March 10, 2014
Astronomers Use Cluster Of Galaxies As A Giant Telescope
[ Watch the Video: A Telescope Bigger Than A Galaxy ]
April Flowers for redOrbit.com - Your Universe OnlineOn a starry night, around 400 years ago, Galileo turned his primitive spyglass toward the sky. In just a few nights, he learned more about the stars than all of the scientists and philosophers before him, combined.
Since those historic nights, astronomers have operated under a single imperative: make bigger telescopes. The power of optics has grown a million-fold as the 21st century has progressed. Today's telescopes cap the highest mountains, sprawl across deserts, fill valleys and even fly through space—providing crystal-clear views of stars and galaxies, billions of light years farther away than Galileo dreamed of seeing. Each breakthrough in telescope size brought a newer and deeper understanding of the cosmos.
Of course, this led scientists to ask a simple question: exactly how big can a telescope can get?
The answer, it turns out, is larger than an entire galaxy. An international team of researchers led by the Instituto de Astrofísica de Canarias and La Laguna University revealed a patch of sky seen through a lens more than 500,000 light years wide at the 2014 meeting of the American Astronomical Society (AAS).
In this case, the lens is a massive cluster of galaxies known as Abell 2744. The mass of the cluster of galaxies warps the fabric of space around it, just as Einstein's Theory of General Relativity predicted. As starlight passes by the cluster, it is bent and magnified—much like an ordinary lens except on a vastly larger scale.
As part of a program called "Frontier Fields," the team has been using the Hubble Space Telescope, along with the Spitzer Space Telescope and the Chandra X-ray Observatory to look through this gravitational lens.
“Frontier Fields is an experiment to explore the first billion years of the Universe’s history,” says Matt Mountain from the Space Telescope Science Institute in Baltimore, Maryland. The question is, “Can we use Hubble’s exquisite image quality and Einstein’s theory of general relativity to search for the first galaxies?”
According to their research, the answer seems to be "yes." The team discussed Hubble and Spitzer observations of the Abell 2744 cluster at the AAS meeting, noting that one of the major results was the discovery of the most distant galaxies ever seen—a star system 30 times smaller yet 10 times more active than our own Milky Way. The tiny galaxy is bursting with newborn stars, giving astronomers a rare glimpse of a galaxy born not long after the Big Bang itself.
Almost 3,000 distant galaxies—magnified as much as 10 to 20 times larger than they would normally appear—have been revealed by the Hubble exposure. Almost every one of these galaxies would be invisible without the boost of gravitational lensing.
The researchers say that Abell 2744 is just the beginning. The Frontier Fields program is targeting six galaxy clusters as gravitational lenses. Together, these galaxy clusters form an array of mighty telescopes capable of probing the heavens as never before.