Cosmic explosions, life in the Universe and the Cosmological Constant

TL;DR

This paper investigates how the value of the cosmological constant affects the likelihood of life surviving gamma-ray bursts in the universe, suggesting our universe's parameters are optimally balanced for life.

Contribution

It combines cosmological simulations and gamma-ray burst data to identify the universe's parameters that maximize life survival chances against cosmic explosions.

Findings

Lambda-dominated universes favor life survival against GRBs.

Our universe's parameters minimize exposure to cosmic explosions while supporting life.

The likelihood of life survival depends on the cosmological constant and universe age.

Abstract

Galactic Gamma-Ray Bursts (GRBs) are copious sources of gamma-rays that can pose a threat to complex life. Using recent determinations of their rate and the probability of GRBs causing massive extinction, we explore what type of universes are most likely to harbour advanced forms of life. For this purpose we use cosmological N-body simulations to determine at what time and for what value of the cosmological constant ($\Lambda$) the chances of life being unaffected by cosmic explosions are maximised. We find that $\Lambda-$dominated universes favour the survival of life against GRBs. Within a $\Lambda$CDM cosmology, the parameters that govern the likelihood of life survival to GRBs are dictated by the value of $\Lambda$ and the age of the Universe. We find that we seem to live in a favorable point in this parameter phase space which minimises the exposure to cosmic explosions, yet maximises the number of main sequence (hydrogen-burning) stars around which advanced life forms can exist.