Blitzars are a hypothetical type of astronomical object in which a spinning pulsar rapidly collapses into a black hole. They are proposed as an explanation for fast radio bursts (FRBs). The idea was proposed in 2013 by Heino Falcke and Luciano Rezzolla.
A blitzar is thought to start from a neutron star with a mass that would cause it to collapse into a black hole if it were not rapidly spinning. Instead, the neutron star spins fast enough so that its centrifugal force keeps the collapse from happening. This makes the neutron star a typical but doomed pulsar. Over a few million years, the pulsar's strong magnetic field radiates energy away and slows its spin. Eventually the weakening centrifugal force is no longer able to stop the pulsar from its transformation into a black hole. At this moment of blitzar formation, part of the pulsar's magnetic field outside the black hole is suddenly cut off from its vanished source. This magnetic energy is instantly transformed into a burst of wide spectrum radio energy. As of January 20, 2015, seven radio events detected so far might represent such possible collapses; they are projected to occur every 10 seconds within the observable universe. Because the magnetic field had previously cleared the surrounding space of gas and dust, there is no nearby material that will fall into the new black hole. Thus there is no burst of X-rays or gamma rays that usually happens when other black holes form.
If blitzars exist, they may offer a new way to observe details of black hole formation.
An alternative explanation for the observed effects has been suggested as anti-gravity from pair production at the pseudo-event horizon. In this case the spinning super-dense object has a "shell" of anti-matter which eventually breaks down so a black hole is then formed, and the effects from this are indistingishable; this has also been proposed as an explanation for repeating fast radio bursts as the shell may breach in one location then re-form as it spins due to a nearby star or other massive object.