The solid lines show the two theoretical models explaining low-energy X-ray emissions seen previously from the spiral galaxy NGC 1365 by the XMM-Newton telescope.
The red line explains the emission with a model where clouds of dust and gas partially obscures the X-ray light, and the green line represents a model in which the emission is reflected off the inner edge of the accretion disk, very close to the black hole.
The blue circles show the latest measurements from XMM-Newton, and the yellow circles show the data from NuSTAR. While both models fit the XMM-Newton data equally well, only the disk reflection model fits the NuSTAR data.
The results show that the iron feature, the sharp peak at left, is being affected by the black hole's immense gravity and not intervening clouds. The degree to which the iron feature is spread out reveals the spin rate of the black hole.