The observed solar X-rays are a result of solar activity and solar flares. Solar flares are intense emissions of electromagnetic radiation from active regions on the Sun. Solar flares, especially larger flares, can be accompanied by coronal mass ejections (CMEs) and Solar Proton Events (SPEs). The increased X-ray flux from solar flares can cause absorption of HF radio signals on the sunlit side of the Earth with the largest solar flares causing complete HF blackout. Some large flares are also accompanied by broadband radio bursts that may cause problems for radar systems, satellite communication, and satellite navigation.
The shown data are from NOAA GOES, and the NOAA Space Weather Prediction Center R-scale thresholds are indicated in the plots.