Extended Data Fig. 4: Results from our template mismatch tests.

Each of the coloured lines shows the results of a test where we generate synthetic data with one set of templates, and attempt to recover the Sgr dSph in those data using a different set. In the upper two panels, the horizontal axis shows the true, energy-integrated Sgr dSph photon flux in the synthetic data, while the vertical axis shows the value (with 1σ statistical error bars) retrieved by our pipeline; the black dashed lines indicate perfect recovery of the input, and the vertical bands show the photon flux we measure for the Sgr dSph in the real Fermi data. In the bottom two panels we plot the recovered energy flux in each energy bin (with 1σ statistical error bars), for the case where the injected photon flux most closely matches the real Sgr dSph flux; the black dashed line again shows perfect recovery of the injected signal. The left panels show experiments where we mismatch the Galactic hadronic and IC templates, while the right panels show experiments where we mismatch the FB templates; see Methods for details.