Rare relic is one of only three fossil clouds known in the universe
Source: W. M. Keck Observatory
A relic cloud of gas, orphaned after the Big Bang, has been discovered in the distant universe by astronomers using the world's most powerful optical telescope, the W. M. Keck Observatory on Maunakea, Hawaii.
The discovery of such a rare fossil, carried out by researchers at Swinburne University of Technology, offers new information about how the first galaxies in the universe formed. Everywhere we look, the gas in the universe is polluted by waste heavy elements from exploding stars. This particular cloud seems pristine, unpolluted by stars even 1.5 billion years after the Big Bang.
The 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 quasar, which emits a bright glow of material falling into a supermassive black hole, provides a light source against which the spectral shadows of the hydrogen in the gas cloud can be seen. The only two other fossil clouds known were discovered in 2011.
The Echellette Spectrograph and Imager (ESI) is a medium-resolution visible-light spectrograph that records spectra from 0.39 to 1.1 microns in each exposure. The High-Resolution Echelle Spectrometer (HIRES) produces spectra of single objects at very high spectral resolution, yet covering a wide wavelength range. The W. M. Keck Observatory telescopes are the most scientifically productive on Earth.