2 Colossal Arcs in Far Galaxies Baffle Scientists
Two brilliant blue arcs stretching for hundreds of trillions of miles across distant galaxies have been discovered by astronomers who are baffled by their discovery, the scientists said Wednesday.
The arcs are by far the largest structures ever seen in the universe through optical instruments, and their color and perfect symmetry suggest that they may be composed of new stars riding the shock waves of a violent explosion, the scientists said.
“It would take 100 million supernova (exploding stars) going off simultaneously” to have created and energized the bright arcs, Vahe Petrosian, professor of applied physics at Stanford University, said Wednesday during the American Astronomical Society meeting in Pasadena.
Although that seems to be the leading theory for explaining the mysterious features, the dimensions of the arcs and the amount of energy required to create them through an explosion mean that the theory is not completely satisfying, Petrosian said.
“It looks like God created something like a long rope, cut it into simple pieces . . . and plopped it up into the sky,” Petrosian said at a press conference. He added that the discovery is enough to give theorists “nightmares.”
What most perplex astronomers who have studied the pictures are the sheer size and perfect form of the arcs.
“You could wrap our galaxy three or four times with this thing,” Petrosian said. The light emitted by each arc is “equal to 100 billion suns,” he added.
Roger Lynds of the Kitt Peak National Observatory in Arizona sighted his first arc 10 years ago, but nothing came of it because instruments in those days were too weak and the image too faint to allow him to carry his research forward.
Last summer, while carrying out a routine study of clusters of galaxies about 5 billion light-years away, he stumbled across another arc. This time Lynds was using Kitt Peak’s four-meter telescope, which is one of the most powerful optical telescopes in the world and is equipped with the latest electronic light-gathering devices.
He said that when he saw the arc, he could hardly believe it.
“It just about floored me,” Lynds said.
“This is an astonishing thing,” he added, especially because of the arc’s size and symmetry. “How do we get such incredible geometric coherence over such a great distance?”
Like his colleague, Lynds said the arcs could have been caused by some sort of shock wave pushing newly formed stars across the sky, but he agreed that, because of the amount of energy required to cause such a phenomenon, the theory cries out for more evidence.
The arcs are blue, a color that usually indicates that the light is coming from young stars. If so, it may be coming from hundreds of millions of stars in the very earliest stages of forming galaxies, Lynds said. Scientists, he added, are still a long way from understanding galaxy formation.
Both scientists said they expect to find many more arcs as they probe similar galaxies.
Although their ideas are extremely tentative, both scientists seem convinced that what they have captured through the big telescope disappeared billions of years ago. It can still be seen from Earth, however, because it has taken 5 billion years for the light to travel this far.
“These (arcs) have to be very young,” Lynds said. “They can’t stay that way (perfectly symmetric).” In time, he said, the powerful gravitational fields from the nearby galaxies would distort the symmetry.
Meanwhile, a team of British astronomers said Wednesday in the science journal Nature that they have discovered a quasar 14.4 billion light-years from Earth, the most distant object yet found in the universe.
The discovery was made with the United Kingdom Schmidt Telescope in Australia by a team led by Paul Hewett of the Institute of Astronomy in Cambridge, England.
Quasars, discovered in 1963, are known as radio sources because they emit powerful blasts of radio waves and have been found by the hundreds in the outer reaches of the universe.
