Left: general constraints on the interaction rate with one-photon emission proportional to matter density (95% confidence) for an isothermal (dashed lines) and NFW profile (solid lines). The grey lines show the combination of previous constraints (Lattanzi et al. 2013, and references therein). The cyan lines are for the entire 2–9 keV interval model, and the purple lines are for the 3–6 keV interval. Right: constraints on the velocity-averaged cross-section for models with two-photon emission from dark matter annihilating into two photons from the total line emission flux for an isothermal (dashed lines) and NFW dark matter profile (solid lines).