A relic cloud of gas over left-over from shortly after the big bang and subsequently isolated has been discovered in a distant galaxy by the W. M. Keck Observatory on Maunakea, Hawaii.

A relic cloud of gas left-over from the big bang and subsequently isolated has been discovered in a distant galaxy by the W. M. Keck Observatory on Maunakea, Hawaii

The observation made by the world’s most powerful optical telescope will reveal new information regarding the formation of galaxies in the early Universe. The results of the study will be published in the journal Monthly Notices of the Royal Astronomical Society.

Fred Robert, a PhD student who led the research with Professor Michael Murphy at the Swinburne University of Technology, explained why this cloud of dust is special: “Everywhere we look, the gas in the universe is polluted by waste heavy elements from exploding stars.

“But this particular cloud seems pristine, unpolluted by stars even 1.5 billion years after the Big Bang.”

Within the gas in the (blue) filaments connecting the (orange) galaxies lurk rare pockets of pristine gas — vestiges of the Big Bang that have somehow been orphaned from the explosive, polluting deaths of stars, seen here as circular shock waves around some orange points (Ting collaboration)

Galaxies evolve as a result of interactions with their gaseous environments which in turn, bare the imprints of the evolution and death of stars. This can be seen in the gradual increase in heavy elements created in stars and jettisoned by violent supernova explosions. Thus gas clouds are expected to steadily increase in heavier elements ( anything heavier than helium which astronomers confusingly refer to as ‘metals’).

Robert and his team used two of Keck Observatory’s instruments, the Echellette Spectrograph and Imager (ESI) and the High-Resolution Echelle Spectrometer (HIRES), to observe the spectrum of a quasar behind the gas cloud.

The twin telescopes of the Keck Observatory sit atop the summit of Mauna Kea, Hawaii (KECK)

The bright glow of the quasar is caused by material falling onto the surface of a supermassive black hole and allows astronomers to observe the spectral emissions of the hydrogen in the cloud.

Thus the researchers were able to determine the cloud’s unpolluted nature by observing the lack of heavy elements in it, a proportion of just 0.0001 in comparison with the Sun.

Robert says: “We targeted quasars where previous researchers had only seen shadows from hydrogen and not from heavy elements in lower-quality spectra."

“This allowed us to discover such a rare fossil quickly with the precious time on Keck Observatory’s twin telescopes.”

This is the third such ‘metal-free’ cloud to be discovered, two other ‘fossil clouds’ were discovered in 2011 by Professor Michele Fumagalli of Durham University, John O’Meara, formerly a professor at St. Michael’s College and now the new Chief Scientist at Keck Observatory, and Professor J. Xavier Prochaska of the University of California, Santa Cruz.

Commenting on the new discovery, O’Meara said: “The first two were serendipitous discoveries, and we thought they were the tip of the iceberg. But no one has discovered anything similar — they are clearly very rare and difficult to see. It’s fantastic to finally discover one systematically.”

The paper’s co-author Professor Michael Murphy indicates the potential for new understanding of the origin of galaxies presented by the study of the clouds: “It’s now possible to survey for these fossil relics of the Big Bang.”

“That will tell us exactly how rare they are and help us understand how some gas formed stars and galaxies in the early universe, and why some didn’t.”

Original work available at http://arxiv.org/abs/1812.05098.