Galactic Cluster Lens


SPACE WATCH

NASA – The giant cluster of elliptical galaxies in the center of this image contains so much dark matter mass that its gravity bends light. This means that for very distant galaxies in the background, the clusters gravitational field acts as a sort of magnifying glass, bending and concentrating the distant objects’ light. These gravitational lenses are one tool astronomers can use to extend the vision of telescopes beyond what they would normally be capable of observing.

This particular lens, called Abell 383, was used to find a galaxy so far away that we see it as it was less than a billion years after the Big Bang. This distant galaxy’s light has been warped into two, very faint images that are hard to see in this view.

Abell 383
This galaxy is not the most distant ever observed, but it is one of the youngest to be observed with such clarity. Normally, galaxies like this one are extremely faint and difficult to study, but, in this case, nature has provided the astronomers with a cosmic magnifying glass. The galaxy’s image is being magnified by the gravity of a massive cluster of galaxies parked in front of it, making it appear 11 times brighter. This phenomenon is called gravitational lensing.

“Without this big lens in space, we could not study galaxies this faint with currently available observing facilities,” said co-author Eiichi Egami of the University of Arizona in Tucson. “Thanks to nature, we have this great opportunity to see our universe as it was eons ago.”

The findings may help explain how the early universe became “reionized.” At some point in our universe’s early history, it transitioned from the so-called dark ages to a period of light, as the first stars and galaxies began to ignite. This starlight ionized neutral hydrogen atoms floating around in space, giving them a charge. Ultraviolet light could then travel unimpeded through what had been an obscuring fog.

The discovery of a galaxy possessing stars that formed only 200 million years after the big bang helps astronomers probe this cosmic reionization epoch. When this galaxy was developing, its hot, young stars would have ionized vast amounts of the neutral hydrogen gas in intergalactic space. A population of similar galaxies probably also contributed to this reionization, but they are too faint to see without the magnifying effects of gravitational lensing. more> http://is.gd/cITcPr

Image credit: NASA, ESA, CRAL, LAM, STScI

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