Saturday , October 23 2021

Eureka! Astronomers Find a Big Bang Fossil | Space


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Simulation of galaxies and gas in the universe. Inside the gas in the (blue) filaments that connect the galaxies (orange) hide rare pockets of gas – traces of the Big Bang that somehow became orphans of the explosive and polluting deaths of stars, seen here as circular shockwaves around some oranges. points. Image via TNG COLLABORATION.

Astronomers using the powerful twin optical telescopes of the W.M. Keck Observatory in Maunakea, Hawaii, used the light of a quasar to uncover a gas cloud relic in the distant universe. They call this the "fossil" of the time of our universe. How do they know it's a young cloud? The cloud is made mostly of the elements born in the Big Bang, hydrogen and helium. Lacking the heavier elements that are born within the stars and are released into the universe through supernova explosions. Astronomers Fred Robert and Michael Murphy of Swinburne University of Technology have made the discovery. Robert commented in a statement:

Everywhere we look, the gas in the universe is polluted by the waste of heavy elements of exploding stars. But this particular cloud looks pure, unpolluted by stars not even 1.5 billion years after the Big Bang.

If it has any heavy element, it should be less than 1 / 10,000 of the proportion we see in our sun. This is extremely low; The most compelling explanation is that it is a true relic of the Big Bang.

The results of Robert and Murphy were accepted for publication in the peer-reviewed journal Royal Astronomical Society Monthly News (preprint 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 spectra of a quasar behind the gas cloud. The quasar – PSS1723 + 2243 – emits a bright glow of material falling into a supermassive black hole, providing a source of light against which astronomers said:

… The spectral shadows of hydrogen in the gas cloud can be seen.

Robert added:

We targeted quasars where previous researchers had only seen shadows of hydrogen and not heavy elements in low-quality spectra. This allowed us to quickly discover a fossil so rare with precious time in the two telescopes of the Keck Observatory.

Only two other Big Bang fossils are known. These two clouds were discovered in 2011 by Michele Fumagalli of the University of Durham, John O & # 39; Meara, recently named the new chief scientist of the Keck Observatory, and J. Xavier Prochaska, of the University of California, Santa Cruz. Both Fumagalli and O'Meara are co-authors of the new research. O & # 39; Meara said:

The first two were discovered right, and we thought they were the tip of the iceberg. But no one has discovered anything like it – they are clearly very rare and hard to see. It's fantastic to finally find one systematically.

Murphy added:

Now you can research these fossil relics of the Big Bang. This will tell us just how rare they are and will help us understand how some gases formed stars and galaxies at the beginning of the universe, and why some did not.

Bottom line: Astronomers used the light of a distant quasar to discover a cloud made mostly of elements released in the Big Bang, without the heavier elements made inside stars. They call this cloud the "fossil" of the Big Bang.

Source: Exploring the origins of a new seemingly metalless gas cloud at z = 4.4

Through the W. Keck Observatory

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