The precise origins of fast radio bursts (FRBs) remain unknown. Multiwavelength observations of nearby FRB sources can provide important insights into the enigmatic FRB phenomenon. Here we present results from a sensitive, broadband X-ray and radio observational campaign of FRB 20200120E, the closest known extragalactic repeating FRB source (located 3.63 Mpc away in an ~10-Gyr-old globular cluster). We place deep limits on the persistent and prompt X-ray emission from FRB 20200120E, which we use to constrain possible origins for the source. We compare our results with various classes of X-ray sources, transients and FRB models. We find that FRB 20200120E is unlikely to be associated with ultraluminous X-ray bursts, magnetar-like giant flares or an SGR 1935+2154-like intermediate flare. Although other types of bright magnetar-like intermediate flares and short X-ray bursts would have been detectable from FRB 20200120E during our observations, we cannot entirely rule them out as a class. We show that FRB 20200120E is unlikely to be powered by an ultraluminous X-ray source or a young extragalactic pulsar embedded in a Crab-like nebula. We also provide new constraints on the compatibility of FRB 20200120E with accretion-based FRB models involving X-ray binaries. These results highlight the power of multiwavelength observations of nearby FRBs for discriminating between FRB models.

快速射电暴 （FRB） 的确切起源仍然未知。对附近 FRB 源的多波长观测可以为神秘的 FRB 现象提供重要的见解。在这里，我们展示了 FRB 20200120E 的敏感、宽带 X 射线和射电观测活动的结果，FRB 20200120E 是已知最近的银河系外重复 FRB 源（位于 3.63 Mpc 外的 ~10 Gyr 球状星团中）。我们对 FRB 20200120E 的持续和瞬时 X 射线发射进行了深入限制，我们用它来限制源的可能来源。我们将结果与各种类别的 X 射线源、瞬态和 FRB 模型进行了比较。我们发现 FRB 20200120E 不太可能与超亮 X 射线暴、磁星状巨大耀斑或类似 SGR 1935+2154 的中间耀斑有关。尽管在我们的观测中可以从 FRB 20200120E 检测到其他类型的明亮磁星状中间耀斑和短 X 射线暴，但我们不能完全排除它们作为一个类别。我们表明，FRB 20200120E 不太可能由超亮 X 射线源或嵌入蟹状星云中的年轻星系外脉冲星提供动力。我们还对 FRB 20200120E 与涉及 X 射线双元的基于吸积的 FRB 模型的兼容性提供了新的约束。这些结果突出了对附近 FRB 进行多波长观测以区分 FRB 模型的能力。