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arXiv 2201.06584astro-ph.GAastro-ph.CO
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早期宇宙中尘埃加速种子黑洞的生长

Accelerated growth of seed black holes by dust in the early universe

KwangHo Park, Gen Chiaki, John H. Wise

摘要:

我们探讨了早期宇宙中尘埃对种子黑洞(BH)生长的影响。以前的一维辐射流体动力学(RHD)模拟表明,增加对尘埃的辐射压力进一步抑制吸积率比化学原始气体的情况下。利用Enzo + Moray程序,我们对尘埃星际介质中黑洞的吸积过程进行了三维RHD模拟。我们使用修改后的Grackle冷却库考虑尘埃物理在其非平衡化学。BH经历了一个早期的进化阶段,电离BH辐射在吸积和反馈之间循环时产生了一个振荡的HII区域。随着模拟的进行,稠密的冷气体在电离区域外聚集,在那里中性介质的流入与辐射压力驱动的流出相遇。在后期阶段,高密度的气体流发展并打破电离区域的准球形对称性,迅速提高吸积速率。晚期的特征是强电离流出和高密度气体流入共存。平均吸积率随着金属丰度的增加而增加,在Z $\sim$ 0.01 - 0.1 $\,Z_\odot$处达到峰值,比原始气体高一个数量级。然而,当金属丰度接近太阳丰度时,平均吸积速率会下降,因为辐射压力变得足够强,足以驱逐高密度气体。我们的研究结果表明,一个充满灰尘的金属贫ISM可以加速宇宙早期的BH的增长速度,然而,可以stunt其增长的ISM是进一步丰富的太阳丰度。

英文摘要:

We explore the effect of dust on the growth of seed black holes (BHs) in the early universe. Previous 1D radiation-hydrodynamic (RHD) simulations show that increased radiation pressure on dust further suppresses the accretion rate than the case for the chemically pristine gas. Using the Enzo+Moray code, we perform a suite of 3D RHD simulations of accreting BHs in a dusty interstellar medium (ISM). We use the modified Grackle cooling library to consider dust physics in its non-equilibrium chemistry. The BH goes through an early evolutionary phase, where ionizing BH radiation creates an oscillating HII region as it cycles between accretion and feedback. As the simulations proceed, dense cold gas accumulates outside the ionized region where inflow from the neutral medium meets the outflow driven by radiation pressure. In the late phase, high-density gas streams develop and break the quasi-spherical symmetry of the ionized region, rapidly boosting the accretion rate. The late phase is characterized by the coexistence of strong ionized outflows and fueling high-density gas inflows. The mean accretion rate increases with metallicity reaching a peak at Z$\sim$0.01-0.1$\,Z_\odot$, one order of magnitude higher than the one for pristine gas. However, as the metallicity approaches the solar abundance, the mean accretion rate drops as the radiation pressure becomes strong enough to drive out the high-density gas. Our results indicate that a dusty metal-poor ISM can accelerate the growth rate of BHs in the early universe, however, can stun its growth as the ISM is further enriched toward the solar abundance.

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