论文标题
辐射性湍流混合层以高马赫数
Radiative turbulent mixing layers at high Mach numbers
论文作者
论文摘要
辐射湍流混合层（TML）在天体物理环境中无处不在，例如，圆形培养基（CGM），并由不同气相之间的界面处的剪切速度触发。为了了解TML的剪切速度依赖性，我们执行一组3D流体动力模拟，重点是高马赫数$ \ Mathcal {M} $的TML属性。由于混合区域中的剪切速度受到混合气体的局部声速的限制，因此高压数TMLS成长为两区结构：一个由马赫数独立的混合区，可通过明显的冷却和混合所追踪，再加上具有较大速度分散体的湍流区域，具有较大的$ \ \ \ \ \ \ \ \ \ \ \ \ \ \ mathcal {m {m} $。低操作数TML没有可区分的混合和湍流区域。在低和高马赫数下，TML的辐射冷却分别通过焓消耗和湍流耗散来平衡。中等温度离子的TML表面亮度和色谱柱密度（例如，O Vi）的比例为$ \ propto \ Mathcal \ Mathcal {M}^{0.5} $ at $ \ Mathcal {M} \ Mathcal {M} \ Lesssim 1 $ 1 $ \ gtrsim 1 $。在高马赫数下，流入的速度和热气夹带被大大抑制，强烈的湍流耗散驱动了冷气的蒸发。这与低计算数TML相反，在$ \ MATHCAL {M} $中，增强流入速度和热气夹带的tmls，并且由于夹带热气的凝结，冷气质量增加。
Radiative turbulent mixing layers (TMLs) are ubiquitous in astrophysical environments, e.g., the circumgalactic medium (CGM), and are triggered by the shear velocity at interfaces between different gas phases. To understand the shear velocity dependence of TMLs, we perform a set of 3D hydrodynamic simulations with an emphasis on the TML properties at high Mach numbers $\mathcal{M}$. Since the shear velocity in mixing regions is limited by the local sound speed of mixed gas, high-Mach number TMLs develop into a two-zone structure: a Mach number-independent mixing zone traced by significant cooling and mixing, plus a turbulent zone with large velocity dispersions which expands with greater $\mathcal{M}$. Low-Mach number TMLs do not have distinguishable mixing and turbulent zones. The radiative cooling of TMLs at low and high Mach numbers is predominantly balanced by enthalpy consumption and turbulent dissipation respectively. Both the TML surface brightness and column densities of intermediate-temperature ions (e.g., O VI) scale as $\propto\mathcal{M}^{0.5}$ at $\mathcal{M} \lesssim 1$, but reach saturation ($\propto \mathcal{M}^0$) at $\mathcal{M} \gtrsim 1$. Inflow velocities and hot gas entrainment into TMLs are substantially suppressed at high Mach numbers, and strong turbulent dissipation drives the evaporation of cold gas. This is in contrast to low-Mach number TMLs where the inflow velocities and hot gas entrainment are enhanced with greater $\mathcal{M}$, and cold gas mass increases due to the condensation of entrained hot gas.
