astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

, an X-ray flash is a transient emission of

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

s originating in a distant

galaxy A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

, probably caused by a hypernova. They have been observed to last 90 to 200 seconds."X-ray flash"
Centre for Astrophysics and Supercomputing, (n.d.), viewed October 29, 2013 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: * One theory assumes that an X-ray-flash hypernova does not differ inherently from gamma-ray-emitting hypernovae, but rather in the orientation, relative to the line of sight to the observer, of the narrow beam of gamma radiation from the hypernova. That is, gamma rays ''are'' assumed to be emitted, but in each case in a direction away from our instruments for observing them. Thus the only initially observable phenomenon is lower-energy x-rays emitted in a beam that diverges more than the gamma-ray beam does. * A competing "dirty fireball" theory suggests that an X-ray flash comes from a hypernova that uses much of the available energy in expelling an unusually large amount of

baryonic matter In particle physics, a baryon is a type of composite subatomic particle which contains an odd number of valence quarks (at least 3). Baryons belong to the hadron family of particles; hadrons are composed of quarks. Baryons are also classified ...

, thus limiting the energy available for electromagnetic radiation, and emitting a much "cooler" spectrum rich in X-rays and very poor in gamma rays.

References

X-ray astronomy {{astronomy-stub

Further reading

References