论文标题
L-galaxies半分析模型的热气体分布，X射线亮度和BARYON预算
The hot gas distribution, X-ray luminosity and baryon budget in the L-Galaxies semi-analytic model of galaxy formation
论文作者
论文摘要
热离子气体在星系的重龙周期中很重要，并贡献了大多数“失踪的巴里子”。到目前为止，大多数半分析模型的星系形成模型几乎没有关注热气旋光环及其X射线排放。在本文中，我们采用了Sharma等人的一维模型。而不是等温球来描述L-Galaxies半分析模型中热气体的径向分布。热气晕可根据本地热不稳定性时间表的比率和自由下落的时间表：具有$ t _ {\ rm ti}/t _ {\ rm ff} = 10 $的较酷核心和稳定的外ho，$ t _ {\ rm t _ {我们根据新的热气体轮廓更新冷却，反馈和剥离的处方，然后再现几个X射线观测结果，例如热气密度的径向曲线以及X射线光度和温度的缩放关系。我们发现：（1）与观察结果一致，光环中心的平整密度曲线产生的X射线发射低于等温球； （2）容易降水的凉爽核心区域的气温比病毒温度高，并且较小的haloes中的$ t _ {\ rm x}/t _ {\ rm 200} $比率会导致$ l _ {\ rm x} -t _ t _ {\ rm x {\ rm x} $ x} $ x} $ l _ {\ rm x} $ x { （3）低质量光环中无界储层中的离子气体和低温层间气体可能是halo的主要组成部分。我们的模型输出可以预测附近宇宙中热气的观察结果，并通过未来X射线望远镜探索的Baryons进行模拟调查。
Hot ionized gas is important in the baryon cycle of galaxies and contributes the majority of their ``missing baryons''. Until now, most semi-analytic models of galaxy formation have paid little attention to hot gaseous haloes and their X-ray emission. In this paper, we adopt the one-dimensional model from Sharma et al. instead of the isothermal sphere to describe the radial distribution of hot gas in the L-Galaxies semi-analytic model. The hot gas halo can be divided into two parts according to the ratio of the local thermal instability time-scale and the free-fall time-scale: a cool core with $t_{\rm TI}/t_{\rm ff}=10$ and a stable outer halo with $t_{\rm TI}/t_{\rm ff}>10$. We update the prescriptions of cooling, feedback and stripping based on the new hot gas profiles, and then reproduce several X-ray observational results, like the radial profiles of hot gas density, and the scaling relations of X-ray luminosity and temperature. We find: (1) Consistent with observations, flatter density profiles in halo centers produce lower X-ray emission than an isothermal sphere; (2) Cool core regions prone to precipitation have higher gas temperature than the virial temperature, and a larger $T_{\rm X}/T_{\rm 200}$ ratio in smaller haloes leads to a steeper slope in the $L_{\rm X}-T_{\rm X}$ relation; (3) The ionized gas in the unbounded reservoir and low temperature intergalactic gas in low mass haloes could be the main components of the halo ``missing baryons''. Our model outputs can predict the observations of hot gas in the nearby universe and produce mock surveys of baryons probed by future X-ray telescopes.
