Astronomers watch 1st black hole ever imaged launch a 3,000‑light‑year‑long cosmic jet from its glowing 'shadow'

Using the Event Horizon Telescope (EHT), astronomers have tracked a 3,000 light-years-long cosmic blowtorch back to its source, the supermassive black hole M87*, which bears the distinction of being the first black hole imaged by humanity. The breakthrough could help scientists better understand what creates these powerful jets of charged particles that travel at speeds approaching the speed of light.

M87* sits at the heart of the galaxy Messier 87 (M87), located around 55 million light-years from Earth. The historic image of this supermassive black hole, which has a mass equivalent to that of 6.5 billion suns, was captured by the EHT in 2017 and was released to the public in April 2019.

Not only is this supermassive black hole more massive than the one at the heart of the Milky Way, Sagittarius A* (Sgr A*), which has a mass around 4 million solar masses, but M87* is also an active black hole. That means it is greedily devouring its surrounding gas and dust as well as launching powerful jets from its poles. However, the exact source of these jets around their black hole central engines and the precise mechanism powering them is still something of a mystery.

To better understand the jet of this supermassive black hole, astronomers turned to the EHT's observations of M87* taken in 2021 using a technique called Very Long Baseline Interferometry (VLBI). This technique can reveal structures around supermassive black holes at small scales, such as the glowing golden ring of super-hot matter that dominates the 2019 image of M87*, which is effectively the "shadow" of this black hole. Using these newer observations, the team was finally able connect the glowing ring of material around M87* to the base of the jet erupting from this supermassive black hole, giving a probable origin point for this jet.

"This study represents an early step toward connecting theoretical ideas about jet launching with direct observations," team leader Saurabh of the Max Planck Institute for Radio Astronomy (MPIfR) said in a statement. "Identifying where the jet may originate and how it connects to the black hole's shadow adds a key piece to the puzzle and points toward a better understanding of how the central engine operates."

Performing modelling of the supermassive black hole, Saurabh discovered that radio emissions that were missing in EHT observations of M87* conducted between 2017 and 2019 but present in the 2021 observations were likely to originate from a compact region located less than a tenth of a light-year away from the black hole. This region is associated with the base of the M87* jet and corresponds with the southern arm of another jet seen in radio waves.

"We have observed the inner part of the jet of M87 with global VLBI experiments for many years, with ever-increasing resolution, and finally managed to resolve the black hole shadow in 2019," team member Hendrik Müller of the National Radio Astronomy Observatory (NRAO) said. "It is amazing to see that we are gradually moving towards combining these breakthrough observations across multiple frequencies and completing the picture of the jet launching region."

The team will now aim to make more observations of M87* to better understand the structure of its jet and to image the jet's fine details. This could lead to a better understanding of how supermassive black holes shape the environments around them.

The future is bright for black hole images.

The team's results were published on Wednesday (Jan. 28) in the journal Astronomy & Astrophysics.