Using the world's most powerful telescope in combination with gravitational lensing, an international team of scientists has detected the faintest-ever early-universe galaxy that was created just after the Big Bang. The galaxy was detected as it was 13 billion years ago in the universe's infancy.
The team using the DEIMOS instrument on the ten-meter Keck II telescope. The observation was possible by using the gravity of another object - in this case, the galaxy cluster MACS2129.4-0741 - to magnify the galaxy, a phenomenon predicted by Einstein.
Given the massive size of MACS2129.4-0741, the team was able to create three different images of the early-universe galaxy.
"Keck Observatory's telescopes are simply the best in the world for this work," said Maruša Bradač of the University of California (UC), Davis and co-author of the study. "Their power, paired with the gravitational force of a massive cluster of galaxies, allows us to truly see where no human has seen before."
"If the light from this galaxy was not magnified by factors of 11, five and two, we would not have been able to see it," said Kuang-Han Huang, also of UC Davis and lead author of the paper. "It lies near the end of the reionization epoch, during which most of the hydrogen gas between galaxies transitioned from being mostly neutral to being mostly ionized (and lit up the stars for the first time)."
"That shows how gravitational lensing is important for understanding the faint galaxy population that dominates the reionization photon production," he added.
The galaxy is of particular interest not only because it was born shortly after the Big Bang, but because of its low stellar mass, making it a very small galaxy located at a very far distance. Furthermore, it can help scientists answer questions related to the nature of the early universe.
"It's a clue in answering one of the fundamental questions astronomy is trying to understand: What is causing the hydrogen gas at the very beginning of the universe to go from neutral to ionized about 13 billion years ago?" said Marc Kassis, a staff astronomer at Keck Observatory who assisted the discovery team at night. "That's when stars turned on and matter became more complex."
The findings were published in the May 18 issue of The Astrophysical Journal Letters.
