Odd Ring of Light in Space May Be ‘Lens’ to Universe
When Jacqueline Hewitt gazed at her computer screen one day, she spied a fuzzy, white, circular image that looked like a smoke ring floating against a black background.
“It was a real surprise. I wasn’t expecting anything like that. At first I thought there was a problem with the software,” said Hewitt, an astronomer at the Massachusetts Institute of Technology who was analyzing data gathered by telescope.
Hewitt double-checked her equipment and found nothing wrong, leading her to suspect that she had found the first evidence of a phenomenon that Albert Einstein had predicted in 1936.
‘Gravitational Lens’
Einstein said if a large object such as a star or galaxy passed precisely between Earth and a more distant object, the gravitational field from the closer object would act as a “gravitational lens” to bend the light or radiation from the more distant object to form what would appear to be a ring surrounding the closer object.
Since Einstein proposed the ring, astronomers have observed partial rings in the forms of cosmic arcs, but no one has actually observed a true, complete ring.
If further research confirms that Hewitt’s observation was indeed an “Einstein ring,” the discovery could lead to a better understanding of many of the mysteries of the universe, Hewitt and other experts said.
“It’s really remarkable to see a ring of light in the heavens,” said Irwin Shapiro, director of the Harvard-Smithsonian Center for Astrophysics. “It’s not your most common, garden-variety sight when you look up at the heavens. Its actual scientific importance will depend on things we do not yet know.”
The ring could lead to a better understanding of what is known as “dark matter,” Hewitt said. About 90% of the universe is made up of this mysterious matter. Scientists have been unable to determine its nature because they have been unable to “see” it in any way. But Hewitt said the gravitational lensing that produced the Einstein ring could provide a way to study dark matter.
“If you have a lump of matter there and you can’t see it (then you can’t study it),” Hewitt said. “If you have a bright source behind it you may be able to tell there’s dark matter there.”
Hewitt first observed the ring in 1986 while analyzing data from a large radiotelescope survey of radio wave sources conducted at the National Radio Astronomy Observatory in Socorro, N.M., in 1984. The data was collected with a huge array of 27 antennas that collect and synthesize detailed images from cosmic microwave emissions.
A year later, Hewitt went back to the observatory to conduct more extensive studies. The first data was collected from only two minutes of observation. The follow-up was for nine hours at higher frequencies.
Follow-Up Experiments
“I was relieved to see it still looked like a ring,” Hewitt said.
Working with other researchers at Princeton, MIT and Caltech, Hewitt conducted experiments to try to confirm the finding. The astronomers published their results in the June 9 issue of the British journal Nature after they could find no other explanation for the observation.
Hewitt and her colleagues are uncertain what may have produced the ring. But they speculate a large galaxy may be acting as the lens for a much more distant object of some kind.
Shapiro cautioned that more research is needed to confirm that Hewitt’s observation was indeed an Einstein ring.
“This is an intriguing result. But there’s no important scientific results that have yet stemmed from it,” he said.
But if the ring is confirmed, Shapiro said it could potentially be used for a variety of research.
The lens could be used to estimate the mass of galaxies, which could help determine whether the universe will continue to expand and collapse or expand forever, Shapiro said.
“The gravitational lens offers the hope of giving another way of estimating the mass of galaxies rather than the other indirect ways we have,” Shapiro said.
“It’s exciting,” Hewitt said. “It will be interesting to see in a few years what’s become of it.”
