New Delhi, May 18: Astronomers from India and Europe have detected carbon monoxide in a distant galaxy and used it to measure the heat left behind by the Big Bang, illustrating a new way to probe the early history of the cosmos.

Using a telescope on the mountains of Chile, Indian astronomer Raghunathan Srianand and his colleagues have spotted the first ever signatures of carbon monoxide molecules from a galaxy so far away that its light takes 11 billion years to reach Earth.

The researchers have used the signatures to measure with the highest precision yet the residual warmth of the Big Bang three billion years after that fireball gave birth to the universe about 14 billion years ago.

“We use the carbon monoxide as a molecular thermometer that also allows us to look back in time because it is located so far away,” said Srianand, a scientist at the Inter University Centre for Astronomy and Astrophysics, Pune.

The current temperature of the leftover heat that scientists call the cosmic microwave background radiation is about 2.7K (or about 270.45° C below zero).

“The carbon monoxide tells us that 11 billion years ago, the temperature was 9.15K, which is very close to the 9.3K predicted by theory. What we see matches nicely with what is predicted,” Srianand told The Telegraph.

Astronomers have been looking for carbon monoxide, among other molecules such as hydrogen, in the interstellar gas of distant galaxies for nearly three decades. Researchers hope to study the chemistry of the interstellar gas in distant galaxies to understand the formation of stars in the early universe.

“The state of this distant galaxy itself was a bit of a surprise,” Srianand said. “It had evolved to something similar to our own Milky Way. So what our galaxy has taken so long to do, that galaxy achieved in just three billion years.”

The astronomers detected the carbon monoxide signatures in the light of a quasar, an extremely bright source of light and radiation, located even farther than the galaxy.

As light from the quasar passed through the galaxy, it acquired a spectral fingerprint unique to carbon monoxide. It also picked up signatures of two kinds of hydrogen molecules.

“This is the first time these three molecules have been observed in absorption in front of a quasar,” said Cedric Ledoux, a team member at the European Southern Observatory.