Astronomers find galaxy born at dawn of the universe
PARIS — Astronomers in Europe and the United States said on Wednesday they had spotted the farthest and oldest galaxy ever found, a star cluster 13.2 billion light years away.
Light reaching Earth today from galaxy MACS 1149-JD is truly ancient, they reported in the British journal Nature.
The rays were sent out 490 million years after the Big Bang that created the Universe some 13.7 billion years ago.
“We estimate that it (the galaxy) formed less than 200 million years after the Big Bang,” the team said.
Until now, researchers have found more than 100 galaxies believed to have formed between 650 and 850 million years after the birth of the cosmos.
But only one, reported last year, has been found that can be dated with confidence back to 500 million years.
Detection of MACS 1149-JD is a breakthrough for a new technique in astronomy, for galaxies that are so distant have a brightness weaker than a candle on the Moon and cannot be detected directly by telescopes on Earth.
In this case, the astronomers used a phenomenon called a gravitational lens to snatch the light.
Galaxies that are grouped together in a tiny arc of the sky contain large amounts of “dark matter,” an enigmatic substance that can only be perceived indirectly, through its gravitational effect on light.
Closely-gathered galaxies make dark matter bundle light together, thus making it brighter and easier detect.
The astronomers searched for old, distant galaxies that lurk behind more recent galaxies which lie in the foreground and so provide the magnification.
The study, using NASA’s orbiting Hubble and Spitzer telescopes, was led by Wei Zheng at Johns Hopkins University in Baltimore, Maryland.