New study sheds light on source of mysterious black hole flares
Observations carriedout by NASA's Swift and Nuclear Spectroscopic Telescope Array(NuSTAR) space telescopes may have located the source of intenseX-ray bursts emitted by supermassive black holes. According to NASA,the phenomenon can be attributed to a component of a black hole knownas a corona.
The black hole aroundwhich the flare was discovered, known as Markarian 335 (Mrk 335),sits roughly 324 million light-years distant from Earth in thePegasus constellation. Whilst black holes give off no light of theirown, telescopes are able to detect light created by gas drawn in bythe intense gravity emanating from bodies such as Mrk 335. As the gasapproaches the event horizon, it becomes superheated, causing it toshine brightly.
Telescopes are alsoable to detect light created by a black hole's corona, a structure ofhigh energy particles that is documented to give off light in theX-ray spectrum. Currently, there are two theories regarding thestructure of a corona.
The first, known as the"lamppost" model,asserts that the corona is a compact, lightbulb-like source of lightpositioned above and below the singularity along its rotational axis.The second possibility contends that the corona takes the form of adiffuse cloud surrounding the black hole, or as two flatter sectionsthat shroud the singularity. This is known as the "sandwich"model.
In September 2014, NASA's Swift telescope was lucky enough to catch an X-ray flare eventin action at Mrk 335, and the astronomers quickly re tasked theNuSTAR platform for follow up observations. By observing X-ray light,it was discovered that the source of the flare was the corona beingejected from the black hole.
Moving at roughly 20percent the speed of light, the corona was observed forming at thebase of the flare prior to being discharged into space. As a sideeffect of the phenomenon, light emitted from the corona was amplifiedvia an effect known as relativistic Doppler boosting.
"This is the firsttime we have been able to link the launching of the corona to aflare," explains lead author of a new paper on the results DanWilkins, of Saint Mary's University in Halifax, Canada. "Thiswill help us understand how supermassive black holes power some ofthe brightest objects in the universe."
The findings support what is known as the "lamppost" model,but many key aspects of coronas are still a total mystery, such ashow they form, or the mechanism by which they trigger the flares.