Still alive: 11 years later, scientists hear supermassive black hole ‘heartbeat’ again

How hard is it to hear the “heartbeat” of a black hole? If you’re lucky enough, it could take 11 years. More than a decade ago, astronomers first discovered an X-ray quasi-periodic shock signal from a supermassive black hole, the “heartbeat” of a black hole. More than a decade later, when astronomers had another chance to observe the black hole, they found that the signal was still going on.

Author . . . Ding Jia

The study was led by a team of researchers at the National Observatory of the Chinese Academy of Sciences, Jin Chichuan, who worked with researchers at Durham University in the UK and published their findings in the June 10 issue of the Monthly Journal of the Royal Astronomical Society.

Still alive: 11 years later, scientists hear supermassive black hole 'heartbeat' again

An imaginary map of the distribution of matter near the black hole’s horizon, as well as X-ray quasi-periodic shock signals observed by the XMM-Newton satellite in 2007 and 2018, respectively. Photo credit: Cassnational Observatory/NASA

“This heartbeat signal is very beautiful seconds! It is the first evidence that these periodic signals from supermassive black holes can remain stable over time. “

According to Kim, this periodic signal carries critical information about the scale and structure of matter near the black hole’s horizon, and it provides an important clue and a great opportunity to delve into its physical mechanisms and origins.

This particular black hole is a supermassive black hole 600 million light-years from Earth with two million solar masses.

In 2007, scientists used a European Space Agency satellite to discover for the first time that the black hole’s X-ray radiation had a periodic shock signal of about an hour.

But then, because the black hole’s line of sight was too close to the sun, the monitoring of its “heartbeat” stopped.

Until 2018, scientists have another chance to observe the black hole.

The team applied to the European Space Agency and NASA for the use of the XMM-Newton satellite, the Nuclear Spectroscopic Telescope Array satellite and the Swift satellite, which carried out joint observations of the black hole and successfully completed all observation missions in October of the same year.

“After detailed data analysis, we finally confirmed that its X-ray shock signal is still present and stronger than it was 10 years ago. “

“This is the longest duration of the ‘heartbeat’ signal of a supermassive black hole currently observed,” Kim said. “

Although there are a large number of black holes in the universe with millions or even hundreds of millions of solar masses, it is not easy to capture their “heartbeats”.

The matter floating in interstellar space is captured by the gravitational pull of the black hole, which, as it gradually falls into the black hole, forms a disk-like structure and releases a lot of energy in the tiny space around the black hole, producing strong high-energy radiation, such as X-rays.

However, periodic repeat signals of this high-energy radiation are rarely detected.

The only known black hole that produces a heartbeat-like signal is a small black hole located in the Milky Way’s spiral arm.

It has a mass of just 12 solar masses and is rapidly absorbing material from a star next to it and generating an X-ray heartbeat signal at a “heart rate” of around 67 Hz.

“Our understanding is that this heartbeat signal originates from the periodic structural changes of high-temperature substances near the black hole’s horizon,” said Chris Done, a professor at Durham University and one of the paper’s co-authors. By comparing the previous small black holes, we have shown that while the mass differences between different types of black holes can be hundreds of thousands of times, they are very similar in their behavior in some particular behaviors. “

The team is currently conducting in-depth analysis of data from multiple satellites in the hope of gaining a better understanding of the nature of the heartbeat signal and comparing it with small mass black holes in the Milky Way to gain a deeper understanding of the physical processes near the black hole’s horizon.

Kim believes the black hole could be one of The next generation of China’s X-ray astronomical satellites, such as The Einstein Probe and eXTP.