Fast radio bursts (FRBs) are millisecond radio pulses originating from powerful enigmatic sources at extragalactic distances. Neutron stars with large magnetic fields (magnetars) have been considered as the sources powering the FRBs, but the connection requires further substantiation. Here we report the detection by the AGILE satellite on 28 April 2020 of an X-ray burst in temporal coincidence with a bright FRB-like radio burst from the Galactic magnetar SGR 1935+2154. The burst observed in the hard X-ray band (18–60 keV) lasted about 0.5 s, it is spectrally cut off above 80 keV and implies an isotropically emitted energy of about 10⁴⁰ erg. This event demonstrates that a magnetar can produce X-ray bursts in coincidence with FRB-like radio bursts. It also suggests that FRBs associated with magnetars can emit X-ray bursts. We discuss SGR 1935+2154 in the context of FRBs with low–intermediate radio energies in the range 10³⁸–10⁴⁰ erg. Magnetars with magnetic fields B ≈ 10¹⁵ G may power these FRBs, and new data on the search for X-ray emission from FRBs are presented. We constrain the bursting X-ray energy of the nearby FRB 180916 to be less than 10⁴⁶ erg, smaller than that observed in giant flares from Galactic magnetars.

快速射电暴 (FRB) 是毫秒无线电脉冲，源自河外距离的强大神秘源。具有大磁场（磁星）的中子星被认为是快速射电暴的动力源，但这种联系需要进一步证实。在这里，我们报告了 AGILE 卫星于 2020 年 4 月 28 日检测到 X 射线爆发与来自银河磁星 SGR 1935+2154 的明亮的类似 FRB 的无线电爆发的时间一致。在硬 X 射线波段 (18-60 keV) 中观察到的爆发持续了大约 0.5 s，它在 80 keV 以上被光谱切断，意味着各向同性发射的能量约为 10 ⁴⁰ 尔格。这一事件表明，磁星可以产生与类似 FRB 的射电暴同时发生的 X 射线暴。它还表明与磁星相关的 FRB 可以发射 X 射线爆发。^{我们在具有 10 38} –10 ⁴⁰  erg范围内的中低无线电能量的 FRB 的背景下讨论 SGR 1935+2154 。磁场B  ≈ 10 ¹⁵  G 的磁星可能为这些 FRB 提供动力，并提供了寻找 FRB X 射线发射的新数据。我们将附近 FRB 180916 的爆发 X 射线能量限制为小于 10 ⁴⁶ 尔格，小于在银河磁星的巨大耀斑中观察到的能量。