Collaborative Research: Cosmological All-wavelength Radiative Transfer (CART)

这个小组将研究新形成的星系和活跃的星系核的光如何在星系间气体中传播。他们把注意力集中在宇宙历史上大约10亿年结束的一段时期，当时星系间的中性气体被星系的紫外线电离。为了计算气体和暗物质如何聚集在一起形成星系，该小组将使用流体动力学模拟。他们将发展和完善他们的计算，以预测一个星系何时应该形成恒星，或何时应该形成一个活跃的核心。然后，从星系中出现的光子将使用李博士的三维辐射传输代码进行跟踪。该代码将得到改进，以处理莱曼α光子、电离和非常小的尘埃颗粒的影响。该小组将制作高红移星系和类星体的大型模拟目录，描述它们从x射线到毫米波长的发射，包括21厘米和莱曼α的氢谱线。两名研究生将通过参与研究得到培训。新的辐射传输代码和模拟目录将提供给天文学界。这些星表总结了我们关于星系如何成长的理论预测。这个小组和其他小组将通过将星表与目前和计划中对遥远星系的深度调查所看到的进行比较，来检验这些理论。李博士和阿贝尔博士都在公共宣传方面有着良好的记录，这个项目将产生有吸引力的静止图像和电影，以说明当前关于星系形成的想法。

This group will investigate how the light of newly-forming galaxies and the active nuclei of galaxies propagates through the intergalactic gas. They focus attention on a period that ended about a billion years into cosmic history, when the neutral intergalactic gas was ionized by the ultraviolet light of galaxies. To calculate how gas and dark matter came together to make the galaxies, the group will use hydrodynamic simulations. They will develop and refine their calculations to predict when a galaxy should form stars, or develop an active nucleus. Then, the photons emerging from the galaxy will be tracked using Dr. Li's 3-dimensional radiative-transfer code. That code will be improved to handle Lyman-alpha photons, ionization, and the effect of very small dust grains. The group will produce large mock catalogs of high-redshift galaxies and quasars that describe their emission from X-ray to millimeter wavelengths, and include the hydrogen lines at 21cm and Lyman alpha. Two graduate students will be trained by participating in the research. The new radiative-transfer code, and the mock catalogs, will be made available to the astronomical community. Those catalogs summarize the predictions of our theories about how galaxies grow. This group and others will test those theories by comparing the catalogs with what is seen in current and planned deep surveys of distant galaxies. Both Dr. Li and Dr. Abel work at institutions with strong records in public outreach, and this project will yield attractive still images and movies to illustrate current ideas about galaxy formation.