Department of Astronomy, Cornell University, Ithaca, NY, USA.
Astrophysics Research Institute, Liverpool John Moores University, Liverpool, UK.
Nature. 2023 Nov;623(7989):927-931. doi: 10.1038/s41586-023-06673-6. Epub 2023 Nov 15.
In recent years, certain luminous extragalactic optical transients have been observed to last only a few days. Their short observed duration implies a different powering mechanism from the most common luminous extragalactic transients (supernovae), whose timescale is weeks. Some short-duration transients, most notably AT2018cow (ref. ), show blue optical colours and bright radio and X-ray emission. Several AT2018cow-like transients have shown hints of a long-lived embedded energy source, such as X-ray variability, prolonged ultraviolet emission, a tentative X-ray quasiperiodic oscillation and large energies coupled to fast (but subrelativistic) radio-emitting ejecta. Here we report observations of minutes-duration optical flares in the aftermath of an AT2018cow-like transient, AT2022tsd (the 'Tasmanian Devil'). The flares occur over a period of months, are highly energetic and are probably nonthermal, implying that they arise from a near-relativistic outflow or jet. Our observations confirm that, in some AT2018cow-like transients, the embedded energy source is a compact object, either a magnetar or an accreting black hole.
近年来，人们观测到某些发光的河外光瞬变体仅持续数天。它们的观测持续时间很短，这意味着它们的驱动机制与最常见的发光河外瞬变体（超新星）不同，超新星的时间尺度为数周。一些短持续时间的瞬变体，特别是 AT2018cow（参考文献），表现出蓝色的光学颜色以及明亮的射电和 X 射线辐射。一些 AT2018cow 类似的瞬变体显示出存在长期存在的嵌入式能源的迹象，例如 X 射线变化、延长的紫外发射、一个暂定的 X 射线准周期震荡以及与快速（但亚相对论）射电发射喷出物相关的大能量。在这里，我们报告了在类似于 AT2018cow 的瞬变体 AT2022tsd（“塔斯马尼亚恶魔”）之后的几分钟光学耀斑的观测结果。耀斑发生在数月的时间内，能量非常高，可能是非热的，这意味着它们来自近相对论性外流或喷流。我们的观测结果证实，在某些类似于 AT2018cow 的瞬变体中，嵌入式能源是一个紧凑的物体，要么是磁星，要么是吸积黑洞。
