Finding new galaxies is a tough task. But a group of researchers from the International School of Advanced Studies (SISSA) say they’ve discovered a new galaxy in a relatively young universe, all thanks to Albert Einstein’s enduring theory of relativity.
“This was a very special celestial body,” Marika Giulietti, who studies astrophysics and cosmology at SISSA, says in a news release. “It is very bright.”
The galaxy’s celestial body was so dark and compact that it was almost invisible, the researchers write in their new study, published in The Astrophysical Journal.
“Very distant galaxies are real mines of information about the past and future evolution of our universe,” Giulietti says. “However, studying them is very challenging. They are very compact and therefore difficult to observe.” Add in the distance away, the weak light we get from them, and the prevalence of interstellar dust, and we have a hard time observing these unknown galaxies.
While scientists have discovered several distant galaxies in recent years, they generally appear “completely invisible even to the most powerful optical instruments, such as the Hubble Space Telescope,” the SISSA scientists write.
So that’s where gravitational lensing comes in. This technique shows that mass bends light, as first predicted with Einstein's theory of relativity. The gravitational field of a large object in space, like a star or a planet, will bend incoming light. Because these large bodies have gravitational fields that extend into space (like how Earth can also control the moon), incoming light can get refracted at a large distance. That can distort large regions of space. The bigger the object, the more dramatic the bending.
“In this way," Giulietti says, “large celestial bodies act as a kind of enormous cosmic lens that makes the ‘background’ galaxies appear larger and brighter, allowing them to be identified and studies.”
So far, observation programs using this approach have discovered about 100 celestial bodies. The latest, though, was special, mostly thanks to the brightness. Using a modern sub-millimeter interferometer located in the Atacama Desert of Chile, scientists determined the features of the complex galaxy.
“Our analysis showed that this object is very compact, presumably young, and forming stars at an extremely high rate,” Giuletti says.
