PX282 - C9e - scattering

rayliegh scattering

• generally, on atoms for low energy photons
• it is elastic, ie: $E_{\gamma }$ is constant

where, $\sigma$ is the cross-section

• it causes the sky to be blue during the day, and red/yellow during dawn/dusk

compton scattering

PX262 - A2 - compton scattering

• on electrons
• inelastic, ie: $E_{\gamma }$ changes

thomson scattering

• on electrons
• elastic, ie: $E_{\gamma }$ is constant
• it is the low-energy limit of compton
• the most important as all observations are in this range

• the cross-section has no $\lambda$ dependence