发表机构
Canadian Institute for Theoretical Astrophysics, University of Toronto; University of Toronto Physics Department McLennan Physical Laboratories; Cornell University; University of Zurich（多伦多大学理论天体物理研究所; 多伦多大学麦克伦纳物理实验室; 康奈尔大学; 苏黎世大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究基于FIRE-2模拟构建后处理管道预测星系CO相关物理量，经观测验证其方法学，为线强度映射mock的CO响应函数研究奠定基础。
AI 中文摘要
我们提出了一个后处理管道，用于为“真实环境反馈（FIRE-2）”模拟中的星系预测CO线光度、分子氢质量及CO丰度，这是构建线强度映射 mock 所需的CO响应函数的第一步。SKIRT提供了到达每个气体单元的辐射场；CLOUDY在一个五参数网格（金属丰度、密度、湍流速度、辐射场、云尺度）上制表并插值，可给出CO(1-0)线的光度$L'_{\rm CO(1-0)}$以及H₂和CO质量。作为三篇系列论文的第一篇，我们将该管道与观测结果进行验证：对于银河系（MW）分子云，预测的$L'_{\rm CO(1-0)}$在$A_V\backsim1$处急剧上升，且在该柱密度以上与观测值匹配；对于均匀的$3Z_\bigodot$，总光度与观测总量的偏差在35%以内；金属丰度增加3倍会使总$L'_{\rm CO(1-0)}$变化一个数量级；沿银河系视线，预测的$N_{\rm CO}/N_{\rm H_2}$在$N_{\rm H_2}$的0.3 dex范围内重现观测到的上升趋势，但在更高柱密度下低于观测数据；在$z=0$时，我们的分子气体质量与xCOLD GASS在恒星形成率${\rm SFR}\backsim0.3M_\bigoplus yr^{-1}$以上一致，且在不同模拟分辨率下收敛；在$z\backsim1$时，固定恒星质量下观测气体质量超过我们的结果，不过选择效应和转换因子假设限制了该比较；CO光度将在论文II中与河外观测结果进行比较。捕获金属丰度依赖的CO光解离尘埃屏蔽效应对建模低质量和高红移星系的CO发射至关重要。
英文摘要
We present a post-processing pipeline that predicts CO line luminosities, molecular hydrogen masses, and CO abundances for galaxies in the Feedback in Realistic Environments (FIRE-2) simulations, as a first step toward CO response functions for line intensity mapping mocks. SKIRT gives the radiation field reaching each gas cell. CLOUDY, tabulated on a five-parameter grid (metallicity, density, turbulent velocity, radiation field, cloud scale) and interpolated, gives $L'_{\rm CO(1-0)}$ and the $\rm H_2$ and CO masses. In this first of three papers we validate the pipeline against observations. For Milky Way (MW) molecular clouds, the predicted $L'_{\rm CO(1-0)}$ rises sharply at $A_V\sim1$ and matches the observed values above that column. For a uniform $3\,Z_\odot$ the summed luminosity is within 35\% of the observed total. A factor of three increase in metallicity changes the total $L'_{\rm CO(1-0)}$ by an order of magnitude. Along MW sight lines, the predicted $N_{\rm CO}/N_{\rm H_2}$ reproduces the observed upturn within 0.3 dex in $N_{\rm H_2}$ but falls below the data at higher columns. At $z=0$ our molecular gas masses agree with xCOLD GASS for ${\rm SFR}\gtrsim0.3\,M_\odot\,yr^{-1}$ and are converged across our simulation resolutions. At $z\gtrsim1$ observed gas masses exceed ours at fixed stellar mass, though selection effects and conversion-factor assumptions limit this comparison. CO luminosities are compared with extragalactic observations in Paper II. Capturing the metallicity-dependent dust shielding of CO from photodissociation is essential for modeling CO emission in low-mass and high-redshift galaxies.
Comments31 pages, 14 figures, 2 tables
