Snapshot of the Oldest Light in the Universe –“Reveals Clues to Its Origin”





Astrophysicists have developed a new method for calculating the effect of Rayleigh scattering on photons, potentially allowing researchers to better understand the formation of the Universe. The CMB is the oldest light in the universe, which originated when electrons combined with protons to form the first atoms. These primordial atoms were also the first to Rayleigh scatter light.

UBC theoretical cosmology graduate student Elham Alipour, UBC physicist Kris Sigurdson and Ohio State University astrophysicist Christopher Hirata probed the effect of Rayleigh scattering — the process that makes the sky appear blue when the Sun's photons are scattered by molecules in the atmosphere — on the cosmic microwave background (CMB).

"Detecting the Rayleigh signal is challenging because the frequency range where Rayleigh scattering has the biggest effect is contaminated by 'noise' and foregrounds, such as galactic dust," lead author Elham Alipour said.

By using different high-frequency channels to observe the CMB and combining this information, researchers may be able to better isolate the Rayleigh signal. This calculation of the effects of Rayleigh scattering on cosmology might help us better understand the formation of our Universe 13.6 billion years ago.




"The CMB sky is a snapshot of the early Universe, it is a single frame in the movie of the Universe, and we have shown that Rayleigh signal gives us another fainter snapshot of the same scene at a slightly different time," co-author Kris Sigurdson explained.

The image at the top of the page is from the Cosmic Background Explorer (COBE), also referred to as Explorer 66, a satellite dedicated to cosmology. Its goals were to investigate the cosmic microwave background radiation (CMB) of the universe and provide measurements that would help shape our understanding of the cosmos.

The findings have been highlighted in Physical Review D.

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