Direct evidence for shock-powered optical emission in a nova
Direct evidence for shock-powered optical emission in a nova
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DOI：
10.1038/s41550-020-1070-y
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发表时间：
2020-04
期刊：
影响因子：
14.1
通讯作者：
E. Aydi;K. Sokolovsky;L. Chomiuk;E. Steinberg;Kwan-Lok Li;I. Vurm;B. Metzger;J. Strader;K. Muka
中科院分区：
文献类型：
--
作者：
E. Aydi;K. Sokolovsky;L. Chomiuk;E. Steinberg;Kwan-Lok Li;I. Vurm;B. Metzger;J. Strader;K. Muka
经典新星是发生在相互作用的双星系统中白矮星表面的热核爆炸。长期以来，人们一直认为，经典新星的亮度是由白矮星在最初的逃逸后表面持续的核燃烧提供的。然而，最近对来自经典新星的千兆电子伏γ射线的观测表明，新星喷射物内部的冲击可能是新星发射的主要原因。冲击波也被认为可以为恒星合并、超新星和潮汐破坏事件等各种事件的亮度提供动力，但缺乏观测证实。在此，我们报告了2018年新星船底座V906 （ASASSN-18fv）的同步天基光学和γ射线观测，揭示了两个波段中一系列明显相关的耀斑。光学耀斑和γ射线耀斑同时发生，意味着在冲击中有一个共同的起源。在耀斑期间，新星的光度加倍，这意味着大部分光度是由激波驱动的。此外，我们探测到深埋激波同时发射的弱x射线，证实了激波功率不会出现在x射线波段，并支持其出现在更长的波长。我们的数据跨越了从无线电到γ射线的光谱，提供了直接的证据，证明冲击可以在经典新星和其他光学瞬态中产生大量的亮度。
Classical novae are thermonuclear explosions that occur on the surfaces of white dwarf stars in interacting binary systems. It has long been thought that the luminosity of classical novae is powered by continued nuclear burning on the surface of the white dwarf after the initial runaway. However, recent observations of gigaelectronvolt γ-rays from classical novae have hinted that shocks internal to the nova ejecta may dominate the nova emission. Shocks have also been suggested to power the luminosity of events as diverse as stellar mergers, supernovae and tidal disruption events, but observational confirmation has been lacking. Here we report simultaneous space-based optical and γ-ray observations of the 2018 nova V906 Carinae (ASASSN-18fv), revealing a remarkable series of distinct correlated flares in both bands. The optical and γ-ray flares occur simultaneously, implying a common origin in shocks. During the flares, the nova luminosity doubles, implying that the bulk of the luminosity is shock powered. Furthermore, we detect concurrent but weak X-ray emission from deeply embedded shocks, confirming that the shock power does not appear in the X-ray band and supporting its emergence at longer wavelengths. Our data, spanning the spectrum from radio to γ-ray, provide direct evidence that shocks can power substantial luminosity in classical novae and other optical transients.