Fig. 3: X-ray and radio burst fluence and energy limits from observations of FRB 20200120E, along with previous measurements from simultaneous X-ray and radio observations of FRB sources and Galactic magnetars.

a, X-ray and radio fluence measurements of repeating FRB sources (purple), non-repeating FRB sources (green) and Galactic magnetars (blue). The red data points correspond to our X-ray and radio fluence measurements from NICER, XMM-Newton and Effelsberg observations of FRB 20200120E at the times of bursts B4 and B9. The black data points highlight X-ray and radio fluence measurements from observations of FRB 20180301A (luminosity distance of d_L = 1.79 Gpc) with NICER and the Five-hundred-meter Aperture Spherical radio Telescope (FAST)²⁰. The blue star indicates the X-ray and radio fluences of the X-ray and radio bursts detected from SGR 1935+2154 during an episode of FRB-like activity on 28 April 2020^8,9,12. The blue upper limits from SGR 1935+2154 show constraints on prompt radio emission from FAST observations during a series of X-ray bursts detected with the Fermi Gamma-ray Burst Monitor on 28 April 2020, close in time to the FRB-like radio burst¹²³. The blue cross corresponds to X-ray and radio measurements of an FRB-like burst from the radio magnetar 1E 1547.0–5408 (ref. ¹⁰). The blue upper limit for SGR 1806–20 is derived from simultaneous radio and gamma-ray measurements at the time of the 27 December 2004 giant magnetar flare¹²⁴. The dashed grey lines indicate constant X-ray-to-radio fluence ratios (\({{\mathcal{F}}}_{{\rm{X}}}/{{\mathcal{F}}}_{{\rm{R}}}\)). b, X-ray and radio energy measurements of repeating FRB sources, non-repeating FRB sources and Galactic magnetars. The data points in b are derived from the same measurements shown in a. Radio and X-ray energies were calculated using the distance and redshift of each object. DM-inferred distances were used for unlocalized FRB sources. The dashed grey lines indicate constant X-ray-to-radio energy ratios (E_X/E_R). In a and b, the yellow crosses highlight measurements from localized FRB sources with measured redshifts.