VOA科学技术2024--Scientists Find Energy Jets Among the Universe's Largest Structures

Scientists say they have found the largest jets of energy ever observed shooting out of a black hole in a distant galaxy¹.

The jets extend 23 million light years from end to end. That is about 140 times the width of our Milky² Way Galaxy. The galaxy responsible is estimated to be 7.5 billion light years from Earth.

The scientists observed the structures using the Low-Frequency Array, or LOFAR, radio telescope network centered in the Netherlands.

Violent, highly energetic events around a black hole in the galaxy are the cause of the jets. A black hole is often the remains³ of a super-massive star that collapses⁴. It is so massive that even light cannot escape its powerful gravity.

Researchers have named the energy jets Porphyrion after a giant in ancient Greek mythology⁵. Porphyrion is 30 percent longer than any other known energy jet.

Martijn Oei of Caltech is an astrophysicist and lead writer of the study published in Nature. Oei said, "Jet systems like Porphyrion appear to be among the most energetic spectacles that have occurred in the universe since the Big Bang."

The Big Bang is the event that scientists say marked the beginning of the universe.

Astrophysicist Martin Hardcastle of the University of Hertfordshire in English was also a writer of the study. He explained how scientists believe the jets formed.

"The general understanding is that jets are formed when magnetized material falls onto a rotating black hole," he said.

He said the jets "need to be sustained by a continued infall of matter into the black hole, something on the order of one solar mass (the mass of the sun) a year of material."

However, although they are huge, the jets cannot be seen in visible light. Scientists used radio telescopes to find them. They start small and grow over time, the scientists say.

"We've known for a while that black holes can generate these jets. But what is interesting is that to generate a large structure like this, the jets must stay on for a long time - about a billion years," Hardcastle said.

The Porphyrion jets reach far beyond their home galaxy. Their total output of energy is equal to trillions of stars like the sun.

Oei said that amount of energy is similar to when two clusters of galaxies⁶ crash into one another, each containing thousands of galaxies.

Hardcastle said the discovery could increase knowledge of magnetic fields in the universe.

He said: "The fact that it extends so far from its parent black hole means that it may be carrying energy, particles and magnetic fields into the voids in the cosmic web..."

Such jets also could heat up gas in interstellar space, suppressing the formation of new stars or could damage planets that could hold life, the researchers said.

Scientists say our Milky Way Galaxy has a black hole at its center, but it does not have a jet, and it is not active.

However, the researchers noted⁷ that the most important finding of the study might be that black holes can create some of the largest structures in the universe.

"This means that individual black holes can have a sphere of influence that extends way beyond the galaxy in which they reside," Oei added.

Words in This Story

jet -n. a forceful rush of liquid, gas, or vapor⁸ especially through a narrow opening

mythology -n. ancient stories of a culture which are often the source of names in astronomy and other sciences

astrophysicist -n. a scientist who studies stars and their physical and chemical qualities

spectacle -n. something that is seen that creates wonder and amazement⁹

rotate -v. to turn (around an axis¹⁰ or center)

generate -v. to create electromagnetic, electric or heat energy

cluster -n. a number of related objects that form a group and which influence each other in some ways

void -n. emptiness

reside -v. to be in, on or at a place