Harnessing the power of two NASA space observatories, an international team of astronomers has turned their telescopes on the faintest known galaxy in the primordial universe.
The galaxy was observed by Hubble and Spitzer, and is part of a discovery of 22 young galaxies from the dawn of time. The object existed 400 million years after the Big Bang and has an expected mass of 10 billion Suns. The galaxy is intensely forming stars, producing two stars like our Sun every year, which is 10 times more than a galaxy its size would form in the current universe.
The discovery was possible thanks to a phenomenon called gravitational lensing. When the light from a distant galaxy passes near a very dense object (in this case, a cluster of galaxies), the light becomes bent and magnified, which allows us to see further than current instruments are able to unaided.
The lens in this specific case is a massive cluster of galaxies, MACS0416.1-2403, which is 4 billion light-years from the Milky Way and has a mass equivalent to a million billion Suns. The magnification from this gravitational lens is so strong that the light from the new galaxy looks 20 times brighter.
The object is nicknamed Tayna, which translates to “first-born” in Aymara, the language of the Native population living in the Andes. Astronomers believe that Tayna is representative of a class of small and faint galaxies that quickly formed after the Big Bang, and which had so far eluded our instruments.
"Thanks to this detection, the team has been able to study for the first time the properties of extremely faint objects formed not long after the Big Bang," said lead author Leopoldo Infante in a statement.
This research, published in the Astrophysical Journal, is part of the Frontier Fields program, which aims to exploit gravitational lenses to look as far back in time as possible. The Frontier Field has been pushing our current detection limit by discovering some of the earliest known galaxies.
This new observation provides scientists with fresh insight on galaxy formation in the early universe. The work suggests that a large number of small galaxies had already formed 400 million years after the Big Bang. Hopefully, when the much more powerful James Webb Space Telescope comes online, it will be able to see them in even greater detail.
