October 23, 2024
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Did colossal black holes shape the early universe?
Supermassive black holes can eject jets of material so vast and powerful that they can shape the large-scale structure of the cosmos.
An artist’s illustration of the longest jet system of black holes ever seen. Nicknamed Porphyrion after a Greek mythological giant, these jets are about 7 megaparsecs, or 23 million light-years across. This is the equivalent of lining up 140 galaxies in the Milky Way.
E. Wernquist/D. Nelson (IllustrisTNG Collaboration)/M. Hey (CC BY-NC-ND)
In a galaxy 7.5 billion light-years away, a supermassive black hole is spewing streams of magnetized plasma that span the 140 Milky Ways. This amazing structure—nicknamed Porphyrion, after a giant in Greek mythology—contains a group of the largest black hole jets physicists have ever seen. notify in the year nature last month And its existence suggests that black holes played a more important role in shaping the cosmos than previously thought.
Black holes occasionally produce jets when they eat too much, as matter piles up around their maws and encounters extreme astrophysical forces. All matter approaching a black hole takes the form of a spiral disk. This disk is running at such a fast speed the material inside glows white-hot and is ionized, transforming into a dense plasma mixing with magnetic fields. A spinning black hole can twist these magnetic fields into narrow cones at each pole of its rotation. Most of the matter leaving the disk will go straight into the mouth of the black hole. But instead, a small fraction is caught in the twisting fields and slingshots outward, creating two straight beams that some astrophysicists compare to Jedi lightsabers.
They first caught the attention of scientists because these jets served as visual markers for black holes. invisible to most telescopes. Only over time did researchers see that the jets were intrinsically important: the intense heat given off by the currents sometimes prevented the surrounding gas from collapsing and forming new stars. However, the effect seemed to be limited, as the jets were believed not to have extended too far beyond the borders of their galaxy. The sky survey underlying the new study has complicated that picture, identifying more than 10,000 jet systems of massive black holes, chief among them Porphyrion.
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As ancient and colossal as Porphyrion may have contributed to some of the early features of the universe, says lead author Martijn Oei, an astronomer at the California Institute of Technology.
In 2022 Oei and his co-researchers discovered another black hole’s jet system, spanning 16 million light-years or 100 Milky Ways. Porphyrion surpasses the previous record holder, Alcyoneus, not only in its absolute size, but also in its relative influence on the cosmic environment. Born when the universe was less than half its current age, and therefore much smaller and denser than it is today, Porphyrion can stretch and touch further than Alcyoneus ever could.
Porphyrion’s jets are estimated to have the total power of a billion suns and raise the temperature of the surrounding gas by a million degrees Celsius. This means that they may have inhibited not only the formation of stars, but the formation of entire galaxies in the early universe. Their high-velocity magnetized ejecta sprays may also have pierced and filled the voids cosmic webnetwork of matter-rich filaments and matter-poor cavities which forms the large-scale structure of the universe.
Oei is most interested in the possibility that jet systems like Porphyrion helped set the stage for life on Earth. Our planet’s magnetic field protects Earth’s biosphere and atmosphere from dangerous bursts of high-energy cosmic rays and solar particles and radiation. However, the Earth’s magnetic field itself is embedded in, and therefore linked to, the magnetic field of our star, which in turn is embedded in other magnetic fields that extend across the Milky Way, and possibly beyond. This scalar path is long and faint, but it may extend back through time and space to a perch on a chain in our cosmic web, and to potential perturbations in structures like Porphyrion.
To better assess the impact these jets may have had on the early universe, researchers will need to create a more extensive catalog of structures. The new study examines just 15 percent of the sky, potentially leaving many more planes yet to be found. And it’s hard to estimate how many of these giant structures exist, Oei notes, because the conditions that create and maintain powerful streams remain poorly understood.
That scientists can detect even large jets is a testament to the sensitivity of modern telescopes. The large size of aircraft makes them difficult to detect in the small field of view available from the most powerful telescopes. In the new study, Oei and his team members turned to a network of European radio telescopes called the Low Frequency Array (LOFAR), whose images of the sky looked for radio light with a wavelength of two meters. These “human-sized waves” offered signs of “where something violent and spectacular is happening,” he says. When Porphyrion appeared, they used two other facilities—the Giant Metrewave Radio Telescope in India and the WM Keck Observatory in Hawaii—to discover and study the galaxy that was the source of the signal. After initially studying the cosmic web, Oei thought Porphyrion’s pair of jets was a double whammy, and he expects much more as the team continues to study Porphyrion and other giant jet systems.
