Black holes aren’t alive, but they do turn out to have a beating heart – if they’re consuming huge amounts of gas. New research has discovered how that heart works.
when Black holes Black holes exist in binary systems—sharing an orbit with another star—and can pull in gas from a stellar companion. When this happens, the gas is compressed and heated to incredibly high temperatures, emitting copious amounts of X-ray radiation in the process. It was through this process that astronomers first identified black holes in the famous case. Cygnus X-1one of the brightest X-ray sources in our sky.
In the midst of this ravenous ferment, which may last for thousands or even millions of years, a massive explosion may occasionally occur. This is the sudden ignition. X-rays As a result of the rapid consumption of a huge amount of material at once.
Astronomers have studied many of these flares over the years, but detailed observations of these flares have sometimes revealed strange behavior. In addition to the overall flare, there is a bit of variability, a regular pulse of activity built into the flare event. Astronomers call these pulses heartbeat flares, because their behavior resembles the electrocardiogram signal of a human heartbeat, with a slow rise, a rapid fall, and then a return to normal.
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A team of astronomers at the Key Laboratory for Astroparticle Physics at the Chinese Academy of Sciences in Beijing studied the latest heartbeat and described the process that may power it in a research paper. It was published in the preprint database arXiv.They have submitted their work for publication in The Astrophysical Journal.
The flare they studied originated from IGR J17091-3624, a black hole located 28,000 light-years from Earth. Using X-ray data taken with the Neutron Star Interior Composition Explorer (NICER) and Nuclear Spectroscopic Telescope Array (NuSTAR) in 2022, the team found clear evidence of a heartbeat-like signal in the flare. By studying the detailed properties of the heartbeats, they concluded that these types of pulses are due to interactions and instabilities within the matter surrounding the black hole.
When matter falls into a black hole, it doesn’t just get compressed, it forms a thin, rapidly rotating disk. The inner edge of this disk is tilted downward toward the black hole’s event horizon, while the rest of the disk glows with X-ray radiation. This creates a highly unstable state where the radiation from the disk competes with the black hole’s gravitational pull.
To trigger a heartbeat, the disk temporarily collapses, losing its cohesion and sending a large clump of material into the black hole. This releases a massive amount of radiation, which starts the heartbeat. The radiation then heats the gas, temporarily stopping it from falling in. The gas then settles down before the process repeats, paving the way for another heartbeat.
These heartbeat signals are incredibly rare — only two black holes out of hundreds of known black holes have shown them — but researchers hope to study more, as they provide valuable insights into the relationships between black holes and their environments.