Why The Universe Is Transparent

Alternatively, with direct measurements of the ionizing escape fraction, their model may be used to constrain the intrinsic production rate of ionizing photons at around two billion years after the Big Bang.

These practical applications of the model will be central to the interpretation of escaping radiation during the cosmic “dark ages,” a topic that is bound to flourish with the coming of 30-meter telescopes, which will allow for research unfeasible today, and the James Webb Space Telescope, NASA’s next orbiting observatory and the successor to the Hubble Space Telescope.

The research ties back to some 400,000 years after the Big Bang, when the universe entered the cosmic “dark ages,” where galaxies and stars had yet to form amongst the dark matter, hydrogen and helium.

A few hundred million years later, the universe entered the “Epoch of Reionization,” where the gravitational effects of dark matter helped hydrogen and helium coalesce into stars and galaxies. A great amount of ultraviolet radiation (photons) was released, stripping electrons from surrounding neutral environments, a process known as “cosmic reionization.”

Reionization, which marks the point at which the hydrogen in the Universe became ionized, has become a major area of current research in astrophysics. Ionization made the Universe transparent to these photons, allowing the release of light from sources to travel mostly freely through the cosmos.

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