CSIRO telescope takes temperature of Universe

January 23rd, 2013 in Astronomy & Space / Astronomy
CSIRO's Australia Telescope Compact Array. Credit: David Smyth

CSIRO's Australia Telescope Compact Array. Credit: David Smyth


"This is the most ever made of how the Universe has cooled down during its 13.77 billion year history," said Dr Robert Braun, Chief Scientist at CSIRO Astronomy and Space Science.


How can we measure a temperature at such a great distance?

CSIRO telescope takes temperature of Universe
Radio waves from a distant quasar pass through another galaxy on their way to Earth. Changes in the radio waves indicate the temperature of the gas. Credit: Onsala Space Observatory

The astronomers studied gas in an unnamed galaxy 7.2 billion light-years away [a of 0.89].

The only thing keeping this gas warm is the —the glow left over from the Big Bang.


Radio waves from this quasar come through the gas of the foreground galaxy. As they do so, the absorb some of the energy of the radio waves. This leaves a distinctive "fingerprint" on the .

From this "fingerprint" the astronomers calculated the gas's temperature. They found it to be 5.08 Kelvin (-267.92 degrees Celsius): extremely cold, but still warmer than today's Universe, which is at 2.73 Kelvin (-270.27 degrees Celsius).

According to the , the temperature of the cosmic background radiation drops smoothly as the Universe expands. "That's just what we see in our measurements. The Universe of a few billion years ago was a few degrees warmer than it is now, exactly as the Big Bang Theory predicts," said research team leader Dr Sebastien Muller of Onsala Space Observatory at Chalmers University of Technology in Sweden.

More information: Muller, S. et al. A precise and accurate determination of the cosmic microwave background temperature at z=0.89. Astronomy & Astrophysics; arxiv.org/abs/1212.5456

Provided by CSIRO

"CSIRO telescope takes temperature of Universe." January 23rd, 2013. http://phys.org/news/2013-01-csiro-telescope-temperature-universe.html