Astronomers probe ancient radio waves for clues about the universe's first light

Jan 13, 2011 By Morgan Bettex
Close up of the EDGES antenna. The four panels are made from aluminum sheet metal and supported by PVC legs. The white bag under the antenna encloses analog amplifiers and calibration circuits. Credit: Judd Bowman/Arizona State University

In the beginning, there was no light.

After the created the universe 13 billion years ago, the universe remained enshrouded in darkness. Based on observations of the radiation left over from the Big Bang, astronomers have theorized that several hundred million years after this event, caused and helium to condense into clouds. The energy from this activity eventually ignited those clouds, setting in motion a chain of events that led to the birth of the first stars. Although the transition between the so-called cosmic dark ages and the birth of stars and galaxies may explain the origin and evolution of many celestial objects, astronomers know very little about this period.

Recently, two astronomers conducted an experiment to try to learn more about this transitional period, which is known as the Epoch of Reionization, or EOR. Because identifying any light from the earliest galaxies is nearly impossible, Alan Rogers, a research affiliate at MIT’s Haystack Observatory, and Judd Bowman, an assistant professor at Arizona State University, instead focused their efforts on detecting emitted by hydrogen that existed between the first galaxies. Some of these radio waves are just reaching us today, and have theorized that certain characteristics of the waves could hold clues about the EOR.

As the first stars started to form during the EOR, their ultraviolet radiation (light) excited nearby hydrogen atoms, knocking off their electrons and giving them a positive electrical charge. This process, known as ionization, is important to cosmologists because it marks a pivotal moment in the transition between the early universe, which contained only hydrogen and gas, and today’s universe, which is filled with diverse galaxies, planets and black holes. Figuring out exactly when — and for how long — this ionization occurred is an important first step for confirming or modifying current models of the evolution of the universe.

To understand more about this period, the researchers focused their study on the frequency of emitted by non-ionized, or neutral, hydrogen. Specifically, they looked to see how the signal changed over time, which would indicate how long it might have taken for the non-ionized hydrogen to become ionized as a result of the birth of stars and galaxies. As the researchers reported in a paper published last month in Nature, it took at least 5 million years for the non-ionized hydrogen to become ionized. It is a good bet, then, that the birth of the first stars and galaxies took the same amount of time or more to develop into the stars and galaxies we recognize today.

A new frontier

The finding isn’t surprising to Harvard astronomer Avi Loeb, who says that many models predict that the EOR lasted for several hundred million years. Even so, the study is significant because it provides the first observational results about the EOR — a research area that Loeb calls the “major frontier” in astronomy over the next decade. By showing that radio observations can probe ancient radio waves, Rogers and Bowman “have basically opened the window for using this simple technique” in parallel with more sophisticated instruments, he says. To refine their estimate, Loeb suggests that the researchers improve the calibration of their antenna in order to remove any interference produced by the instrument itself.

Rogers and Bowman hope to deploy a system with improved calibration later this month. They are also involved in developing a large radio telescope that will attempt to make much more sophisticated measurements from the EOR. Known as the Murchison Widefield Array, the telescope consists of 512 antenna “tiles” that will try to discover low-frequency radio phenomena that may reveal details about how the galaxies formed and evolved.

Rogers and Bowman’s study was supported by the National Science Foundation and NASA.


This story is republished courtesy of MIT News (web.mit.edu/newsoffice/), a popular site that covers news about MIT research, innovation and teaching.

Explore further: Quest for extraterrestrial life not over, experts say

Related Stories

ASU astronomer opens new window into early universe

Dec 08, 2010

Thirteen billion years ago our universe was dark. There were neither stars nor galaxies; there was only hydrogen gas left over after the Big Bang. Eventually that mysterious time came to an end as the first ...

When Dwarfs Gave Way to Giants

May 17, 2006

The first galaxies were small - about 10,000 times less massive than the Milky Way. Billions of years ago, those mini-furnaces forged a multitude of hot, massive stars. In the process, they sowed the seeds ...

Astronomers peer back to 'dawn of galaxies'

Oct 01, 2004

Detailed analysis of Hubble Space Telescope images has allowed astronomers to determine a major event in the evolution of the universe. The astronomers used the Hubble Space Telescope’s Ultra Deep Field (UDF) to peer 95 percent of the ...

Arecibo Begins Search for Dark Galaxies

Feb 08, 2005

Fitted with a new compound eye, the Arecibo radio telescope in Puerto Rico last week began a multiyear effort to survey all the galaxies in a large swath of sky out to a distance of 800 million light years—a ...

Fossil Galaxy Reveals Clues to Early Universe

Jan 12, 2006

A tiny galaxy has given astronomers a glimpse of a time when the first bright objects in the universe formed, ending the dark ages that followed the birth of the universe.

Recommended for you

Quest for extraterrestrial life not over, experts say

Apr 18, 2014

The discovery of an Earth-sized planet in the "habitable" zone of a distant star, though exciting, is still a long way from pointing to the existence of extraterrestrial life, experts said Friday. ...

Continents may be a key feature of Super-Earths

Apr 18, 2014

Huge Earth-like planets that have both continents and oceans may be better at harboring extraterrestrial life than those that are water-only worlds. A new study gives hope for the possibility that many super-Earth ...

Exoplanets soon to gleam in the eye of NESSI

Apr 18, 2014

(Phys.org) —The New Mexico Exoplanet Spectroscopic Survey Instrument (NESSI) will soon get its first "taste" of exoplanets, helping astronomers decipher their chemical composition. Exoplanets are planets ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

hemitite
1.3 / 5 (3) Jan 13, 2011
The "Big Bang" didn't create the universe, the BB was the universe.
71STARS
1 / 5 (5) Jan 14, 2011
You are right, hermitite. The Big Bang did not create the Universe. The atom-seed-egg may not have exploded at all. It may have just grown to be a dominant Sun, which is the most prevalent entity in the Universe.
elsahli
not rated yet Jan 19, 2011
Ignition due to ionization produced photons that were encountered by non-baryonic(dark matter) resulting in multiverse..EOR =non-baryonic matter constitute 100%...the following events after ionization process :
The dark matter is not similar to the known matter in that it is sub-atomic where the incident photons behaviour differ widely from it,s behaviour with the known matter or the baryonic in that the incident light or photons cannot find suitable position to stay within so they are kicked out causing light flashes ...the light flashes in other words mean the beginning of multiverse building

More news stories

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Cosmologists weigh cosmic filaments and voids

(Phys.org) —Cosmologists have established that much of the stuff of the universe is made of dark matter, a mysterious, invisible substance that can't be directly detected but which exerts a gravitational ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.