论文标题
Eagle中的星系合并不会引起大量黑洞的生长，但确实提高了发光AGN的速率
Galaxy mergers in EAGLE do not induce a significant amount of black hole growth yet do increase the rate of luminous AGN
论文作者
论文摘要
我们使用宇宙学水动力鹰模拟研究了银河系合并与增强的黑洞（BH）生长之间的联系。我们通过三种分析方法进行研究：AGN的合并部分，合并系统的AGN部分以及与近距离伴侣的星系的AGN分数。在每种情况下，我们发现相对于控制无活动或孤立星系的控制样品的合并系统中的AGN丰度增加（根据所使用的分析方法，最高$ \ 3 $），证实合并正在提高至少一个星系子集的子集的BH积聚率。通过合并触发的最大过量的AGN在较低的质量（$ m_* \ sim 10^{10} $〜\ MSOL）含量富含（$ f _ {\ Mathrm {alsrm {gas}}> 0.2 $）中央星系中，具有较低的质量BHS（$ m _ {$ m _ {\ mathrm {\ sim} $ {红移（$ z <1 $）。我们发现通过更大的星系中的合并触发的AGN没有增强（$ M_* \ gtrsim 10^{11} $〜\ msol）。在合并的整个阶段，AGN的增强并不统一，而是在合并系统的早期\ emph {Remnants}中达到峰值（通常落后于$ \ 300 $ \ 300 $ 〜MYR，在两个星系后$ Z = 0.5 $）。我们认为，两者都不主要（$ M _ {\ Mathrm {*，1}} / m _ {\ Mathrm {*，2}} \ geq \ frac {1} {1} {4} {4} $）又m _ {\ mathrm {*，2}} <\ frac {1} {4} $）在统计上与全球增强BH质量相关。虽然在所有红移中，但经历合并的星系的吸积率平均是孤立星系的2--3倍，而BHS上积聚的大多数质量发生在合并时期之外。我们计算，平均不超过15％的BHS最后一天质量来自通过合并触发的增强率
We investigate the connection between galaxy--galaxy mergers and enhanced black hole (BH) growth using the cosmological hydrodynamical EAGLE simulation. We do this via three methods of analysis, investigating: the merger fraction of AGN, the AGN fraction of merging systems and the AGN fraction of galaxies with close companions. In each case, we find an increased abundance of AGN within merging systems relative to control samples of inactive or isolated galaxies (by up to a factor of $\approx 3$ depending on the analysis method used), confirming that mergers are enhancing BH accretion rates for at least a subset of the galaxy population. The greatest excess of AGN triggered via a merger are found in lower mass ($M_* \sim 10^{10}$~\Msol) gas rich ($f_{\mathrm{gas}} > 0.2$) central galaxies with lower mass BHs ($M_{\mathrm{BH}} \sim 10^{7}$~\Msol) at lower redshifts ($z<1$). We find no enhancement of AGN triggered via mergers in more massive galaxies ($M_* \gtrsim 10^{11}$~\Msol). The enhancement of AGN is not uniform throughout the phases of a merger, and instead peaks within the early \emph{remnants} of merging systems (typically lagging $\approx 300$~Myr post-coalescence of the two galaxies at $z=0.5$). We argue that neither major ($M_{\mathrm{*,1}} / M_{\mathrm{*,2}} \geq \frac{1}{4}$) nor minor mergers ($\frac{1}{10} < M_{\mathrm{*,1}} / M_{\mathrm{*,2}} < \frac{1}{4}$) are statistically relevant for enhancing BH masses globally. Whilst at all redshifts the galaxies experiencing a merger have accretion rates that are on average 2--3 times that of isolated galaxies, the majority of mass that is accreted onto BHs occurs outside the periods of a merger. We compute that on average no more than 15\% of a BHs final day mass comes from the enhanced accretion rates triggered via a merger
