A multinational team of astronomers has reported the discovery of Abell2744 Y1 – one of the most distant galaxies ever found.
Abell2744 Y1 is about 2,300 light-years wide, which is 50 times smaller than our Milky Way Galaxy. It is producing about ten times more stars than our Galaxy, as is typical for galaxies in the young Universe.
The galaxy has a redshift of 8, which is a measure of the degree to which its light has been shifted to redder wavelengths due to the expansion of Universe. The farthest confirmed galaxy has a redshift of more than 7.
Abell2744 Y1 was found with the help of NASA’s Spitzer and Hubble Space Telescopes and a gravitational lens produced by the galaxy cluster Abell 2744 – gravity from the mass in the cluster (located about 3.5 billion light-years away) acts to magnify the light of more distant galaxies behind it.
The discovery was part of NASA’s Frontier Fields program, designed to push the limits of how far we can see into the early Universe.
“We expected to find very distant galaxies close to the cluster core, where the light amplification is maximum,” said Dr Nicolas Laporte of the Instituto de Astrofísica de Canarias, who is the lead author of a paper accepted for publication in the journal Astronomy and Astrophysics Letters (arXiv.org).
“However, this galaxy is very close to the edge of the Hubble image where the light is not strongly amplified. We are really lucky that we could find it in the small field of view of Hubble.”
“The long exposure image of the cluster Abell 2744 is the deepest one obtained so far of a cluster of galaxies and is comparable to the Hubble Ultra Deep Field,” the astronomers said.
N. Laporte et al. 2014. The first Frontier Fields cluster: 4.5mum excess in a z-8 galaxy candidate in Abell 2744. A&A, accepted for publication; doi: 10.1051/0004-6361/201323179