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вторник, 7 апреля 2015 г.

ALMA sees Einstein ring in stunning image of lensed galaxy

ALMA sees Einstein ring in stunning image of lensed galaxy
Astronomers have discovered that a distant galaxy—seen from Earth with the aid of a gravitational lens—appears like a cosmic ring, thanks to the highest resolution images ever taken with the Atacama Large Millimeter/submillimeter Array (ALMA).
Forged by the chance alignment of two distant galaxies, this striking ring-like structure is a rare and peculiar manifestation of as predicted by Albert Einstein in his theory of general relativity.
Gravitational lensing occurs when a massive galaxy or cluster of galaxies bends the light emitted from a more , forming a highly magnified, though much distorted image. In this particular case, the galaxy known as SDP.81 and an intervening galaxy line up so perfectly that the light from the more distant one forms a nearly complete circle as seen from Earth.
Discovered by the Herschel Space Observatory, SDP.81 is an active star-forming galaxy nearly 12 billion light-years away, seen at a time when the Universe was only 15 percent of its current age. It is being lensed by a massive foreground galaxy that is a comparatively nearby 4 billion light-years away.
"Gravitational lensing is used in astronomy to study the very distant, very early Universe because it gives even our best telescopes an impressive boost in power," said ALMA Deputy Program Scientist Catherine Vlahakis. "With the astounding level of detail in these new ALMA images, astronomers will now be able to reassemble the information contained in the distorted image we see as a ring and produce a reconstruction of the true image of the distant galaxy."
The new SDP.81 images were taken in October 2014 as part of ALMA's Long Baseline Campaign, an essential program to test and verify the telescope's highest resolving power, achieved when the antennas are at their greatest separation: up to 15 kilometers apart.


Read more at: http://phys.org/news/2015-04-alma-einstein-stunning-image-lensed.html#jCp