Detailed examination of the cosmic microwave background suggests that the material from which it scattered had been re-ionized. What do we believe to be the source of this reionization?
A)The cosmic microwave background itself caused the reionization of hydrogen and helium.
B)Large, hot Population III stars emitted enough high-energy radiation during their lifetimes to cause reionization.
C)The intense background of neutrinos and antineutrinos released much earlier than the cosmic microwave background radiation had enough energy to cause reionization.
D)The explosions of giant Population III stars would cause a shower of high-speed particles that could result in reionization.

Question

Quizplus · Accepted Answer

Large, hot Population III stars emitted enough high-energy radiation during their lifetimes to cause reionization. As the first generation of stars formed in the universe, they were much larger and hotter than the stars we see today. These massive stars were capable of producing enough ultraviolet radiation to strip electrons from hydrogen and helium atoms, reionizing the neutral gas in the universe. This period of reionization likely occurred between about 200 million and 1 billion years after the Big Bang. The cosmic microwave background radiation itself did not cause reionization, as it was emitted much earlier in the universe's history. The background of neutrinos and antineutrinos was not energetic enough to cause reionization. The explosions of giant Population III stars are a possibility, but it is the high-energy radiation emitted by these stars that is the most likely cause of reionization.

Detailed Examination of the Cosmic Microwave Background Suggests That the Material