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Cosmic Gravitational Lensing Reveals Ancient Galaxies

Massive galaxies acting as lenses have revealed five ancient galaxies behind the lensing galaxies. Hundreds more old galaxies should be discovered this way. Steve Mirsky reports

Five very old galaxies are now known to astrophysicists, thanks to Albert Einstein. A century ago, Einstein predicted an effect called cosmic gravitational lensing. Picture a massive galaxy out in space. From our vantage point, a second galaxy happens to be behind the first galaxy. That second galaxy should be hidden to us. Except that the nearer galaxy bends the light of the far galaxy coming our way. That light can sometimes become so distorted that it actually appears to ring the nearer galaxy. It’s called an Einstein ring, because he predicted that, too.

In the new study, researchers used the Herschel Space Observatory. The brightest spots on their sky map all turned out to be gravitationally magnified galaxies. The study is in the journal Science. [Mattia Negrello et al., "The Detection of a Population of Submillimeter-Bright, Strongly Lensed Galaxies"]

The observatory is really detecting infrared info, or heat, rather than visible light from the newly discovered galaxies. That radiation started coming our way when the universe was only two to four billion years old, less than a third of its current age. Researchers expect to find hundreds of new, old galaxies this way, along with new info about the early universe.

—Steve Mirsky




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