London: An international team of scientists led by researchers at Tel Aviv University has developed a method for detecting galaxies of stars that formed when the universe was in its infancy, during the first 180 million years of its existence.
The method is able to observe stars that were previously believed too old to find, said Prof. Rennan Barkana of TAU’s School of Physics and Astronomy.
The researchers’ method uses radio telescopes to seek out radio waves emitted by hydrogen atoms, which were abundant in the early days of the universe. Emitting waves measuring about eight inches (21 centimeters) long, the atoms reflect the radiation of the stars, making their emission detectable by radio telescopes, explained Prof. Barkana. This development opens the way to learning more about the universe’s oldest galaxies.
According to Prof. Barkana, these waves show a specific pattern in the sky, a clear signature of the early galaxies, which were one-millionth the size of galaxies today. Differences in the motion of dark matter and gas from the early period of the universe, which affect the formation of stars, produce a specific fluctuation pattern that makes it much easier to distinguish these early waves from bright local radio emissions.
The intensity of waves from this early era depends on the temperature of the gas, allowing researchers to begin to piece together a rough map of the galaxies in an area of the sky. If the gas is very hot, it means that there are many stars there; if cooler, there are fewer stars, said Prof. Barkana.
These initial steps into the mysterious origins of the universe will allow radio astronomers to reconstruct for the first time what the early universe looked like, specifically in terms of the distribution of stars and galaxies across the sky, he believes.
This field of astronomical research, now being called “21-centimeter cosmology,” is just getting underway. Five different international collaborations are building radio telescopes to detect these types of emissions, currently focusing on the era around 500 million years after the Big Bang. Equipment can also be specifically designed for detecting signals from the earlier eras, said Prof. Barkana.
He hopes that this area of research will illuminate the enigmatic period between the birth of the universe and modern times, and allow for the opportunity to test predictions about the early days of the universe.
The study was published in the journal Nature.