New observations from the Hubble Space Telescope provide a stunning glimpse into some of the universe's earliest and faintest galaxies.
The new findings use gravitational lensing to look at galaxies that formed only 600 million years after the Big Bang, the European Space Agency reported. The findings highlight the vital role these early galaxies played in the creation of the universe we see today.
The Hubble observations provide one of the largest samples of dwarf galaxies ever to be discovered at these epochs, and the included galaxies are some of the faintest ever to be seen by Hubble. By looking at the light from these galaxies, the researchers determined it likely was important in the development of one of the universe's most mysterious periods, the epoch of reionization. During this time, a thick cloak of hydrogen gas fog started to dissipate, allowing ultraviolet light to travel farther distances. The team looked at ultraviolet light from the galaxies to determine which ones were involved in the process.
The findings revealed the smallest and most abundant of the galaxies seen in the study were primarily responsible for keeping the universe transparent. This suggests the epoch of reionization ended about 700 million years after the Big Bang.
"If we took into account only the contributions from bright and massive galaxies, we found that these were insufficient to [reionize ] the Universe. We also needed to add in the contribution of a more abundant population of faint dwarf galaxies," said Hakim Atek of the Ecole Polytechnique Fédérale de Lausanne.
To accomplish this, the team studied the deepest images of gravitational lensing made so far in three galaxy clusters. The clusters emit intense gravitational fields that have the ability to magnify the galaxies' faint light.
"Hubble remains unrivalled in its ability to observe the most distant galaxies. The sheer depth of the Hubble Frontier Field data guarantees a very precise understanding of the cluster magnification effect, allowing us to make discoveries like these," said co-author of the study Mathilde Jauzac, from Durham University, UK, and the University of KwaZulu-Natal.
The findings were part of the Hubble Frontier Fields program, and publication of the research in the Astrophysical Journal is pending.
