Kollapsar

Kollapsar, also known as collapsar in English, is a theoretical model in high-energy astrophysics that describes the collapse of a rapidly rotating, massive star’s core to form a black hole surrounded by a hot, dense accretion disk. The accreting material powers ultra-relativistic jets that are launched along the star’s rotation axis. If these jets puncture the stellar envelope, a long-duration gamma-ray burst (GRB) is produced, typically accompanied by a core-collapse supernova of type Ic with broad spectral lines.

The collapsar scenario was first proposed to explain long GRBs and their association with energetic core-collapse supernovae. In the model, the star must retain substantial angular momentum, which favours low metallicity and certain stellar evolutionary paths that prevent excessive angular-momentum loss. The collapse leads to a black hole with a high-rate accretion flow, from which energy is extracted either by neutrino processes or by magnetic mechanisms to power collimated, relativistic jets.

Observationally, long GRBs are linked to star-forming galaxies and to broad-lined type Ic supernovae, supporting the collapsar connection. The model accounts for the burst duration, energetics, and afterglow emissions. Variants include magnetar-powered scenarios, where a rapidly spinning neutron star substitutes for the black hole as the energy source. The term kollapsar is common in some languages and serves as a direct translation of collapsar in discussions of long GRBs and related supernovae.