Billions of light years from Earth, the hot, energetic, swirling areas around supermassive black holes shoot jets of a trillion electron volts of gamma-radiated gas into space. As hard to miss as that seems, the jets from some of these objects, known as blazars, have never been seen before—until now.
Whittier College Professor of Physics Glenn Piner and a colleague, Philip Edwards of Australia’s federal agency for scientific research, have created the first images of 20 blazar jets across the universe. Their findings of their four-year study, which was funded by the National Aeronautics and Space Administration (NASA), have been published in a January edition of The Astrophysical Journal.
To find these blazar jets, they needed the right tool, though that’s easier said than done. There are orbiting satellites that can detect high-energy gamma rays, but the resolution of the pictures they take is too low to see any of the details in the objects that they were looking for.
The highest resolution pictures come from the Very Long Baseline Array, a network of 10 telescopes linked across the country, from Hawaii to the Virgin Islands. The array is powerful—highest-magnification-on-the-planet powerful. But they’re radio telescopes, not gamma-ray. The blazar jets emit a ton of gamma radiation, but the radio signals that these specific blazars give off are weak. Through the lens of radio, the jets may simply get lost in the noise.
“It was challenging because these were at the faint end of the limit that this telescope can do,” Piner said. “They’re right at the edge. We weren’t sure. They hadn’t been imaged with radio telescopes before, if they would even be detectable.”
For a more complete picture, he teamed up with Edwards, who has access to a similar network of radio telescopes in his half of the world. It’s common for astronomers in different hemispheres to work together, since neither can see the stars on the other’s side of the globe.
After pointing their giant lenses heavenward, the results came in—and the jets were visible amid the noise.
“We’re able to actually look at the structure of the jet. The images suggest a hollow structure, with the area in the middle evacuated,” Piner said. “So we were able to get some of the structural details for the first time and then hopefully that’ll help theoretical physicists construct models.”