NIHAO X：通过模拟HI观测用冷暗物质验证局部星系速度函数
NIHAO X: Reconciling the local galaxy velocity function with Cold Dark Matter via mock HI observations
摘要：
利用NIHAO的87个高分辨率流体动力学宇宙学模拟，研究了无碰撞模拟中暗物质晕的最大圆速度（Vmax）与流体动力学模拟中同一晕中HI气体速度宽度之间的关系.这两个量通常用于比较理论和观测速度函数，并导致观测和基于冷暗物质（CDM）模型的预测之间可能存在差异。我们发现，低于100公里/秒，有明显的偏见之间的HI为基础的速度和Vmax，导致低估的实际圆速度的晕。当考虑到这种偏差时，CDM模型在再现观测到的速度函数方面没有问题，并且实际上并不缺乏低速星系。我们的模拟还再现了线宽恒星质量（塔利-费舍尔）的关系和HI的大小，表明HI气体在我们的模拟是延长观察。低于预期线宽的物理原因是，与高质量星系相反，低质量星系不再像通常假设的那样具有延伸的薄HI旋转盘。
英文摘要：
We used 87 high resolution hydrodynamical cosmological simulations from the NIHAO suite to investigate the relation between the maximum circular velocity (Vmax) of a dark matter halo in a collisionless simulation and the velocity width of the HI gas in the same halo in the hydrodynamical simulation. These two quantities are normally used to compare theoretical and observational velocity functions and have led to a possible discrepancy between observations and predictions based on the Cold Dark Matter (CDM) model. We show that below 100 km/s, there is clear bias between HI based velocities and Vmax, that leads to an underestimation of the actual circular velocity of the halo. When this bias is taken into account the CDM model has no trouble in reproducing the observed velocity function and no lack of low velocity galaxies is actually present. Our simulations also reproduce the linewidth - stellar mass (Tully-Fisher) relation and HI sizes, indicating that the HI gas in our simulations is as extended as observed. The physical reason for the lower than expected linewidths is that, in contrast to high mass galaxies, low mass galaxies no longer have extended thin HI rotating disks, as is commonly assumed.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
