The hot gas shell produces a lot of light suddenly. (astronomynotes.com)
One scenario is the «explosion model» in which an expanding gas shell of the supernova remnant passes by a static black hole. (sciencedaily.com)
According to the researchers, there are two possible scenarios in which such a cloud could have been created — the first one that involves the expanding gas shell of the supernova remnant passing by a static black hole, and the other wherein a fast - moving black hole plunges through a cloud of dense gas that is then dragged along by the former's strong gravity. (ibtimes.com)