20 September 2012

Nature: Early galaxy now in view

By combining NASA's Spitzer and Hubble space telescopes, as well as a cosmic magnification effect, a team of astronomers led by Wei Zheng of The Johns Hopkins University has spotted what could be the most distant galaxy ever detected. DARK Fellow Claudio Grillo and former DARK PhD student, Ole Høst, currently at the University College London, are among the researchers who describe the discovery in this week's Nature, "A magnified young galaxy from about 500 million years after the Big Bang."

Age of reionization revealed

Composite color image og galaxy

This figure shows the composite color image of galaxy MACS J1149.6+2223

Light from the young galaxy captured by satellites when the 13.7-billion-year-old universe was just 500 million years old.  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.