Astronomers Plan to Study the Earliest Moments of the Universe

Astronomers believe that for approximately 300,000 to just over a billion years after the Big Bang, there was nothing in the universe but clouds of gas that would someday coalesce to form galaxies, stars and planets. When the first celestial objects formed, radiation appeared in the universe for the first time.  Astronomers are trying to learn more about this time, and about the first sources of radiation in the universe.

Sometimes, a hydrogen atom in a gas cloud will emit a low energy radio signal. While the radio wave starts out being tiny, only 21 centimetres long, the expansion of the universe causes it to stretch to several metres by the time it reaches earth. This means that ordinary radio receivers can perceive it, and thus detect these primordial clouds.

The Low Frequency Array (LOFAR), which was developed by the Netherlands Institute for Radio Astronomy (ASTRON), has been testing the ability to detect these radio waves since 2006. ASTRON is now in the process of constructing satellite stations across Europe.  The first was completed in November 2008 at the Max Planck Institute for Radio Astronomy in Effelsberg, Germany.

Astronomers hope that they will find not only the gas that filled the universe in primordial times, but also see the “bubbles” that were blown in the universe by the radiation that was released from the first celestial objects. These objects would have filled their corner of space with highly energetic radiation that would have ripped apart hydrogen atoms in a process called re-ionisation, and thus prevented them from giving off radio waves.  LOFAR should be able to detect how the radio emissions have dwindled as radiation began to be given off.

Meanwhile, Planck, a new European Space Agency (ESA) telescope launching this year, will detect the microwave radiation that was released by the Big Bang. About one in every 10 million microwaves has bounced off a free electron on its way to the Earth. These electrons were freed when the universe’s hydrogen atoms were ripped apart by the radiation from the first celestial objects. Planck will be sensitive enough to supply details about how quickly the atoms were ripped apart, which will help provide a better understanding about the first celestial objects, for example, whether they were stars or black holes.

Herschel, another ESA telescope set to launch at the same time as Planck, will have a primary mirror of 3.5 metres, over one and a half times larger than Hubble’s. Astronomers hope that Herschel will detect the first star clusters to form in the universe.

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