An international team studying data from NASA’s Fermi Gamma-ray Space Telescope concludes the mission detected a rare, unusually luminous supernova. The researchers say it likely received its power-up from a supermagnetized neutron star born in the stellar collapse that triggered the explosion.
一个国际团队研究了美国宇航局费米伽马射线太空望远镜的数据，得出结论，该任务发现了一颗罕见的、异常明亮的超新星。研究人员表示，它很可能从引发爆炸的恒星塌缩中诞生的超磁化中子星获得能量。
The Fermi mission is part of NASA’s fleet of observatories monitoring the changing cosmos to help humanity better understand how the universe works.
费米任务是美国宇航局天文台群的一部分，这些天文台监测不断变化的宇宙，以帮助人类更好地了解宇宙是如何运作的。
“For nearly 20 years, astronomers have searched Fermi data for gamma-ray signals from thousands of supernovae, and while a few intriguing hints have been reported, none were definitive until now,” study lead Fabio Acero at the French National Centre for Scientific Research (CNRS) and the University of Paris-Saclay .
法国国家科学研究中心 (CNRS) 和巴黎萨克雷大学的研究负责人法比奥·阿塞罗 (Fabio Acero) 表示：“近 20 年来，天文学家一直在费米数据中搜索来自数千颗超新星的伽马射线信号，虽然报道了一些有趣的线索，但到目前为止还没有一个是明确的。”
A paper describing the findings published Wednesday in the journal Astronomy & Astrophysics.
周三发表在《天文学与天体物理学》杂志上的一篇论文描述了这一发现。
Core-collapse supernovae occur when the energy-producing center of a star many times our Sun’s mass runs out of fuel, collapses under its own weight, and explodes. During the collapse, a city-sized neutron star or an even smaller black hole may form. A blast wave blows away the rest of the star, which rapidly expands as a hot, dense cloud of ionized gas.
当质量是太阳质量许多倍的恒星的能量产生中心耗尽燃料、在自身重量作用下塌陷并爆炸时，就会发生核心塌缩超新星。在坍缩过程中，可能会形成城市大小的中子星或更小的黑洞。爆炸波吹走了恒星的其余部分，恒星迅速膨胀为炽热、致密的电离气体云。
In the last couple of decades, nearly 400 exceptional core-collapse supernovae have been identified. Each of these events, dubbed superluminous supernovae, produced 10 or more times the amount of visible light normally seen.
在过去的几十年里，已经发现了近 400 颗特殊的核心塌陷超新星。这些事件中的每一个都被称为超发光超新星，产生的可见光量是正常情况下的 10 倍或更多。
In 2024, a study led by Li Shang at Anhui University in Hefei, China, noted that Fermi’s Large Area Telescope may have seen gamma rays — the most energetic form of light — from a superluminous supernova that occurred years earlier.
2024年，中国合肥安徽大学李尚领导的一项研究指出，费米大面积望远镜可能已经看到了多年前发生的超光度超新星发出的伽马射线——能量最高的光形式。
Dubbed SN 2017egm, this supercharged outburst occurred in galaxy NGC 3191, located about 440 million light-years away in the constellation Ursa Major. Even at this distance, the explosion remains one of the closest of its type to us on Earth.
这次被称为 SN 2017egm 的超强爆发发生在距离我们约 4.4 亿光年的大熊座星系 NGC 3191 中。即使在这个距离，这次爆炸仍然是地球上距离我们最近的同类爆炸之一。
“We searched for gamma rays from the six nearest superluminous supernovae seen during the first 16 years of Fermi’s mission,” said Guillem Martí-Devesa, a researcher previously at the University of Trieste in Italy and now a fellow at the Institute of Space Sciences in Barcelona, Spain. “Only SN 2017egm shows evidence for gamma rays, confirming earlier hints that some supernovae can be as luminous in gamma rays as they are in visible light. This opens up a new window for studying these fascinating events.”
“在费米任务的前 16 年中，我们从最近的六颗超光度超新星中寻找伽马射线，”吉列姆·马蒂-德维萨 (Guillem Martí-Devesa) 说，他曾是意大利的里雅斯特大学的研究员，现在是西班牙巴塞罗那空间科学研究所的研究员。 “只有 SN 2017egm 显示了伽马射线的证据，证实了之前的暗示，即一些超新星在伽马射线中可以像在可见光中一样发光。这为研究这些令人着迷的事件打开了一个新窗口。”
Theorists have debated the possible energy sources that give these explosions their extra punch. High on the list has been the formation of a magnetar, a type of neutron star with the strongest magnetic fields known — up to 1,000 times the intensity of typical neutron stars. That’s 10 trillion times stronger than a refrigerator magnet.
理论家们一直在争论赋予这些爆炸额外威力的可能能源。其中最重要的是磁星的形成，磁星是一种已知磁场最强的中子星，其强度高达典型中子星的 1000 倍。这比冰箱磁铁强 10 万亿倍。
The team undertook a deeper analysis of the supernova’s observed optical and gamma-ray features to compare how well different theoretical models reproduced them. A model developed by co-authors Indrek Vurm at the University of Tartu in Estonia and Brian Metzger at Columbia University in New York City traced how light and particles produced by a newborn magnetar would move outward and interact with the supernova’s expanding debris.
该团队对观测到的超新星光学和伽马射线特征进行了更深入的分析，以比较不同理论模型再现它们的效果。爱沙尼亚塔尔图大学的 Indrek Vorm 和纽约哥伦比亚大学的 Brian Metzger 共同开发的模型追踪了新生磁星产生的光和粒子如何向外移动并与超新星膨胀的碎片相互作用。
Scientists expect a newly formed magnetar to spin a few hundred times a second. This rapid rotation produces a strong outflow of electrons and positrons, their antimatter counterparts, that forms a vast cloud of energetic particles.
科学家预计新形成的磁星每秒旋转数百次。这种快速旋转产生了电子和正电子（它们的反物质对应物）的强烈流出，形成了巨大的高能粒子云。
Within this cloud — called a magnetar wind nebula — various interactions fuel the production and absorption of gamma rays. For example, an electron and a positron can annihilate into a pair of gamma-ray photons, or two gamma rays can collide and produce the particles. In these and other ways, gamma rays interact with the supernova debris. Unable to escape directly, they become reprocessed, downshifted into lower-energy visible light that provides the supernova with its extra boost in luminosity.
在这个被称为磁星风星云的云中，各种相互作用促进了伽马射线的产生和吸收。例如，电子和正电子可以湮灭成一对伽马射线光子，或者两个伽马射线可以碰撞并产生粒子。通过这些和其他方式，伽马射线与超新星碎片相互作用。由于无法直接逃逸，它们会被重新处理，降级为较低能量的可见光，为超新星提供额外的光度提升。
“About three months after the collapse, as the supernova debris expands and cools, the gamma rays can begin to leak out,” Acero said. “This magnetar model best reproduces the supernova’s luminosity and the arrival time of its gamma rays during the first months, but we see room for improvement at later times, when the visible light fades quite irregularly.”
“塌陷后大约三个月，随着超新星碎片的膨胀和冷却，伽马射线可能开始泄漏，”阿塞罗说。 “这个磁星模型最好地再现了超新星的光度和伽马射线在最初几个月的到达时间，但我们看到了后期的改进空间，当可见光非常不规则地消退时。”
Acero and his colleagues suggest that additional processes likely played contributing roles during SN 2017egm’s long fade-out. These include debris falling back onto the magnetar and interactions between the blast wave and matter ejected by the star in the centuries prior to its demise.
Acero 和他的同事认为，其他流程可能在 SN 2017egm 的长期淡出过程中发挥了重要作用。其中包括落回磁星上的碎片，以及恒星消亡前几个世纪中爆炸波与恒星喷射出的物质之间的相互作用。
The team also examined how well a new ground-based gamma-ray facility, the Cerenkov Telescope Array Observatory , might detect events like SN 2017egm. With about 50 hours of observing time, they say, a similar supernova could be detected out to about 500 million light-years. Our understanding of phenomena like SN 2017egm will improve thanks to cooperation between such facilities and NASA’s fleet of space-based observatories that watch for rapid changes in the universe.
该团队还研究了新的地面伽马射线设施（切伦科夫望远镜阵列天文台）检测 SN 2017egm 等事件的能力。他们表示，通过大约 50 小时的观测时间，可以在大约 5 亿光年之外探测到类似的超新星。由于此类设施与 NASA 监视宇宙快速变化的天基观测站之间的合作，我们对 SN 2017egm 这样的现象的理解将会得到改善。
“The magnetar central engine mechanism discussed in this paper builds upon a lot of observational and theoretical advances in magnetars over the last 20 years,” said Judy Racusin, a deputy project scientist for the Fermi mission at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Observing gamma rays from supernovae will give us a new way to explore their inner workings.”
“本文讨论的磁星中央引擎机制建立在过去 20 年磁星观测和理论进展的基础上，”马里兰州格林贝尔特 NASA 戈达德太空飞行中心费米任务副项目科学家朱迪·拉库辛 (Judy Racusin) 说。 “观测超新星发出的伽马射线将为我们提供一种探索其内部运作的新方法。”
By Francis Reddy NASA’s Goddard Space Flight Center , Greenbelt, Md. Media Contact: Claire Andreoli 301-286-1940 claire.andreoli@nasa.gov NASA’s Goddard Space Flight Center, Greenbelt, Md.
作者：Francis Reddy NASA 戈达德太空飞行中心，马里兰州格林贝尔特。 媒体联系人：Claire Andreoli 301-286-1940 claire.andreoli@nasa.gov NASA 戈达德太空飞行中心，马里兰州格林贝尔特。