The most distant galaxy (for now)

Back when I wrote Measuring the Universe, the most distant object then known had a measured redshift, z, of 5.64. That particular distance record was broken while the book was still in press, and since then numerous objects – primarily galaxies, but also quasars and gamma-ray bursts – have been detected at z > 5.64.

Today, the record holder for “most distant object” changed hands once again. Astsronomers using NASA’s Hubble Space Telescope measured the redshift of the galaxy GN-z11 to be 11.09. This is a HUGE redshift. It corresponds to an age of about 13.4 billion years. In other words, we are seeing the object as it was just 400 million years after the Big Bang!

As galaxies go, GN-z11 is quite small: about 25 times smaller than our own Galaxy and with only 1% of our Galaxy’s mass in stars. Nevertheless, it is surprising that a galaxy as large as this could form so soon after the Big Bang. Presumably we will learn more about the conditions that gave rise to these early galaxies as astronomers push the distance record back to z = 12 and beyond. Exciting times!


The inset in this field of galaxies shows GN-z11, the farthest galaxy ever seen (to date). We see the galaxy as it appeared 13.4 billion years in the past. The expansion of the universe has shifted the light from the GN-z11’s young, blue stars to the red.
(Credit: NASA, ESA, P. Oesch, G. Brammer, P. van Dokkum, and G. Illingworth)