Astronomers using the powerful twin optical telescopes of the W. M. Keck Observatory on Maunakea, Hawaii, have discovered a cloud of gas in the distant universe using the light of a quasar. They call it a "fossil" from the earliest days of our universe. How do you know it's a young cloud? The cloud consists mainly of the elements of the big bang, hydrogen and helium. It lacks the heavier elements that are born in stars and released into the universe through supernova explosions. The astronomers Fred Robert and Michael Murphy from Swinburne University of Technology made the discovery. Robert commented this in a statement:
Everywhere we look, the gas in the universe is polluted by heavy elements created by exploding stars. But this particular cloud seems to be untouched, even after 1.5 billion years after the big bang of stars not polluted.
If it contains heavy elements at all, it must be less than 1 / 10,000th of the proportion that we see in our sun. That's extremely low. The most convincing explanation is that it is a true relic of the Big Bang.
The results of Robert and Murphy were published in the Peer Review Journal . Monthly Announcements of the Royal Astronomical Society (form available here)).
These astronomers used two instruments from the Keck Observatory, 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, called PSS1723 + 2243, emits a bright glow of material that falls into a supermassive black hole and represents a source of light against which these astronomers speak:
… the spectral shadows of hydrogen in the gas cloud can be seen ,
We have targeted quasars in which earlier researchers had seen only shadows of hydrogen rather than heavy elements in lower quality spectra. This enabled us to quickly discover such a rare fossil in precious time on the twin telescopes of the Keck Observatory.
Only two other big bang fossils are known. These two clouds were discovered in 2011 by Michele Fumagalli of Durham University, John O'Meara, who was recently appointed as the new Chief Scientist at the Keck Observatory, and J. Xavier Prochaska of the University of California at Santa Cruz. Both Fumagalli and O & Meara are co-authors of the new research. O & Meara said:
The first two were coincidental discoveries, and we thought they were the tip of the iceberg. But no one has discovered something similar – they are clearly very rare and hard to see. It's fantastic to finally discover one thing systematically.
It is now possible to study these fossil relics of the Big Bang. This tells us exactly how rare they are and helps us understand how some gases formed stars and galaxies in the early Universe and why some did not.
Conclusion: Astronomers use the light of a distant quasar to discover a cloud. It consists mainly of elements released in the Big Bang, without the heavier elements made in stars. They call this cloud a "fossil" of the Big Bang.
Source: Exploring the origins of a new, seemingly metal-free gas cloud at z = 4.4
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