Astronomers who have been observing a supermassive black hole for more than ten years now have confirmed that its heartbeat is still going strong and said this was the most long lived heartbeat ever observed in a black hole.
When astronomers talk about the heartbeat of a black hole they refer to the periodic pulsating around the black hole that creates a repetitive signal.
The black hole's heartbeat was first detected in 2007 at the centre of a galaxy, which is approximately 600 million light years from Earth. X-ray satellite observations spotted the repeated beat after its signal had been blocked by our Sun for a number of years.
The report, published in the Monthly Notices of the Royal Astronomical Society, tells us more about the size and structure close to its event horizon—the space around a black hole from which nothing, including light, can escape.
The research team included scientists from the National Astronomical Observatories, Chinese Academy of Sciences, China, and Durham University, UK.
The signal from this galactic giant repeated every hour and this behaviour was seen in several snapshots taken before satellite observations were blocked by our Sun in 2011.
In 2018 the European Space Agency's XMM-Newton X-ray satellite was able to finally re-observe the black hole and to scientists' amazement the same repeated heartbeat could still be seen.
Matter falling on to a supermassive black hole as it feeds from the accretion disc of material surrounding it releases an enormous amount of power from a comparatively tiny region of space, but this is rarely seen as a specific repeatable pattern like a heartbeat.
The time between beats can tell us about the size and structure of the matter close to the black hole's event horizon.
Professor Chris Done, in Durham University's Centre for Extragalactic Astronomy collaborated on the findings with colleague Professor Martin Ward, Temple Chevallier Chair of Astronomy.
Professor Done said: "The main idea for how this heartbeat is formed is that the inner parts of the accretion disc are expanding and contracting.
"The only other system we know which seems to do the same thing is a 100,000 times smaller stellar-mass black hole in our Milky Way, fed by a binary companion star, with correspondingly smaller luminosities and timescales.
"This shows us that simple scalings with black hole mass work even for the rarest types of behaviour."
Lead author Dr Chichuan Jin of the National Astronomical Observatories, Chinese Academy of Sciences, said: "This heartbeat is amazing! It proves that such signals arising from a supermassive black hole can be very strong and persistent. It also provides the best opportunity for scientists to further investigate the nature and origin of this heartbeat signal."
Astronomers are aiming to perform a comprehensive analysis of this intriguing signal, and compare it with the behaviour of stellar-mass black holes in our Milky Way.
