The Farthest Galaxy Found!

Astronomers have discovered the farthest galaxy in the universe through the NASA/ESA Hubble Space Telescope.  They call it GN-z11, a 13.3-billion-year-old galaxy, existing 400 million years after the Big Bang.

Through the Hubble’s Wide Field Camera 3 (WFC3), the astronomers have determined that GN-z11 is 25 times smaller than the Milky Way and has one percent of its mass. The stars, however, grow quickly in GN-z11, about 20 times faster than the stars grow in the Milky Way.


The Milky Way’s Galactic Center in the night sky above Paranal Observatory. Wikimedia/ESO/Y. Beletsky

To be more reliable, instead of specifying the distance in terms of miles, astronomers refer to redshift when the object existed in the history of the Universe, hence they determined this galaxy to be 13.3 billion years old.

The study, to be published in the Astrophysical Journal, involved measuring the galaxy’s redshift, a result of the universe’s expansion that stretches every cosmic object’s light to longer, redder wavelengths. GN-z11 has a redshift of 11.1 while the most distant galaxy previously found, EGSY8p7, has a redshift of 8.68.

“The previous record-holder was seen in the middle of the epoch when starlight from primordial galaxies was beginning to heat and lift a fog of cold, hydrogen gas,” says co-author Rychard Bouwens from the University of Leiden, the Netherlands. “This transitional period is known as the reionisation era. GN-z11 is observed 150 million years earlier, near the very beginning of this transition in the evolution of the universe.”

This galaxy is extremely faint. However, it is unusually bright considering its distance from Earth and good enough for the Hubble to be seen in detail. Additionally, this demonstrates that other bright galaxies discovered before are actually extremely far.

“The discovery of GN-z11 was a great surprise to us, as our earlier work had suggested that such bright galaxies should not exist so early in the Universe,” Marijn Franx, from the University of Leiden says.

“The discovery of GN-z11 showed us that our knowledge about the early Universe is still very restricted. How GN-z11 was created remains somewhat of a mystery for now. Probably we are seeing the first generations of stars forming around black holes?” adds team member Ivo Labbe.

“This new discovery shows that JWST will surely find many such young galaxies reaching back to when the first galaxies were forming,” concludes Garth Illingworth of the University of California, Santa Cruz.


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