Astronomers have discovered a relic cloud of gas in the distant universe, left behind by the big bang itself. The discovery of this rare “fossil” was possible because of the highly powerful and precise telescopes at the W.M. Keck Observatory in Maunakea, Hawaii. It offers new insight into how the first galaxies were formed.
The research that led to this finding was led by PhD student Fred Robert and Professor Michael Murphy at Swinburne University of Technology. They utilized 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.
This quasar emits a bright glow created by material falling into a supermassive black hole, providing a light source against which spectral shadows of hydrogen in the gas cloud could be observed.
“We targeted quasars where previous researchers had only seen shadows from hydrogen and not from heavy elements in lower-quality spectra,” says Robert. “This allowed us to discover such a rare fossil quickly with the precious time on Keck Observatory’s twin telescopes.”
This is the third fossil cloud to be discovered. The other two were found 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; both Fumagalli and O’Meara are co-authors of this new research on the third fossil cloud.
“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,” says O’Meara.
“It’s now possible to survey for these fossil relics of the Big Bang,” says Murphy. “That will tell us exactly how rare they are and help us understand how some gases formed stars and galaxies in the early universe, and why some didn’t.”