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NASA Astronomers Capture Rare Flaring Black Hole


This artist's concept illustrates what the flaring black hole called GX 339-4 might look like.
Image by NASA

By Mark Dunphy - Wed Sep 21, 1:43 pm

NASA astronomers say they have captured a flaring black hole, which is extremely uncommon, allowing them to find new details about these rare cosmic events.

The blazing jets were captured with NASA’s Wide-field Infrared Survey Explorer (WISE), on the black hole, called GX 339-4. Scientists have studied these jets to learn more about the extreme environments around black holes, and this particular GX 339-4 had been observed previously.

It lies more than 20,000 light-years away from Earth near the center of our galaxy, and it has a mass at least six times greater than the sun. Like other black holes, it is an ultra-dense collection of matter, with gravity that is so great even light cannot escape. In this case, the black hole is orbited by a companion star that feeds it. Most of the material from the companion star is pulled into the black hole, but some of it is blasted away as a jet flowing at nearly the speed of light.

Through decades of work and investigation, much has been learned about the material feeding black holes, called accretion disks, and the jets themselves through studies using X-rays, gamma rays and radio waves.

However, key measurements of the brightest part of the jets, located at their bases, have been difficult despite the years of work. With the new images, a new window into this missing link through its infrared observations has been offered.

“Imagine what it would be like if our sun were to undergo sudden, random bursts, becoming three times brighter in a matter of hours, and then fading back again,” said Poshak Gandhi, a scientist with the Japan Aerospace Exploration Agency (JAXA).

“That’s the kind of fury we observed in this jet,” added Gandhi, who is lead author of a new study on the results appearing in the Astrophysical Journal Letters. “With WISE’s infrared vision, we were able to zoom in on the inner regions near the base of the stellar-mass black hole’s jet for the first time and the physics of jets in action.”


WISE images showing strong bursts and dimming of infrared light in the black hole GX 339-4. The data cover a period of approximately 1 day, speeded up. Infrared light has a wavelength about 15 times longer than the eye can see.
Animation made by Poshak Gandhi (JAXA) using WISE images.

Observing the jet’s variability was possible because of images taken of the same patch of sky over time, a feature of NEOWISE, the asteroid-hunting portion of the WISE mission. WISE data also enabled the team to zoom in on the very compact region around the base of the jet streaming from the black hole. The size of the region is equivalent to the width of a dime seen at the distance of our sun.

“To see bright flaring activity from a black hole you need to be looking at the right place at the right time,” said Peter Eisenhardt, the project scientist for WISE at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “WISE snapped sensitive infrared pictures every 11 seconds for a year, covering the whole sky, allowing it to catch this rare event.”

Huge and erratic fluctuations in the jet activity on timescales ranging from 11 seconds to a few hours were seen as a result of the observatations, which are like a dance of infrared colors and show the size of the jet’s base varies.

Its radius is approximately 15,000 miles (24,140 kilometers) with dramatic changes by as large as a factor of 10 or more.

The new data also allowed astronomers to make the best measurements yet of the black hole’s magnetic field, which is 30,000 times more powerful than the one generated by Earth at its surface. Such a strong field is required for accelerating and channeling the flow of matter into a narrow jet. The WISE data are bringing astronomers closer than ever to understanding how this exotic phenomenon works.

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