Lethal Radiation from Nearby Supernovae Helps Explain the Small Cosmological Constant.

The observed value Λ of the cosmological constant Λ is extremely smaller than theoretical expectations, and the anthropic argument has been proposed as a solution to this problem because galaxies do not form when Λ ≫ Λ. However, the contemporary galaxy formation theory predicts that stars form even with a high value of Λ/Λ ∼ 50, which makes the anthropic argument less persuasive. Here we calculate the probability distribution of Λ using a model of cosmological galaxy formation, considering extinction of observers caused by radiation from nearby supernovae.