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What is the cosmic reionization?
Abstract: The universe goes through several phase transitions during its formative stages. Cosmic reionization is the last of them, where ultraviolet and X-ray radiation escape from the first generations of galaxies heating and ionizing their surroundings and subsequently the entire intergalactic medium.
What is reionization in the early universe?
Overview: The “Epoch of Reionization” is a period in the history of the universe that likely arose as a result of the arrival of the first stars and galaxies. As the universe cooled and expanded, electrons and protons were able to combine to form the first neutral atoms.
What is the period reionization?
The Epoch of Reionization (EoR) refers to the period in the history of the universe during which the predominantly neutral intergalactic medium was ionized by the emergence of the first luminous sources. These sources may have been stars, galaxies, quasars, or some combination of the above.
What does the word reionization mean?
(also reionisation) 1Physics. The action of ionizing something for a second or further time; an instance of this. 2Astronomy. The ionization of neutral hydrogen atoms formed during recombination in the early universe (108 to 109 years after the Big Bang).
What caused reionization?
In the fields of Big Bang theory and cosmology, reionization is the process that caused matter in the universe to reionize after the lapse of the “dark ages”. It is believed that the primordial helium also experienced the same phase of reionization changes, but at different points in the history of the universe.
How did universe became transparent?
A great amount of ultraviolet radiation (photons) was released, stripping electrons from surrounding neutral environments, a process known as “cosmic reionization.” Ionization made the Universe transparent to these photons, allowing the release of light from sources to travel mostly freely through the cosmos.
Why did reionization happen?
The Era of Recombination When the universe started cooling, the protons and neutrons began combining into ionized atoms of hydrogen and deuterium. Deuterium further fused into helium-4. These ionized atoms of hydrogen and helium attracted electrons turning them into neutral atoms.
What are ionized the universe?
The sparsely distributed hot gas that exists in the space between galaxies, the intergalactic medium, is ionized. The question is, how? Astronomers know that once the early universe expanded and cooled enough, hydrogen (its main constituent) recombined into neutral atoms.
When did the epoch of reionization start?
This occurred between 150 million and one billion years after the Big Bang (at a redshift 6 < z < 20).
Why the universe was opaque?
This situation persisted for about 375,000 years after the Big Bang, at which time the Universe had cooled enough for neutral hydrogen to exist. Then, any light produced by interactions among these hydrogen atoms was at a wavelength where it was quickly re-absorbed by other hydrogen atoms—the Universe was opaque.
Why can’t we see past the era of recombination?
We cannot actually observe the Universe before the epoch of recombination, since the ionised plasma that existed before this time was very efficient at scattering radiation.
What is reionization in the Big Bang?
In Big Bang cosmology, reionization is the process that reionized the matter in the universe after the “dark ages,” and is the second of two major phase transitions of gas in the universe.
What is reionization in cosmology?
In Big Bang cosmology, reionization is the process that reionized the matter in the universe after the “dark ages,” and is the second of two major phase transitions of gas in the universe. As the majority of baryonic matter is in the form of hydrogen, reionization usually refers to the reionization of hydrogen gas.
What is helium reionization?
As the majority of baryonic matter is in the form of hydrogen, reionization usually refers to the reionization of hydrogen gas. The primordial helium in the universe experienced the same phase changes, but at different points in the history of the universe, and is usually referred to as helium reionization.
What is the epoch of reionization of the universe?
This era, from the end of the dark ages to when the universe was around a billion years old, is known as “the epoch of reionization.” It refers to the point when most of the neutral hydrogen was reionized by the increasing radiation from the first massive stars.