A new image of the deep universe has been realized thanks to the data received by the MeerKAT radio telescope made by 64 antennas located in South Africa. The image shows tens of thousands of small points of light but they are not stars: each of these points is a distant galaxy and each of them could potentially contain hundreds or thousands of billions of stars.
The most interesting feature of the image, however, is that the most distant galaxies represent the weakest points of light. Acquiring data and information about these “primordial” galaxies can in fact help astronomers understand when the first stars and galaxies were born. Most stars are currently thought to have been born between 8 and 11 billion years ago, an era also known as “cosmic noon.”
It is usually very difficult to acquire light from these galaxies so far away not only because of the distance but also because of the gas clouds that can overlap and make them invisible. And this is where radio telescopes come into play, operating at a wavelength through which these gas clouds can be “surpassed” to catch a glimpse of the farthest hidden galaxies.
In fact, an international team of astronomers has succeeded in using the MeerKAT radio telescope, now sensitive enough to detect even these galaxies billions of light years away. The result is the image that can be seen on this page that represents a portion of the southern sky, comparable to that occupied by five full moons, with tens of thousands of galaxies, an area that does not contain particular radio sources whose glow could disturb the data acquisition.
Of course, as with all objects located at a certain distance, here too we can speak of a sort of “time machine” with which we can look at the past of the cosmos. And, as James Condon, one of the authors of the study and researcher at the National Radio Astronomy Observatory, USA, explains, “since only short-lived stars that are less than 30 million years old send radio waves, we know that the image is not contaminated by old stars. The radio light we see from each galaxy is therefore proportional to its speed of stellar formation at that time”.
Thanks to this image and the data collected with MeerKAT, researchers now know that during the “cosmic noon” era, even more stars were formed than previously calculated and that there are probably many more galaxies in the universe than ever theorized.