Searching for the cosmic dawn

Abstract

The Hubble Space Telescope, teaming up with a 'cosmic lens', has revealed a highly magnified galaxy thought to date back to 500 million years after the Big Bang. The find provides a glimpse of the first stages of galaxy formation. See Letter p.406 Young galaxies at a cosmic age of less than 500 million years remain largely unexplored because they are at or beyond the sensitivity limits of current large telescopes. This paper reports the use of strong gravitational lensing from a massive cluster of galaxies to observe a galaxy from the early Universe, at a redshift of z ≈ 9.6, equivalent to a cosmic age of approximately 490 million years. The authors suggest that because faint galaxies seem to be abundant at such a young cosmic age they are probably the dominant source for the early re-ionization of the intergalactic medium.