Gamma-ray bursts (GRBs) are brief but extremely powerful explosions that occur in distant galaxies, releasing enormous amounts of energy—often more in a few seconds than our Sun emits over its entire lifetime. GRBs are classified into two types based on their duration: long GRBs (lasting more than 2 seconds), typically associated with the collapse of massive stars into black holes, and short GRBs (lasting less than 2 seconds), often linked to mergers of neutron stars.

GRBs emit intense gamma-ray radiation during their prompt phase, followed by a longer-lasting, multi-wavelength emission known as the afterglow.

Afterglows occur when the high-speed ejecta from the GRB collide with the surrounding interstellar medium, producing shocks that generate lower-energy radiation across the electromagnetic spectrum—from X-rays and ultraviolet light to visible light, radio waves, and sometimes even very-high-energy gamma rays.

These afterglows fade over time but are crucial for understanding the environment around the burst, the mechanisms driving particle acceleration, and the energy distribution in the explosion. In some cases, afterglows include very-high-energy (TeV) emission, providing valuable insights into extreme astrophysical processes like shock acceleration and magnetic field dynamics.

GRB 221009A

GRB 190114C