Many black holes are known to fire jets of plasma out into space at huge speeds, approaching the speed of light, but there’s one major problem: We don’t know how these jets form or, to be honest, what’s really going on at all.
Now though, in a fascinating and first-of-its-kind study, scientists have used a galaxy and a star as a magnifying lens of sorts to get the highest-resolution views ever of one of these jets, coming from a black hole 11 billion light-years away called PKS 1830-211. The results could finally reveal exactly what’s going on, lead researcher Andrii Neronov from the University of Geneva told IFLScience.
The effect at play here is something called gravitational microlensing, which occurs when a massive object – like a galaxy – passes in front of a more distant object in our line of sight. The huge gravitational forces involved mean that the light from the more distant object is bent around the intervening galaxy and magnified, giving us a better view that regular observations by a telescope simply can't match.
This graphic shows how a galaxy can be used as a lens to observe a more distant object. Credit: ESA/ATG medialab
While the effect has been observed and used before in visible wavelengths, this research is important because it is the first time that gamma rays have been observed using it. And gamma rays are produced by the jets from black holes, meaning this data will give us our best glimpse yet of what’s going on.
“Gamma rays are the energy band needed to understand the phenomenon of jets in active galactic nuclei,” Neronov explained to IFLScience. “Nobody has observed a jet in this high resolution before.”
This was made possible thanks not just to the galaxy, which is not named, but also the chance alignment of a star moving in the galaxy as observed by the combined power of three gamma-ray space observatories: ESA's Integral and NASA's Fermi and Swift. Observing the differences between the lensing effect around the galaxy and the star separately produced the high-resolution views.
Without this effect, Neronov compared observing this black hole to "trying to look at an ant sitting on the Moon" in a statement. “None of our telescopes can observe something so small, so we used a trick to resolve the ant: a huge gravitational lens," he added.
This is a simulated view of a supermassive black hole magnified by the lensing effect. Credit: A. Neronov, ISDC, University of Geneva
For now, the team has simply provided the data on this particular observation. The next step will be for scientists to interpret the results, and see if they can work out how black holes produce these intriguing jets.
“It’s amazing to be able to see such tiny things at such enormous distances from us," Neronov added in the statement. "I’m very excited to have a ‘black-hole-scope’ to investigate the inner regions of the jets.”