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Lethal Radiation from Nearby Supernovae Helps Explain the Small Cosmological Constant
Tomonori Totani1,2, Hidetoshi Omiya1, Takahiro Sudoh1
11 Department of Astronomy, School of Science, The University of Tokyo , Bunkyo-ku, Tokyo, Japan .
Abstract:
The observed value Λobs 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 ≫ Λobs. However, the contemporary galaxy formation theory predicts that stars form even with a high value of Λ/Λobs ∼ 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. The life survival probability decreases in a large Λ universe because of higher stellar density. Using a reasonable rate of lethal supernovae, we find that the mean expectation value of Λ can be close to Λobs; hence this effect may be essential to understand the small but nonzero value of Λ. It is predicted that we are located on the edge of habitable regions about stellar density in the Galaxy, which may be tested by future exoplanet studies.
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