Astronomers destroy former record for most distant galaxy
An international team of astronomers that includes researchers from Leiden has discovered the most distant galaxy yet. The galaxy, called EGS8p7, is 13.23 billion light years away from Earth and already existed when the universe was only 550 million years old.
This new discovery pulverises the former record (650 million years), a find to which the same Leiden scientists also contributed. ‘Our ability to make such a huge leap now is thanks to an innovative technique we’ve developed,’ second author Ivo Labbé from Leiden University explains. ‘We discovered the galaxies by comparing the colours visible through the Hubble Telescope with infrared images from the Spitzer Space Telescope. After further research, three of the candidates we selected a year ago with this technique are now in the first, second and fourth places on the world ranking.’
The galaxy’s official name is EGSY8p7 and it can be found 13.23 billion light years away from Earth. It cannot be seen with the naked eye, though it is in the vicinity of the Great Bear constellation, in a much studied strip of the sky named the Extended Groth Strip. Co-author Rychard Bouwens from Leiden University: ‘The record breaker can be found in almost the exact direction as the previous record holder; we were also involved in that discovery in May. That’s a big coincidence, as we expected them to be more evenly distributed across the universe.’
The astronomers relied on the powerful MOSFIRE infrared spectrograph of the Keck I Telescope, which is stationed in Hawaii. Using this instrument, they spent two nights searching the sky for the characteristic radiation of hydrogen. These hydrogen bubbles are heated by strong ultraviolet emissions from newly born stars.
The astronomers didn’t expect to find galaxies at such a huge distance with the help of hydrogen radiation. That’s because during the earliest years of the universe, the space between galaxies used to be filled with dark clouds of hydrogen, which were capable of absorbing all this radiation. Computer simulations have already shown that the universe underwent far-reaching changes about 400 million years after it came into existence. Those clouds of hydrogen began to transform into hot, transparent plasma due to the influence of light from the young stars in the earliest galaxies.
Ivo Labbé: ‘Confirming the existence of galaxies like EGSY8p7 enables us to piece together more information about the development of the earliest galaxies, as well as about the role they played in altering that early universe.’ The success of this project has already led hopeful astrophysicists to believe that a lot more distant galaxies will be discovered in the near future.
(10 August 2015/NOVA)
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