Around 400,000 years after the Big Bang, the fledgling universe finally cooled enough to form atoms — mostly hydrogen. But these neutral, non-electrically charged hydrogen atoms shrouded the cosmos in a fog that made it opaque to ultraviolet (UV) light.
A chart showing the evolution of the universe, from the Big Bang to today. The first stars started to appear from the hydrogen fog a few hundred million years after the Big Bang. (Image credit: (NASA/Wikimedia Commons))
"We don't know exactly what objects caused reionization or how it evolved," Cody Carr, an astronomer who focuses on galaxy evolution at the University of Michigan and first author of a new study of the epoch, said in a statement. "We know that it took place, but we don't have complete answers to those questions."
But in the new study, published Oct. 15 in the journal Nature Astronomy, Carr and colleagues presented evidence that supernovas exerted the opposite effect, trapping the so-called Lyman continuum (LyC) photons of ionizing UV radiation that dispelled the celestial fog instead of scattering them.
Which way the winds blow
The researchers used the Hubble Space Telescope to observe an analogue of the ancient universe in the local cosmos: six star-forming, wind-launching galaxies around 3.5 billion light-years away.
The galaxies' spectra, or light-based fingerprints, revealed the origin, chemical composition, speed and direction of their stellar winds, which were whipped up by the radiation from their newly formed stars.
These nearby galaxies highlighted a counterintuitive two-phase process.
The second phase, which emerged around 3 million years after star formation, seemed to reverse this process. As O-type stars — the hottest, bluest and most massive stars in the cosmos — lived fast and died young, their expelled stellar guts added to the opaque galactic gas and dust, churning it and loading it with mass, which created a trap for LyC light.
The oldest galaxies in this study — and, therefore, the ones with the fastest supernova-generated galactic winds — allowed the least amount of ionizing radiation to escape their environs.
Future research could aim to obtain additional galactic samples and higher-resolution observations across other wavelengths.
Hence then, the article about astronomers may have been wrong about what ended the cosmic dark age was published today ( ) and is available on Live Science ( Middle East ) The editorial team at PressBee has edited and verified it, and it may have been modified, fully republished, or quoted. You can read and follow the updates of this news or article from its original source.
Read More Details
Finally We wish PressBee provided you with enough information of ( Astronomers may have been wrong about what ended the 'Cosmic Dark Age' )
Also on site :