The Cosmological Baryon Density

宇宙重子密度大卫·R·泰特勒。泰特勒正在进行一个由两部分组成的项目。第一部分是关于早期宇宙中氢和氢原子相对数目D/H的测量。D/H提供了对宇宙中普通物质(重子)平均密度的最佳测量。在标准宇宙学中，D/H给出了重子密度和光子密度之比的最佳度量，这是一个基本的宇宙学常数。D/H提供了一种更直接的大爆炸核合成测试。泰特勒博士正在测量从低密度电离气体中产生的紫外线吸收线到遥远类星体的D/H。第二部分使用这些相同的数据来测量金属的宇宙分布。这一部分解决的问题是，是否存在分布广泛的早期银河系前恒星。泰特勒博士正在测量星际介质中氧到氢(O/H)的分布，并将其与最近的理论预测进行比较。泰特勒博士也在使用这些数据来估计热的碰撞电离气体中的金属丰度。

AST-9900842The cosmological baryon densityDavid R. TytlerDr. Tytler is conducting a two part project. The first part concerns the measurement of the ratio of the relative number of deuterium and hydrogen atoms, D/H, in the early universe. D/H provides the best measurement of the average density of ordinary matter (baryons) in the universe. In standard cosmology, D/H gives the best measure of the ratio between baryon density and photon density, which is a fundamental cosmological constant. D/H provides one of the more direct tests of the big bang nucleosynthesis. Dr. Tytler is measuring D/H from ultraviolet absorption lines that arise in low density ionized gas along the lines of sight to distant quasar stellar objects. The second part uses these same data to measure the cosmological distribution of metals. This part addresses the question if there was an early generation of widely distributed pregalactic stars. Dr. Tytler is measuring the distribution of Oxygen to Hydrogen (O/H) in the intergalactic medium and comparing it with recent theory predictions. Dr. Tytler is also using these data to estimate the metal abundance in hot collisionally ionized gas.***