Quenching star formation with quasar outflows launched by trapped IR radiation
Quenching star formation with quasar outflows launched by trapped IR radiation
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DOI：
10.1093/mnras/sty1514
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发表时间：
2017-09
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
我们用Ramses-RT程序对大质量类星体主晕中辐射驱动的外流进行了宇宙辐射-流体动力学模拟。我们的模拟包括类星体尘埃的单散射和多散射辐射压力，并与有热反馈的模拟进行了比较。对于辐射压力驱动，我们证明了存在一个临界类星体光度，超过这个光度，星系外流就会被发射，这是由引力和辐射力的平衡所决定的。虽然这个临界光度在黑洞质量的单次散射极限下是不切实际的高，但如果计入红外(IR)多次散射辐射压力，它与黑洞在爱丁顿极限处增长的约3倍10^9的MODOT是一致的。流出速度快(v、rm、1000、rm km、S^-1)，具有较强的质量流出峰值，约为10^3-10^4、mOot、yr^-1，但持续时间较短($<；10、rm Myr)。流出的物质是多相的，尽管主要由冷气体组成，通过受冲击的卷起成分中的热不稳定形成。辐射压力和热驱动的外流都对它们的宿主星系产生了重大影响，但影响方式不同，是互补的。热驱动的外流更有效地耦合扩散晕气体，产生更强大、更热和更充满体积的外流。红外辐射通过扩散穿透稠密气体的能力，更有效地将气体从凸起中喷射出来。通过流出的气体喷射和被捕获的红外辐射的内部增压相结合，导致在凸起中恒星的形成完全停止。因此，我们认为辐射压力驱动的反馈可能是调节致密恒星爆发中恒星形成的一个重要因素，特别是在类星体的“模糊”阶段。
We present cosmological radiation-hydrodynamic simulations, performed with the code Ramses-RT, of radiatively-driven outflows in a massive quasar host halo at $z = 6$. Our simulations include both single- and multi-scattered radiation pressure on dust from a quasar and are compared against simulations performed with thermal feedback. For radiation pressure-driving, we show that there is a critical quasar luminosity above which a galactic outflow is launched, set by the equilibrium of gravitational and radiation forces. While this critical luminosity is unrealistically high in the single-scattering limit for plausible black hole masses, it is in line with a $\approx 3 \times 10^9 \, \rm M_\odot$ black hole accreting at its Eddington limit, if infrared (IR) multi-scattering radiation pressure is included. The outflows are fast ($v \, \gtrsim \, 1000 \, \rm km \, s^{-1}$) and strongly mass-loaded with peak mass outflow rates $\approx 10^3 - 10^4 \, \rm M_\odot \, yr^{-1}$, but short-lived ($< 10 \, \rm Myr$). Outflowing material is multi-phase, though predominantly composed of cool gas, forming via a thermal instability in the shocked swept-up component. Radiation pressure- and thermally-driven outflows both affect their host galaxies significantly, but in different, complementary ways. Thermally-driven outflows couple more efficiently to diffuse halo gas, generating more powerful, hotter and more volume-filling outflows. IR radiation, through its ability to penetrate dense gas via diffusion, is more efficient at ejecting gas from the bulge. The combination of gas ejection through outflows with internal pressurisation by trapped IR radiation leads to a complete shut down of star formation in the bulge. We hence argue that radiation pressure-driven feedback may be an important ingredient in regulating star formation in compact starbursts, especially during the quasar's `obscured' phase.