超大质量黑洞的旋转
(原标题: Spin up of a Supermassive Black Hole)
2025-05-04
浏览次数: 46
黑洞旋转的速度有多快？如果任何由常规物质构成的物体旋转得太快——它就会分裂。但黑洞可能无法分裂——而且它的最大自旋速率真的是未知的。理论学家通常用爱因斯坦广义相对论的克尔解来模拟快速旋转的黑洞，该理论预测了一些惊人而不寻常的事情。也许它最容易验证的预测是，进入最大旋转黑洞的物质最后一次被看到的速度应该接近光速，就像从远处看到的那样。NASA的NuSTAR卫星和ESA的XMM卫星通过观测螺旋星系NGC 1365中心的超大质量黑洞验证了这一预测。通过测量周围吸积盘内缘核辐射的加热和谱线展宽，证实了接近光速的极限。这是一位艺术家的插图，描绘了一个正常物质的吸积盘在黑洞周围旋转，顶部有一股喷流。由于随机落入黑洞的物质不应该使黑洞旋转这么多，所以NuSTAR和XMM的测量也证实了周围吸积盘的存在。黑洞新世界：这是NASA的黑洞周！
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How fast can a black hole spin? If any object made of regular matter spins too fast -- it breaks apart. But a black hole might not be able to break apart -- and its maximum spin rate is really unknown. Theorists usually model rapidly rotating black holes with the Kerr solution to Einstein's General Theory of Relativity, which predicts several amazing and unusual things. Perhaps its most easily testable prediction, though, is that matter entering a maximally rotating black hole should be last seen orbiting at near the speed of light, as seen from far away. This prediction was tested by NASA's NuSTAR and ESA's XMM satellites by observing the supermassive black hole at the center of spiral galaxy NGC 1365. The near light-speed limit was confirmed by measuring the heating and spectral line broadening of nuclear emissions at the inner edge of the surrounding accretion disk. Pictured here is an artist's illustration depicting an accretion disk of normal matter swirling around a black hole, with a jet emanating from the top. Since matter randomly falling into the black hole should not spin up a black hole this much, the NuSTAR and XMM measurements also validate the existence of the surrounding accretion disk. Hole New Worlds: It's Black Hole Week at NASA!