Detection of the faintest galaxy in the early universe

color_image_of_clusterCredit: Bradac/HST/W. M. Keck Observatory


Color image of the cluster taken with Hubble Space Telescope (images in three different filters were combined to make an RGB image). In the inset we show three spectra of the multiply imaged systems. They have peaks at the same wavelength, hence showing that they belong to the same source.



Astronomers used the W. M. Keck Observatory on Mauna Kea, Hawaii to detect the faintest galaxy of the early universe. The detection was made possible through a phenomenon known as gravitational lensing. The phenomenon was predicted by Einstein and occurs when a foreground massive structure, like a galaxy cluster, acts as a lens and magnifies and creates multiple images of objects in the background. In this case, three images of the faint galaxy were created and each one was magnified by a factor of eleven, five and two.

The galaxy was observed as it was about 13 billion years ago, when the reionization era of the universe ended. As Prof. Huang, the lead author of the relevant paper said, the detection will help scientists to answer one of the fundamental questions: What is causing the hydrogen gas at the very beginning of the universe to go from neutral to ionized, when stars turned on and matter became more complex.


Publication: Huang et al. 2016