Spectacular new Hubble Space Telescope images reveal 250 previously unknown galaxies that formed just 600 million years after the Big Bang.
Astronomers use the Hubble Space Telescope and Albert Einstein's General Theory of Relativity to obtain gravitational lensing images of galaxy cluster. Photo: Supplied/NASA
This amazing collection of ancient galaxies is fainter than anything previously seen by the Earth-orbiting space telescope.
An international team of researchers, led by Hakim Atek of the Ecole Polytechnique Fédérale de Lausanne in Switzerland, captured the galaxies using a technique called gravitational lensing.
This technique takes advantage of the ability of gravity to bend light -- a property predicted by Albert Einstein's General Theory of Relativity -- to peer back in space-time.
The astronomers used this property to focus Hubble on massive clusters of galaxies which generate immense gravitational fields.
By using these foreground galaxy clusters as gravitational lenses, the researchers were able to see the far more distant and far fainter galaxies behind the clusters, making it possible to study them for the first time.
Early galaxies key to universe's history
The light from these galaxies, which has taken over 13 billion years to reach us, is believed to have played a major role in one of the most mysterious periods of the universe's early history -- the epoch of reionisation.
Prior to reionisation the cosmos was filled with an opaque fog of neutral hydrogen gas.
Ultraviolet light from massive young stars in these first galaxies, ionised this hydrogen, carving out transparent bubbles in the gas.
Over time these bubbles grew bigger and merged to fill all the space between the stars, turning the universe transparent for the first time.
By observing the ultraviolet light from the galaxies in these new Hubble images, astronomers determined that the smallest and most abundant of these galaxies could have played a major role in making the universe transparent.
This allowed the researchers to establish that the epoch of reionisation -- which ends at the point when the universe is fully transparent -- came to a close about 700 million years after the Big Bang 13.8 billion years ago.
- ABC