The number of galaxies in the universe is a fundamental question in astronomy. Now, an international team of astronomers, led by Christopher Conselice, Professor of Astrophysics at the University of Nottingham (UK), has discovered that the universe contains at least 2 trillion galaxies, 10 times more than previously believed.
Determining how many galaxies there are in the observable universe has been a key question in the field of astronomy. Thus, during the last 20 years and thanks to images from the Hubble Space Telescope, scientists estimated that the observable universe contained around 100-200 million galaxies.
After 15 years of work , experts converted pencil beam images of deep space from telescopes around the world, and especially the Hubble telescope, into three-dimensional maps. This allowed them to calculate the density of galaxies , as well as the volume of one small region of space after another. Thanks to this meticulous investigation, astronomers have been able to establish how many galaxies are missing, as if it were a cosmic archaeological excavation.
Walking through the history of the universe , the experts were able to know how many galaxies existed at a certain time, determining that when the universe was only a few billion years old, there were a dozen more galaxies ; most of them were low-mass systems with masses similar to those of the satellite galaxies surrounding the Milky Way.
“This is very surprising, since we know that during the 13.7 billion years of cosmic evolution since the Big Bang, galaxies have developed through star formation and mergers with other galaxies. It must have happened to reduce their number to through a wide fusion of systems “, explains Conselice.
Who knows what interesting properties we will find when we study these galaxies with the next generation of telescopes? In the future we will know.
The study has been published in The Astrophysical Journal.
