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arXiv 1805.08293astro-ph.GA
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超大质量黑洞的快速增长阶段

The rapid growth phase of supermassive black holes

Stuart McAlpine, Richard G. Bower, David J. Rosario, Robert A. Crain, Joop Schaye, Tom Theuns

摘要:

利用流体动力学宇宙学\eagle模拟研究了超大质量黑洞的快速生长阶段。这种BH增长的非线性阶段发生在$\sim$ $L_{*}$星系中,嵌入在星系宿主的两个调节状态之间:在子$L_{*}$星系中,有效的恒星反馈调节了进入星系的气体流入,并显着降低了中央BH的增长,而在比$L_{*}$更大的星系中,有效的活动星系核反馈调节了进入星系的气体流入,并抑制了进一步的非线性BH增长。我们发现不断演变的临界星系和晕质量尺度在快速BH增长开始。低红移宇宙中的半乳糖醛酸过渡到快速BH增长阶段,其质量大约比高红移对应物大一个数量级(\M{200} $\approx 10^{12.4}$ ~ \Msol at $z \approx 0$减少到\M{200} $\approx 10^{11.2}$ ~ \Msol at $z \approx 6$)。相反,BH在固定的临界晕圈维里温度($T_{\mathrm{vir}} \approx 10^{5.6}$ ~K)下进入快速生长阶段。我们还表明,主要的星系-星系相互作用($μ\geq \frac{1}{4}$,其中$μ$是恒星质量比)发挥了重大作用,触发的快速增长阶段的BH在低红移宇宙,而可能有一个较低的影响在高红移。大约有40%的黑洞在$z \approx 0$开始快速的黑洞生长阶段,在一个主要星系-星系合并的$\pm 0.5$动力学时间内这样做,比背景合并率预期的增加了四倍。我们发现,轻微的合并($\frac{1}{10} \leq μ< \frac{1}{4}$)有一个实质上较低的影响,在触发快速增长阶段在所有的时代。

英文摘要:

We investigate the rapid growth phase of supermassive black holes (BHs) within the hydrodynamical cosmological \eagle simulation. This non-linear phase of BH growth occurs within $\sim$$L_{*}$ galaxies, embedded between two regulatory states of the galaxy host: in sub $L_{*}$ galaxies efficient stellar feedback regulates the gas inflow onto the galaxy and significantly reduces the growth of the central BH, while in galaxies more massive than $L_{*}$ efficient AGN feedback regulates the gas inflow onto the galaxy and curbs further non-linear BH growth. We find evolving critical galaxy and halo mass scales at which rapid BH growth begins. Galaxies in the low-redshift Universe transition into the rapid BH growth phase in haloes that are approximately an order of magnitude more massive than their high-redshift counterparts (\M{200} $\approx 10^{12.4}$~\Msol at $z \approx 0$ decreasing to \M{200} $\approx 10^{11.2}$~\Msol at $z \approx 6$). Instead, BHs enter the rapid growth phase at a fixed critical halo virial temperature ($T_{\mathrm{vir}} \approx 10^{5.6}$~K). We additionally show that major galaxy--galaxy interactions ($μ\geq \frac{1}{4}$, where $μ$ is the stellar mass ratio) play a substantial role in triggering the rapid growth phase of BHs in the low-redshift Universe, whilst potentially having a lower influence at high redshift. Approximately 40\% of BHs that initiate the rapid BH growth phase at $z \approx 0$ do so within $\pm 0.5$ dynamical times of a major galaxy--galaxy merger, a fourfold increase above what is expected from the background merger rate. We find that minor mergers ($\frac{1}{10} \leq μ< \frac{1}{4}$) have a substantially lower influence in triggering the rapid growth phase at all epochs.

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