论文标题
逐云,多相,贝叶斯建模:应用于四个弱,低电离吸收器
Cloud-by-cloud, multiphase, Bayesian modeling: Application to four weak, low ionization absorbers
论文作者
论文摘要
我们提出了一种新方法,旨在通过中间类星体吸收线系统的组件电离建模来提高组件的效率。我们逐一进行多相建模,利用多云和贝叶斯方法从吸收曲线合奏中提取物理性能。在这里,作为方法的证明,我们将重点放在低红移时的四个弱,低电离吸收器上,因为它们是多相,但相对简单的约束。我们将误差放在单个云的推断金属性和电离参数上,并表明该值在整个吸收曲线上因组件而异。我们的方法需要用户对阶段数量的输入,并依赖于每个阶段的优化过渡,其中一个阶段以高分辨率和信噪比观察到。优化过渡的测得的多普勒参数对HI的多普勒参数提供了约束,因此即使氢管饱和,也可以在金属度测量中提供杠杆作用。我们提供了我们方法的几个测试,表明我们可以从模拟配置文件中恢复输入参数。我们还考虑了如何影响模型结果,该模型结果如何受到观测值涵盖的辐射过渡(例如多少个HI过渡)以及优化过渡的B参数中的不确定性。我们讨论了该方法的成功和局限性,并考虑了其对大型统计研究的潜力。这种改进的方法将有助于建立来自表征吸收剂的多种属性与在狭窄培养基中发挥作用的多个物理过程之间的直接连接。
We present a new method aimed at improving the efficiency of component by component ionization modeling of intervening quasar absorption line systems. We carry out cloud-by-cloud, multiphase modeling making use of CLOUDY and Bayesian methods to extract physical properties from an ensemble of absorption profiles. Here, as a demonstration of method, we focus on four weak, low ionization absorbers at low redshift, because they are multi-phase but relatively simple to constrain. We place errors on the inferred metallicities and ionization parameters for individual clouds, and show that the values differ from component to component across the absorption profile. Our method requires user input on the number of phases and relies on an optimized transition for each phase, one observed with high resolution and signal-to-noise. The measured Doppler parameter of the optimized transition provides a constraint on the Doppler parameter of HI, thus providing leverage in metallicity measurements even when hydrogen lines are saturated. We present several tests of our methodology, demonstrating that we can recover the input parameters from simulated profiles. We also consider how our model results are affected by which radiative transitions are covered by observations (for example how many HI transitions) and by uncertainties in the b parameters of optimized transitions. We discuss the successes and limitations of the method, and consider its potential for large statistical studies. This improved methodology will help to establish direct connections between the diverse properties derived from characterizing the absorbers and the multiple physical processes at play in the circumgalactic medium.