New experiment may reveal how first galaxies formed and evolved

December 9th, 2010 - 4:34 pm ICT by ANI  

London, Dec 9 (ANI): Astronomers at Massachusetts Institute of Technology and Arizona State University have developed a small-scale radio astronomy experiment designed to detect a never-before-seen signal from the early universe, a development that has the potential to revolutionize the understanding of how the first galaxies formed and evolved.

This phase of the universe’s history is called the Epoch of Reionization (EoR), and it is the time when the first stars ignited and their radiation transformed the nearby gas atoms into ions.

“Our goal is to detect a signal from the time of the Epoch of Reionization. We want to pin down when the first galaxies formed and then understand what types of stars existed in them and how they affected their environments,” said Arizona State University’s Judd Bowman.

He and Alan Rogers of MIT deployed a custom-built radio spectrometer called EDGES to the Murchison Radio-astronomy Observatory in Western Australia to measure the radio spectrum between 100 and 200 MHz.

It consists of an antenna, an amplifier, some calibration circuits, and a computer, all connected to a solar-powered energy source.

The experiment looks for the hydrogen gas that existed between the galaxies. Though an extremely difficult observation to make, it isn’t impossible.

“This gas would have emitted a radio line at a wavelength of 21 cm - stretched to about 2 meters by the time we see it today, which is about the size of a person,” explained Bowman.

“As galaxies formed, they would have ionized the primordial hydrogen around them and caused the radio line to disappear. Therefore, by constraining when the line was present or not present, we can learn indirectly about the first galaxies and how they evolved in the early universe.”

“We’re breaking down barriers to open an entirely new window into the early universe,” Bowman said.

According to him, the most likely physical picture for the EoR looked like a lot of bubbles that started percolating out from galaxies and then grew together - but that idea needs to be tested.

“Our goal, eventually, is to make radio maps of the sky showing how and when reionization occurred. Since we can’t make those maps yet, we are starting with these simple experiments to begin to constrain the basic properties of the gas and how long it took for galaxies to change it,” explained Bowman.

“This will improve our understanding of the large-scale evolution of the universe.”

The study appears in Nature. (ANI)

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