Jet black: ‘little’ black holes emulate their supergiant siblings

Just like younger siblings, ‘little’ black holes do their best to act the same as big ones, according to a study published in Nature Astronomy.

An international team, including researchers from CSIRO, used the Event Horizon Telescope – the telescope that captured the first Messier 87 black hole image – to image the heart of the Centaurus A radio galaxy – one of closest radio galaxies to Earth  – which has a central, supermassive black hole.

The ‘little’ black hole has a mass of about 55 million suns, which puts it between the mass of Messier 87 (6.5 billion suns) and the centre of the Milky Way (four million suns). It behaves like Messer 87, albeit on a smaller scale.

The team was able to make this observation because the Event Horizon Telescope caught the galaxy in unprecedented detail – with all its jets and glory.

Supermassive black holes feed off gas and dust that gets pulled in by their immense gravitational pull. Most of the matter is ‘consumed’ but some of it escapes just before capture and is blown out into space – these are called jets. They are very energetic, but little is known about how they are launched.

“This allows us for the first time to see and study an extragalactic radio jet on scales smaller than the distance light travels in one day,” says astronomer Michael Janssen from the Max Planck Institute for Radio Astronomy, Germany, and Radboud University, Netherlands. “We see up close and personally how a monstrously gigantic jet launched by a supermassive black hole is being born.”

Read More: Astronomers find ‘Goldilocks’ black hole

Despite its small size, the Centaurus A black hole produced jets – outflows of matter – that were similar to Messier 87, except they were on a smaller scale. Only the outer edges of the jet seemed to emit radiation, which challenges some theoretical models.

“Now we are able to rule out theoretical jet models that are unable to reproduce this edge-brightening,” says Matthias Kadler, professor for astrophysics at the University of Würzburg in Germany. “It’s a striking feature that will help us better understand jets produced by black holes.”.

Using these observations of the jets’ launch locations helped the astronomers estimate the position of the black hole. This will help them get better future images, now they know where to look.

“These data are from the same observing campaign that delivered the famous image of the black hole in Messier 87,” says Heino Falcke, professor for astrophysics at Radboud University, Netherlands. “The new results show that the Event Horizon Telescope provides a treasure trove of data on the rich variety of black holes and there is still more to come.”.

An info graphic showing how the images zoomed into the galaxy to find the jets
Credit: R. Bors; CSIRO/ATNF/I. Feain et al., R. Morganti et al., N. Junkes et al.; ESO/WFI; MPIfR/ESO/APEX/A. Weiß et al.; NASA/CXC/CfA/R. Kraft et al.; TANAMI/C. Müller et al.; EHT/M. Janßen et al..

Please login to favourite this article.