Driving gas shells with radiation pressure on dust in radiation-hydrodynamic simulations
Driving gas shells with radiation pressure on dust in radiation-hydrodynamic simulations
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DOI：
10.1093/mnras/stx2598
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发表时间：
2017-03
影响因子：
4.8
通讯作者：
T. Costa;J. Rosdahl;D. Sijacki;M. Haehnelt
中科院分区：
文献类型：
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作者：
T. Costa;J. Rosdahl;D. Sijacki;M. Haehnelt
我们提出了在孤立的暗物质晕中由明亮的活动星系核（AGN）发射的辐射驱动的气体壳的辐射流体动力学模拟。我们的目标是：(1)研究AGN辐射压力对尘埃发射星系外流的能力；(2)限制红外（IR）多重散射在促进外流加速方面的效率。我们的模拟是用辐射流体动力学代码RAMSES-RT进行的，包括来自AGN的单散射和多散射辐射压力、辐射冷却和自重力。由于流出的壳层最终对入射辐射场来说总是透明的，因此即使在AGN的高光度下，横扫所有中间气体的流出物很可能仍然被引力束缚在它们的光晕上。只要壳层对红外辐射具有轻微的光学厚度，就可以用简单的解析模型很好地描述流出壳层的膨胀。在这种情况下，正如预测的那样，通过红外多重散射增强了壳层的加速度，即施加在气体上的力dP/dt = tau_IR L/c。然而，对于高光深tau_IR bbb50，即使辐射被有效地限制，流出的光学厚气体和红外辐射之间的动量传递也被迅速抑制。在高tau_IR下，特征流时间比红外辐射所需的捕获时间短，动量通量dP/dt << tau_IR L/c。我们认为，虽然不太可能解开大质量星系气体晕，但AGN对尘埃的辐射压力可能在调节高红移大质量致密星系核中的恒星形成和黑洞吸积中发挥重要作用。
We present radiation-hydrodynamic simulations of radiatively-driven gas shells launched by bright active galactic nuclei (AGN) in isolated dark matter haloes. Our goals are (1) to investigate the ability of AGN radiation pressure on dust to launch galactic outflows and (2) to constrain the efficiency of infrared (IR) multi-scattering in boosting outflow acceleration. Our simulations are performed with the radiation-hydrodynamic code RAMSES-RT and include both single- and multi-scattered radiation pressure from an AGN, radiative cooling and self-gravity. Since outflowing shells always eventually become transparent to the incident radiation field, outflows that sweep up all intervening gas are likely to remain gravitationally bound to their halo even at high AGN luminosities. The expansion of outflowing shells is well described by simple analytic models as long as the shells are mildly optically thick to IR radiation. In this case, an enhancement in the acceleration of shells through IR multi-scattering occurs as predicted, i.e. a force dP/dt = tau_IR L/c is exerted on the gas. For high optical depths tau_IR > 50, however, momentum transfer between outflowing optically thick gas and IR radiation is rapidly suppressed, even if the radiation is efficiently confined. At high tau_IR, the characteristic flow time becomes shorter than the required trapping time of IR radiation such that the momentum flux dP/dt << tau_IR L/c. We argue that while unlikely to unbind massive galactic gaseous haloes, AGN radiation pressure on dust could play an important role in regulating star formation and black hole accretion in the nuclei of massive compact galaxies at high redshift.