In astronomy, an X-ray flash is a transient emission of X-rays originating in a distant galaxy, probably caused by a hypernova.
They have been observed to last 90 to 200 seconds.
[1] Nearly all hypernovae are detected via (higher-energy) gamma-ray photons, at distances too great for any associated X-ray emissions from them to be observed; nevertheless, the two main theories of the nature of an X-ray flash each assume that a hypernova is involved:[1] This astronomy-related article is a stub.
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