quasaars

Quasaars are a proposed class of luminous extragalactic transients speculated to originate in the nuclei of distant galaxies. In this concept, a quaasaar represents a brief, intense episode of energy output powered by rapid accretion onto a supermassive black hole or by sudden reconfiguration of relativistic jets. The emission is predicted to span radio to gamma-ray wavelengths, often with a non-thermal spectrum and rapid variability on timescales of hours to days.

The name quaasaar blends the familiar term quasar with an emphasis on its transient character. The idea arose in discussions of unexplained short-duration brightening events in deep-field surveys and has been debated in theoretical and observational contexts. Quasaars are expected to differ from ordinary quasars by their fleeting nature and by signatures that may include featureless continua or peculiar line evolution, depending on the exact mechanism.

Observational evidence for quasaars remains circumstantial. Reported candidates have faced alternative explanations, such as microlensing of distant active galactic nuclei, tidal disruption events, or instrumental artifacts. As a result, quasaars have not been established as a distinct, confirmed class of objects, and ongoing surveys seek to identify consistent, repeatable signatures.

See also: Quasars, Active galactic nuclei, Blazars, Transients, Tidal disruption events.