New research just shed light on the properties of rare, ultracompact galaxies that formed at the dawn of the Universe.
At about 6 light years away, Barnard’s Star is the closest single star to our solar system. Though it hosts at least one rocky super-Earth, this star bears no resemblance to our home star.
To find siblings of the Sun, which were born in the same place and then scattered throughout the galaxy, we have to look further afield.
Called HD 186302, this identical solar sibling lies some 184 light years away form us.
Now, IA researchers, and colleagues from the Faculty of Science at the University of Lisboa made another astronomy discovery, this time about a rare breed of galaxies.
Primordial Ultracompact Galaxies: Time Capsules From the Early Universe
“They are massive, they are very small and they are extremely rare,” this is how IA astronomers describe the dozens of galaxies that they have just discovered.
Using data from the GAMA survey, the IA team scanned large swathes of the sky to identify 29 of these bizarre galaxies from the early Universe.
Located between two and five billion light-years away, these galaxies are massive and hold several times more stars than the Milky Way, “more than the equivalent to 80 billion suns”, packed into a much smaller space.
Out of this galactic bundle, seven are primordial galaxies that formed over ten billion years ago.
As relic galaxies that remained “untouched by others since their formation”, Massive Ultracompact Galaxies (MUGs) provide a window on the early Universe, even if “they are in our galactic neighbourhood”.
“When you study very small objects and you study them in the faraway Universe, it is very hard to tell anything about them. As this sample of galaxies we studied is in the nearby Universe and relatively close to us, even being truly small, we have a better chance of probing them,” says Fernando Buitrago, leader of the research team and lead author of the study.
These primordial galaxies are so rare that astronomers need to scan a 500 million light-years span to find a single one.
The findings of the present study defy previous assumptions about how galaxies form and evolve.
Primordial galaxies aren’t a new concept, but they were thought to exist only in crowded galactic clusters.
“The surprise came when we realized that not all the galaxies in our sample live in such systems. We found them in a range of environments, and for those that live in underdense neighborhoods, this is very hard to explain.”
The team is now looking forward to having observation time to investigate MUGs and their surroundings more closely. They hope to get more insights about their properties to “understand the eventual fate of all the other galaxies, including our own Milky Way.”