Left: resulting density distribution from the model fit after 8000 yr for the XMM-Newton data with the 1420-MHz contours of CTB 109 overlaid in black. Right: resulting density distribution from the model fit after 11 000 yr for the Chandra data with the 1420-MHz contours of CTB 109 overlaid in black. The position of the SN explosion is marked with a black star and the position of the AXP with a magenta star.