Jet simulations and Gamma-ray burst afterglow jet breaks

Understand

The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break.

• We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break.
• Depending on circumstances, the radio jet break may be postponed significantly.
• Using high-accuracy adaptive mesh fluid simulations in one dimension, coupled to a detailed synchrotron radiation code, we demonstrate that this is true even for the standard fireball model and hard-edged jets.