Realistic simulations of the intergalactic medium CDS&E

星际介质 CDS 的真实模拟

• 批准号: 1413568
• 负责人: David Tytler
• 金额: $ 39.26万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-15 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1413568&HistoricalAwards=false
• 关键词: Realistic; simulations; intergalactic; medium; CDS&amp

The material that fills the vast spaces between galaxies (the Intergalactic Medium, or IGM) is surprisingly poorly understood. One primary method of investigating the IGM is through the light it absorbs from very distant very bright quasi-stellar objects (quasars), which show hundreds of measurable features at very specific wavelengths. Unfortunately, detailed computational work is still unable to reproduce key aspects of the IGM, all at the same time and using the same input parameters. This must mean that those simulations do not correctly represent the real Universe. This study attempts to correct this failing with a systematic investigation of the physics included in the numerical studies, and a rigorous delineation of the valid regions of the large parameter space to be investigated.The IGM makes hundreds of absorption lines in quasar spectra that are sensitive to the thermal history of the Universe, but, as noted, current numerical simulations cannot simultaneously match several key features. The discrepancy is too large to be due to observational errors, and is seen in multiple comparisons even when using different numerical methods. This research team has decades of experience observing the IGM and running high fidelity simulations, and is forced to conclude that the simulations simply do not correctly represent our Universe. Therefore, this project will search for a realistic representation of the IGM through four new types of simulation, including a new radiation transport solver, a high resolution large box simulation with parameterized feedback, the first ever simulation of the IGM with self-consistent 3D radiative transfer, and physically motivated simulations that explore a wide variety of other possible heat sources. All these results will be synthesized, parameterizing precisely how they change the appearance of the IGM, so as to select those parameter values that will faithfully generate observations of the IGM. The work should locate what is missing from our understanding of the IGM, and discover and specify simulations that can exactly reproduce the main physical processes in the IGM. It will lead to more accurate and robust estimates of the IGM temperature, density and ionization, the intensity of the ultraviolet background radiation, and the clustering of matter on small scales that is used to set limits on neutrino masses. All of the simulations and the generating codes will be publicly available. This team has a two decade record of integrating education and diversity into their core research. Undergraduate students will receive instruction in cosmology, astrophysics, spectroscopy, and simulations, and they will work with advanced software tools.

令人惊讶的是，人们对填充在星系之间巨大空间（星系际介质，或IGM）的物质知之甚少。 研究IGM的一个主要方法是通过它从非常遥远的非常明亮的类星体（类星体）吸收的光，这些类星体在非常特定的波长下显示出数百个可测量的特征。 不幸的是，详细的计算工作仍然无法再现IGM的关键方面，所有这些都在同一时间使用相同的输入参数。 这一定意味着这些模拟并不能正确地代表真实的宇宙。 本研究试图纠正这一缺陷，包括在数值研究中的物理系统的调查，并严格划定的大参数空间的有效区域investigated.The IGM使数百个吸收线的类星体光谱是敏感的宇宙的热历史，但如前所述，目前的数值模拟不能同时匹配的几个关键功能。 这种差异太大，不可能是由于观测误差造成的，即使使用不同的数值方法，也可以在多重比较中看到。 这个研究团队拥有数十年的观测IGM和运行高保真模拟的经验，并被迫得出结论，这些模拟并不能正确地代表我们的宇宙。 因此，该项目将通过四种新类型的模拟来寻找IGM的现实表示，包括新的辐射传输求解器，具有参数化反馈的高分辨率大盒子模拟，有史以来第一次对IGM进行自洽三维辐射传输模拟，以及探索各种其他可能热源的物理激励模拟。 所有这些结果将被合成，精确地参数化它们如何改变IGM的外观，以便选择那些将忠实地生成IGM的观察结果的参数值。 这项工作应该找到我们对IGM的理解中所缺少的东西，并发现和指定可以精确再现IGM中主要物理过程的模拟。 它将导致对IGM温度，密度和电离，紫外线背景辐射强度以及用于限制中微子质量的小尺度物质聚集的更准确和可靠的估计。 所有的模拟和生成代码都将公开。 这个团队有二十年的记录，将教育和多样性融入他们的核心研究。 本科生将接受宇宙学，天体物理学，光谱学和模拟方面的指导，他们将使用先进的软件工具。