An international team of researchers, which included astronomers from the Netherlands Institutes for Radio Astronomy (ASTRON) and Space Research (SRON) as well as Leiden University, observed the full extent of the evolution of hot gas produced by an active black hole for the first time. As it evolves, the hot gas encompasses a much larger area than previously thought and even impacts objects residing at great distances. Their study is published today in Nature Astronomy.
Published by the editorial team, 18 October 2021
Bubbles and filaments
The findings came from studies of Nest200047 – an otherwise innocuous group of galaxies about 200 million light years away that houses a spectacular black hole in the galaxy at its centre. The black hole is actively accreting any surrounding matter and releasing powerful streams of particles as a result. These particles have formed pairs of bubbles and filaments of hot gas that have gradually drifted away from the black hole, reaching distances of hundreds of thousands of light-years and impacting anything that stands in their way. These structures that are now observable are strongly reminiscent of the smoke streams produced in the Earth’s atmosphere by volcanic eruptions.
“Our investigation shows how the gas bubbles accelerated by the black hole are expanding and transforming in time. Indeed, they create spectacular mushroom-shaped structures, rings and filaments that are similar to those originating from a powerful volcanic eruption on planet Earth”, states Marisa Brienza (University of Bologna, Italian National Astrophysics Institute INAF) who led the study.
LOFAR and eROSITA
Timothy Shimwell (Netherlands Institute for Radio Astronomy, ASTRON), a co-author of the study, is thrilled with the result. “For many years researchers have been trying to figure out how much of the surrounding area a black hole can influence. The images we have created of this incredible system show that the answer is astonishingly large. The black hole doesn’t just influence the host galaxy but instead it impacts a vast intergalactic environment which may contain hundreds of other galaxies, and it will affect aspects such as the rate at which stars form in those galaxies.”
As a black hole accretes the surrounding matter it produces bright and energetic beams of plasma at its poles. Over time these beams grow into large bubbles and filaments of hot gas that drift progressively further from their origin. Here we first see on a young object where the beams of matter are still close to a central black hole. This movie shows this gradually evolve until the bubbles and filaments have moved hundreds of thousands of light years from their origin and impacted everything in their path. Evidence for this evolutionary path was discovered in Nest200047.
Observations that made this research possible were conducted by the Low Frequency Array (LOFAR) and the extended Roentgen Survey with an Imaging Telescope Array (eROSITA). LOFAR, which is centred in the Netherlands, is the largest low-frequency radio telescope in the world, and eROSITA, is a state-of-the-art space telescope. These facilities have allowed researchers to “travel in time” and witness an eruption from a black hole more than 100 million years ago and map out its consequences. Much like studying artefacts from ancient volcanic eruptions on Earth, such as those in Pompei.
LOFAR is proving to be amongst the world’s most prolific radio telescopes. “This is yet another fantastic scientific breakthrough that LOFAR has facilitated and it’s opened up a new avenue of research that is going to be actively pursued” says Huub Rottgering (Leiden University). This comes after substantial and sustained development efforts, with Reinout van Weeren (Leiden University) noting that “the techniques required to fully exploit a pioneering telescope such as LOFAR take years to develop, and rely on some of the nation’s largest compute facilities to operate, so getting this type of result is a mammoth effort, but one that is very gratifying to be part of.”
“A snapshot of the oldest AGN feedback phases” published in Nature Astronomy. It is the result of a combined effort of experts in radio, optical and X-ray astronomy from the University of Bologna, INAF, ASTRON, Leiden Observatory, Hamburger Sternwarte, Kazan University, Space Research Institute (IKI), Max Planck Institute for Astrophysics, University of Hertfordshire, SRON, Observatoire de Paris. Link to Nature Astronomy article: https://www.nature.com/articles/s41550-021-01491-0
The International LOFAR Telescope is a trans-European network of radio antennas, with a core located in Exloo in the Netherlands. LOFAR works by combining the signals from nearly 110,000 individual antenna dipoles, located in ‘antenna stations’ across the Netherlands and in partner European countries. The stations are connected by a high-speed fibre optic network, with powerful computers used to process the radio signals in order to simulate a trans-European radio antenna that stretches over 2000 kilometres. The International LOFAR Telescope is unique, given its sensitivity, wide field-of-view, and image resolution or clarity. The LOFAR data archive is the largest astronomical data collection in the world.
LOFAR was designed, built and is presently operated by ASTRON, the Netherlands Institute for Radio Astronomy. France, Germany, Ireland, Italy, Latvia, the Netherlands, Poland, Sweden and the UK are all partner countries in the International LOFAR Telescope.