Numerical simulations suggest that the first water molecules may have formed shortly after the Big Bang and were probably a key constituent of the first galaxies.
The first water molecules may have actually appeared in the Universe earlier than previously thought: only 100 to 200 million years – not 1 billion years – after the Big Bang. At least that’s what numerical simulations suggest, the results of which were published in Nature Astronomy on March 3.
“Water is considered a crucial ingredient in the cosmic origins of life as we understand it,” the authors of the study recall. According to their work, the association of two hydrogen atoms and one oxygen atom that makes up the water molecule “was probably a key component in the formation of the first galaxies, decrypts Cosmos Magazine. According to the researchers, it is also possible that habitable planets suitable for life formed very early in the history of the Universe.”
To reach these conclusions, the researchers simulated two types of supernovae, those sets of phenomena resulting from the implosion of stars at the end of their lives. They chose supernovae that are thought to have been frequent in the early days of the Universe: a population III star (a hypothetical population of extremely massive and luminous stars) with thirteen times the mass of our Sun and another, 200 times more massive.
What observable signs?
The simulations made it possible to calculate the amount of oxygen created in these two cases and to show that the oxygen cooled and mixed with the surrounding matter, where hydrogen was already present, to form water. However, this work is based only on numerical models. The search for observable signs of the presence of water molecules in the early Universe remains a major challenge.
Daniel Whalen of the University of Portsmouth in the United Kingdom, first author of the study, and his colleagues “are trying to determine what kind of signal these early water-rich stars and planets could have emitted as a whole,” explains the website of the American magazine Astronomy. It could be in the form of a background noise made up of a kind of cloud of water vapor emitted in the early Universe.
Researchers hope that large observatories such as SKA, under construction in South Africa and Australia, will detect these signals, confirming the early formation of a key element of life as we know it on Earth.