Detecting Reionization Epoch Signals Is Possibel

Billions of years ago, when the entire Universe was only a fraction of its current age, things were not set up as clearly as they are now. There should have been more concentrations of matter, and therefore more new objects being born, but was not the case. Experts now try to grapple the mystery of this.

They know that, by and large, a universal phenomenon started developing after the Big Bang exploded everything into being, which prevented hydrogen gas from collapsing to form new stars, and all the class of structures and objects that derive from this.

In other words, the Cosmos itself has a dark age of sorts, in which star formation was minimal, and during which very few things worthy of mention happened. Things changed about 1 billion years after the Big Bang, when the reionization epoch concluded.

What astrophysicists are currently trying to understand is the time in universal history that took place before the first stars coalesced, and began emitting light. Most evidence of this time are buried so deep in the Universe, and are so faint, that they are tremendously difficult to study.

Before the reionization epoch kick-started stellar formation, the Universe was an uniform hydrogen gas mass, that simply laid there and expanded. This happened around 200 hundred million years after the Big Bang.

Using ancient radio waves (ARW) as a starting point, researchers now want to refine their understanding of the universal dark age, and to determine when exactly it reigned supreme with increased accuracy.

“We call that the dark ages because there wasn't really any light being generated,” explains the leader of the new investigation Arizona State University(ASU) astronomer Judd Bowman.

The uniform hydrogen spreads were broken apart when slight ripples that developed within began clumping together the gas around gravitationally-denser areas.

When these locations accumulated enough mass, they collapsed onto themselves, triggering nuclear fusion as they did so, and forming new stars. Precisely how and when this happened is still unknown.

The period that led to the generation of the Universe's first light is called the reionization epoch because the radiations emitted by the earliest stars were able to strip electrons of the hydrogen atoms in their surrounding, creating hydrogen ions with a positive charge.

“Nobody really knows when the first stars formed. That's one of the questions we're trying to get at,” Bowmann explains, quoted by Space.

In a paper published in the December 9 issue of the esteemed journal Nature, experts explain how they used a newly-developed instrument to look for radio signals emanating from hydrogen gas located between the earliest stars and galaxies.

The research group, which included Massachusetts Institute of Technology (MIT) expert Alan Rogers, says that seeing the stars themselves is nearly impossible.

Using a custom-built a radio antenna called EDGES, the group set up shop at the Murchison Radio-astronomy Observatory in Western Australia, their base of studies.

They then began looking for how ARW emanating from the oldest hydrogen gas in the Universe changed over time, under the influence of emerging stars and galaxies, which continuously ionized it.

This neutral hydrogen signal should disappear entirely once the last atom in the Universe has been ionized, the theory goes.

“Our experiment was designed to constrain whether or not that step was very fast. We didn't detect any change, which means it took longer than about 3 to 12 million years” for reionization to the initiated, the ASU expert says.

“Our result has not tested the mainstream theories yet. We're getting our toe in the door,” Bowman adds, saying that the most important achievement was that the team demonstrated the new observations technique.