Figure 4
X-ray flashes
When a star collapses, collisions within the jets it produces create gamma-ray bursts. However, the collisions also create X-ray flashes. This figure shows the optical afterglow (red circles) from X-ray flash 030723 at wavelengths of about 650 nm. These flashes quickly fade away (fitted with the blue line). After about 10 days, however, the intensity rises again, which suggests that a supernova explosion occurred at the site of the flash. A model of a supernova has been used to fit this data (dashed curve). The x-axis is the square root of time and has been manipulated to show both the early and late parts of the light curve within one graph.