Thursday, February 11, 2021

GN-z11

GN-z11 is a small dot like many others immersed in the immensity of the Universe. Even if we zoom in as shown in the insert GN-z11 appears as a small shapeless spot of red color. GN-z11 may seem at first glance an insignificant object, but actually it is the most distant galaxy from Earth observed so far!

GN-z11 was discovered during a survey conducted with the Hubble Telescope. Using the instruments aboard Hubble and Spitzer, astronomers were able to determine the galaxy's redshift, from which it was then traced back to its distance. GN-z11 was thus found to be at an impressive distance of 13.4 billion light years. Independent confirmation of this value was obtained from spectroscopic observations conducted with the Japanese Subaru telescope in late 2020.

The galaxy was formed just 400 million years after the Big Bang. The data obtained by Hubble and Spitzer then allowed to deepen the nature of GN-z11. This should be about 25 times smaller than the Milky Way and have a stellar mass just 1% of that of our galaxy. Despite its small size, GN-z11 is growing very fast, with a star formation rate twenty times greater than that of the Milky Way.

The existence of GN-z11 will force astronomers to revise their theories on the formation of primordial galaxies, as it is not clear how a galaxy could form so close to the Big Bang, a few million years after the formation of the first stars.

Credit: NASA, ESA, P. Oesch, G. Brammer, P. van Dokkum, G. Illingworth. 

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