NASA astronomers were able to get a closer look at the inner environment nearing the base of a black hole's jet through infrared observation.
By using the agency's Wide-field Infrared Survey Explorer (WISE) astronomers captured some rare data of a flaring black hole, illuminating new details about these powerful stellar-mass black holes and their raging jets.
Much is known about accretion disks, the materials that feed black holes. Scientists have also so learned a lot about the jets themselves through studies that used X-rays, gamma rays and radio waves. But what scientists didn't have much knowledge on were the key measurements of the brightest part of the jets, which is located at their bases.
NASA said getting this kind of measurements have been hard, despite decades of work. The data collected by WISE is now offering a new look into this missing link.
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) and lead author of the study, in a press statement. That's the kind of fury we observed in this jet. 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 observe the physics of jets in action.
Astronomers recently observed the black hole GX 339-4, which is more than 20,000 light-years away from Earth, near the center of our galaxy.
Researchers said that GX 339-4 has a mass that's at least six times greater than the sun, and like other black holes, it's an ultra-dense collection of matter. This black hole has gravity so great that even light cannot escape, according to researchers.
GX 339-4 is orbited by a star friend that feeds it, and most of the material from that companion star is pulled into the black hole. However, some of that material ends up being blasted away as a jet flowing at nearly the speed of light, researchers said.
Peter Eisenhardt, the project scientist for WISE at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said on order for scientists to see the bright flaring activity from a black hole, he or she needs to be looking at the right place and at the right time.
WISE snapped sensitive infrared pictures every 11 seconds for a year, covering the whole sky, allowing it to catch this rare event, Eisenhardt also said in a statement.
NASA astronomers were able to see GX 339-4 jet's variability because of images taken of the same patch of sky over time. This ability to capture the same patch of sky is a feature of NEOWISE, which serves as the asteroid-hunting portion of NASA's WISE mission.
Data collected by WISE enabled the team to pinpoint the very compact region around the base of the jet streaming from the black hole.
NASA said the size of the region is equivalent to the width of a dime seen at the distance of our sun. Of course, this result surprised astronomers, as it showed huge and erratic fluctuations in the jet activity on timescales ranging from 11 seconds to a few hours.
NASA described the observations stating that they are like a dance of infrared colors, and that they show the varying size of the jet's base. According to the NASA, its radius is approximately 15,000 miles (24,140 kilometers) with changes by as large as a factor of 10 or more.
This type of new data will allow astronomers to make the best measurements of the black hole's magnetic field, which is said to be 30,000 times more powerful than the one generated by Earth at its surface.
NASA said a strong field like that is required for accelerating and channeling the flow of matter into a narrow jet.
The agency also believes the data from WISE will bring astronomers closer to understanding how such an exotic phenomenon works.
If you think of the black hole's jet as a firehose, then it's as if we've discovered the flow is intermittent and the hose itself is varying wildly in size, Gandhi said.
Below is 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. This animation was made by Poshak Gandhi (JAXA) using WISE images.