February 17, 2016
Big Bang’s glow leads to discovery of distant black hole jet
Using some of the oldest light in the history of the universe as a sort of cosmic flashlight, a team of astronomers have discovered a jet being emitted by an extremely distant black hole, indicating that such phenomena were likely more common after the Big Bang than previously believed.
According to NASA, Aurora Simionescu at JAXA’s Institute of Space and Astronautical Studies (ISAS) and her colleagues used the Chandra X-ray Observatory to detect light emitted by this jet at a time when the universe was a mere 2.7 billion years old – one-fifth its current age.During this time, the cosmic microwave background radiation or CMB remaining from the Big Bang was far more intense than it is today, and the length of the jet, which was found in a system called B3 0727+409, indicates that it is at least 300,000 light years long, the agency added.
“Because we’re seeing this jet when the Universe was less than three billion years old, the jet is about 150 times brighter in X-rays than it would be in the nearby Universe,” Simionescu said in a statement. Her team’s findings have been published in the Astrophysical Journal Letters.
Accidental find could shed new light on black hole evolution
While the newfound jet is far from the only one emitted by supermassive black holes that have been found in the nearby universe, little had been known about how these jets emitted X-rays. In the new study, the authors have found that electrons in the jet are apparently being boosted to X-ray wavelengths as they travel through CMB radiation at near light-speed.
As these electrons travel through the radiation, they collide with microwave photons and increase in energy so that they enter the X-ray band and can be detected by Chandra, the researchers said. This suggests that the electrons in the B3 0727+409 jet must continue moving at nearly the speed of light for several hundred-thousand light years.
These electrons typically emit strongly at radio wavelengths, NASA explained, which means that black hole jets are usually found by radio observatories. This particular jet is unusual in that, thus far, almost no radio signal has been detected from it, yet it is easily detected in the X-ray band.
The B3 0727+409 jet, as it turns out, was discovered by good fortune while the team was using the Chandra instruments to observe something else, co-author Lukasz Stawarz from Jagiellonian University in Poland said in a statement. Hardly any jets distant enough to have their X-ray brightness amplified by the CMB have been discovered thus far, he added, but now that they are known to exist, “it means there could be many more of them out there.”
“Supermassive black hole activity, including the launching of jets, may be different in the early Universe than what we see later on,” noted co-author Teddy Cheung from the Naval Research Laboratory in Washington DC. “By finding and studying more of these distant jets, we can start to grasp how the properties of supermassive black holes might change over billions of years.”