BLACK HOLE HAS MAJOR FLARE
Jet Propulsion Lab | OCTOBER 27, 2015
"The baffling and strange behaviors of black holes have become somewhat less mysterious recently, with new observations from NASA's Explorer missions Swift and the Nuclear Spectroscopic Telescope Array, or NuSTAR.
The two space telescopes caught a supermassive black hole in the midst of a giant eruption of X-ray light, helping astronomers address an ongoing puzzle:
How do super massive black holes flare?
The results suggest that supermassive black holes send out beams of X-rays when their surrounding coronas
-- which are sources of extremely energetic particles -- shoot, or launch, away from the black holes.
Supermassive black holes don't give off any light themselves,
but they are often encircled by disks of hot, glowing material.
The gravity of a black hole pulls swirling gas into it,
heating this material and causing it to shine with different types of light.
Another source of radiation near a black hole is the corona.
Coronas are made up of highly energetic particles that generate X-ray light,
but details about their appearance, and how they form, are unclear.
"Something very strange happened in 2007,
when Mrk 335 faded by a factor of 30.
What we have found is that it continues to erupt in flares,
but has not reached the brightness levels and stability seen before,"
said Luigi Gallo, the principal investigator for the project at Saint Mary's University.
Another co-author, Dirk Grupe of Morehead State University in Kentucky,
has been using Swift to regularly monitor the black hole since 2007.
After careful scrutiny of the data,
the astronomers realized they were seeing the ejection,
and eventual collapse, of the black hole's corona.
"The corona gathered inward at first and then launched upwards like a jet," said Wilkins.
"We still don't know how jets in black holes form,
but it's an exciting possibility that this black hole's corona was beginning to form the base of a jet before it collapsed."
Coronas can move very fast.
The corona associated with Mrk 335, according to the scientists,
was traveling at about 20 percent the speed of light.
When this happens, and the corona launches in our direction,
its light is brightened in an effect called relativistic Doppler boosting.
Putting this all together,
the results show that the X-ray flare from this black hole was caused by the ejected corona.
"The nature of the energetic source of X-rays we call the corona is mysterious,
but now with the ability to see dramatic changes like this we are getting clues about its size and structure,"
said Fiona Harrison,
the principal investigator of NuSTAR at the California Institute of Technology in Pasadena, who was not affiliated with the study.
Many other black hole brainteasers remain.
For example, astronomers want to understand what causes the ejection of the corona in the first place.
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