CADAC provides powerful data-storage and data-analysis resources to the astrophysical community, encouraging the early publication of numerical datasets and data-analysis tools. Through CADAC, data from this project and computational resources will be available to the scientific community, including graduate students.