Astronomers using the Subaru telescope in Hawai'i have looked 60 million years further back in time than any other astronomers, to find the most distant known galaxy in the universe. In doing so, they are upholding Subaru's record for finding the most distant and earliest galaxies known. Their most recent discovery is of a galaxy called I0K-1 that lies so far away that astronomers are seeing it as it appeared 12.88 billion years ago.
This discovery, based on observations made by Masanori Iye of the National Astronomical Observatory of Japan (NAOJ), Kazuaki Ota of the University of Tokyo, Nobunari Kashikawa of NAOJ, and others indicates that galaxies existed only 780 million years after the universe came into existence about 13.66 billion years ago as a hot soup of elementary particles.
To detect the light from this galaxy, the astronomers used Subaru telescope's Suprime-Cam camera outfitted with a special filter to look for candidate distant galaxies. They found 41,533 objects, and from those identified two candidate galaxies for further study using the Faint Object Camera and Spectrograph (FOCAS) on Subaru. They found that IOK-1, the brighter of the two, has a redshift of 6.964, confirming its 12.88 billion-light-year distance.
The discovery challenges astronomers to determine exactly what happened between 780 and 840 million years after the Big Bang. IOK-1 is one of only two galaxies in the new study that could belong to this distant epoch. Given the number of galaxies that have been discovered from 840 million years after the Big Bang, the research team had expected to find as many as six galaxies at this distance. The comparative rarity of objects like IOK-1 means that the universe must have changed over the 60 million years that separate the two epochs.
The most exciting interpretation of what happened is that we are seeing an event known to astronomers as the reionization of the universe. In this case, 780 million years after the Big Bang, the universe still had enough neutral hydrogen to block our view of young galaxies by absorbing the light produced by their hot young stars. Sixty million years later, there were enough hot young stars to ionize the remaining neutral hydrogen, making the universe transparent and allowing us to see their stars.
Another interpretation of the results says that there were fewer big and bright young galaxies 780 million years after the Big Bang than 60 million years later. In this case, most of the reionization would have taken place earlier than 12.88 billion years ago.
No matter which interpretation finally prevails, the discovery signals that astronomers are now excavating light from the "Dark Ages" of the universe. This is the epoch when the first generations of stars and galaxies came into existence, and an epoch which astronomers have not been able to observe until now.
This discovery, based on observations made by Masanori Iye of the National Astronomical Observatory of Japan (NAOJ), Kazuaki Ota of the University of Tokyo, Nobunari Kashikawa of NAOJ, and others indicates that galaxies existed only 780 million years after the universe came into existence about 13.66 billion years ago as a hot soup of elementary particles.
To detect the light from this galaxy, the astronomers used Subaru telescope's Suprime-Cam camera outfitted with a special filter to look for candidate distant galaxies. They found 41,533 objects, and from those identified two candidate galaxies for further study using the Faint Object Camera and Spectrograph (FOCAS) on Subaru. They found that IOK-1, the brighter of the two, has a redshift of 6.964, confirming its 12.88 billion-light-year distance.
The discovery challenges astronomers to determine exactly what happened between 780 and 840 million years after the Big Bang. IOK-1 is one of only two galaxies in the new study that could belong to this distant epoch. Given the number of galaxies that have been discovered from 840 million years after the Big Bang, the research team had expected to find as many as six galaxies at this distance. The comparative rarity of objects like IOK-1 means that the universe must have changed over the 60 million years that separate the two epochs.
The most exciting interpretation of what happened is that we are seeing an event known to astronomers as the reionization of the universe. In this case, 780 million years after the Big Bang, the universe still had enough neutral hydrogen to block our view of young galaxies by absorbing the light produced by their hot young stars. Sixty million years later, there were enough hot young stars to ionize the remaining neutral hydrogen, making the universe transparent and allowing us to see their stars.
Another interpretation of the results says that there were fewer big and bright young galaxies 780 million years after the Big Bang than 60 million years later. In this case, most of the reionization would have taken place earlier than 12.88 billion years ago.
No matter which interpretation finally prevails, the discovery signals that astronomers are now excavating light from the "Dark Ages" of the universe. This is the epoch when the first generations of stars and galaxies came into existence, and an epoch which astronomers have not been able to observe until now.
on January 22, 2010, 2:17 pm
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