According to a news release, an international team of astronomers, lead by researchers from the University of Cambridge, has just cast new light on the cosmic dawn of the universe.
The universe’s very early stage, known as the cosmic dawn, is when the first stars and galaxies created. The researchers used data from the SARAS3 radio telescope to analyze this period of the cosmos and determine the limits of mass and energy output for the first stars & galaxies.
In essence, the researchers were able to look back in time to a moment that was just 200 million years after the Big Bang and offer fresh information about the properties of galaxies at that time.
Peering far back into the cosmic dawn
Since they weren’t able to find what they were looking for, the scientists were actually able to set these boundaries. The scientists had gone out to study the 21-centimeter hydrogen line. Because the hydrogen line was missing, they were able to rule out some scenarios, such as galaxies that were inefficient at cosmic heating gas and useless at producing radio emissions.
“We were seeking for a signal of a certain amplitude,” noted Harry Bevins, the paper’s lead author and a Ph.D. student at Cambridge’s Cavendish Laboratory. “However, by not identifying that signal, we can limit its depth.” This, in turn, begins to tell us about the brightness of the first galaxies.”
Although our current technology doesn’t give us the ability to observe these early galaxies directly, the new findings reported in a study in the journal Nature Astronomy , crucial clues to the early evolution of the cosmos. They also serve as a guide for future projects that can look further into the past. The SKA project, for example, will use 2 next-generation telescopes by the end of the decade to take image of the early Universe , by looking further than ever.
Today, astronomers are using data from existing telescopes to try to detect the cosmological signal from the first stars to be re-illuminated by thick hydrogen clouds. Known as the 21-centimeter line, this radio signal is produced by hydrogen atoms in the early universe. The observations could allow scientists to better understand galaxies further back in time than can be observed by NASA’s James Webb Space Telescope.
Figuring out the early universe’s mysteries
The examination of the SARAS3 data by the Cambridge-led multinational team was the first time that radio measurements of the averaged 21-centimeter line provided insight into the properties of the early galaxies by allowing scientists to determine the limits of their physical properties.
“Our research demonstrated that the hydrogen signal can teach us about the population of earliest stars and galaxies,” said Dr. Anastasia Fialkov of Cambridge’s Institute of Astronomy, a co-lead author. “Our analysis constrains some of the key properties of the first light sources, including the masses of the first galaxies and the efficiency with which these galaxies can form stars. We also address the question of how efficiently these sources emit X-ray, radio & ultraviolet radiation“.
The scientists’ discoveries are a first step toward gradually unravelling the secrets of the early cosmos, which are currently buried in figurative and literal darkness. “This is an early step for us in what we hope will be a decade of discoveries about how the Universe transitioned from darkness and emptiness to the complex realm of stars, galaxies, & other celestial objects we can see from Earth today,” said Dr. Eloy de Lera Acedo, co-leader of the research at Cambridge’s Cavendish Laboratory.
