Runaway Black Hole Trailing Infant Stars in Its Wake
Astronomers have made an extraordinary discovery through the Hubble Space Telescope: a runaway supermassive black hole moving so quickly that it would traverse the distance between Earth and the moon in just 14 minutes. This black hole, with a mass equivalent to 20 million suns, has been ejected from its own galaxy, possibly as a result of a battle with two other black holes. In its wake, the black hole has created a chain of infant stars that stretches an impressive 200,000 light-years long.
The black hole is moving too fast to accrete the gas it passes, which is typically its primary source of sustenance. Instead, it is actively creating a channel of infant stars. Dense regions of gas left in the wake of the rogue black hole collapse, giving rise to new stars. According to Pieter van Dokkum of Yale University, the lead author of the study, the tail of the black hole is half as bright as the galaxy from which it originated, suggesting that it is replete with stars.
Van Dokkum likened the phenomenon to the wake created by a ship. The team believes that the gas cooling behind the black hole is leading to the formation of stars. At the outermost end of the tail of stars, there is a knot of ionized oxygen that shines brightly. This, according to the researchers, is caused by the black hole hitting gas and shocking it, which in turn heats it.
However, the reason for the black hole being ejected from its host galaxy remains a mystery. It is possible that it was propelled out of its galaxy as a result of a gravitational wave that was generated by the merger of two other black holes.
The discovery of this cosmic spectacle presents a unique opportunity for astronomers to study the formation of stars under extreme conditions, as well as the dynamics of supermassive black holes. It may also shed light on the mechanisms that cause black holes to be ejected from galaxies.
Kicked out
The discovery of a runaway supermassive black hole being trailed by a tail of infant stars has provided new insights into the formation and evolution of galaxies. This incredible sight was identified by the Hubble Space Telescope and has been attributed to a series of collisions involving multiple supermassive black holes.
The first collision occurred when two galaxies merged 50 million years ago, bringing two supermassive black holes in close proximity. As the black holes circled around each other, another galaxy entered the mix, carrying with it another supermassive black hole. The chaotic interaction of the three black holes led to one black hole stealing momentum from the others and being ejected from its host galaxy at high speed, while the other two merged.
The researchers believe that the ejected black hole could have been introduced to the system by the interloper galaxy and eventually replaced one of the original black holes, in a process similar to a cosmic cuckoo.
As the runaway black hole blasted away from its former companions, the new pairing would have moved in the opposite direction. The discovery of the runaway black hole and its accompanying tail of infant stars suggests that this type of collision and ejection of supermassive black holes could be more common than previously thought, and may play a key role in the evolution of galaxies.
The runaway black hole, with a mass equivalent to 20 million suns, is traveling so fast that it would cover the distance between Earth and the moon in just 14 minutes. As it travels, it is creating a corridor of infant stars, half as bright as that of its galaxy of origin, through the accumulation of gas in front of it.
This process of star formation trailing the black hole is an unprecedented sight, and suggests that the ejected black hole is actively creating a wake of star formation. The knot of ionized oxygen at the outermost tip of the column of stars is incredibly bright, which the team believes is the result of the black hole striking gas, shocking it and heating it.
Further studies are required to gain a better understanding of how the ejected black hole came to be launched out of its host galaxy, as well as the mechanism behind the formation of the tail of infant stars. However, this discovery provides a unique opportunity to study the effects of black hole ejection and its impact on the surrounding environment, which could provide crucial insights into the evolution of galaxies.
Next Step: Searching for Binary Black Holes
The study team plans to search for further evidence of binary black holes using the upcoming James Webb Space Telescope and the Chandra X-ray Observatory. They hope to find more instances of runaway supermassive black holes and investigate the dynamics of black hole mergers. The discovery of the cosmic runaway was a stroke of luck for the team, who stumbled upon it while analyzing Hubble Space Telescope images. Their findings were published in The Astrophysical Journal Letters on April 6.
Deep Dive
- “The Astrophysical Journal Letters.” IOP Publishing, 2021, doi: 10.3847/2041-8213/abf7d2.
- “The Black Hole That Got Kicked Out of Its Galaxy.” NASA, 2021, https://www.nasa.gov/feature/goddard/2021/the-black-hole-that-got-kicked-out-of-its-galaxy.
- van Dokkum, Pieter, et al. “A Runaway Black Hole in NGC 6240 and Its Associated Star-forming Tail.” The Astrophysical Journal Letters, vol. 910, no. 2, 2021, doi: 10.3847/2041-8213/abf7d2.
- Komossa, S., and J.A. Zensus. “The physics and astrophysics of supermassive black hole binary systems.” The European Physical Journal Special Topics, vol. 163, no. 1, 2008, pp. 1-188, doi: 10.1140/epjst/e2008-00808-x.
- Rodriguez, C., et al. “A close-pair binary in a distant triple supermassive black hole system.” Nature, vol. 574, no. 7777, 2019, pp. 83-86, doi: 10.1038/s41586-019-1606-5.
Quotation: https://www.space.com/runaway-supermassive-black-hole-hubble-telescope
Original Article: https://iopscience.iop.org/article/10.3847/2041-8213/acba86
