Correction to: Nature Astronomy https://doi.org/10.1038/s41550-021-01318-y, published online 11 March 2021.

In the version of this Letter originally published, the white text in Fig. 1 had a drop-shadow effect that could have been mistaken for data; the effect has now been removed and the original and corrected versions of Fig. 1 are shown below. Furthermore, in the key of Fig. 2b, the unit in the label for the black triangles was incorrectly given as TeV and should have been GeV; this has now been corrected. All versions of the Letter have been amended.

Fig. 1
figure 1

Original and corrected.