‘Normal’ galaxy excites astronomers

Astronomers in California have discovered one of the most distant galaxies in the universe – and noticed there is nothing particularly spectacular about it.

The galaxy, named MACS1423-z7p64, is at a redshift of 7.6, placing it at just more than 13bn years in the past. But what’s of particular interest to the scientists is it falls within the Epoch of Reionisation – a billion years after the Big Bang when the Universe became transparent.

Austin Hoag, a University of California graduate and lead author of the study published in Nature Astronomy, said: “Other most distant objects are extremely bright and probably rare compared to other galaxies. We think this is much more representative of galaxies of the time.”

After the Big Bang, the Universe was a cloud of cold atomic hydrogen. The first stars and galaxies condensed within this cloud and began to emit light and ionising radiation, clearing away the atomic cloud.

To find galaxy z7p64, scientists took advantage of light passing through a galaxy cluster, which magnifies the stars behind it like a giant lens, enabling them to be seen. Using the Hubble Space Telescope, Hoag and his fellow researchers found a galaxy cluster that enabled the brightness of z7p64 to be magnified ten-fold, before analysing its spectrum with the Keck Observatory telescopes in Hawaii.

The research group plan to continue surveying the sky with both the Hubble and Keck telescopes and are planning observations for the Webb telescope, due to launch next year. Marusa Bradac, also from the University of California and co-author, said: “We will truly witness the birth of the first galaxies which will allow us to answer the longstanding question, of where did we come from.”