The origin of black hole mergers discovered by the LIGO¹ and Virgo² gravitational-wave observatories is currently unknown. GW190521^3,4 is the heaviest black hole merger detected so far. Its observed high mass and possible spin-induced orbital precession could arise from the binary having formed following a close encounter. An observational signature of close encounters is eccentric binary orbit^5,6,7; however, this feature is currently difficult to identify due to the lack of suitable gravitational waveforms. No eccentric merger has been previously found⁸. Here we report 611 numerical relativity simulations covering the full eccentricity range and an estimation approach to probe the eccentricity of mergers. Our set of simulations corresponds to ~10⁵ waveforms, comparable to the number used in gravitational-wave searches, albeit with coarser mass ratio and spin resolution. We applied our approach to GW190521 and found that it is most consistent with a highly eccentric (\(e=0.6{9}_{-0.22}^{+0.17}\); 90% credible level) merger within our set of waveforms. This interpretation is supported over a non-eccentric merger with >10 odds ratio if ≳10% of GW190521-like mergers are highly eccentric. Detectable orbital eccentricity would be evidence against an isolated binary origin, which is otherwise difficult to rule out on the basis of observed mass and spin^9,10.

LIGO ¹和 Virgo ²引力波天文台发现的黑洞合并的起源目前尚不清楚。GW190521 ^3,4是迄今为止探测到的最重的黑洞合并。它观察到的高质量和可能的自旋引起的轨道进动可能来自于在近距离相遇后形成的双星。近距离接触的观测特征是偏心双星轨道^5,6,7；然而，由于缺乏合适的引力波形，这一特征目前难以识别。以前没有发现过奇怪的合并⁸. 在这里，我们报告了 611 个数值相对论模拟，涵盖了整个偏心率范围，以及一种探索合并偏心率的估计方法。我们的一组模拟对应于约 10 ^{5 个}波形，与引力波搜索中使用的数量相当，尽管质量比和自旋分辨率较粗。我们将我们的方法应用于 GW190521，发现它与我们的一组波形中的高度偏心 ( \(e=0.6{9}_{-0.22}^{+0.17}\) ; 90% 可信水平) 合并最为一致. 如果≳10% 的类似 GW190521 的合并是非常古怪的。可检测到的轨道离心率将是反对孤立的二元起源的证据，否则很难根据观察到的质量和自旋^9,10排除。